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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
![Linus Torvalds](/assets/img/avatar_default.png)
- Mark arch_cpu_idle_dead() __noreturn, make all architectures & drivers that did this inconsistently follow this new, common convention, and fix all the fallout that objtool can now detect statically. - Fix/improve the ORC unwinder becoming unreliable due to UNWIND_HINT_EMPTY ambiguity, split it into UNWIND_HINT_END_OF_STACK and UNWIND_HINT_UNDEFINED to resolve it. - Fix noinstr violations in the KCSAN code and the lkdtm/stackleak code. - Generate ORC data for __pfx code - Add more __noreturn annotations to various kernel startup/shutdown/panic functions. - Misc improvements & fixes. Signed-off-by: Ingo Molnar <mingo@kernel.org> -----BEGIN PGP SIGNATURE----- iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmRK1x0RHG1pbmdvQGtl cm5lbC5vcmcACgkQEnMQ0APhK1ghxQ/+IkCynMYtdF5OG9YwbcGJqsPSfOPMEcEM pUSFYg+gGPBDT/fJfcVSqvUtdnWbLC2kXt9yiswXz3X3J2nmNkBk5YKQftsNDcul TmKeqIIAK51XTncpegKH0EGnOX63oZ9Vxa8CTPdDlb+YF23Km2FoudGRI9F5qbUd LoraXqGYeiaeySkGyWmZVl6Uc8dIxnMkTN3H/oI9aB6TOrsi059hAtFcSaFfyemP c4LqXXCH7k2baiQt+qaLZ8cuZVG/+K5r2N2cmjO5kmJc6ynIaFnfMe4XxZLjp5LT /PulYI15bXkvSARKx5CRh/CDHMOx5Blw+ASO0RhWbdy0WH4ZhhcaVF5AeIpPW86a 1LBcz97rMp72WmvKgrJeVO1r9+ll4SI6/YKGJRsxsCMdP3hgFpqntXyVjTFNdTM1 0gH6H5v55x06vJHvhtTk8SR3PfMTEM2fRU5jXEOrGowoGifx+wNUwORiwj6LE3KQ SKUdT19RNzoW3VkFxhgk65ThK1S7YsJUKRoac3YdhttpqqqtFV//erenrZoR4k/p vzvKy68EQ7RCNyD5wNWNFe0YjeJl5G8gQ8bUm4Xmab7djjgz+pn4WpQB8yYKJLAo x9dqQ+6eUbw3Hcgk6qQ9E+r/svbulnAL0AeALAWK/91DwnZ2mCzKroFkLN7napKi fRho4CqzrtM= =NwEV -----END PGP SIGNATURE----- Merge tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool updates from Ingo Molnar: - Mark arch_cpu_idle_dead() __noreturn, make all architectures & drivers that did this inconsistently follow this new, common convention, and fix all the fallout that objtool can now detect statically - Fix/improve the ORC unwinder becoming unreliable due to UNWIND_HINT_EMPTY ambiguity, split it into UNWIND_HINT_END_OF_STACK and UNWIND_HINT_UNDEFINED to resolve it - Fix noinstr violations in the KCSAN code and the lkdtm/stackleak code - Generate ORC data for __pfx code - Add more __noreturn annotations to various kernel startup/shutdown and panic functions - Misc improvements & fixes * tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits) x86/hyperv: Mark hv_ghcb_terminate() as noreturn scsi: message: fusion: Mark mpt_halt_firmware() __noreturn x86/cpu: Mark {hlt,resume}_play_dead() __noreturn btrfs: Mark btrfs_assertfail() __noreturn objtool: Include weak functions in global_noreturns check cpu: Mark nmi_panic_self_stop() __noreturn cpu: Mark panic_smp_self_stop() __noreturn arm64/cpu: Mark cpu_park_loop() and friends __noreturn x86/head: Mark *_start_kernel() __noreturn init: Mark start_kernel() __noreturn init: Mark [arch_call_]rest_init() __noreturn objtool: Generate ORC data for __pfx code x86/linkage: Fix padding for typed functions objtool: Separate prefix code from stack validation code objtool: Remove superfluous dead_end_function() check objtool: Add symbol iteration helpers objtool: Add WARN_INSN() scripts/objdump-func: Support multiple functions context_tracking: Fix KCSAN noinstr violation objtool: Add stackleak instrumentation to uaccess safe list ...
4691 lines
107 KiB
C
4691 lines
107 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
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*/
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#include <string.h>
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#include <stdlib.h>
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#include <inttypes.h>
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#include <sys/mman.h>
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#include <arch/elf.h>
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#include <objtool/builtin.h>
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#include <objtool/cfi.h>
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#include <objtool/arch.h>
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#include <objtool/check.h>
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#include <objtool/special.h>
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#include <objtool/warn.h>
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#include <objtool/endianness.h>
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#include <linux/objtool_types.h>
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#include <linux/hashtable.h>
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#include <linux/kernel.h>
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#include <linux/static_call_types.h>
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struct alternative {
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struct alternative *next;
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struct instruction *insn;
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bool skip_orig;
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};
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static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;
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static struct cfi_init_state initial_func_cfi;
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static struct cfi_state init_cfi;
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static struct cfi_state func_cfi;
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struct instruction *find_insn(struct objtool_file *file,
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struct section *sec, unsigned long offset)
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{
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struct instruction *insn;
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hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
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if (insn->sec == sec && insn->offset == offset)
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return insn;
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}
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return NULL;
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}
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struct instruction *next_insn_same_sec(struct objtool_file *file,
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struct instruction *insn)
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{
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if (insn->idx == INSN_CHUNK_MAX)
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return find_insn(file, insn->sec, insn->offset + insn->len);
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insn++;
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if (!insn->len)
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return NULL;
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return insn;
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}
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static struct instruction *next_insn_same_func(struct objtool_file *file,
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struct instruction *insn)
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{
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struct instruction *next = next_insn_same_sec(file, insn);
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struct symbol *func = insn_func(insn);
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if (!func)
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return NULL;
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if (next && insn_func(next) == func)
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return next;
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/* Check if we're already in the subfunction: */
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if (func == func->cfunc)
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return NULL;
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/* Move to the subfunction: */
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return find_insn(file, func->cfunc->sec, func->cfunc->offset);
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}
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static struct instruction *prev_insn_same_sec(struct objtool_file *file,
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struct instruction *insn)
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{
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if (insn->idx == 0) {
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if (insn->prev_len)
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return find_insn(file, insn->sec, insn->offset - insn->prev_len);
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return NULL;
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}
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return insn - 1;
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}
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static struct instruction *prev_insn_same_sym(struct objtool_file *file,
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struct instruction *insn)
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{
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struct instruction *prev = prev_insn_same_sec(file, insn);
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if (prev && insn_func(prev) == insn_func(insn))
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return prev;
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return NULL;
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}
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#define for_each_insn(file, insn) \
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for (struct section *__sec, *__fake = (struct section *)1; \
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__fake; __fake = NULL) \
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for_each_sec(file, __sec) \
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sec_for_each_insn(file, __sec, insn)
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#define func_for_each_insn(file, func, insn) \
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for (insn = find_insn(file, func->sec, func->offset); \
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insn; \
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insn = next_insn_same_func(file, insn))
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#define sym_for_each_insn(file, sym, insn) \
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for (insn = find_insn(file, sym->sec, sym->offset); \
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insn && insn->offset < sym->offset + sym->len; \
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insn = next_insn_same_sec(file, insn))
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#define sym_for_each_insn_continue_reverse(file, sym, insn) \
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for (insn = prev_insn_same_sec(file, insn); \
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insn && insn->offset >= sym->offset; \
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insn = prev_insn_same_sec(file, insn))
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#define sec_for_each_insn_from(file, insn) \
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for (; insn; insn = next_insn_same_sec(file, insn))
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#define sec_for_each_insn_continue(file, insn) \
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for (insn = next_insn_same_sec(file, insn); insn; \
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insn = next_insn_same_sec(file, insn))
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static inline struct symbol *insn_call_dest(struct instruction *insn)
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{
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if (insn->type == INSN_JUMP_DYNAMIC ||
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insn->type == INSN_CALL_DYNAMIC)
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return NULL;
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return insn->_call_dest;
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}
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static inline struct reloc *insn_jump_table(struct instruction *insn)
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{
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if (insn->type == INSN_JUMP_DYNAMIC ||
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insn->type == INSN_CALL_DYNAMIC)
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return insn->_jump_table;
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return NULL;
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}
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static bool is_jump_table_jump(struct instruction *insn)
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{
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struct alt_group *alt_group = insn->alt_group;
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if (insn_jump_table(insn))
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return true;
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/* Retpoline alternative for a jump table? */
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return alt_group && alt_group->orig_group &&
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insn_jump_table(alt_group->orig_group->first_insn);
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}
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static bool is_sibling_call(struct instruction *insn)
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{
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/*
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* Assume only STT_FUNC calls have jump-tables.
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*/
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if (insn_func(insn)) {
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/* An indirect jump is either a sibling call or a jump to a table. */
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if (insn->type == INSN_JUMP_DYNAMIC)
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return !is_jump_table_jump(insn);
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}
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/* add_jump_destinations() sets insn_call_dest(insn) for sibling calls. */
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return (is_static_jump(insn) && insn_call_dest(insn));
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}
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/*
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* This checks to see if the given function is a "noreturn" function.
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*
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* For global functions which are outside the scope of this object file, we
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* have to keep a manual list of them.
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*
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* For local functions, we have to detect them manually by simply looking for
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* the lack of a return instruction.
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*/
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static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
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int recursion)
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{
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int i;
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struct instruction *insn;
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bool empty = true;
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/*
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* Unfortunately these have to be hard coded because the noreturn
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* attribute isn't provided in ELF data. Keep 'em sorted.
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*/
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static const char * const global_noreturns[] = {
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"__invalid_creds",
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"__module_put_and_kthread_exit",
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"__reiserfs_panic",
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"__stack_chk_fail",
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"__ubsan_handle_builtin_unreachable",
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"arch_call_rest_init",
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"arch_cpu_idle_dead",
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"btrfs_assertfail",
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"cpu_bringup_and_idle",
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"cpu_startup_entry",
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"do_exit",
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"do_group_exit",
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"do_task_dead",
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"ex_handler_msr_mce",
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"fortify_panic",
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"hlt_play_dead",
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"hv_ghcb_terminate",
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"kthread_complete_and_exit",
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"kthread_exit",
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"kunit_try_catch_throw",
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"lbug_with_loc",
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"machine_real_restart",
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"make_task_dead",
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"mpt_halt_firmware",
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"nmi_panic_self_stop",
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"panic",
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"panic_smp_self_stop",
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"rest_init",
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"resume_play_dead",
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"rewind_stack_and_make_dead",
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"sev_es_terminate",
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"snp_abort",
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"start_kernel",
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"stop_this_cpu",
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"usercopy_abort",
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"x86_64_start_kernel",
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"x86_64_start_reservations",
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"xen_cpu_bringup_again",
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"xen_start_kernel",
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};
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if (!func)
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return false;
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if (func->bind == STB_GLOBAL || func->bind == STB_WEAK)
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for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
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if (!strcmp(func->name, global_noreturns[i]))
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return true;
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if (func->bind == STB_WEAK)
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return false;
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if (!func->len)
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return false;
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insn = find_insn(file, func->sec, func->offset);
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if (!insn || !insn_func(insn))
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return false;
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func_for_each_insn(file, func, insn) {
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empty = false;
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if (insn->type == INSN_RETURN)
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return false;
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}
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if (empty)
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return false;
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/*
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* A function can have a sibling call instead of a return. In that
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* case, the function's dead-end status depends on whether the target
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* of the sibling call returns.
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*/
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func_for_each_insn(file, func, insn) {
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if (is_sibling_call(insn)) {
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struct instruction *dest = insn->jump_dest;
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if (!dest)
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/* sibling call to another file */
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return false;
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/* local sibling call */
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if (recursion == 5) {
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/*
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* Infinite recursion: two functions have
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* sibling calls to each other. This is a very
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* rare case. It means they aren't dead ends.
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*/
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return false;
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}
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return __dead_end_function(file, insn_func(dest), recursion+1);
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}
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}
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return true;
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}
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static bool dead_end_function(struct objtool_file *file, struct symbol *func)
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{
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return __dead_end_function(file, func, 0);
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}
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static void init_cfi_state(struct cfi_state *cfi)
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{
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int i;
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for (i = 0; i < CFI_NUM_REGS; i++) {
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cfi->regs[i].base = CFI_UNDEFINED;
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cfi->vals[i].base = CFI_UNDEFINED;
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}
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cfi->cfa.base = CFI_UNDEFINED;
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cfi->drap_reg = CFI_UNDEFINED;
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cfi->drap_offset = -1;
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}
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static void init_insn_state(struct objtool_file *file, struct insn_state *state,
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struct section *sec)
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{
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memset(state, 0, sizeof(*state));
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init_cfi_state(&state->cfi);
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/*
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* We need the full vmlinux for noinstr validation, otherwise we can
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* not correctly determine insn_call_dest(insn)->sec (external symbols
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* do not have a section).
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*/
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if (opts.link && opts.noinstr && sec)
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state->noinstr = sec->noinstr;
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}
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static struct cfi_state *cfi_alloc(void)
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{
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struct cfi_state *cfi = calloc(sizeof(struct cfi_state), 1);
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if (!cfi) {
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WARN("calloc failed");
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exit(1);
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}
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nr_cfi++;
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return cfi;
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}
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static int cfi_bits;
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static struct hlist_head *cfi_hash;
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static inline bool cficmp(struct cfi_state *cfi1, struct cfi_state *cfi2)
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{
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return memcmp((void *)cfi1 + sizeof(cfi1->hash),
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(void *)cfi2 + sizeof(cfi2->hash),
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sizeof(struct cfi_state) - sizeof(struct hlist_node));
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}
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static inline u32 cfi_key(struct cfi_state *cfi)
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{
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return jhash((void *)cfi + sizeof(cfi->hash),
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sizeof(*cfi) - sizeof(cfi->hash), 0);
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}
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static struct cfi_state *cfi_hash_find_or_add(struct cfi_state *cfi)
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{
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struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
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struct cfi_state *obj;
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hlist_for_each_entry(obj, head, hash) {
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if (!cficmp(cfi, obj)) {
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nr_cfi_cache++;
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return obj;
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}
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}
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obj = cfi_alloc();
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*obj = *cfi;
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hlist_add_head(&obj->hash, head);
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return obj;
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}
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static void cfi_hash_add(struct cfi_state *cfi)
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{
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struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
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hlist_add_head(&cfi->hash, head);
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}
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static void *cfi_hash_alloc(unsigned long size)
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{
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cfi_bits = max(10, ilog2(size));
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cfi_hash = mmap(NULL, sizeof(struct hlist_head) << cfi_bits,
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PROT_READ|PROT_WRITE,
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MAP_PRIVATE|MAP_ANON, -1, 0);
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if (cfi_hash == (void *)-1L) {
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WARN("mmap fail cfi_hash");
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cfi_hash = NULL;
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} else if (opts.stats) {
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printf("cfi_bits: %d\n", cfi_bits);
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}
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return cfi_hash;
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}
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static unsigned long nr_insns;
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static unsigned long nr_insns_visited;
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/*
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* Call the arch-specific instruction decoder for all the instructions and add
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* them to the global instruction list.
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*/
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static int decode_instructions(struct objtool_file *file)
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{
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struct section *sec;
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struct symbol *func;
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unsigned long offset;
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struct instruction *insn;
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int ret;
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for_each_sec(file, sec) {
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struct instruction *insns = NULL;
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u8 prev_len = 0;
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u8 idx = 0;
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if (!(sec->sh.sh_flags & SHF_EXECINSTR))
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continue;
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|
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if (strcmp(sec->name, ".altinstr_replacement") &&
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strcmp(sec->name, ".altinstr_aux") &&
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strncmp(sec->name, ".discard.", 9))
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sec->text = true;
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|
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if (!strcmp(sec->name, ".noinstr.text") ||
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!strcmp(sec->name, ".entry.text") ||
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!strcmp(sec->name, ".cpuidle.text") ||
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!strncmp(sec->name, ".text.__x86.", 12))
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sec->noinstr = true;
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|
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/*
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|
* .init.text code is ran before userspace and thus doesn't
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|
* strictly need retpolines, except for modules which are
|
|
* loaded late, they very much do need retpoline in their
|
|
* .init.text
|
|
*/
|
|
if (!strcmp(sec->name, ".init.text") && !opts.module)
|
|
sec->init = true;
|
|
|
|
for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
|
|
if (!insns || idx == INSN_CHUNK_MAX) {
|
|
insns = calloc(sizeof(*insn), INSN_CHUNK_SIZE);
|
|
if (!insns) {
|
|
WARN("malloc failed");
|
|
return -1;
|
|
}
|
|
idx = 0;
|
|
} else {
|
|
idx++;
|
|
}
|
|
insn = &insns[idx];
|
|
insn->idx = idx;
|
|
|
|
INIT_LIST_HEAD(&insn->call_node);
|
|
insn->sec = sec;
|
|
insn->offset = offset;
|
|
insn->prev_len = prev_len;
|
|
|
|
ret = arch_decode_instruction(file, sec, offset,
|
|
sec->sh.sh_size - offset,
|
|
insn);
|
|
if (ret)
|
|
return ret;
|
|
|
|
prev_len = insn->len;
|
|
|
|
/*
|
|
* By default, "ud2" is a dead end unless otherwise
|
|
* annotated, because GCC 7 inserts it for certain
|
|
* divide-by-zero cases.
|
|
*/
|
|
if (insn->type == INSN_BUG)
|
|
insn->dead_end = true;
|
|
|
|
hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
|
|
nr_insns++;
|
|
}
|
|
|
|
// printf("%s: last chunk used: %d\n", sec->name, (int)idx);
|
|
|
|
sec_for_each_sym(sec, func) {
|
|
if (func->type != STT_NOTYPE && func->type != STT_FUNC)
|
|
continue;
|
|
|
|
if (func->offset == sec->sh.sh_size) {
|
|
/* Heuristic: likely an "end" symbol */
|
|
if (func->type == STT_NOTYPE)
|
|
continue;
|
|
WARN("%s(): STT_FUNC at end of section",
|
|
func->name);
|
|
return -1;
|
|
}
|
|
|
|
if (func->return_thunk || func->alias != func)
|
|
continue;
|
|
|
|
if (!find_insn(file, sec, func->offset)) {
|
|
WARN("%s(): can't find starting instruction",
|
|
func->name);
|
|
return -1;
|
|
}
|
|
|
|
sym_for_each_insn(file, func, insn) {
|
|
insn->sym = func;
|
|
if (func->type == STT_FUNC &&
|
|
insn->type == INSN_ENDBR &&
|
|
list_empty(&insn->call_node)) {
|
|
if (insn->offset == func->offset) {
|
|
list_add_tail(&insn->call_node, &file->endbr_list);
|
|
file->nr_endbr++;
|
|
} else {
|
|
file->nr_endbr_int++;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (opts.stats)
|
|
printf("nr_insns: %lu\n", nr_insns);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Read the pv_ops[] .data table to find the static initialized values.
|
|
*/
|
|
static int add_pv_ops(struct objtool_file *file, const char *symname)
|
|
{
|
|
struct symbol *sym, *func;
|
|
unsigned long off, end;
|
|
struct reloc *rel;
|
|
int idx;
|
|
|
|
sym = find_symbol_by_name(file->elf, symname);
|
|
if (!sym)
|
|
return 0;
|
|
|
|
off = sym->offset;
|
|
end = off + sym->len;
|
|
for (;;) {
|
|
rel = find_reloc_by_dest_range(file->elf, sym->sec, off, end - off);
|
|
if (!rel)
|
|
break;
|
|
|
|
func = rel->sym;
|
|
if (func->type == STT_SECTION)
|
|
func = find_symbol_by_offset(rel->sym->sec, rel->addend);
|
|
|
|
idx = (rel->offset - sym->offset) / sizeof(unsigned long);
|
|
|
|
objtool_pv_add(file, idx, func);
|
|
|
|
off = rel->offset + 1;
|
|
if (off > end)
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Allocate and initialize file->pv_ops[].
|
|
*/
|
|
static int init_pv_ops(struct objtool_file *file)
|
|
{
|
|
static const char *pv_ops_tables[] = {
|
|
"pv_ops",
|
|
"xen_cpu_ops",
|
|
"xen_irq_ops",
|
|
"xen_mmu_ops",
|
|
NULL,
|
|
};
|
|
const char *pv_ops;
|
|
struct symbol *sym;
|
|
int idx, nr;
|
|
|
|
if (!opts.noinstr)
|
|
return 0;
|
|
|
|
file->pv_ops = NULL;
|
|
|
|
sym = find_symbol_by_name(file->elf, "pv_ops");
|
|
if (!sym)
|
|
return 0;
|
|
|
|
nr = sym->len / sizeof(unsigned long);
|
|
file->pv_ops = calloc(sizeof(struct pv_state), nr);
|
|
if (!file->pv_ops)
|
|
return -1;
|
|
|
|
for (idx = 0; idx < nr; idx++)
|
|
INIT_LIST_HEAD(&file->pv_ops[idx].targets);
|
|
|
|
for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++)
|
|
add_pv_ops(file, pv_ops);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct instruction *find_last_insn(struct objtool_file *file,
|
|
struct section *sec)
|
|
{
|
|
struct instruction *insn = NULL;
|
|
unsigned int offset;
|
|
unsigned int end = (sec->sh.sh_size > 10) ? sec->sh.sh_size - 10 : 0;
|
|
|
|
for (offset = sec->sh.sh_size - 1; offset >= end && !insn; offset--)
|
|
insn = find_insn(file, sec, offset);
|
|
|
|
return insn;
|
|
}
|
|
|
|
/*
|
|
* Mark "ud2" instructions and manually annotated dead ends.
|
|
*/
|
|
static int add_dead_ends(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
struct reloc *reloc;
|
|
struct instruction *insn;
|
|
|
|
/*
|
|
* Check for manually annotated dead ends.
|
|
*/
|
|
sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
|
|
if (!sec)
|
|
goto reachable;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
if (reloc->sym->type != STT_SECTION) {
|
|
WARN("unexpected relocation symbol type in %s", sec->name);
|
|
return -1;
|
|
}
|
|
insn = find_insn(file, reloc->sym->sec, reloc->addend);
|
|
if (insn)
|
|
insn = prev_insn_same_sec(file, insn);
|
|
else if (reloc->addend == reloc->sym->sec->sh.sh_size) {
|
|
insn = find_last_insn(file, reloc->sym->sec);
|
|
if (!insn) {
|
|
WARN("can't find unreachable insn at %s+0x%" PRIx64,
|
|
reloc->sym->sec->name, reloc->addend);
|
|
return -1;
|
|
}
|
|
} else {
|
|
WARN("can't find unreachable insn at %s+0x%" PRIx64,
|
|
reloc->sym->sec->name, reloc->addend);
|
|
return -1;
|
|
}
|
|
|
|
insn->dead_end = true;
|
|
}
|
|
|
|
reachable:
|
|
/*
|
|
* These manually annotated reachable checks are needed for GCC 4.4,
|
|
* where the Linux unreachable() macro isn't supported. In that case
|
|
* GCC doesn't know the "ud2" is fatal, so it generates code as if it's
|
|
* not a dead end.
|
|
*/
|
|
sec = find_section_by_name(file->elf, ".rela.discard.reachable");
|
|
if (!sec)
|
|
return 0;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
if (reloc->sym->type != STT_SECTION) {
|
|
WARN("unexpected relocation symbol type in %s", sec->name);
|
|
return -1;
|
|
}
|
|
insn = find_insn(file, reloc->sym->sec, reloc->addend);
|
|
if (insn)
|
|
insn = prev_insn_same_sec(file, insn);
|
|
else if (reloc->addend == reloc->sym->sec->sh.sh_size) {
|
|
insn = find_last_insn(file, reloc->sym->sec);
|
|
if (!insn) {
|
|
WARN("can't find reachable insn at %s+0x%" PRIx64,
|
|
reloc->sym->sec->name, reloc->addend);
|
|
return -1;
|
|
}
|
|
} else {
|
|
WARN("can't find reachable insn at %s+0x%" PRIx64,
|
|
reloc->sym->sec->name, reloc->addend);
|
|
return -1;
|
|
}
|
|
|
|
insn->dead_end = false;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int create_static_call_sections(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
struct static_call_site *site;
|
|
struct instruction *insn;
|
|
struct symbol *key_sym;
|
|
char *key_name, *tmp;
|
|
int idx;
|
|
|
|
sec = find_section_by_name(file->elf, ".static_call_sites");
|
|
if (sec) {
|
|
INIT_LIST_HEAD(&file->static_call_list);
|
|
WARN("file already has .static_call_sites section, skipping");
|
|
return 0;
|
|
}
|
|
|
|
if (list_empty(&file->static_call_list))
|
|
return 0;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->static_call_list, call_node)
|
|
idx++;
|
|
|
|
sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
|
|
sizeof(struct static_call_site), idx);
|
|
if (!sec)
|
|
return -1;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->static_call_list, call_node) {
|
|
|
|
site = (struct static_call_site *)sec->data->d_buf + idx;
|
|
memset(site, 0, sizeof(struct static_call_site));
|
|
|
|
/* populate reloc for 'addr' */
|
|
if (elf_add_reloc_to_insn(file->elf, sec,
|
|
idx * sizeof(struct static_call_site),
|
|
R_X86_64_PC32,
|
|
insn->sec, insn->offset))
|
|
return -1;
|
|
|
|
/* find key symbol */
|
|
key_name = strdup(insn_call_dest(insn)->name);
|
|
if (!key_name) {
|
|
perror("strdup");
|
|
return -1;
|
|
}
|
|
if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
|
|
STATIC_CALL_TRAMP_PREFIX_LEN)) {
|
|
WARN("static_call: trampoline name malformed: %s", key_name);
|
|
free(key_name);
|
|
return -1;
|
|
}
|
|
tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
|
|
memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
|
|
|
|
key_sym = find_symbol_by_name(file->elf, tmp);
|
|
if (!key_sym) {
|
|
if (!opts.module) {
|
|
WARN("static_call: can't find static_call_key symbol: %s", tmp);
|
|
free(key_name);
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* For modules(), the key might not be exported, which
|
|
* means the module can make static calls but isn't
|
|
* allowed to change them.
|
|
*
|
|
* In that case we temporarily set the key to be the
|
|
* trampoline address. This is fixed up in
|
|
* static_call_add_module().
|
|
*/
|
|
key_sym = insn_call_dest(insn);
|
|
}
|
|
free(key_name);
|
|
|
|
/* populate reloc for 'key' */
|
|
if (elf_add_reloc(file->elf, sec,
|
|
idx * sizeof(struct static_call_site) + 4,
|
|
R_X86_64_PC32, key_sym,
|
|
is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
|
|
return -1;
|
|
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int create_retpoline_sites_sections(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn;
|
|
struct section *sec;
|
|
int idx;
|
|
|
|
sec = find_section_by_name(file->elf, ".retpoline_sites");
|
|
if (sec) {
|
|
WARN("file already has .retpoline_sites, skipping");
|
|
return 0;
|
|
}
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->retpoline_call_list, call_node)
|
|
idx++;
|
|
|
|
if (!idx)
|
|
return 0;
|
|
|
|
sec = elf_create_section(file->elf, ".retpoline_sites", 0,
|
|
sizeof(int), idx);
|
|
if (!sec) {
|
|
WARN("elf_create_section: .retpoline_sites");
|
|
return -1;
|
|
}
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
|
|
|
|
int *site = (int *)sec->data->d_buf + idx;
|
|
*site = 0;
|
|
|
|
if (elf_add_reloc_to_insn(file->elf, sec,
|
|
idx * sizeof(int),
|
|
R_X86_64_PC32,
|
|
insn->sec, insn->offset)) {
|
|
WARN("elf_add_reloc_to_insn: .retpoline_sites");
|
|
return -1;
|
|
}
|
|
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int create_return_sites_sections(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn;
|
|
struct section *sec;
|
|
int idx;
|
|
|
|
sec = find_section_by_name(file->elf, ".return_sites");
|
|
if (sec) {
|
|
WARN("file already has .return_sites, skipping");
|
|
return 0;
|
|
}
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->return_thunk_list, call_node)
|
|
idx++;
|
|
|
|
if (!idx)
|
|
return 0;
|
|
|
|
sec = elf_create_section(file->elf, ".return_sites", 0,
|
|
sizeof(int), idx);
|
|
if (!sec) {
|
|
WARN("elf_create_section: .return_sites");
|
|
return -1;
|
|
}
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->return_thunk_list, call_node) {
|
|
|
|
int *site = (int *)sec->data->d_buf + idx;
|
|
*site = 0;
|
|
|
|
if (elf_add_reloc_to_insn(file->elf, sec,
|
|
idx * sizeof(int),
|
|
R_X86_64_PC32,
|
|
insn->sec, insn->offset)) {
|
|
WARN("elf_add_reloc_to_insn: .return_sites");
|
|
return -1;
|
|
}
|
|
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int create_ibt_endbr_seal_sections(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn;
|
|
struct section *sec;
|
|
int idx;
|
|
|
|
sec = find_section_by_name(file->elf, ".ibt_endbr_seal");
|
|
if (sec) {
|
|
WARN("file already has .ibt_endbr_seal, skipping");
|
|
return 0;
|
|
}
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->endbr_list, call_node)
|
|
idx++;
|
|
|
|
if (opts.stats) {
|
|
printf("ibt: ENDBR at function start: %d\n", file->nr_endbr);
|
|
printf("ibt: ENDBR inside functions: %d\n", file->nr_endbr_int);
|
|
printf("ibt: superfluous ENDBR: %d\n", idx);
|
|
}
|
|
|
|
if (!idx)
|
|
return 0;
|
|
|
|
sec = elf_create_section(file->elf, ".ibt_endbr_seal", 0,
|
|
sizeof(int), idx);
|
|
if (!sec) {
|
|
WARN("elf_create_section: .ibt_endbr_seal");
|
|
return -1;
|
|
}
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->endbr_list, call_node) {
|
|
|
|
int *site = (int *)sec->data->d_buf + idx;
|
|
struct symbol *sym = insn->sym;
|
|
*site = 0;
|
|
|
|
if (opts.module && sym && sym->type == STT_FUNC &&
|
|
insn->offset == sym->offset &&
|
|
(!strcmp(sym->name, "init_module") ||
|
|
!strcmp(sym->name, "cleanup_module")))
|
|
WARN("%s(): not an indirect call target", sym->name);
|
|
|
|
if (elf_add_reloc_to_insn(file->elf, sec,
|
|
idx * sizeof(int),
|
|
R_X86_64_PC32,
|
|
insn->sec, insn->offset)) {
|
|
WARN("elf_add_reloc_to_insn: .ibt_endbr_seal");
|
|
return -1;
|
|
}
|
|
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int create_cfi_sections(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
struct symbol *sym;
|
|
unsigned int *loc;
|
|
int idx;
|
|
|
|
sec = find_section_by_name(file->elf, ".cfi_sites");
|
|
if (sec) {
|
|
INIT_LIST_HEAD(&file->call_list);
|
|
WARN("file already has .cfi_sites section, skipping");
|
|
return 0;
|
|
}
|
|
|
|
idx = 0;
|
|
for_each_sym(file, sym) {
|
|
if (sym->type != STT_FUNC)
|
|
continue;
|
|
|
|
if (strncmp(sym->name, "__cfi_", 6))
|
|
continue;
|
|
|
|
idx++;
|
|
}
|
|
|
|
sec = elf_create_section(file->elf, ".cfi_sites", 0, sizeof(unsigned int), idx);
|
|
if (!sec)
|
|
return -1;
|
|
|
|
idx = 0;
|
|
for_each_sym(file, sym) {
|
|
if (sym->type != STT_FUNC)
|
|
continue;
|
|
|
|
if (strncmp(sym->name, "__cfi_", 6))
|
|
continue;
|
|
|
|
loc = (unsigned int *)sec->data->d_buf + idx;
|
|
memset(loc, 0, sizeof(unsigned int));
|
|
|
|
if (elf_add_reloc_to_insn(file->elf, sec,
|
|
idx * sizeof(unsigned int),
|
|
R_X86_64_PC32,
|
|
sym->sec, sym->offset))
|
|
return -1;
|
|
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int create_mcount_loc_sections(struct objtool_file *file)
|
|
{
|
|
int addrsize = elf_class_addrsize(file->elf);
|
|
struct instruction *insn;
|
|
struct section *sec;
|
|
int idx;
|
|
|
|
sec = find_section_by_name(file->elf, "__mcount_loc");
|
|
if (sec) {
|
|
INIT_LIST_HEAD(&file->mcount_loc_list);
|
|
WARN("file already has __mcount_loc section, skipping");
|
|
return 0;
|
|
}
|
|
|
|
if (list_empty(&file->mcount_loc_list))
|
|
return 0;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->mcount_loc_list, call_node)
|
|
idx++;
|
|
|
|
sec = elf_create_section(file->elf, "__mcount_loc", 0, addrsize, idx);
|
|
if (!sec)
|
|
return -1;
|
|
|
|
sec->sh.sh_addralign = addrsize;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
|
|
void *loc;
|
|
|
|
loc = sec->data->d_buf + idx;
|
|
memset(loc, 0, addrsize);
|
|
|
|
if (elf_add_reloc_to_insn(file->elf, sec, idx,
|
|
addrsize == sizeof(u64) ? R_ABS64 : R_ABS32,
|
|
insn->sec, insn->offset))
|
|
return -1;
|
|
|
|
idx += addrsize;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int create_direct_call_sections(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn;
|
|
struct section *sec;
|
|
unsigned int *loc;
|
|
int idx;
|
|
|
|
sec = find_section_by_name(file->elf, ".call_sites");
|
|
if (sec) {
|
|
INIT_LIST_HEAD(&file->call_list);
|
|
WARN("file already has .call_sites section, skipping");
|
|
return 0;
|
|
}
|
|
|
|
if (list_empty(&file->call_list))
|
|
return 0;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->call_list, call_node)
|
|
idx++;
|
|
|
|
sec = elf_create_section(file->elf, ".call_sites", 0, sizeof(unsigned int), idx);
|
|
if (!sec)
|
|
return -1;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(insn, &file->call_list, call_node) {
|
|
|
|
loc = (unsigned int *)sec->data->d_buf + idx;
|
|
memset(loc, 0, sizeof(unsigned int));
|
|
|
|
if (elf_add_reloc_to_insn(file->elf, sec,
|
|
idx * sizeof(unsigned int),
|
|
R_X86_64_PC32,
|
|
insn->sec, insn->offset))
|
|
return -1;
|
|
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Warnings shouldn't be reported for ignored functions.
|
|
*/
|
|
static void add_ignores(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn;
|
|
struct section *sec;
|
|
struct symbol *func;
|
|
struct reloc *reloc;
|
|
|
|
sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
|
|
if (!sec)
|
|
return;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
switch (reloc->sym->type) {
|
|
case STT_FUNC:
|
|
func = reloc->sym;
|
|
break;
|
|
|
|
case STT_SECTION:
|
|
func = find_func_by_offset(reloc->sym->sec, reloc->addend);
|
|
if (!func)
|
|
continue;
|
|
break;
|
|
|
|
default:
|
|
WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type);
|
|
continue;
|
|
}
|
|
|
|
func_for_each_insn(file, func, insn)
|
|
insn->ignore = true;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This is a whitelist of functions that is allowed to be called with AC set.
|
|
* The list is meant to be minimal and only contains compiler instrumentation
|
|
* ABI and a few functions used to implement *_{to,from}_user() functions.
|
|
*
|
|
* These functions must not directly change AC, but may PUSHF/POPF.
|
|
*/
|
|
static const char *uaccess_safe_builtin[] = {
|
|
/* KASAN */
|
|
"kasan_report",
|
|
"kasan_check_range",
|
|
/* KASAN out-of-line */
|
|
"__asan_loadN_noabort",
|
|
"__asan_load1_noabort",
|
|
"__asan_load2_noabort",
|
|
"__asan_load4_noabort",
|
|
"__asan_load8_noabort",
|
|
"__asan_load16_noabort",
|
|
"__asan_storeN_noabort",
|
|
"__asan_store1_noabort",
|
|
"__asan_store2_noabort",
|
|
"__asan_store4_noabort",
|
|
"__asan_store8_noabort",
|
|
"__asan_store16_noabort",
|
|
"__kasan_check_read",
|
|
"__kasan_check_write",
|
|
/* KASAN in-line */
|
|
"__asan_report_load_n_noabort",
|
|
"__asan_report_load1_noabort",
|
|
"__asan_report_load2_noabort",
|
|
"__asan_report_load4_noabort",
|
|
"__asan_report_load8_noabort",
|
|
"__asan_report_load16_noabort",
|
|
"__asan_report_store_n_noabort",
|
|
"__asan_report_store1_noabort",
|
|
"__asan_report_store2_noabort",
|
|
"__asan_report_store4_noabort",
|
|
"__asan_report_store8_noabort",
|
|
"__asan_report_store16_noabort",
|
|
/* KCSAN */
|
|
"__kcsan_check_access",
|
|
"__kcsan_mb",
|
|
"__kcsan_wmb",
|
|
"__kcsan_rmb",
|
|
"__kcsan_release",
|
|
"kcsan_found_watchpoint",
|
|
"kcsan_setup_watchpoint",
|
|
"kcsan_check_scoped_accesses",
|
|
"kcsan_disable_current",
|
|
"kcsan_enable_current_nowarn",
|
|
/* KCSAN/TSAN */
|
|
"__tsan_func_entry",
|
|
"__tsan_func_exit",
|
|
"__tsan_read_range",
|
|
"__tsan_write_range",
|
|
"__tsan_read1",
|
|
"__tsan_read2",
|
|
"__tsan_read4",
|
|
"__tsan_read8",
|
|
"__tsan_read16",
|
|
"__tsan_write1",
|
|
"__tsan_write2",
|
|
"__tsan_write4",
|
|
"__tsan_write8",
|
|
"__tsan_write16",
|
|
"__tsan_read_write1",
|
|
"__tsan_read_write2",
|
|
"__tsan_read_write4",
|
|
"__tsan_read_write8",
|
|
"__tsan_read_write16",
|
|
"__tsan_volatile_read1",
|
|
"__tsan_volatile_read2",
|
|
"__tsan_volatile_read4",
|
|
"__tsan_volatile_read8",
|
|
"__tsan_volatile_read16",
|
|
"__tsan_volatile_write1",
|
|
"__tsan_volatile_write2",
|
|
"__tsan_volatile_write4",
|
|
"__tsan_volatile_write8",
|
|
"__tsan_volatile_write16",
|
|
"__tsan_atomic8_load",
|
|
"__tsan_atomic16_load",
|
|
"__tsan_atomic32_load",
|
|
"__tsan_atomic64_load",
|
|
"__tsan_atomic8_store",
|
|
"__tsan_atomic16_store",
|
|
"__tsan_atomic32_store",
|
|
"__tsan_atomic64_store",
|
|
"__tsan_atomic8_exchange",
|
|
"__tsan_atomic16_exchange",
|
|
"__tsan_atomic32_exchange",
|
|
"__tsan_atomic64_exchange",
|
|
"__tsan_atomic8_fetch_add",
|
|
"__tsan_atomic16_fetch_add",
|
|
"__tsan_atomic32_fetch_add",
|
|
"__tsan_atomic64_fetch_add",
|
|
"__tsan_atomic8_fetch_sub",
|
|
"__tsan_atomic16_fetch_sub",
|
|
"__tsan_atomic32_fetch_sub",
|
|
"__tsan_atomic64_fetch_sub",
|
|
"__tsan_atomic8_fetch_and",
|
|
"__tsan_atomic16_fetch_and",
|
|
"__tsan_atomic32_fetch_and",
|
|
"__tsan_atomic64_fetch_and",
|
|
"__tsan_atomic8_fetch_or",
|
|
"__tsan_atomic16_fetch_or",
|
|
"__tsan_atomic32_fetch_or",
|
|
"__tsan_atomic64_fetch_or",
|
|
"__tsan_atomic8_fetch_xor",
|
|
"__tsan_atomic16_fetch_xor",
|
|
"__tsan_atomic32_fetch_xor",
|
|
"__tsan_atomic64_fetch_xor",
|
|
"__tsan_atomic8_fetch_nand",
|
|
"__tsan_atomic16_fetch_nand",
|
|
"__tsan_atomic32_fetch_nand",
|
|
"__tsan_atomic64_fetch_nand",
|
|
"__tsan_atomic8_compare_exchange_strong",
|
|
"__tsan_atomic16_compare_exchange_strong",
|
|
"__tsan_atomic32_compare_exchange_strong",
|
|
"__tsan_atomic64_compare_exchange_strong",
|
|
"__tsan_atomic8_compare_exchange_weak",
|
|
"__tsan_atomic16_compare_exchange_weak",
|
|
"__tsan_atomic32_compare_exchange_weak",
|
|
"__tsan_atomic64_compare_exchange_weak",
|
|
"__tsan_atomic8_compare_exchange_val",
|
|
"__tsan_atomic16_compare_exchange_val",
|
|
"__tsan_atomic32_compare_exchange_val",
|
|
"__tsan_atomic64_compare_exchange_val",
|
|
"__tsan_atomic_thread_fence",
|
|
"__tsan_atomic_signal_fence",
|
|
"__tsan_unaligned_read16",
|
|
"__tsan_unaligned_write16",
|
|
/* KCOV */
|
|
"write_comp_data",
|
|
"check_kcov_mode",
|
|
"__sanitizer_cov_trace_pc",
|
|
"__sanitizer_cov_trace_const_cmp1",
|
|
"__sanitizer_cov_trace_const_cmp2",
|
|
"__sanitizer_cov_trace_const_cmp4",
|
|
"__sanitizer_cov_trace_const_cmp8",
|
|
"__sanitizer_cov_trace_cmp1",
|
|
"__sanitizer_cov_trace_cmp2",
|
|
"__sanitizer_cov_trace_cmp4",
|
|
"__sanitizer_cov_trace_cmp8",
|
|
"__sanitizer_cov_trace_switch",
|
|
/* KMSAN */
|
|
"kmsan_copy_to_user",
|
|
"kmsan_report",
|
|
"kmsan_unpoison_entry_regs",
|
|
"kmsan_unpoison_memory",
|
|
"__msan_chain_origin",
|
|
"__msan_get_context_state",
|
|
"__msan_instrument_asm_store",
|
|
"__msan_metadata_ptr_for_load_1",
|
|
"__msan_metadata_ptr_for_load_2",
|
|
"__msan_metadata_ptr_for_load_4",
|
|
"__msan_metadata_ptr_for_load_8",
|
|
"__msan_metadata_ptr_for_load_n",
|
|
"__msan_metadata_ptr_for_store_1",
|
|
"__msan_metadata_ptr_for_store_2",
|
|
"__msan_metadata_ptr_for_store_4",
|
|
"__msan_metadata_ptr_for_store_8",
|
|
"__msan_metadata_ptr_for_store_n",
|
|
"__msan_poison_alloca",
|
|
"__msan_warning",
|
|
/* UBSAN */
|
|
"ubsan_type_mismatch_common",
|
|
"__ubsan_handle_type_mismatch",
|
|
"__ubsan_handle_type_mismatch_v1",
|
|
"__ubsan_handle_shift_out_of_bounds",
|
|
"__ubsan_handle_load_invalid_value",
|
|
/* STACKLEAK */
|
|
"stackleak_track_stack",
|
|
/* misc */
|
|
"csum_partial_copy_generic",
|
|
"copy_mc_fragile",
|
|
"copy_mc_fragile_handle_tail",
|
|
"copy_mc_enhanced_fast_string",
|
|
"ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
|
|
"rep_stos_alternative",
|
|
"rep_movs_alternative",
|
|
"__copy_user_nocache",
|
|
NULL
|
|
};
|
|
|
|
static void add_uaccess_safe(struct objtool_file *file)
|
|
{
|
|
struct symbol *func;
|
|
const char **name;
|
|
|
|
if (!opts.uaccess)
|
|
return;
|
|
|
|
for (name = uaccess_safe_builtin; *name; name++) {
|
|
func = find_symbol_by_name(file->elf, *name);
|
|
if (!func)
|
|
continue;
|
|
|
|
func->uaccess_safe = true;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* FIXME: For now, just ignore any alternatives which add retpolines. This is
|
|
* a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
|
|
* But it at least allows objtool to understand the control flow *around* the
|
|
* retpoline.
|
|
*/
|
|
static int add_ignore_alternatives(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
struct reloc *reloc;
|
|
struct instruction *insn;
|
|
|
|
sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
|
|
if (!sec)
|
|
return 0;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
if (reloc->sym->type != STT_SECTION) {
|
|
WARN("unexpected relocation symbol type in %s", sec->name);
|
|
return -1;
|
|
}
|
|
|
|
insn = find_insn(file, reloc->sym->sec, reloc->addend);
|
|
if (!insn) {
|
|
WARN("bad .discard.ignore_alts entry");
|
|
return -1;
|
|
}
|
|
|
|
insn->ignore_alts = true;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
__weak bool arch_is_retpoline(struct symbol *sym)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
__weak bool arch_is_rethunk(struct symbol *sym)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
|
|
{
|
|
struct reloc *reloc;
|
|
|
|
if (insn->no_reloc)
|
|
return NULL;
|
|
|
|
if (!file)
|
|
return NULL;
|
|
|
|
reloc = find_reloc_by_dest_range(file->elf, insn->sec,
|
|
insn->offset, insn->len);
|
|
if (!reloc) {
|
|
insn->no_reloc = 1;
|
|
return NULL;
|
|
}
|
|
|
|
return reloc;
|
|
}
|
|
|
|
static void remove_insn_ops(struct instruction *insn)
|
|
{
|
|
struct stack_op *op, *next;
|
|
|
|
for (op = insn->stack_ops; op; op = next) {
|
|
next = op->next;
|
|
free(op);
|
|
}
|
|
insn->stack_ops = NULL;
|
|
}
|
|
|
|
static void annotate_call_site(struct objtool_file *file,
|
|
struct instruction *insn, bool sibling)
|
|
{
|
|
struct reloc *reloc = insn_reloc(file, insn);
|
|
struct symbol *sym = insn_call_dest(insn);
|
|
|
|
if (!sym)
|
|
sym = reloc->sym;
|
|
|
|
/*
|
|
* Alternative replacement code is just template code which is
|
|
* sometimes copied to the original instruction. For now, don't
|
|
* annotate it. (In the future we might consider annotating the
|
|
* original instruction if/when it ever makes sense to do so.)
|
|
*/
|
|
if (!strcmp(insn->sec->name, ".altinstr_replacement"))
|
|
return;
|
|
|
|
if (sym->static_call_tramp) {
|
|
list_add_tail(&insn->call_node, &file->static_call_list);
|
|
return;
|
|
}
|
|
|
|
if (sym->retpoline_thunk) {
|
|
list_add_tail(&insn->call_node, &file->retpoline_call_list);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Many compilers cannot disable KCOV or sanitizer calls with a function
|
|
* attribute so they need a little help, NOP out any such calls from
|
|
* noinstr text.
|
|
*/
|
|
if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) {
|
|
if (reloc) {
|
|
reloc->type = R_NONE;
|
|
elf_write_reloc(file->elf, reloc);
|
|
}
|
|
|
|
elf_write_insn(file->elf, insn->sec,
|
|
insn->offset, insn->len,
|
|
sibling ? arch_ret_insn(insn->len)
|
|
: arch_nop_insn(insn->len));
|
|
|
|
insn->type = sibling ? INSN_RETURN : INSN_NOP;
|
|
|
|
if (sibling) {
|
|
/*
|
|
* We've replaced the tail-call JMP insn by two new
|
|
* insn: RET; INT3, except we only have a single struct
|
|
* insn here. Mark it retpoline_safe to avoid the SLS
|
|
* warning, instead of adding another insn.
|
|
*/
|
|
insn->retpoline_safe = true;
|
|
}
|
|
|
|
return;
|
|
}
|
|
|
|
if (opts.mcount && sym->fentry) {
|
|
if (sibling)
|
|
WARN_INSN(insn, "tail call to __fentry__ !?!?");
|
|
if (opts.mnop) {
|
|
if (reloc) {
|
|
reloc->type = R_NONE;
|
|
elf_write_reloc(file->elf, reloc);
|
|
}
|
|
|
|
elf_write_insn(file->elf, insn->sec,
|
|
insn->offset, insn->len,
|
|
arch_nop_insn(insn->len));
|
|
|
|
insn->type = INSN_NOP;
|
|
}
|
|
|
|
list_add_tail(&insn->call_node, &file->mcount_loc_list);
|
|
return;
|
|
}
|
|
|
|
if (insn->type == INSN_CALL && !insn->sec->init)
|
|
list_add_tail(&insn->call_node, &file->call_list);
|
|
|
|
if (!sibling && dead_end_function(file, sym))
|
|
insn->dead_end = true;
|
|
}
|
|
|
|
static void add_call_dest(struct objtool_file *file, struct instruction *insn,
|
|
struct symbol *dest, bool sibling)
|
|
{
|
|
insn->_call_dest = dest;
|
|
if (!dest)
|
|
return;
|
|
|
|
/*
|
|
* Whatever stack impact regular CALLs have, should be undone
|
|
* by the RETURN of the called function.
|
|
*
|
|
* Annotated intra-function calls retain the stack_ops but
|
|
* are converted to JUMP, see read_intra_function_calls().
|
|
*/
|
|
remove_insn_ops(insn);
|
|
|
|
annotate_call_site(file, insn, sibling);
|
|
}
|
|
|
|
static void add_retpoline_call(struct objtool_file *file, struct instruction *insn)
|
|
{
|
|
/*
|
|
* Retpoline calls/jumps are really dynamic calls/jumps in disguise,
|
|
* so convert them accordingly.
|
|
*/
|
|
switch (insn->type) {
|
|
case INSN_CALL:
|
|
insn->type = INSN_CALL_DYNAMIC;
|
|
break;
|
|
case INSN_JUMP_UNCONDITIONAL:
|
|
insn->type = INSN_JUMP_DYNAMIC;
|
|
break;
|
|
case INSN_JUMP_CONDITIONAL:
|
|
insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
|
|
break;
|
|
default:
|
|
return;
|
|
}
|
|
|
|
insn->retpoline_safe = true;
|
|
|
|
/*
|
|
* Whatever stack impact regular CALLs have, should be undone
|
|
* by the RETURN of the called function.
|
|
*
|
|
* Annotated intra-function calls retain the stack_ops but
|
|
* are converted to JUMP, see read_intra_function_calls().
|
|
*/
|
|
remove_insn_ops(insn);
|
|
|
|
annotate_call_site(file, insn, false);
|
|
}
|
|
|
|
static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
|
|
{
|
|
/*
|
|
* Return thunk tail calls are really just returns in disguise,
|
|
* so convert them accordingly.
|
|
*/
|
|
insn->type = INSN_RETURN;
|
|
insn->retpoline_safe = true;
|
|
|
|
if (add)
|
|
list_add_tail(&insn->call_node, &file->return_thunk_list);
|
|
}
|
|
|
|
static bool is_first_func_insn(struct objtool_file *file,
|
|
struct instruction *insn, struct symbol *sym)
|
|
{
|
|
if (insn->offset == sym->offset)
|
|
return true;
|
|
|
|
/* Allow direct CALL/JMP past ENDBR */
|
|
if (opts.ibt) {
|
|
struct instruction *prev = prev_insn_same_sym(file, insn);
|
|
|
|
if (prev && prev->type == INSN_ENDBR &&
|
|
insn->offset == sym->offset + prev->len)
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* A sibling call is a tail-call to another symbol -- to differentiate from a
|
|
* recursive tail-call which is to the same symbol.
|
|
*/
|
|
static bool jump_is_sibling_call(struct objtool_file *file,
|
|
struct instruction *from, struct instruction *to)
|
|
{
|
|
struct symbol *fs = from->sym;
|
|
struct symbol *ts = to->sym;
|
|
|
|
/* Not a sibling call if from/to a symbol hole */
|
|
if (!fs || !ts)
|
|
return false;
|
|
|
|
/* Not a sibling call if not targeting the start of a symbol. */
|
|
if (!is_first_func_insn(file, to, ts))
|
|
return false;
|
|
|
|
/* Disallow sibling calls into STT_NOTYPE */
|
|
if (ts->type == STT_NOTYPE)
|
|
return false;
|
|
|
|
/* Must not be self to be a sibling */
|
|
return fs->pfunc != ts->pfunc;
|
|
}
|
|
|
|
/*
|
|
* Find the destination instructions for all jumps.
|
|
*/
|
|
static int add_jump_destinations(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn, *jump_dest;
|
|
struct reloc *reloc;
|
|
struct section *dest_sec;
|
|
unsigned long dest_off;
|
|
|
|
for_each_insn(file, insn) {
|
|
if (insn->jump_dest) {
|
|
/*
|
|
* handle_group_alt() may have previously set
|
|
* 'jump_dest' for some alternatives.
|
|
*/
|
|
continue;
|
|
}
|
|
if (!is_static_jump(insn))
|
|
continue;
|
|
|
|
reloc = insn_reloc(file, insn);
|
|
if (!reloc) {
|
|
dest_sec = insn->sec;
|
|
dest_off = arch_jump_destination(insn);
|
|
} else if (reloc->sym->type == STT_SECTION) {
|
|
dest_sec = reloc->sym->sec;
|
|
dest_off = arch_dest_reloc_offset(reloc->addend);
|
|
} else if (reloc->sym->retpoline_thunk) {
|
|
add_retpoline_call(file, insn);
|
|
continue;
|
|
} else if (reloc->sym->return_thunk) {
|
|
add_return_call(file, insn, true);
|
|
continue;
|
|
} else if (insn_func(insn)) {
|
|
/*
|
|
* External sibling call or internal sibling call with
|
|
* STT_FUNC reloc.
|
|
*/
|
|
add_call_dest(file, insn, reloc->sym, true);
|
|
continue;
|
|
} else if (reloc->sym->sec->idx) {
|
|
dest_sec = reloc->sym->sec;
|
|
dest_off = reloc->sym->sym.st_value +
|
|
arch_dest_reloc_offset(reloc->addend);
|
|
} else {
|
|
/* non-func asm code jumping to another file */
|
|
continue;
|
|
}
|
|
|
|
jump_dest = find_insn(file, dest_sec, dest_off);
|
|
if (!jump_dest) {
|
|
struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
|
|
|
|
/*
|
|
* This is a special case for zen_untrain_ret().
|
|
* It jumps to __x86_return_thunk(), but objtool
|
|
* can't find the thunk's starting RET
|
|
* instruction, because the RET is also in the
|
|
* middle of another instruction. Objtool only
|
|
* knows about the outer instruction.
|
|
*/
|
|
if (sym && sym->return_thunk) {
|
|
add_return_call(file, insn, false);
|
|
continue;
|
|
}
|
|
|
|
WARN_INSN(insn, "can't find jump dest instruction at %s+0x%lx",
|
|
dest_sec->name, dest_off);
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* Cross-function jump.
|
|
*/
|
|
if (insn_func(insn) && insn_func(jump_dest) &&
|
|
insn_func(insn) != insn_func(jump_dest)) {
|
|
|
|
/*
|
|
* For GCC 8+, create parent/child links for any cold
|
|
* subfunctions. This is _mostly_ redundant with a
|
|
* similar initialization in read_symbols().
|
|
*
|
|
* If a function has aliases, we want the *first* such
|
|
* function in the symbol table to be the subfunction's
|
|
* parent. In that case we overwrite the
|
|
* initialization done in read_symbols().
|
|
*
|
|
* However this code can't completely replace the
|
|
* read_symbols() code because this doesn't detect the
|
|
* case where the parent function's only reference to a
|
|
* subfunction is through a jump table.
|
|
*/
|
|
if (!strstr(insn_func(insn)->name, ".cold") &&
|
|
strstr(insn_func(jump_dest)->name, ".cold")) {
|
|
insn_func(insn)->cfunc = insn_func(jump_dest);
|
|
insn_func(jump_dest)->pfunc = insn_func(insn);
|
|
}
|
|
}
|
|
|
|
if (jump_is_sibling_call(file, insn, jump_dest)) {
|
|
/*
|
|
* Internal sibling call without reloc or with
|
|
* STT_SECTION reloc.
|
|
*/
|
|
add_call_dest(file, insn, insn_func(jump_dest), true);
|
|
continue;
|
|
}
|
|
|
|
insn->jump_dest = jump_dest;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
|
|
{
|
|
struct symbol *call_dest;
|
|
|
|
call_dest = find_func_by_offset(sec, offset);
|
|
if (!call_dest)
|
|
call_dest = find_symbol_by_offset(sec, offset);
|
|
|
|
return call_dest;
|
|
}
|
|
|
|
/*
|
|
* Find the destination instructions for all calls.
|
|
*/
|
|
static int add_call_destinations(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn;
|
|
unsigned long dest_off;
|
|
struct symbol *dest;
|
|
struct reloc *reloc;
|
|
|
|
for_each_insn(file, insn) {
|
|
if (insn->type != INSN_CALL)
|
|
continue;
|
|
|
|
reloc = insn_reloc(file, insn);
|
|
if (!reloc) {
|
|
dest_off = arch_jump_destination(insn);
|
|
dest = find_call_destination(insn->sec, dest_off);
|
|
|
|
add_call_dest(file, insn, dest, false);
|
|
|
|
if (insn->ignore)
|
|
continue;
|
|
|
|
if (!insn_call_dest(insn)) {
|
|
WARN_INSN(insn, "unannotated intra-function call");
|
|
return -1;
|
|
}
|
|
|
|
if (insn_func(insn) && insn_call_dest(insn)->type != STT_FUNC) {
|
|
WARN_INSN(insn, "unsupported call to non-function");
|
|
return -1;
|
|
}
|
|
|
|
} else if (reloc->sym->type == STT_SECTION) {
|
|
dest_off = arch_dest_reloc_offset(reloc->addend);
|
|
dest = find_call_destination(reloc->sym->sec, dest_off);
|
|
if (!dest) {
|
|
WARN_INSN(insn, "can't find call dest symbol at %s+0x%lx",
|
|
reloc->sym->sec->name, dest_off);
|
|
return -1;
|
|
}
|
|
|
|
add_call_dest(file, insn, dest, false);
|
|
|
|
} else if (reloc->sym->retpoline_thunk) {
|
|
add_retpoline_call(file, insn);
|
|
|
|
} else
|
|
add_call_dest(file, insn, reloc->sym, false);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* The .alternatives section requires some extra special care over and above
|
|
* other special sections because alternatives are patched in place.
|
|
*/
|
|
static int handle_group_alt(struct objtool_file *file,
|
|
struct special_alt *special_alt,
|
|
struct instruction *orig_insn,
|
|
struct instruction **new_insn)
|
|
{
|
|
struct instruction *last_new_insn = NULL, *insn, *nop = NULL;
|
|
struct alt_group *orig_alt_group, *new_alt_group;
|
|
unsigned long dest_off;
|
|
|
|
orig_alt_group = orig_insn->alt_group;
|
|
if (!orig_alt_group) {
|
|
struct instruction *last_orig_insn = NULL;
|
|
|
|
orig_alt_group = malloc(sizeof(*orig_alt_group));
|
|
if (!orig_alt_group) {
|
|
WARN("malloc failed");
|
|
return -1;
|
|
}
|
|
orig_alt_group->cfi = calloc(special_alt->orig_len,
|
|
sizeof(struct cfi_state *));
|
|
if (!orig_alt_group->cfi) {
|
|
WARN("calloc failed");
|
|
return -1;
|
|
}
|
|
|
|
insn = orig_insn;
|
|
sec_for_each_insn_from(file, insn) {
|
|
if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
|
|
break;
|
|
|
|
insn->alt_group = orig_alt_group;
|
|
last_orig_insn = insn;
|
|
}
|
|
orig_alt_group->orig_group = NULL;
|
|
orig_alt_group->first_insn = orig_insn;
|
|
orig_alt_group->last_insn = last_orig_insn;
|
|
orig_alt_group->nop = NULL;
|
|
} else {
|
|
if (orig_alt_group->last_insn->offset + orig_alt_group->last_insn->len -
|
|
orig_alt_group->first_insn->offset != special_alt->orig_len) {
|
|
WARN_INSN(orig_insn, "weirdly overlapping alternative! %ld != %d",
|
|
orig_alt_group->last_insn->offset +
|
|
orig_alt_group->last_insn->len -
|
|
orig_alt_group->first_insn->offset,
|
|
special_alt->orig_len);
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
new_alt_group = malloc(sizeof(*new_alt_group));
|
|
if (!new_alt_group) {
|
|
WARN("malloc failed");
|
|
return -1;
|
|
}
|
|
|
|
if (special_alt->new_len < special_alt->orig_len) {
|
|
/*
|
|
* Insert a fake nop at the end to make the replacement
|
|
* alt_group the same size as the original. This is needed to
|
|
* allow propagate_alt_cfi() to do its magic. When the last
|
|
* instruction affects the stack, the instruction after it (the
|
|
* nop) will propagate the new state to the shared CFI array.
|
|
*/
|
|
nop = malloc(sizeof(*nop));
|
|
if (!nop) {
|
|
WARN("malloc failed");
|
|
return -1;
|
|
}
|
|
memset(nop, 0, sizeof(*nop));
|
|
|
|
nop->sec = special_alt->new_sec;
|
|
nop->offset = special_alt->new_off + special_alt->new_len;
|
|
nop->len = special_alt->orig_len - special_alt->new_len;
|
|
nop->type = INSN_NOP;
|
|
nop->sym = orig_insn->sym;
|
|
nop->alt_group = new_alt_group;
|
|
nop->ignore = orig_insn->ignore_alts;
|
|
}
|
|
|
|
if (!special_alt->new_len) {
|
|
*new_insn = nop;
|
|
goto end;
|
|
}
|
|
|
|
insn = *new_insn;
|
|
sec_for_each_insn_from(file, insn) {
|
|
struct reloc *alt_reloc;
|
|
|
|
if (insn->offset >= special_alt->new_off + special_alt->new_len)
|
|
break;
|
|
|
|
last_new_insn = insn;
|
|
|
|
insn->ignore = orig_insn->ignore_alts;
|
|
insn->sym = orig_insn->sym;
|
|
insn->alt_group = new_alt_group;
|
|
|
|
/*
|
|
* Since alternative replacement code is copy/pasted by the
|
|
* kernel after applying relocations, generally such code can't
|
|
* have relative-address relocation references to outside the
|
|
* .altinstr_replacement section, unless the arch's
|
|
* alternatives code can adjust the relative offsets
|
|
* accordingly.
|
|
*/
|
|
alt_reloc = insn_reloc(file, insn);
|
|
if (alt_reloc && arch_pc_relative_reloc(alt_reloc) &&
|
|
!arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
|
|
|
|
WARN_INSN(insn, "unsupported relocation in alternatives section");
|
|
return -1;
|
|
}
|
|
|
|
if (!is_static_jump(insn))
|
|
continue;
|
|
|
|
if (!insn->immediate)
|
|
continue;
|
|
|
|
dest_off = arch_jump_destination(insn);
|
|
if (dest_off == special_alt->new_off + special_alt->new_len) {
|
|
insn->jump_dest = next_insn_same_sec(file, orig_alt_group->last_insn);
|
|
if (!insn->jump_dest) {
|
|
WARN_INSN(insn, "can't find alternative jump destination");
|
|
return -1;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!last_new_insn) {
|
|
WARN_FUNC("can't find last new alternative instruction",
|
|
special_alt->new_sec, special_alt->new_off);
|
|
return -1;
|
|
}
|
|
|
|
end:
|
|
new_alt_group->orig_group = orig_alt_group;
|
|
new_alt_group->first_insn = *new_insn;
|
|
new_alt_group->last_insn = last_new_insn;
|
|
new_alt_group->nop = nop;
|
|
new_alt_group->cfi = orig_alt_group->cfi;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* A jump table entry can either convert a nop to a jump or a jump to a nop.
|
|
* If the original instruction is a jump, make the alt entry an effective nop
|
|
* by just skipping the original instruction.
|
|
*/
|
|
static int handle_jump_alt(struct objtool_file *file,
|
|
struct special_alt *special_alt,
|
|
struct instruction *orig_insn,
|
|
struct instruction **new_insn)
|
|
{
|
|
if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
|
|
orig_insn->type != INSN_NOP) {
|
|
|
|
WARN_INSN(orig_insn, "unsupported instruction at jump label");
|
|
return -1;
|
|
}
|
|
|
|
if (opts.hack_jump_label && special_alt->key_addend & 2) {
|
|
struct reloc *reloc = insn_reloc(file, orig_insn);
|
|
|
|
if (reloc) {
|
|
reloc->type = R_NONE;
|
|
elf_write_reloc(file->elf, reloc);
|
|
}
|
|
elf_write_insn(file->elf, orig_insn->sec,
|
|
orig_insn->offset, orig_insn->len,
|
|
arch_nop_insn(orig_insn->len));
|
|
orig_insn->type = INSN_NOP;
|
|
}
|
|
|
|
if (orig_insn->type == INSN_NOP) {
|
|
if (orig_insn->len == 2)
|
|
file->jl_nop_short++;
|
|
else
|
|
file->jl_nop_long++;
|
|
|
|
return 0;
|
|
}
|
|
|
|
if (orig_insn->len == 2)
|
|
file->jl_short++;
|
|
else
|
|
file->jl_long++;
|
|
|
|
*new_insn = next_insn_same_sec(file, orig_insn);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Read all the special sections which have alternate instructions which can be
|
|
* patched in or redirected to at runtime. Each instruction having alternate
|
|
* instruction(s) has them added to its insn->alts list, which will be
|
|
* traversed in validate_branch().
|
|
*/
|
|
static int add_special_section_alts(struct objtool_file *file)
|
|
{
|
|
struct list_head special_alts;
|
|
struct instruction *orig_insn, *new_insn;
|
|
struct special_alt *special_alt, *tmp;
|
|
struct alternative *alt;
|
|
int ret;
|
|
|
|
ret = special_get_alts(file->elf, &special_alts);
|
|
if (ret)
|
|
return ret;
|
|
|
|
list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
|
|
|
|
orig_insn = find_insn(file, special_alt->orig_sec,
|
|
special_alt->orig_off);
|
|
if (!orig_insn) {
|
|
WARN_FUNC("special: can't find orig instruction",
|
|
special_alt->orig_sec, special_alt->orig_off);
|
|
ret = -1;
|
|
goto out;
|
|
}
|
|
|
|
new_insn = NULL;
|
|
if (!special_alt->group || special_alt->new_len) {
|
|
new_insn = find_insn(file, special_alt->new_sec,
|
|
special_alt->new_off);
|
|
if (!new_insn) {
|
|
WARN_FUNC("special: can't find new instruction",
|
|
special_alt->new_sec,
|
|
special_alt->new_off);
|
|
ret = -1;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
if (special_alt->group) {
|
|
if (!special_alt->orig_len) {
|
|
WARN_INSN(orig_insn, "empty alternative entry");
|
|
continue;
|
|
}
|
|
|
|
ret = handle_group_alt(file, special_alt, orig_insn,
|
|
&new_insn);
|
|
if (ret)
|
|
goto out;
|
|
} else if (special_alt->jump_or_nop) {
|
|
ret = handle_jump_alt(file, special_alt, orig_insn,
|
|
&new_insn);
|
|
if (ret)
|
|
goto out;
|
|
}
|
|
|
|
alt = malloc(sizeof(*alt));
|
|
if (!alt) {
|
|
WARN("malloc failed");
|
|
ret = -1;
|
|
goto out;
|
|
}
|
|
|
|
alt->insn = new_insn;
|
|
alt->skip_orig = special_alt->skip_orig;
|
|
orig_insn->ignore_alts |= special_alt->skip_alt;
|
|
alt->next = orig_insn->alts;
|
|
orig_insn->alts = alt;
|
|
|
|
list_del(&special_alt->list);
|
|
free(special_alt);
|
|
}
|
|
|
|
if (opts.stats) {
|
|
printf("jl\\\tNOP\tJMP\n");
|
|
printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
|
|
printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
|
|
}
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
static int add_jump_table(struct objtool_file *file, struct instruction *insn,
|
|
struct reloc *table)
|
|
{
|
|
struct reloc *reloc = table;
|
|
struct instruction *dest_insn;
|
|
struct alternative *alt;
|
|
struct symbol *pfunc = insn_func(insn)->pfunc;
|
|
unsigned int prev_offset = 0;
|
|
|
|
/*
|
|
* Each @reloc is a switch table relocation which points to the target
|
|
* instruction.
|
|
*/
|
|
list_for_each_entry_from(reloc, &table->sec->reloc_list, list) {
|
|
|
|
/* Check for the end of the table: */
|
|
if (reloc != table && reloc->jump_table_start)
|
|
break;
|
|
|
|
/* Make sure the table entries are consecutive: */
|
|
if (prev_offset && reloc->offset != prev_offset + 8)
|
|
break;
|
|
|
|
/* Detect function pointers from contiguous objects: */
|
|
if (reloc->sym->sec == pfunc->sec &&
|
|
reloc->addend == pfunc->offset)
|
|
break;
|
|
|
|
dest_insn = find_insn(file, reloc->sym->sec, reloc->addend);
|
|
if (!dest_insn)
|
|
break;
|
|
|
|
/* Make sure the destination is in the same function: */
|
|
if (!insn_func(dest_insn) || insn_func(dest_insn)->pfunc != pfunc)
|
|
break;
|
|
|
|
alt = malloc(sizeof(*alt));
|
|
if (!alt) {
|
|
WARN("malloc failed");
|
|
return -1;
|
|
}
|
|
|
|
alt->insn = dest_insn;
|
|
alt->next = insn->alts;
|
|
insn->alts = alt;
|
|
prev_offset = reloc->offset;
|
|
}
|
|
|
|
if (!prev_offset) {
|
|
WARN_INSN(insn, "can't find switch jump table");
|
|
return -1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* find_jump_table() - Given a dynamic jump, find the switch jump table
|
|
* associated with it.
|
|
*/
|
|
static struct reloc *find_jump_table(struct objtool_file *file,
|
|
struct symbol *func,
|
|
struct instruction *insn)
|
|
{
|
|
struct reloc *table_reloc;
|
|
struct instruction *dest_insn, *orig_insn = insn;
|
|
|
|
/*
|
|
* Backward search using the @first_jump_src links, these help avoid
|
|
* much of the 'in between' code. Which avoids us getting confused by
|
|
* it.
|
|
*/
|
|
for (;
|
|
insn && insn_func(insn) && insn_func(insn)->pfunc == func;
|
|
insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
|
|
|
|
if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
|
|
break;
|
|
|
|
/* allow small jumps within the range */
|
|
if (insn->type == INSN_JUMP_UNCONDITIONAL &&
|
|
insn->jump_dest &&
|
|
(insn->jump_dest->offset <= insn->offset ||
|
|
insn->jump_dest->offset > orig_insn->offset))
|
|
break;
|
|
|
|
table_reloc = arch_find_switch_table(file, insn);
|
|
if (!table_reloc)
|
|
continue;
|
|
dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
|
|
if (!dest_insn || !insn_func(dest_insn) || insn_func(dest_insn)->pfunc != func)
|
|
continue;
|
|
|
|
return table_reloc;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* First pass: Mark the head of each jump table so that in the next pass,
|
|
* we know when a given jump table ends and the next one starts.
|
|
*/
|
|
static void mark_func_jump_tables(struct objtool_file *file,
|
|
struct symbol *func)
|
|
{
|
|
struct instruction *insn, *last = NULL;
|
|
struct reloc *reloc;
|
|
|
|
func_for_each_insn(file, func, insn) {
|
|
if (!last)
|
|
last = insn;
|
|
|
|
/*
|
|
* Store back-pointers for unconditional forward jumps such
|
|
* that find_jump_table() can back-track using those and
|
|
* avoid some potentially confusing code.
|
|
*/
|
|
if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
|
|
insn->offset > last->offset &&
|
|
insn->jump_dest->offset > insn->offset &&
|
|
!insn->jump_dest->first_jump_src) {
|
|
|
|
insn->jump_dest->first_jump_src = insn;
|
|
last = insn->jump_dest;
|
|
}
|
|
|
|
if (insn->type != INSN_JUMP_DYNAMIC)
|
|
continue;
|
|
|
|
reloc = find_jump_table(file, func, insn);
|
|
if (reloc) {
|
|
reloc->jump_table_start = true;
|
|
insn->_jump_table = reloc;
|
|
}
|
|
}
|
|
}
|
|
|
|
static int add_func_jump_tables(struct objtool_file *file,
|
|
struct symbol *func)
|
|
{
|
|
struct instruction *insn;
|
|
int ret;
|
|
|
|
func_for_each_insn(file, func, insn) {
|
|
if (!insn_jump_table(insn))
|
|
continue;
|
|
|
|
ret = add_jump_table(file, insn, insn_jump_table(insn));
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* For some switch statements, gcc generates a jump table in the .rodata
|
|
* section which contains a list of addresses within the function to jump to.
|
|
* This finds these jump tables and adds them to the insn->alts lists.
|
|
*/
|
|
static int add_jump_table_alts(struct objtool_file *file)
|
|
{
|
|
struct symbol *func;
|
|
int ret;
|
|
|
|
if (!file->rodata)
|
|
return 0;
|
|
|
|
for_each_sym(file, func) {
|
|
if (func->type != STT_FUNC)
|
|
continue;
|
|
|
|
mark_func_jump_tables(file, func);
|
|
ret = add_func_jump_tables(file, func);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void set_func_state(struct cfi_state *state)
|
|
{
|
|
state->cfa = initial_func_cfi.cfa;
|
|
memcpy(&state->regs, &initial_func_cfi.regs,
|
|
CFI_NUM_REGS * sizeof(struct cfi_reg));
|
|
state->stack_size = initial_func_cfi.cfa.offset;
|
|
state->type = UNWIND_HINT_TYPE_CALL;
|
|
}
|
|
|
|
static int read_unwind_hints(struct objtool_file *file)
|
|
{
|
|
struct cfi_state cfi = init_cfi;
|
|
struct section *sec, *relocsec;
|
|
struct unwind_hint *hint;
|
|
struct instruction *insn;
|
|
struct reloc *reloc;
|
|
int i;
|
|
|
|
sec = find_section_by_name(file->elf, ".discard.unwind_hints");
|
|
if (!sec)
|
|
return 0;
|
|
|
|
relocsec = sec->reloc;
|
|
if (!relocsec) {
|
|
WARN("missing .rela.discard.unwind_hints section");
|
|
return -1;
|
|
}
|
|
|
|
if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
|
|
WARN("struct unwind_hint size mismatch");
|
|
return -1;
|
|
}
|
|
|
|
file->hints = true;
|
|
|
|
for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
|
|
hint = (struct unwind_hint *)sec->data->d_buf + i;
|
|
|
|
reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
|
|
if (!reloc) {
|
|
WARN("can't find reloc for unwind_hints[%d]", i);
|
|
return -1;
|
|
}
|
|
|
|
insn = find_insn(file, reloc->sym->sec, reloc->addend);
|
|
if (!insn) {
|
|
WARN("can't find insn for unwind_hints[%d]", i);
|
|
return -1;
|
|
}
|
|
|
|
insn->hint = true;
|
|
|
|
if (hint->type == UNWIND_HINT_TYPE_SAVE) {
|
|
insn->hint = false;
|
|
insn->save = true;
|
|
continue;
|
|
}
|
|
|
|
if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
|
|
insn->restore = true;
|
|
continue;
|
|
}
|
|
|
|
if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
|
|
struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
|
|
|
|
if (sym && sym->bind == STB_GLOBAL) {
|
|
if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
|
|
WARN_INSN(insn, "UNWIND_HINT_IRET_REGS without ENDBR");
|
|
}
|
|
}
|
|
}
|
|
|
|
if (hint->type == UNWIND_HINT_TYPE_FUNC) {
|
|
insn->cfi = &func_cfi;
|
|
continue;
|
|
}
|
|
|
|
if (insn->cfi)
|
|
cfi = *(insn->cfi);
|
|
|
|
if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
|
|
WARN_INSN(insn, "unsupported unwind_hint sp base reg %d", hint->sp_reg);
|
|
return -1;
|
|
}
|
|
|
|
cfi.cfa.offset = bswap_if_needed(file->elf, hint->sp_offset);
|
|
cfi.type = hint->type;
|
|
cfi.signal = hint->signal;
|
|
|
|
insn->cfi = cfi_hash_find_or_add(&cfi);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int read_noendbr_hints(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
struct instruction *insn;
|
|
struct reloc *reloc;
|
|
|
|
sec = find_section_by_name(file->elf, ".rela.discard.noendbr");
|
|
if (!sec)
|
|
return 0;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
insn = find_insn(file, reloc->sym->sec, reloc->sym->offset + reloc->addend);
|
|
if (!insn) {
|
|
WARN("bad .discard.noendbr entry");
|
|
return -1;
|
|
}
|
|
|
|
insn->noendbr = 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int read_retpoline_hints(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
struct instruction *insn;
|
|
struct reloc *reloc;
|
|
|
|
sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
|
|
if (!sec)
|
|
return 0;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
if (reloc->sym->type != STT_SECTION) {
|
|
WARN("unexpected relocation symbol type in %s", sec->name);
|
|
return -1;
|
|
}
|
|
|
|
insn = find_insn(file, reloc->sym->sec, reloc->addend);
|
|
if (!insn) {
|
|
WARN("bad .discard.retpoline_safe entry");
|
|
return -1;
|
|
}
|
|
|
|
if (insn->type != INSN_JUMP_DYNAMIC &&
|
|
insn->type != INSN_CALL_DYNAMIC &&
|
|
insn->type != INSN_RETURN &&
|
|
insn->type != INSN_NOP) {
|
|
WARN_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
|
|
return -1;
|
|
}
|
|
|
|
insn->retpoline_safe = true;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int read_instr_hints(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
struct instruction *insn;
|
|
struct reloc *reloc;
|
|
|
|
sec = find_section_by_name(file->elf, ".rela.discard.instr_end");
|
|
if (!sec)
|
|
return 0;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
if (reloc->sym->type != STT_SECTION) {
|
|
WARN("unexpected relocation symbol type in %s", sec->name);
|
|
return -1;
|
|
}
|
|
|
|
insn = find_insn(file, reloc->sym->sec, reloc->addend);
|
|
if (!insn) {
|
|
WARN("bad .discard.instr_end entry");
|
|
return -1;
|
|
}
|
|
|
|
insn->instr--;
|
|
}
|
|
|
|
sec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
|
|
if (!sec)
|
|
return 0;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
if (reloc->sym->type != STT_SECTION) {
|
|
WARN("unexpected relocation symbol type in %s", sec->name);
|
|
return -1;
|
|
}
|
|
|
|
insn = find_insn(file, reloc->sym->sec, reloc->addend);
|
|
if (!insn) {
|
|
WARN("bad .discard.instr_begin entry");
|
|
return -1;
|
|
}
|
|
|
|
insn->instr++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int read_validate_unret_hints(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
struct instruction *insn;
|
|
struct reloc *reloc;
|
|
|
|
sec = find_section_by_name(file->elf, ".rela.discard.validate_unret");
|
|
if (!sec)
|
|
return 0;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
if (reloc->sym->type != STT_SECTION) {
|
|
WARN("unexpected relocation symbol type in %s", sec->name);
|
|
return -1;
|
|
}
|
|
|
|
insn = find_insn(file, reloc->sym->sec, reloc->addend);
|
|
if (!insn) {
|
|
WARN("bad .discard.instr_end entry");
|
|
return -1;
|
|
}
|
|
insn->unret = 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
static int read_intra_function_calls(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn;
|
|
struct section *sec;
|
|
struct reloc *reloc;
|
|
|
|
sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
|
|
if (!sec)
|
|
return 0;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
unsigned long dest_off;
|
|
|
|
if (reloc->sym->type != STT_SECTION) {
|
|
WARN("unexpected relocation symbol type in %s",
|
|
sec->name);
|
|
return -1;
|
|
}
|
|
|
|
insn = find_insn(file, reloc->sym->sec, reloc->addend);
|
|
if (!insn) {
|
|
WARN("bad .discard.intra_function_call entry");
|
|
return -1;
|
|
}
|
|
|
|
if (insn->type != INSN_CALL) {
|
|
WARN_INSN(insn, "intra_function_call not a direct call");
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* Treat intra-function CALLs as JMPs, but with a stack_op.
|
|
* See add_call_destinations(), which strips stack_ops from
|
|
* normal CALLs.
|
|
*/
|
|
insn->type = INSN_JUMP_UNCONDITIONAL;
|
|
|
|
dest_off = arch_jump_destination(insn);
|
|
insn->jump_dest = find_insn(file, insn->sec, dest_off);
|
|
if (!insn->jump_dest) {
|
|
WARN_INSN(insn, "can't find call dest at %s+0x%lx",
|
|
insn->sec->name, dest_off);
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Return true if name matches an instrumentation function, where calls to that
|
|
* function from noinstr code can safely be removed, but compilers won't do so.
|
|
*/
|
|
static bool is_profiling_func(const char *name)
|
|
{
|
|
/*
|
|
* Many compilers cannot disable KCOV with a function attribute.
|
|
*/
|
|
if (!strncmp(name, "__sanitizer_cov_", 16))
|
|
return true;
|
|
|
|
/*
|
|
* Some compilers currently do not remove __tsan_func_entry/exit nor
|
|
* __tsan_atomic_signal_fence (used for barrier instrumentation) with
|
|
* the __no_sanitize_thread attribute, remove them. Once the kernel's
|
|
* minimum Clang version is 14.0, this can be removed.
|
|
*/
|
|
if (!strncmp(name, "__tsan_func_", 12) ||
|
|
!strcmp(name, "__tsan_atomic_signal_fence"))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static int classify_symbols(struct objtool_file *file)
|
|
{
|
|
struct symbol *func;
|
|
|
|
for_each_sym(file, func) {
|
|
if (func->bind != STB_GLOBAL)
|
|
continue;
|
|
|
|
if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
|
|
strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
|
|
func->static_call_tramp = true;
|
|
|
|
if (arch_is_retpoline(func))
|
|
func->retpoline_thunk = true;
|
|
|
|
if (arch_is_rethunk(func))
|
|
func->return_thunk = true;
|
|
|
|
if (arch_ftrace_match(func->name))
|
|
func->fentry = true;
|
|
|
|
if (is_profiling_func(func->name))
|
|
func->profiling_func = true;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void mark_rodata(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
bool found = false;
|
|
|
|
/*
|
|
* Search for the following rodata sections, each of which can
|
|
* potentially contain jump tables:
|
|
*
|
|
* - .rodata: can contain GCC switch tables
|
|
* - .rodata.<func>: same, if -fdata-sections is being used
|
|
* - .rodata..c_jump_table: contains C annotated jump tables
|
|
*
|
|
* .rodata.str1.* sections are ignored; they don't contain jump tables.
|
|
*/
|
|
for_each_sec(file, sec) {
|
|
if (!strncmp(sec->name, ".rodata", 7) &&
|
|
!strstr(sec->name, ".str1.")) {
|
|
sec->rodata = true;
|
|
found = true;
|
|
}
|
|
}
|
|
|
|
file->rodata = found;
|
|
}
|
|
|
|
static int decode_sections(struct objtool_file *file)
|
|
{
|
|
int ret;
|
|
|
|
mark_rodata(file);
|
|
|
|
ret = init_pv_ops(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/*
|
|
* Must be before add_{jump_call}_destination.
|
|
*/
|
|
ret = classify_symbols(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = decode_instructions(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
add_ignores(file);
|
|
add_uaccess_safe(file);
|
|
|
|
ret = add_ignore_alternatives(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/*
|
|
* Must be before read_unwind_hints() since that needs insn->noendbr.
|
|
*/
|
|
ret = read_noendbr_hints(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/*
|
|
* Must be before add_jump_destinations(), which depends on 'func'
|
|
* being set for alternatives, to enable proper sibling call detection.
|
|
*/
|
|
if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr) {
|
|
ret = add_special_section_alts(file);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
ret = add_jump_destinations(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/*
|
|
* Must be before add_call_destination(); it changes INSN_CALL to
|
|
* INSN_JUMP.
|
|
*/
|
|
ret = read_intra_function_calls(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = add_call_destinations(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/*
|
|
* Must be after add_call_destinations() such that it can override
|
|
* dead_end_function() marks.
|
|
*/
|
|
ret = add_dead_ends(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = add_jump_table_alts(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = read_unwind_hints(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = read_retpoline_hints(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = read_instr_hints(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = read_validate_unret_hints(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static bool is_fentry_call(struct instruction *insn)
|
|
{
|
|
if (insn->type == INSN_CALL &&
|
|
insn_call_dest(insn) &&
|
|
insn_call_dest(insn)->fentry)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
|
|
{
|
|
struct cfi_state *cfi = &state->cfi;
|
|
int i;
|
|
|
|
if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
|
|
return true;
|
|
|
|
if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
|
|
return true;
|
|
|
|
if (cfi->stack_size != initial_func_cfi.cfa.offset)
|
|
return true;
|
|
|
|
for (i = 0; i < CFI_NUM_REGS; i++) {
|
|
if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
|
|
cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
static bool check_reg_frame_pos(const struct cfi_reg *reg,
|
|
int expected_offset)
|
|
{
|
|
return reg->base == CFI_CFA &&
|
|
reg->offset == expected_offset;
|
|
}
|
|
|
|
static bool has_valid_stack_frame(struct insn_state *state)
|
|
{
|
|
struct cfi_state *cfi = &state->cfi;
|
|
|
|
if (cfi->cfa.base == CFI_BP &&
|
|
check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
|
|
check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
|
|
return true;
|
|
|
|
if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static int update_cfi_state_regs(struct instruction *insn,
|
|
struct cfi_state *cfi,
|
|
struct stack_op *op)
|
|
{
|
|
struct cfi_reg *cfa = &cfi->cfa;
|
|
|
|
if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
|
|
return 0;
|
|
|
|
/* push */
|
|
if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
|
|
cfa->offset += 8;
|
|
|
|
/* pop */
|
|
if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
|
|
cfa->offset -= 8;
|
|
|
|
/* add immediate to sp */
|
|
if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
|
|
op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
|
|
cfa->offset -= op->src.offset;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
|
|
{
|
|
if (arch_callee_saved_reg(reg) &&
|
|
cfi->regs[reg].base == CFI_UNDEFINED) {
|
|
cfi->regs[reg].base = base;
|
|
cfi->regs[reg].offset = offset;
|
|
}
|
|
}
|
|
|
|
static void restore_reg(struct cfi_state *cfi, unsigned char reg)
|
|
{
|
|
cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
|
|
cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
|
|
}
|
|
|
|
/*
|
|
* A note about DRAP stack alignment:
|
|
*
|
|
* GCC has the concept of a DRAP register, which is used to help keep track of
|
|
* the stack pointer when aligning the stack. r10 or r13 is used as the DRAP
|
|
* register. The typical DRAP pattern is:
|
|
*
|
|
* 4c 8d 54 24 08 lea 0x8(%rsp),%r10
|
|
* 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
|
|
* 41 ff 72 f8 pushq -0x8(%r10)
|
|
* 55 push %rbp
|
|
* 48 89 e5 mov %rsp,%rbp
|
|
* (more pushes)
|
|
* 41 52 push %r10
|
|
* ...
|
|
* 41 5a pop %r10
|
|
* (more pops)
|
|
* 5d pop %rbp
|
|
* 49 8d 62 f8 lea -0x8(%r10),%rsp
|
|
* c3 retq
|
|
*
|
|
* There are some variations in the epilogues, like:
|
|
*
|
|
* 5b pop %rbx
|
|
* 41 5a pop %r10
|
|
* 41 5c pop %r12
|
|
* 41 5d pop %r13
|
|
* 41 5e pop %r14
|
|
* c9 leaveq
|
|
* 49 8d 62 f8 lea -0x8(%r10),%rsp
|
|
* c3 retq
|
|
*
|
|
* and:
|
|
*
|
|
* 4c 8b 55 e8 mov -0x18(%rbp),%r10
|
|
* 48 8b 5d e0 mov -0x20(%rbp),%rbx
|
|
* 4c 8b 65 f0 mov -0x10(%rbp),%r12
|
|
* 4c 8b 6d f8 mov -0x8(%rbp),%r13
|
|
* c9 leaveq
|
|
* 49 8d 62 f8 lea -0x8(%r10),%rsp
|
|
* c3 retq
|
|
*
|
|
* Sometimes r13 is used as the DRAP register, in which case it's saved and
|
|
* restored beforehand:
|
|
*
|
|
* 41 55 push %r13
|
|
* 4c 8d 6c 24 10 lea 0x10(%rsp),%r13
|
|
* 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
|
|
* ...
|
|
* 49 8d 65 f0 lea -0x10(%r13),%rsp
|
|
* 41 5d pop %r13
|
|
* c3 retq
|
|
*/
|
|
static int update_cfi_state(struct instruction *insn,
|
|
struct instruction *next_insn,
|
|
struct cfi_state *cfi, struct stack_op *op)
|
|
{
|
|
struct cfi_reg *cfa = &cfi->cfa;
|
|
struct cfi_reg *regs = cfi->regs;
|
|
|
|
/* stack operations don't make sense with an undefined CFA */
|
|
if (cfa->base == CFI_UNDEFINED) {
|
|
if (insn_func(insn)) {
|
|
WARN_INSN(insn, "undefined stack state");
|
|
return -1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
if (cfi->type == UNWIND_HINT_TYPE_REGS ||
|
|
cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
|
|
return update_cfi_state_regs(insn, cfi, op);
|
|
|
|
switch (op->dest.type) {
|
|
|
|
case OP_DEST_REG:
|
|
switch (op->src.type) {
|
|
|
|
case OP_SRC_REG:
|
|
if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
|
|
cfa->base == CFI_SP &&
|
|
check_reg_frame_pos(®s[CFI_BP], -cfa->offset)) {
|
|
|
|
/* mov %rsp, %rbp */
|
|
cfa->base = op->dest.reg;
|
|
cfi->bp_scratch = false;
|
|
}
|
|
|
|
else if (op->src.reg == CFI_SP &&
|
|
op->dest.reg == CFI_BP && cfi->drap) {
|
|
|
|
/* drap: mov %rsp, %rbp */
|
|
regs[CFI_BP].base = CFI_BP;
|
|
regs[CFI_BP].offset = -cfi->stack_size;
|
|
cfi->bp_scratch = false;
|
|
}
|
|
|
|
else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
|
|
|
|
/*
|
|
* mov %rsp, %reg
|
|
*
|
|
* This is needed for the rare case where GCC
|
|
* does:
|
|
*
|
|
* mov %rsp, %rax
|
|
* ...
|
|
* mov %rax, %rsp
|
|
*/
|
|
cfi->vals[op->dest.reg].base = CFI_CFA;
|
|
cfi->vals[op->dest.reg].offset = -cfi->stack_size;
|
|
}
|
|
|
|
else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
|
|
(cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) {
|
|
|
|
/*
|
|
* mov %rbp, %rsp
|
|
*
|
|
* Restore the original stack pointer (Clang).
|
|
*/
|
|
cfi->stack_size = -cfi->regs[CFI_BP].offset;
|
|
}
|
|
|
|
else if (op->dest.reg == cfa->base) {
|
|
|
|
/* mov %reg, %rsp */
|
|
if (cfa->base == CFI_SP &&
|
|
cfi->vals[op->src.reg].base == CFI_CFA) {
|
|
|
|
/*
|
|
* This is needed for the rare case
|
|
* where GCC does something dumb like:
|
|
*
|
|
* lea 0x8(%rsp), %rcx
|
|
* ...
|
|
* mov %rcx, %rsp
|
|
*/
|
|
cfa->offset = -cfi->vals[op->src.reg].offset;
|
|
cfi->stack_size = cfa->offset;
|
|
|
|
} else if (cfa->base == CFI_SP &&
|
|
cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
|
|
cfi->vals[op->src.reg].offset == cfa->offset) {
|
|
|
|
/*
|
|
* Stack swizzle:
|
|
*
|
|
* 1: mov %rsp, (%[tos])
|
|
* 2: mov %[tos], %rsp
|
|
* ...
|
|
* 3: pop %rsp
|
|
*
|
|
* Where:
|
|
*
|
|
* 1 - places a pointer to the previous
|
|
* stack at the Top-of-Stack of the
|
|
* new stack.
|
|
*
|
|
* 2 - switches to the new stack.
|
|
*
|
|
* 3 - pops the Top-of-Stack to restore
|
|
* the original stack.
|
|
*
|
|
* Note: we set base to SP_INDIRECT
|
|
* here and preserve offset. Therefore
|
|
* when the unwinder reaches ToS it
|
|
* will dereference SP and then add the
|
|
* offset to find the next frame, IOW:
|
|
* (%rsp) + offset.
|
|
*/
|
|
cfa->base = CFI_SP_INDIRECT;
|
|
|
|
} else {
|
|
cfa->base = CFI_UNDEFINED;
|
|
cfa->offset = 0;
|
|
}
|
|
}
|
|
|
|
else if (op->dest.reg == CFI_SP &&
|
|
cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
|
|
cfi->vals[op->src.reg].offset == cfa->offset) {
|
|
|
|
/*
|
|
* The same stack swizzle case 2) as above. But
|
|
* because we can't change cfa->base, case 3)
|
|
* will become a regular POP. Pretend we're a
|
|
* PUSH so things don't go unbalanced.
|
|
*/
|
|
cfi->stack_size += 8;
|
|
}
|
|
|
|
|
|
break;
|
|
|
|
case OP_SRC_ADD:
|
|
if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
|
|
|
|
/* add imm, %rsp */
|
|
cfi->stack_size -= op->src.offset;
|
|
if (cfa->base == CFI_SP)
|
|
cfa->offset -= op->src.offset;
|
|
break;
|
|
}
|
|
|
|
if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
|
|
|
|
/* lea disp(%rbp), %rsp */
|
|
cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
|
|
break;
|
|
}
|
|
|
|
if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
|
|
|
|
/* drap: lea disp(%rsp), %drap */
|
|
cfi->drap_reg = op->dest.reg;
|
|
|
|
/*
|
|
* lea disp(%rsp), %reg
|
|
*
|
|
* This is needed for the rare case where GCC
|
|
* does something dumb like:
|
|
*
|
|
* lea 0x8(%rsp), %rcx
|
|
* ...
|
|
* mov %rcx, %rsp
|
|
*/
|
|
cfi->vals[op->dest.reg].base = CFI_CFA;
|
|
cfi->vals[op->dest.reg].offset = \
|
|
-cfi->stack_size + op->src.offset;
|
|
|
|
break;
|
|
}
|
|
|
|
if (cfi->drap && op->dest.reg == CFI_SP &&
|
|
op->src.reg == cfi->drap_reg) {
|
|
|
|
/* drap: lea disp(%drap), %rsp */
|
|
cfa->base = CFI_SP;
|
|
cfa->offset = cfi->stack_size = -op->src.offset;
|
|
cfi->drap_reg = CFI_UNDEFINED;
|
|
cfi->drap = false;
|
|
break;
|
|
}
|
|
|
|
if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) {
|
|
WARN_INSN(insn, "unsupported stack register modification");
|
|
return -1;
|
|
}
|
|
|
|
break;
|
|
|
|
case OP_SRC_AND:
|
|
if (op->dest.reg != CFI_SP ||
|
|
(cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
|
|
(cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
|
|
WARN_INSN(insn, "unsupported stack pointer realignment");
|
|
return -1;
|
|
}
|
|
|
|
if (cfi->drap_reg != CFI_UNDEFINED) {
|
|
/* drap: and imm, %rsp */
|
|
cfa->base = cfi->drap_reg;
|
|
cfa->offset = cfi->stack_size = 0;
|
|
cfi->drap = true;
|
|
}
|
|
|
|
/*
|
|
* Older versions of GCC (4.8ish) realign the stack
|
|
* without DRAP, with a frame pointer.
|
|
*/
|
|
|
|
break;
|
|
|
|
case OP_SRC_POP:
|
|
case OP_SRC_POPF:
|
|
if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {
|
|
|
|
/* pop %rsp; # restore from a stack swizzle */
|
|
cfa->base = CFI_SP;
|
|
break;
|
|
}
|
|
|
|
if (!cfi->drap && op->dest.reg == cfa->base) {
|
|
|
|
/* pop %rbp */
|
|
cfa->base = CFI_SP;
|
|
}
|
|
|
|
if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
|
|
op->dest.reg == cfi->drap_reg &&
|
|
cfi->drap_offset == -cfi->stack_size) {
|
|
|
|
/* drap: pop %drap */
|
|
cfa->base = cfi->drap_reg;
|
|
cfa->offset = 0;
|
|
cfi->drap_offset = -1;
|
|
|
|
} else if (cfi->stack_size == -regs[op->dest.reg].offset) {
|
|
|
|
/* pop %reg */
|
|
restore_reg(cfi, op->dest.reg);
|
|
}
|
|
|
|
cfi->stack_size -= 8;
|
|
if (cfa->base == CFI_SP)
|
|
cfa->offset -= 8;
|
|
|
|
break;
|
|
|
|
case OP_SRC_REG_INDIRECT:
|
|
if (!cfi->drap && op->dest.reg == cfa->base &&
|
|
op->dest.reg == CFI_BP) {
|
|
|
|
/* mov disp(%rsp), %rbp */
|
|
cfa->base = CFI_SP;
|
|
cfa->offset = cfi->stack_size;
|
|
}
|
|
|
|
if (cfi->drap && op->src.reg == CFI_BP &&
|
|
op->src.offset == cfi->drap_offset) {
|
|
|
|
/* drap: mov disp(%rbp), %drap */
|
|
cfa->base = cfi->drap_reg;
|
|
cfa->offset = 0;
|
|
cfi->drap_offset = -1;
|
|
}
|
|
|
|
if (cfi->drap && op->src.reg == CFI_BP &&
|
|
op->src.offset == regs[op->dest.reg].offset) {
|
|
|
|
/* drap: mov disp(%rbp), %reg */
|
|
restore_reg(cfi, op->dest.reg);
|
|
|
|
} else if (op->src.reg == cfa->base &&
|
|
op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
|
|
|
|
/* mov disp(%rbp), %reg */
|
|
/* mov disp(%rsp), %reg */
|
|
restore_reg(cfi, op->dest.reg);
|
|
|
|
} else if (op->src.reg == CFI_SP &&
|
|
op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
|
|
|
|
/* mov disp(%rsp), %reg */
|
|
restore_reg(cfi, op->dest.reg);
|
|
}
|
|
|
|
break;
|
|
|
|
default:
|
|
WARN_INSN(insn, "unknown stack-related instruction");
|
|
return -1;
|
|
}
|
|
|
|
break;
|
|
|
|
case OP_DEST_PUSH:
|
|
case OP_DEST_PUSHF:
|
|
cfi->stack_size += 8;
|
|
if (cfa->base == CFI_SP)
|
|
cfa->offset += 8;
|
|
|
|
if (op->src.type != OP_SRC_REG)
|
|
break;
|
|
|
|
if (cfi->drap) {
|
|
if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
|
|
|
|
/* drap: push %drap */
|
|
cfa->base = CFI_BP_INDIRECT;
|
|
cfa->offset = -cfi->stack_size;
|
|
|
|
/* save drap so we know when to restore it */
|
|
cfi->drap_offset = -cfi->stack_size;
|
|
|
|
} else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
|
|
|
|
/* drap: push %rbp */
|
|
cfi->stack_size = 0;
|
|
|
|
} else {
|
|
|
|
/* drap: push %reg */
|
|
save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
|
|
}
|
|
|
|
} else {
|
|
|
|
/* push %reg */
|
|
save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
|
|
}
|
|
|
|
/* detect when asm code uses rbp as a scratch register */
|
|
if (opts.stackval && insn_func(insn) && op->src.reg == CFI_BP &&
|
|
cfa->base != CFI_BP)
|
|
cfi->bp_scratch = true;
|
|
break;
|
|
|
|
case OP_DEST_REG_INDIRECT:
|
|
|
|
if (cfi->drap) {
|
|
if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
|
|
|
|
/* drap: mov %drap, disp(%rbp) */
|
|
cfa->base = CFI_BP_INDIRECT;
|
|
cfa->offset = op->dest.offset;
|
|
|
|
/* save drap offset so we know when to restore it */
|
|
cfi->drap_offset = op->dest.offset;
|
|
} else {
|
|
|
|
/* drap: mov reg, disp(%rbp) */
|
|
save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
|
|
}
|
|
|
|
} else if (op->dest.reg == cfa->base) {
|
|
|
|
/* mov reg, disp(%rbp) */
|
|
/* mov reg, disp(%rsp) */
|
|
save_reg(cfi, op->src.reg, CFI_CFA,
|
|
op->dest.offset - cfi->cfa.offset);
|
|
|
|
} else if (op->dest.reg == CFI_SP) {
|
|
|
|
/* mov reg, disp(%rsp) */
|
|
save_reg(cfi, op->src.reg, CFI_CFA,
|
|
op->dest.offset - cfi->stack_size);
|
|
|
|
} else if (op->src.reg == CFI_SP && op->dest.offset == 0) {
|
|
|
|
/* mov %rsp, (%reg); # setup a stack swizzle. */
|
|
cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
|
|
cfi->vals[op->dest.reg].offset = cfa->offset;
|
|
}
|
|
|
|
break;
|
|
|
|
case OP_DEST_MEM:
|
|
if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
|
|
WARN_INSN(insn, "unknown stack-related memory operation");
|
|
return -1;
|
|
}
|
|
|
|
/* pop mem */
|
|
cfi->stack_size -= 8;
|
|
if (cfa->base == CFI_SP)
|
|
cfa->offset -= 8;
|
|
|
|
break;
|
|
|
|
default:
|
|
WARN_INSN(insn, "unknown stack-related instruction");
|
|
return -1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* The stack layouts of alternatives instructions can sometimes diverge when
|
|
* they have stack modifications. That's fine as long as the potential stack
|
|
* layouts don't conflict at any given potential instruction boundary.
|
|
*
|
|
* Flatten the CFIs of the different alternative code streams (both original
|
|
* and replacement) into a single shared CFI array which can be used to detect
|
|
* conflicts and nicely feed a linear array of ORC entries to the unwinder.
|
|
*/
|
|
static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
|
|
{
|
|
struct cfi_state **alt_cfi;
|
|
int group_off;
|
|
|
|
if (!insn->alt_group)
|
|
return 0;
|
|
|
|
if (!insn->cfi) {
|
|
WARN("CFI missing");
|
|
return -1;
|
|
}
|
|
|
|
alt_cfi = insn->alt_group->cfi;
|
|
group_off = insn->offset - insn->alt_group->first_insn->offset;
|
|
|
|
if (!alt_cfi[group_off]) {
|
|
alt_cfi[group_off] = insn->cfi;
|
|
} else {
|
|
if (cficmp(alt_cfi[group_off], insn->cfi)) {
|
|
struct alt_group *orig_group = insn->alt_group->orig_group ?: insn->alt_group;
|
|
struct instruction *orig = orig_group->first_insn;
|
|
char *where = offstr(insn->sec, insn->offset);
|
|
WARN_INSN(orig, "stack layout conflict in alternatives: %s", where);
|
|
free(where);
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int handle_insn_ops(struct instruction *insn,
|
|
struct instruction *next_insn,
|
|
struct insn_state *state)
|
|
{
|
|
struct stack_op *op;
|
|
|
|
for (op = insn->stack_ops; op; op = op->next) {
|
|
|
|
if (update_cfi_state(insn, next_insn, &state->cfi, op))
|
|
return 1;
|
|
|
|
if (!insn->alt_group)
|
|
continue;
|
|
|
|
if (op->dest.type == OP_DEST_PUSHF) {
|
|
if (!state->uaccess_stack) {
|
|
state->uaccess_stack = 1;
|
|
} else if (state->uaccess_stack >> 31) {
|
|
WARN_INSN(insn, "PUSHF stack exhausted");
|
|
return 1;
|
|
}
|
|
state->uaccess_stack <<= 1;
|
|
state->uaccess_stack |= state->uaccess;
|
|
}
|
|
|
|
if (op->src.type == OP_SRC_POPF) {
|
|
if (state->uaccess_stack) {
|
|
state->uaccess = state->uaccess_stack & 1;
|
|
state->uaccess_stack >>= 1;
|
|
if (state->uaccess_stack == 1)
|
|
state->uaccess_stack = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
|
|
{
|
|
struct cfi_state *cfi1 = insn->cfi;
|
|
int i;
|
|
|
|
if (!cfi1) {
|
|
WARN("CFI missing");
|
|
return false;
|
|
}
|
|
|
|
if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
|
|
|
|
WARN_INSN(insn, "stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
|
|
cfi1->cfa.base, cfi1->cfa.offset,
|
|
cfi2->cfa.base, cfi2->cfa.offset);
|
|
|
|
} else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
|
|
for (i = 0; i < CFI_NUM_REGS; i++) {
|
|
if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
|
|
sizeof(struct cfi_reg)))
|
|
continue;
|
|
|
|
WARN_INSN(insn, "stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
|
|
i, cfi1->regs[i].base, cfi1->regs[i].offset,
|
|
i, cfi2->regs[i].base, cfi2->regs[i].offset);
|
|
break;
|
|
}
|
|
|
|
} else if (cfi1->type != cfi2->type) {
|
|
|
|
WARN_INSN(insn, "stack state mismatch: type1=%d type2=%d",
|
|
cfi1->type, cfi2->type);
|
|
|
|
} else if (cfi1->drap != cfi2->drap ||
|
|
(cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
|
|
(cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
|
|
|
|
WARN_INSN(insn, "stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
|
|
cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
|
|
cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
|
|
|
|
} else
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static inline bool func_uaccess_safe(struct symbol *func)
|
|
{
|
|
if (func)
|
|
return func->uaccess_safe;
|
|
|
|
return false;
|
|
}
|
|
|
|
static inline const char *call_dest_name(struct instruction *insn)
|
|
{
|
|
static char pvname[19];
|
|
struct reloc *rel;
|
|
int idx;
|
|
|
|
if (insn_call_dest(insn))
|
|
return insn_call_dest(insn)->name;
|
|
|
|
rel = insn_reloc(NULL, insn);
|
|
if (rel && !strcmp(rel->sym->name, "pv_ops")) {
|
|
idx = (rel->addend / sizeof(void *));
|
|
snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
|
|
return pvname;
|
|
}
|
|
|
|
return "{dynamic}";
|
|
}
|
|
|
|
static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
|
|
{
|
|
struct symbol *target;
|
|
struct reloc *rel;
|
|
int idx;
|
|
|
|
rel = insn_reloc(file, insn);
|
|
if (!rel || strcmp(rel->sym->name, "pv_ops"))
|
|
return false;
|
|
|
|
idx = (arch_dest_reloc_offset(rel->addend) / sizeof(void *));
|
|
|
|
if (file->pv_ops[idx].clean)
|
|
return true;
|
|
|
|
file->pv_ops[idx].clean = true;
|
|
|
|
list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) {
|
|
if (!target->sec->noinstr) {
|
|
WARN("pv_ops[%d]: %s", idx, target->name);
|
|
file->pv_ops[idx].clean = false;
|
|
}
|
|
}
|
|
|
|
return file->pv_ops[idx].clean;
|
|
}
|
|
|
|
static inline bool noinstr_call_dest(struct objtool_file *file,
|
|
struct instruction *insn,
|
|
struct symbol *func)
|
|
{
|
|
/*
|
|
* We can't deal with indirect function calls at present;
|
|
* assume they're instrumented.
|
|
*/
|
|
if (!func) {
|
|
if (file->pv_ops)
|
|
return pv_call_dest(file, insn);
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* If the symbol is from a noinstr section; we good.
|
|
*/
|
|
if (func->sec->noinstr)
|
|
return true;
|
|
|
|
/*
|
|
* If the symbol is a static_call trampoline, we can't tell.
|
|
*/
|
|
if (func->static_call_tramp)
|
|
return true;
|
|
|
|
/*
|
|
* The __ubsan_handle_*() calls are like WARN(), they only happen when
|
|
* something 'BAD' happened. At the risk of taking the machine down,
|
|
* let them proceed to get the message out.
|
|
*/
|
|
if (!strncmp(func->name, "__ubsan_handle_", 15))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static int validate_call(struct objtool_file *file,
|
|
struct instruction *insn,
|
|
struct insn_state *state)
|
|
{
|
|
if (state->noinstr && state->instr <= 0 &&
|
|
!noinstr_call_dest(file, insn, insn_call_dest(insn))) {
|
|
WARN_INSN(insn, "call to %s() leaves .noinstr.text section", call_dest_name(insn));
|
|
return 1;
|
|
}
|
|
|
|
if (state->uaccess && !func_uaccess_safe(insn_call_dest(insn))) {
|
|
WARN_INSN(insn, "call to %s() with UACCESS enabled", call_dest_name(insn));
|
|
return 1;
|
|
}
|
|
|
|
if (state->df) {
|
|
WARN_INSN(insn, "call to %s() with DF set", call_dest_name(insn));
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int validate_sibling_call(struct objtool_file *file,
|
|
struct instruction *insn,
|
|
struct insn_state *state)
|
|
{
|
|
if (insn_func(insn) && has_modified_stack_frame(insn, state)) {
|
|
WARN_INSN(insn, "sibling call from callable instruction with modified stack frame");
|
|
return 1;
|
|
}
|
|
|
|
return validate_call(file, insn, state);
|
|
}
|
|
|
|
static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
|
|
{
|
|
if (state->noinstr && state->instr > 0) {
|
|
WARN_INSN(insn, "return with instrumentation enabled");
|
|
return 1;
|
|
}
|
|
|
|
if (state->uaccess && !func_uaccess_safe(func)) {
|
|
WARN_INSN(insn, "return with UACCESS enabled");
|
|
return 1;
|
|
}
|
|
|
|
if (!state->uaccess && func_uaccess_safe(func)) {
|
|
WARN_INSN(insn, "return with UACCESS disabled from a UACCESS-safe function");
|
|
return 1;
|
|
}
|
|
|
|
if (state->df) {
|
|
WARN_INSN(insn, "return with DF set");
|
|
return 1;
|
|
}
|
|
|
|
if (func && has_modified_stack_frame(insn, state)) {
|
|
WARN_INSN(insn, "return with modified stack frame");
|
|
return 1;
|
|
}
|
|
|
|
if (state->cfi.bp_scratch) {
|
|
WARN_INSN(insn, "BP used as a scratch register");
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct instruction *next_insn_to_validate(struct objtool_file *file,
|
|
struct instruction *insn)
|
|
{
|
|
struct alt_group *alt_group = insn->alt_group;
|
|
|
|
/*
|
|
* Simulate the fact that alternatives are patched in-place. When the
|
|
* end of a replacement alt_group is reached, redirect objtool flow to
|
|
* the end of the original alt_group.
|
|
*
|
|
* insn->alts->insn -> alt_group->first_insn
|
|
* ...
|
|
* alt_group->last_insn
|
|
* [alt_group->nop] -> next(orig_group->last_insn)
|
|
*/
|
|
if (alt_group) {
|
|
if (alt_group->nop) {
|
|
/* ->nop implies ->orig_group */
|
|
if (insn == alt_group->last_insn)
|
|
return alt_group->nop;
|
|
if (insn == alt_group->nop)
|
|
goto next_orig;
|
|
}
|
|
if (insn == alt_group->last_insn && alt_group->orig_group)
|
|
goto next_orig;
|
|
}
|
|
|
|
return next_insn_same_sec(file, insn);
|
|
|
|
next_orig:
|
|
return next_insn_same_sec(file, alt_group->orig_group->last_insn);
|
|
}
|
|
|
|
/*
|
|
* Follow the branch starting at the given instruction, and recursively follow
|
|
* any other branches (jumps). Meanwhile, track the frame pointer state at
|
|
* each instruction and validate all the rules described in
|
|
* tools/objtool/Documentation/objtool.txt.
|
|
*/
|
|
static int validate_branch(struct objtool_file *file, struct symbol *func,
|
|
struct instruction *insn, struct insn_state state)
|
|
{
|
|
struct alternative *alt;
|
|
struct instruction *next_insn, *prev_insn = NULL;
|
|
struct section *sec;
|
|
u8 visited;
|
|
int ret;
|
|
|
|
sec = insn->sec;
|
|
|
|
while (1) {
|
|
next_insn = next_insn_to_validate(file, insn);
|
|
|
|
if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
|
|
/* Ignore KCFI type preambles, which always fall through */
|
|
if (!strncmp(func->name, "__cfi_", 6) ||
|
|
!strncmp(func->name, "__pfx_", 6))
|
|
return 0;
|
|
|
|
WARN("%s() falls through to next function %s()",
|
|
func->name, insn_func(insn)->name);
|
|
return 1;
|
|
}
|
|
|
|
if (func && insn->ignore) {
|
|
WARN_INSN(insn, "BUG: why am I validating an ignored function?");
|
|
return 1;
|
|
}
|
|
|
|
visited = VISITED_BRANCH << state.uaccess;
|
|
if (insn->visited & VISITED_BRANCH_MASK) {
|
|
if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
|
|
return 1;
|
|
|
|
if (insn->visited & visited)
|
|
return 0;
|
|
} else {
|
|
nr_insns_visited++;
|
|
}
|
|
|
|
if (state.noinstr)
|
|
state.instr += insn->instr;
|
|
|
|
if (insn->hint) {
|
|
if (insn->restore) {
|
|
struct instruction *save_insn, *i;
|
|
|
|
i = insn;
|
|
save_insn = NULL;
|
|
|
|
sym_for_each_insn_continue_reverse(file, func, i) {
|
|
if (i->save) {
|
|
save_insn = i;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!save_insn) {
|
|
WARN_INSN(insn, "no corresponding CFI save for CFI restore");
|
|
return 1;
|
|
}
|
|
|
|
if (!save_insn->visited) {
|
|
WARN_INSN(insn, "objtool isn't smart enough to handle this CFI save/restore combo");
|
|
return 1;
|
|
}
|
|
|
|
insn->cfi = save_insn->cfi;
|
|
nr_cfi_reused++;
|
|
}
|
|
|
|
state.cfi = *insn->cfi;
|
|
} else {
|
|
/* XXX track if we actually changed state.cfi */
|
|
|
|
if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) {
|
|
insn->cfi = prev_insn->cfi;
|
|
nr_cfi_reused++;
|
|
} else {
|
|
insn->cfi = cfi_hash_find_or_add(&state.cfi);
|
|
}
|
|
}
|
|
|
|
insn->visited |= visited;
|
|
|
|
if (propagate_alt_cfi(file, insn))
|
|
return 1;
|
|
|
|
if (!insn->ignore_alts && insn->alts) {
|
|
bool skip_orig = false;
|
|
|
|
for (alt = insn->alts; alt; alt = alt->next) {
|
|
if (alt->skip_orig)
|
|
skip_orig = true;
|
|
|
|
ret = validate_branch(file, func, alt->insn, state);
|
|
if (ret) {
|
|
if (opts.backtrace)
|
|
BT_FUNC("(alt)", insn);
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
if (skip_orig)
|
|
return 0;
|
|
}
|
|
|
|
if (handle_insn_ops(insn, next_insn, &state))
|
|
return 1;
|
|
|
|
switch (insn->type) {
|
|
|
|
case INSN_RETURN:
|
|
return validate_return(func, insn, &state);
|
|
|
|
case INSN_CALL:
|
|
case INSN_CALL_DYNAMIC:
|
|
ret = validate_call(file, insn, &state);
|
|
if (ret)
|
|
return ret;
|
|
|
|
if (opts.stackval && func && !is_fentry_call(insn) &&
|
|
!has_valid_stack_frame(&state)) {
|
|
WARN_INSN(insn, "call without frame pointer save/setup");
|
|
return 1;
|
|
}
|
|
|
|
if (insn->dead_end)
|
|
return 0;
|
|
|
|
break;
|
|
|
|
case INSN_JUMP_CONDITIONAL:
|
|
case INSN_JUMP_UNCONDITIONAL:
|
|
if (is_sibling_call(insn)) {
|
|
ret = validate_sibling_call(file, insn, &state);
|
|
if (ret)
|
|
return ret;
|
|
|
|
} else if (insn->jump_dest) {
|
|
ret = validate_branch(file, func,
|
|
insn->jump_dest, state);
|
|
if (ret) {
|
|
if (opts.backtrace)
|
|
BT_FUNC("(branch)", insn);
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
if (insn->type == INSN_JUMP_UNCONDITIONAL)
|
|
return 0;
|
|
|
|
break;
|
|
|
|
case INSN_JUMP_DYNAMIC:
|
|
case INSN_JUMP_DYNAMIC_CONDITIONAL:
|
|
if (is_sibling_call(insn)) {
|
|
ret = validate_sibling_call(file, insn, &state);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
if (insn->type == INSN_JUMP_DYNAMIC)
|
|
return 0;
|
|
|
|
break;
|
|
|
|
case INSN_CONTEXT_SWITCH:
|
|
if (func && (!next_insn || !next_insn->hint)) {
|
|
WARN_INSN(insn, "unsupported instruction in callable function");
|
|
return 1;
|
|
}
|
|
return 0;
|
|
|
|
case INSN_STAC:
|
|
if (state.uaccess) {
|
|
WARN_INSN(insn, "recursive UACCESS enable");
|
|
return 1;
|
|
}
|
|
|
|
state.uaccess = true;
|
|
break;
|
|
|
|
case INSN_CLAC:
|
|
if (!state.uaccess && func) {
|
|
WARN_INSN(insn, "redundant UACCESS disable");
|
|
return 1;
|
|
}
|
|
|
|
if (func_uaccess_safe(func) && !state.uaccess_stack) {
|
|
WARN_INSN(insn, "UACCESS-safe disables UACCESS");
|
|
return 1;
|
|
}
|
|
|
|
state.uaccess = false;
|
|
break;
|
|
|
|
case INSN_STD:
|
|
if (state.df) {
|
|
WARN_INSN(insn, "recursive STD");
|
|
return 1;
|
|
}
|
|
|
|
state.df = true;
|
|
break;
|
|
|
|
case INSN_CLD:
|
|
if (!state.df && func) {
|
|
WARN_INSN(insn, "redundant CLD");
|
|
return 1;
|
|
}
|
|
|
|
state.df = false;
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
|
|
if (insn->dead_end)
|
|
return 0;
|
|
|
|
if (!next_insn) {
|
|
if (state.cfi.cfa.base == CFI_UNDEFINED)
|
|
return 0;
|
|
WARN("%s: unexpected end of section", sec->name);
|
|
return 1;
|
|
}
|
|
|
|
prev_insn = insn;
|
|
insn = next_insn;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int validate_unwind_hint(struct objtool_file *file,
|
|
struct instruction *insn,
|
|
struct insn_state *state)
|
|
{
|
|
if (insn->hint && !insn->visited && !insn->ignore) {
|
|
int ret = validate_branch(file, insn_func(insn), insn, *state);
|
|
if (ret && opts.backtrace)
|
|
BT_FUNC("<=== (hint)", insn);
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
|
|
{
|
|
struct instruction *insn;
|
|
struct insn_state state;
|
|
int warnings = 0;
|
|
|
|
if (!file->hints)
|
|
return 0;
|
|
|
|
init_insn_state(file, &state, sec);
|
|
|
|
if (sec) {
|
|
sec_for_each_insn(file, sec, insn)
|
|
warnings += validate_unwind_hint(file, insn, &state);
|
|
} else {
|
|
for_each_insn(file, insn)
|
|
warnings += validate_unwind_hint(file, insn, &state);
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
/*
|
|
* Validate rethunk entry constraint: must untrain RET before the first RET.
|
|
*
|
|
* Follow every branch (intra-function) and ensure VALIDATE_UNRET_END comes
|
|
* before an actual RET instruction.
|
|
*/
|
|
static int validate_unret(struct objtool_file *file, struct instruction *insn)
|
|
{
|
|
struct instruction *next, *dest;
|
|
int ret, warnings = 0;
|
|
|
|
for (;;) {
|
|
next = next_insn_to_validate(file, insn);
|
|
|
|
if (insn->visited & VISITED_UNRET)
|
|
return 0;
|
|
|
|
insn->visited |= VISITED_UNRET;
|
|
|
|
if (!insn->ignore_alts && insn->alts) {
|
|
struct alternative *alt;
|
|
bool skip_orig = false;
|
|
|
|
for (alt = insn->alts; alt; alt = alt->next) {
|
|
if (alt->skip_orig)
|
|
skip_orig = true;
|
|
|
|
ret = validate_unret(file, alt->insn);
|
|
if (ret) {
|
|
if (opts.backtrace)
|
|
BT_FUNC("(alt)", insn);
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
if (skip_orig)
|
|
return 0;
|
|
}
|
|
|
|
switch (insn->type) {
|
|
|
|
case INSN_CALL_DYNAMIC:
|
|
case INSN_JUMP_DYNAMIC:
|
|
case INSN_JUMP_DYNAMIC_CONDITIONAL:
|
|
WARN_INSN(insn, "early indirect call");
|
|
return 1;
|
|
|
|
case INSN_JUMP_UNCONDITIONAL:
|
|
case INSN_JUMP_CONDITIONAL:
|
|
if (!is_sibling_call(insn)) {
|
|
if (!insn->jump_dest) {
|
|
WARN_INSN(insn, "unresolved jump target after linking?!?");
|
|
return -1;
|
|
}
|
|
ret = validate_unret(file, insn->jump_dest);
|
|
if (ret) {
|
|
if (opts.backtrace) {
|
|
BT_FUNC("(branch%s)", insn,
|
|
insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
if (insn->type == INSN_JUMP_UNCONDITIONAL)
|
|
return 0;
|
|
|
|
break;
|
|
}
|
|
|
|
/* fallthrough */
|
|
case INSN_CALL:
|
|
dest = find_insn(file, insn_call_dest(insn)->sec,
|
|
insn_call_dest(insn)->offset);
|
|
if (!dest) {
|
|
WARN("Unresolved function after linking!?: %s",
|
|
insn_call_dest(insn)->name);
|
|
return -1;
|
|
}
|
|
|
|
ret = validate_unret(file, dest);
|
|
if (ret) {
|
|
if (opts.backtrace)
|
|
BT_FUNC("(call)", insn);
|
|
return ret;
|
|
}
|
|
/*
|
|
* If a call returns without error, it must have seen UNTRAIN_RET.
|
|
* Therefore any non-error return is a success.
|
|
*/
|
|
return 0;
|
|
|
|
case INSN_RETURN:
|
|
WARN_INSN(insn, "RET before UNTRAIN");
|
|
return 1;
|
|
|
|
case INSN_NOP:
|
|
if (insn->retpoline_safe)
|
|
return 0;
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
|
|
if (!next) {
|
|
WARN_INSN(insn, "teh end!");
|
|
return -1;
|
|
}
|
|
insn = next;
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
/*
|
|
* Validate that all branches starting at VALIDATE_UNRET_BEGIN encounter
|
|
* VALIDATE_UNRET_END before RET.
|
|
*/
|
|
static int validate_unrets(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn;
|
|
int ret, warnings = 0;
|
|
|
|
for_each_insn(file, insn) {
|
|
if (!insn->unret)
|
|
continue;
|
|
|
|
ret = validate_unret(file, insn);
|
|
if (ret < 0) {
|
|
WARN_INSN(insn, "Failed UNRET validation");
|
|
return ret;
|
|
}
|
|
warnings += ret;
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
static int validate_retpoline(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn;
|
|
int warnings = 0;
|
|
|
|
for_each_insn(file, insn) {
|
|
if (insn->type != INSN_JUMP_DYNAMIC &&
|
|
insn->type != INSN_CALL_DYNAMIC &&
|
|
insn->type != INSN_RETURN)
|
|
continue;
|
|
|
|
if (insn->retpoline_safe)
|
|
continue;
|
|
|
|
if (insn->sec->init)
|
|
continue;
|
|
|
|
if (insn->type == INSN_RETURN) {
|
|
if (opts.rethunk) {
|
|
WARN_INSN(insn, "'naked' return found in RETHUNK build");
|
|
} else
|
|
continue;
|
|
} else {
|
|
WARN_INSN(insn, "indirect %s found in RETPOLINE build",
|
|
insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
|
|
}
|
|
|
|
warnings++;
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
static bool is_kasan_insn(struct instruction *insn)
|
|
{
|
|
return (insn->type == INSN_CALL &&
|
|
!strcmp(insn_call_dest(insn)->name, "__asan_handle_no_return"));
|
|
}
|
|
|
|
static bool is_ubsan_insn(struct instruction *insn)
|
|
{
|
|
return (insn->type == INSN_CALL &&
|
|
!strcmp(insn_call_dest(insn)->name,
|
|
"__ubsan_handle_builtin_unreachable"));
|
|
}
|
|
|
|
static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
|
|
{
|
|
int i;
|
|
struct instruction *prev_insn;
|
|
|
|
if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP)
|
|
return true;
|
|
|
|
/*
|
|
* Ignore alternative replacement instructions. This can happen
|
|
* when a whitelisted function uses one of the ALTERNATIVE macros.
|
|
*/
|
|
if (!strcmp(insn->sec->name, ".altinstr_replacement") ||
|
|
!strcmp(insn->sec->name, ".altinstr_aux"))
|
|
return true;
|
|
|
|
/*
|
|
* Whole archive runs might encounter dead code from weak symbols.
|
|
* This is where the linker will have dropped the weak symbol in
|
|
* favour of a regular symbol, but leaves the code in place.
|
|
*
|
|
* In this case we'll find a piece of code (whole function) that is not
|
|
* covered by a !section symbol. Ignore them.
|
|
*/
|
|
if (opts.link && !insn_func(insn)) {
|
|
int size = find_symbol_hole_containing(insn->sec, insn->offset);
|
|
unsigned long end = insn->offset + size;
|
|
|
|
if (!size) /* not a hole */
|
|
return false;
|
|
|
|
if (size < 0) /* hole until the end */
|
|
return true;
|
|
|
|
sec_for_each_insn_continue(file, insn) {
|
|
/*
|
|
* If we reach a visited instruction at or before the
|
|
* end of the hole, ignore the unreachable.
|
|
*/
|
|
if (insn->visited)
|
|
return true;
|
|
|
|
if (insn->offset >= end)
|
|
break;
|
|
|
|
/*
|
|
* If this hole jumps to a .cold function, mark it ignore too.
|
|
*/
|
|
if (insn->jump_dest && insn_func(insn->jump_dest) &&
|
|
strstr(insn_func(insn->jump_dest)->name, ".cold")) {
|
|
struct instruction *dest = insn->jump_dest;
|
|
func_for_each_insn(file, insn_func(dest), dest)
|
|
dest->ignore = true;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
if (!insn_func(insn))
|
|
return false;
|
|
|
|
if (insn_func(insn)->static_call_tramp)
|
|
return true;
|
|
|
|
/*
|
|
* CONFIG_UBSAN_TRAP inserts a UD2 when it sees
|
|
* __builtin_unreachable(). The BUG() macro has an unreachable() after
|
|
* the UD2, which causes GCC's undefined trap logic to emit another UD2
|
|
* (or occasionally a JMP to UD2).
|
|
*
|
|
* It may also insert a UD2 after calling a __noreturn function.
|
|
*/
|
|
prev_insn = prev_insn_same_sec(file, insn);
|
|
if (prev_insn->dead_end &&
|
|
(insn->type == INSN_BUG ||
|
|
(insn->type == INSN_JUMP_UNCONDITIONAL &&
|
|
insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
|
|
return true;
|
|
|
|
/*
|
|
* Check if this (or a subsequent) instruction is related to
|
|
* CONFIG_UBSAN or CONFIG_KASAN.
|
|
*
|
|
* End the search at 5 instructions to avoid going into the weeds.
|
|
*/
|
|
for (i = 0; i < 5; i++) {
|
|
|
|
if (is_kasan_insn(insn) || is_ubsan_insn(insn))
|
|
return true;
|
|
|
|
if (insn->type == INSN_JUMP_UNCONDITIONAL) {
|
|
if (insn->jump_dest &&
|
|
insn_func(insn->jump_dest) == insn_func(insn)) {
|
|
insn = insn->jump_dest;
|
|
continue;
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
if (insn->offset + insn->len >= insn_func(insn)->offset + insn_func(insn)->len)
|
|
break;
|
|
|
|
insn = next_insn_same_sec(file, insn);
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)
|
|
{
|
|
struct instruction *insn, *prev;
|
|
struct cfi_state *cfi;
|
|
|
|
insn = find_insn(file, func->sec, func->offset);
|
|
if (!insn)
|
|
return -1;
|
|
|
|
for (prev = prev_insn_same_sec(file, insn);
|
|
prev;
|
|
prev = prev_insn_same_sec(file, prev)) {
|
|
u64 offset;
|
|
|
|
if (prev->type != INSN_NOP)
|
|
return -1;
|
|
|
|
offset = func->offset - prev->offset;
|
|
|
|
if (offset > opts.prefix)
|
|
return -1;
|
|
|
|
if (offset < opts.prefix)
|
|
continue;
|
|
|
|
elf_create_prefix_symbol(file->elf, func, opts.prefix);
|
|
break;
|
|
}
|
|
|
|
if (!prev)
|
|
return -1;
|
|
|
|
if (!insn->cfi) {
|
|
/*
|
|
* This can happen if stack validation isn't enabled or the
|
|
* function is annotated with STACK_FRAME_NON_STANDARD.
|
|
*/
|
|
return 0;
|
|
}
|
|
|
|
/* Propagate insn->cfi to the prefix code */
|
|
cfi = cfi_hash_find_or_add(insn->cfi);
|
|
for (; prev != insn; prev = next_insn_same_sec(file, prev))
|
|
prev->cfi = cfi;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int add_prefix_symbols(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
struct symbol *func;
|
|
int warnings = 0;
|
|
|
|
for_each_sec(file, sec) {
|
|
if (!(sec->sh.sh_flags & SHF_EXECINSTR))
|
|
continue;
|
|
|
|
sec_for_each_sym(sec, func) {
|
|
if (func->type != STT_FUNC)
|
|
continue;
|
|
|
|
add_prefix_symbol(file, func);
|
|
}
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
static int validate_symbol(struct objtool_file *file, struct section *sec,
|
|
struct symbol *sym, struct insn_state *state)
|
|
{
|
|
struct instruction *insn;
|
|
int ret;
|
|
|
|
if (!sym->len) {
|
|
WARN("%s() is missing an ELF size annotation", sym->name);
|
|
return 1;
|
|
}
|
|
|
|
if (sym->pfunc != sym || sym->alias != sym)
|
|
return 0;
|
|
|
|
insn = find_insn(file, sec, sym->offset);
|
|
if (!insn || insn->ignore || insn->visited)
|
|
return 0;
|
|
|
|
state->uaccess = sym->uaccess_safe;
|
|
|
|
ret = validate_branch(file, insn_func(insn), insn, *state);
|
|
if (ret && opts.backtrace)
|
|
BT_FUNC("<=== (sym)", insn);
|
|
return ret;
|
|
}
|
|
|
|
static int validate_section(struct objtool_file *file, struct section *sec)
|
|
{
|
|
struct insn_state state;
|
|
struct symbol *func;
|
|
int warnings = 0;
|
|
|
|
sec_for_each_sym(sec, func) {
|
|
if (func->type != STT_FUNC)
|
|
continue;
|
|
|
|
init_insn_state(file, &state, sec);
|
|
set_func_state(&state.cfi);
|
|
|
|
warnings += validate_symbol(file, sec, func, &state);
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
static int validate_noinstr_sections(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
int warnings = 0;
|
|
|
|
sec = find_section_by_name(file->elf, ".noinstr.text");
|
|
if (sec) {
|
|
warnings += validate_section(file, sec);
|
|
warnings += validate_unwind_hints(file, sec);
|
|
}
|
|
|
|
sec = find_section_by_name(file->elf, ".entry.text");
|
|
if (sec) {
|
|
warnings += validate_section(file, sec);
|
|
warnings += validate_unwind_hints(file, sec);
|
|
}
|
|
|
|
sec = find_section_by_name(file->elf, ".cpuidle.text");
|
|
if (sec) {
|
|
warnings += validate_section(file, sec);
|
|
warnings += validate_unwind_hints(file, sec);
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
static int validate_functions(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
int warnings = 0;
|
|
|
|
for_each_sec(file, sec) {
|
|
if (!(sec->sh.sh_flags & SHF_EXECINSTR))
|
|
continue;
|
|
|
|
warnings += validate_section(file, sec);
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
static void mark_endbr_used(struct instruction *insn)
|
|
{
|
|
if (!list_empty(&insn->call_node))
|
|
list_del_init(&insn->call_node);
|
|
}
|
|
|
|
static bool noendbr_range(struct objtool_file *file, struct instruction *insn)
|
|
{
|
|
struct symbol *sym = find_symbol_containing(insn->sec, insn->offset-1);
|
|
struct instruction *first;
|
|
|
|
if (!sym)
|
|
return false;
|
|
|
|
first = find_insn(file, sym->sec, sym->offset);
|
|
if (!first)
|
|
return false;
|
|
|
|
if (first->type != INSN_ENDBR && !first->noendbr)
|
|
return false;
|
|
|
|
return insn->offset == sym->offset + sym->len;
|
|
}
|
|
|
|
static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
|
|
{
|
|
struct instruction *dest;
|
|
struct reloc *reloc;
|
|
unsigned long off;
|
|
int warnings = 0;
|
|
|
|
/*
|
|
* Looking for function pointer load relocations. Ignore
|
|
* direct/indirect branches:
|
|
*/
|
|
switch (insn->type) {
|
|
case INSN_CALL:
|
|
case INSN_CALL_DYNAMIC:
|
|
case INSN_JUMP_CONDITIONAL:
|
|
case INSN_JUMP_UNCONDITIONAL:
|
|
case INSN_JUMP_DYNAMIC:
|
|
case INSN_JUMP_DYNAMIC_CONDITIONAL:
|
|
case INSN_RETURN:
|
|
case INSN_NOP:
|
|
return 0;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
for (reloc = insn_reloc(file, insn);
|
|
reloc;
|
|
reloc = find_reloc_by_dest_range(file->elf, insn->sec,
|
|
reloc->offset + 1,
|
|
(insn->offset + insn->len) - (reloc->offset + 1))) {
|
|
|
|
/*
|
|
* static_call_update() references the trampoline, which
|
|
* doesn't have (or need) ENDBR. Skip warning in that case.
|
|
*/
|
|
if (reloc->sym->static_call_tramp)
|
|
continue;
|
|
|
|
off = reloc->sym->offset;
|
|
if (reloc->type == R_X86_64_PC32 || reloc->type == R_X86_64_PLT32)
|
|
off += arch_dest_reloc_offset(reloc->addend);
|
|
else
|
|
off += reloc->addend;
|
|
|
|
dest = find_insn(file, reloc->sym->sec, off);
|
|
if (!dest)
|
|
continue;
|
|
|
|
if (dest->type == INSN_ENDBR) {
|
|
mark_endbr_used(dest);
|
|
continue;
|
|
}
|
|
|
|
if (insn_func(dest) && insn_func(dest) == insn_func(insn)) {
|
|
/*
|
|
* Anything from->to self is either _THIS_IP_ or
|
|
* IRET-to-self.
|
|
*
|
|
* There is no sane way to annotate _THIS_IP_ since the
|
|
* compiler treats the relocation as a constant and is
|
|
* happy to fold in offsets, skewing any annotation we
|
|
* do, leading to vast amounts of false-positives.
|
|
*
|
|
* There's also compiler generated _THIS_IP_ through
|
|
* KCOV and such which we have no hope of annotating.
|
|
*
|
|
* As such, blanket accept self-references without
|
|
* issue.
|
|
*/
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Accept anything ANNOTATE_NOENDBR.
|
|
*/
|
|
if (dest->noendbr)
|
|
continue;
|
|
|
|
/*
|
|
* Accept if this is the instruction after a symbol
|
|
* that is (no)endbr -- typical code-range usage.
|
|
*/
|
|
if (noendbr_range(file, dest))
|
|
continue;
|
|
|
|
WARN_INSN(insn, "relocation to !ENDBR: %s", offstr(dest->sec, dest->offset));
|
|
|
|
warnings++;
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
static int validate_ibt_data_reloc(struct objtool_file *file,
|
|
struct reloc *reloc)
|
|
{
|
|
struct instruction *dest;
|
|
|
|
dest = find_insn(file, reloc->sym->sec,
|
|
reloc->sym->offset + reloc->addend);
|
|
if (!dest)
|
|
return 0;
|
|
|
|
if (dest->type == INSN_ENDBR) {
|
|
mark_endbr_used(dest);
|
|
return 0;
|
|
}
|
|
|
|
if (dest->noendbr)
|
|
return 0;
|
|
|
|
WARN_FUNC("data relocation to !ENDBR: %s",
|
|
reloc->sec->base, reloc->offset,
|
|
offstr(dest->sec, dest->offset));
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Validate IBT rules and remove used ENDBR instructions from the seal list.
|
|
* Unused ENDBR instructions will be annotated for sealing (i.e., replaced with
|
|
* NOPs) later, in create_ibt_endbr_seal_sections().
|
|
*/
|
|
static int validate_ibt(struct objtool_file *file)
|
|
{
|
|
struct section *sec;
|
|
struct reloc *reloc;
|
|
struct instruction *insn;
|
|
int warnings = 0;
|
|
|
|
for_each_insn(file, insn)
|
|
warnings += validate_ibt_insn(file, insn);
|
|
|
|
for_each_sec(file, sec) {
|
|
|
|
/* Already done by validate_ibt_insn() */
|
|
if (sec->sh.sh_flags & SHF_EXECINSTR)
|
|
continue;
|
|
|
|
if (!sec->reloc)
|
|
continue;
|
|
|
|
/*
|
|
* These sections can reference text addresses, but not with
|
|
* the intent to indirect branch to them.
|
|
*/
|
|
if ((!strncmp(sec->name, ".discard", 8) &&
|
|
strcmp(sec->name, ".discard.ibt_endbr_noseal")) ||
|
|
!strncmp(sec->name, ".debug", 6) ||
|
|
!strcmp(sec->name, ".altinstructions") ||
|
|
!strcmp(sec->name, ".ibt_endbr_seal") ||
|
|
!strcmp(sec->name, ".orc_unwind_ip") ||
|
|
!strcmp(sec->name, ".parainstructions") ||
|
|
!strcmp(sec->name, ".retpoline_sites") ||
|
|
!strcmp(sec->name, ".smp_locks") ||
|
|
!strcmp(sec->name, ".static_call_sites") ||
|
|
!strcmp(sec->name, "_error_injection_whitelist") ||
|
|
!strcmp(sec->name, "_kprobe_blacklist") ||
|
|
!strcmp(sec->name, "__bug_table") ||
|
|
!strcmp(sec->name, "__ex_table") ||
|
|
!strcmp(sec->name, "__jump_table") ||
|
|
!strcmp(sec->name, "__mcount_loc") ||
|
|
!strcmp(sec->name, ".kcfi_traps") ||
|
|
strstr(sec->name, "__patchable_function_entries"))
|
|
continue;
|
|
|
|
list_for_each_entry(reloc, &sec->reloc->reloc_list, list)
|
|
warnings += validate_ibt_data_reloc(file, reloc);
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
static int validate_sls(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn, *next_insn;
|
|
int warnings = 0;
|
|
|
|
for_each_insn(file, insn) {
|
|
next_insn = next_insn_same_sec(file, insn);
|
|
|
|
if (insn->retpoline_safe)
|
|
continue;
|
|
|
|
switch (insn->type) {
|
|
case INSN_RETURN:
|
|
if (!next_insn || next_insn->type != INSN_TRAP) {
|
|
WARN_INSN(insn, "missing int3 after ret");
|
|
warnings++;
|
|
}
|
|
|
|
break;
|
|
case INSN_JUMP_DYNAMIC:
|
|
if (!next_insn || next_insn->type != INSN_TRAP) {
|
|
WARN_INSN(insn, "missing int3 after indirect jump");
|
|
warnings++;
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
return warnings;
|
|
}
|
|
|
|
static int validate_reachable_instructions(struct objtool_file *file)
|
|
{
|
|
struct instruction *insn;
|
|
|
|
if (file->ignore_unreachables)
|
|
return 0;
|
|
|
|
for_each_insn(file, insn) {
|
|
if (insn->visited || ignore_unreachable_insn(file, insn))
|
|
continue;
|
|
|
|
WARN_INSN(insn, "unreachable instruction");
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int check(struct objtool_file *file)
|
|
{
|
|
int ret, warnings = 0;
|
|
|
|
arch_initial_func_cfi_state(&initial_func_cfi);
|
|
init_cfi_state(&init_cfi);
|
|
init_cfi_state(&func_cfi);
|
|
set_func_state(&func_cfi);
|
|
|
|
if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
|
|
goto out;
|
|
|
|
cfi_hash_add(&init_cfi);
|
|
cfi_hash_add(&func_cfi);
|
|
|
|
ret = decode_sections(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
|
|
warnings += ret;
|
|
|
|
if (!nr_insns)
|
|
goto out;
|
|
|
|
if (opts.retpoline) {
|
|
ret = validate_retpoline(file);
|
|
if (ret < 0)
|
|
return ret;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.stackval || opts.orc || opts.uaccess) {
|
|
ret = validate_functions(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
|
|
ret = validate_unwind_hints(file, NULL);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
|
|
if (!warnings) {
|
|
ret = validate_reachable_instructions(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
|
|
} else if (opts.noinstr) {
|
|
ret = validate_noinstr_sections(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.unret) {
|
|
/*
|
|
* Must be after validate_branch() and friends, it plays
|
|
* further games with insn->visited.
|
|
*/
|
|
ret = validate_unrets(file);
|
|
if (ret < 0)
|
|
return ret;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.ibt) {
|
|
ret = validate_ibt(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.sls) {
|
|
ret = validate_sls(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.static_call) {
|
|
ret = create_static_call_sections(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.retpoline) {
|
|
ret = create_retpoline_sites_sections(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.cfi) {
|
|
ret = create_cfi_sections(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.rethunk) {
|
|
ret = create_return_sites_sections(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
|
|
if (opts.hack_skylake) {
|
|
ret = create_direct_call_sections(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
}
|
|
|
|
if (opts.mcount) {
|
|
ret = create_mcount_loc_sections(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.prefix) {
|
|
ret = add_prefix_symbols(file);
|
|
if (ret < 0)
|
|
return ret;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.ibt) {
|
|
ret = create_ibt_endbr_seal_sections(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
|
|
if (opts.orc && nr_insns) {
|
|
ret = orc_create(file);
|
|
if (ret < 0)
|
|
goto out;
|
|
warnings += ret;
|
|
}
|
|
|
|
|
|
if (opts.stats) {
|
|
printf("nr_insns_visited: %ld\n", nr_insns_visited);
|
|
printf("nr_cfi: %ld\n", nr_cfi);
|
|
printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
|
|
printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
|
|
}
|
|
|
|
out:
|
|
/*
|
|
* For now, don't fail the kernel build on fatal warnings. These
|
|
* errors are still fairly common due to the growing matrix of
|
|
* supported toolchains and their recent pace of change.
|
|
*/
|
|
return 0;
|
|
}
|