mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-29 23:53:32 +00:00
a56ff24efb
- Make objtool work for big-endian cross compiles - Make stack tracking via stack pointer memory operations match push/pop semantics to prepare for architectures w/o PUSH/POP instructions. - Add support for analyzing alternatives - Improve retpoline detection and handling - Improve assembly code coverage on x86 - Provide support for inlined stack switching -----BEGIN PGP SIGNATURE----- iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAmA1FUcTHHRnbHhAbGlu dXRyb25peC5kZQAKCRCmGPVMDXSYoe+0D/9ytW3AfQUOGlVHVPTwCAd2LSCL2kQR zrUAyUEwEXDuZi2vOcmgndr9AToszdBnAlxSOStJYE1/ia/ptbYjj9eFOWkCwPw2 R0DSjTHh+Ui2yPjcbYvOcMphc7DTT1ssMvRWzw0I3fjfJaYBJjNx1qdseN2yhFrL BNhdh4B4StEfCbNBMhnzKTZNM1yXNN93ojot9suxnqPIAV6ruc5SUrd9Pmii2odX gRHQthGSPMR9nJYWrT2QzbDrM2DWkKIGUol0Xr1LTFYWNFsK3sTQkFiMevTP5Msw qO01lw4IKCMKMonaE0t/vxFBz5vhIyivxLQMI3LBixmf2dbE9UbZqW0ONPYoZJgf MrYyz4Tdv2u/MklTPM263cbTsdtmGEuW2iVRqaDDWP/Py1A187bUaVkw8p/9O/9V CBl8dMF3ag1FquxnsyHDowHKu8DaIZyeBHu69aNfAlcOrtn8ZtY4MwQbQkL9cNYe ywLEmCm8zdYNrXlVOuMX/0AAWnSpqCgDYUmKhOLW4W1r4ewNpAUCmvIL8cpLtko0 FDbMTdKU2pd5SQv5YX6Bvvra483DvP9rNAuQGHpxZ7ubSlj8cFOT9UmjuuOb4fxQ EFj8JrF9KEN5sxGUu4tjg0D0Ee3wDdSTGs0cUN5FBMXelQOM7U4n4Y7n/Pas/LMa B5TVW3JiDcMcPg== =0AHf -----END PGP SIGNATURE----- Merge tag 'objtool-core-2021-02-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool updates from Thomas Gleixner: - Make objtool work for big-endian cross compiles - Make stack tracking via stack pointer memory operations match push/pop semantics to prepare for architectures w/o PUSH/POP instructions. - Add support for analyzing alternatives - Improve retpoline detection and handling - Improve assembly code coverage on x86 - Provide support for inlined stack switching * tag 'objtool-core-2021-02-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits) objtool: Support stack-swizzle objtool,x86: Additionally decode: mov %rsp, (%reg) x86/unwind/orc: Change REG_SP_INDIRECT x86/power: Support objtool validation in hibernate_asm_64.S x86/power: Move restore_registers() to top of the file x86/power: Annotate indirect branches as safe x86/acpi: Support objtool validation in wakeup_64.S x86/acpi: Annotate indirect branch as safe x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S x86/xen/pvh: Annotate indirect branch as safe x86/xen: Support objtool vmlinux.o validation in xen-head.S x86/xen: Support objtool validation in xen-asm.S objtool: Add xen_start_kernel() to noreturn list objtool: Combine UNWIND_HINT_RET_OFFSET and UNWIND_HINT_FUNC objtool: Add asm version of STACK_FRAME_NON_STANDARD objtool: Assume only ELF functions do sibling calls x86/ftrace: Add UNWIND_HINT_FUNC annotation for ftrace_stub objtool: Support retpoline jump detection for vmlinux.o objtool: Fix ".cold" section suffix check for newer versions of GCC objtool: Fix retpoline detection in asm code ...
1006 lines
21 KiB
C
1006 lines
21 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* elf.c - ELF access library
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*
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* Adapted from kpatch (https://github.com/dynup/kpatch):
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* Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
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* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include <objtool/builtin.h>
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#include <objtool/elf.h>
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#include <objtool/warn.h>
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#define MAX_NAME_LEN 128
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static inline u32 str_hash(const char *str)
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{
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return jhash(str, strlen(str), 0);
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}
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static inline int elf_hash_bits(void)
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{
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return vmlinux ? ELF_HASH_BITS : 16;
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}
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#define elf_hash_add(hashtable, node, key) \
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hlist_add_head(node, &hashtable[hash_min(key, elf_hash_bits())])
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static void elf_hash_init(struct hlist_head *table)
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{
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__hash_init(table, 1U << elf_hash_bits());
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}
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#define elf_hash_for_each_possible(name, obj, member, key) \
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hlist_for_each_entry(obj, &name[hash_min(key, elf_hash_bits())], member)
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static bool symbol_to_offset(struct rb_node *a, const struct rb_node *b)
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{
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struct symbol *sa = rb_entry(a, struct symbol, node);
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struct symbol *sb = rb_entry(b, struct symbol, node);
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if (sa->offset < sb->offset)
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return true;
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if (sa->offset > sb->offset)
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return false;
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if (sa->len < sb->len)
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return true;
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if (sa->len > sb->len)
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return false;
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sa->alias = sb;
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return false;
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}
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static int symbol_by_offset(const void *key, const struct rb_node *node)
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{
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const struct symbol *s = rb_entry(node, struct symbol, node);
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const unsigned long *o = key;
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if (*o < s->offset)
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return -1;
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if (*o >= s->offset + s->len)
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return 1;
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return 0;
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}
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struct section *find_section_by_name(const struct elf *elf, const char *name)
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{
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struct section *sec;
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elf_hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name))
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if (!strcmp(sec->name, name))
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return sec;
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return NULL;
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}
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static struct section *find_section_by_index(struct elf *elf,
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unsigned int idx)
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{
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struct section *sec;
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elf_hash_for_each_possible(elf->section_hash, sec, hash, idx)
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if (sec->idx == idx)
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return sec;
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return NULL;
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}
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static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
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{
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struct symbol *sym;
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elf_hash_for_each_possible(elf->symbol_hash, sym, hash, idx)
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if (sym->idx == idx)
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return sym;
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return NULL;
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}
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struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
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{
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struct rb_node *node;
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rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
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struct symbol *s = rb_entry(node, struct symbol, node);
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if (s->offset == offset && s->type != STT_SECTION)
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return s;
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}
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return NULL;
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}
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struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
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{
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struct rb_node *node;
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rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
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struct symbol *s = rb_entry(node, struct symbol, node);
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if (s->offset == offset && s->type == STT_FUNC)
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return s;
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}
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return NULL;
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}
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struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset)
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{
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struct rb_node *node;
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rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
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struct symbol *s = rb_entry(node, struct symbol, node);
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if (s->type != STT_SECTION)
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return s;
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}
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return NULL;
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}
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struct symbol *find_func_containing(struct section *sec, unsigned long offset)
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{
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struct rb_node *node;
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rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
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struct symbol *s = rb_entry(node, struct symbol, node);
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if (s->type == STT_FUNC)
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return s;
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}
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return NULL;
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}
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struct symbol *find_symbol_by_name(const struct elf *elf, const char *name)
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{
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struct symbol *sym;
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elf_hash_for_each_possible(elf->symbol_name_hash, sym, name_hash, str_hash(name))
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if (!strcmp(sym->name, name))
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return sym;
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return NULL;
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}
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struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
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unsigned long offset, unsigned int len)
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{
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struct reloc *reloc, *r = NULL;
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unsigned long o;
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if (!sec->reloc)
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return NULL;
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sec = sec->reloc;
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for_offset_range(o, offset, offset + len) {
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elf_hash_for_each_possible(elf->reloc_hash, reloc, hash,
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sec_offset_hash(sec, o)) {
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if (reloc->sec != sec)
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continue;
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if (reloc->offset >= offset && reloc->offset < offset + len) {
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if (!r || reloc->offset < r->offset)
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r = reloc;
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}
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}
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if (r)
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return r;
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}
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return NULL;
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}
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struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset)
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{
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return find_reloc_by_dest_range(elf, sec, offset, 1);
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}
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void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,
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struct reloc *reloc)
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{
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if (sec->sym) {
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reloc->sym = sec->sym;
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reloc->addend = offset;
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return;
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}
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/*
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* The Clang assembler strips section symbols, so we have to reference
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* the function symbol instead:
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*/
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reloc->sym = find_symbol_containing(sec, offset);
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if (!reloc->sym) {
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/*
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* Hack alert. This happens when we need to reference the NOP
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* pad insn immediately after the function.
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*/
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reloc->sym = find_symbol_containing(sec, offset - 1);
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}
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if (reloc->sym)
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reloc->addend = offset - reloc->sym->offset;
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}
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static int read_sections(struct elf *elf)
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{
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Elf_Scn *s = NULL;
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struct section *sec;
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size_t shstrndx, sections_nr;
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int i;
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if (elf_getshdrnum(elf->elf, §ions_nr)) {
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WARN_ELF("elf_getshdrnum");
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return -1;
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}
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if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
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WARN_ELF("elf_getshdrstrndx");
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return -1;
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}
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for (i = 0; i < sections_nr; i++) {
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sec = malloc(sizeof(*sec));
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if (!sec) {
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perror("malloc");
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return -1;
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}
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memset(sec, 0, sizeof(*sec));
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INIT_LIST_HEAD(&sec->symbol_list);
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INIT_LIST_HEAD(&sec->reloc_list);
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s = elf_getscn(elf->elf, i);
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if (!s) {
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WARN_ELF("elf_getscn");
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return -1;
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}
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sec->idx = elf_ndxscn(s);
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if (!gelf_getshdr(s, &sec->sh)) {
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WARN_ELF("gelf_getshdr");
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return -1;
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}
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sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
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if (!sec->name) {
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WARN_ELF("elf_strptr");
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return -1;
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}
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if (sec->sh.sh_size != 0) {
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sec->data = elf_getdata(s, NULL);
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if (!sec->data) {
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WARN_ELF("elf_getdata");
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return -1;
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}
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if (sec->data->d_off != 0 ||
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sec->data->d_size != sec->sh.sh_size) {
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WARN("unexpected data attributes for %s",
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sec->name);
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return -1;
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}
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}
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sec->len = sec->sh.sh_size;
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list_add_tail(&sec->list, &elf->sections);
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elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
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elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
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}
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if (stats)
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printf("nr_sections: %lu\n", (unsigned long)sections_nr);
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/* sanity check, one more call to elf_nextscn() should return NULL */
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if (elf_nextscn(elf->elf, s)) {
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WARN("section entry mismatch");
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return -1;
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}
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return 0;
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}
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static int read_symbols(struct elf *elf)
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{
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struct section *symtab, *symtab_shndx, *sec;
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struct symbol *sym, *pfunc;
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struct list_head *entry;
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struct rb_node *pnode;
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int symbols_nr, i;
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char *coldstr;
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Elf_Data *shndx_data = NULL;
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Elf32_Word shndx;
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symtab = find_section_by_name(elf, ".symtab");
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if (!symtab) {
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/*
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* A missing symbol table is actually possible if it's an empty
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* .o file. This can happen for thunk_64.o.
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*/
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return 0;
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}
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symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
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if (symtab_shndx)
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shndx_data = symtab_shndx->data;
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symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
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for (i = 0; i < symbols_nr; i++) {
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sym = malloc(sizeof(*sym));
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if (!sym) {
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perror("malloc");
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return -1;
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}
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memset(sym, 0, sizeof(*sym));
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sym->alias = sym;
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sym->idx = i;
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if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym,
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&shndx)) {
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WARN_ELF("gelf_getsymshndx");
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goto err;
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}
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sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
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sym->sym.st_name);
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if (!sym->name) {
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WARN_ELF("elf_strptr");
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goto err;
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}
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sym->type = GELF_ST_TYPE(sym->sym.st_info);
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sym->bind = GELF_ST_BIND(sym->sym.st_info);
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if ((sym->sym.st_shndx > SHN_UNDEF &&
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sym->sym.st_shndx < SHN_LORESERVE) ||
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(shndx_data && sym->sym.st_shndx == SHN_XINDEX)) {
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if (sym->sym.st_shndx != SHN_XINDEX)
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shndx = sym->sym.st_shndx;
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sym->sec = find_section_by_index(elf, shndx);
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if (!sym->sec) {
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WARN("couldn't find section for symbol %s",
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sym->name);
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goto err;
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}
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if (sym->type == STT_SECTION) {
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sym->name = sym->sec->name;
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sym->sec->sym = sym;
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}
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} else
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sym->sec = find_section_by_index(elf, 0);
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sym->offset = sym->sym.st_value;
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sym->len = sym->sym.st_size;
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rb_add(&sym->node, &sym->sec->symbol_tree, symbol_to_offset);
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pnode = rb_prev(&sym->node);
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if (pnode)
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entry = &rb_entry(pnode, struct symbol, node)->list;
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else
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entry = &sym->sec->symbol_list;
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list_add(&sym->list, entry);
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elf_hash_add(elf->symbol_hash, &sym->hash, sym->idx);
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elf_hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name));
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/*
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* Don't store empty STT_NOTYPE symbols in the rbtree. They
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* can exist within a function, confusing the sorting.
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*/
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if (!sym->len)
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rb_erase(&sym->node, &sym->sec->symbol_tree);
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}
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if (stats)
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printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);
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/* Create parent/child links for any cold subfunctions */
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list_for_each_entry(sec, &elf->sections, list) {
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list_for_each_entry(sym, &sec->symbol_list, list) {
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char pname[MAX_NAME_LEN + 1];
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size_t pnamelen;
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if (sym->type != STT_FUNC)
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continue;
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if (sym->pfunc == NULL)
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sym->pfunc = sym;
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if (sym->cfunc == NULL)
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sym->cfunc = sym;
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coldstr = strstr(sym->name, ".cold");
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if (!coldstr)
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continue;
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pnamelen = coldstr - sym->name;
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if (pnamelen > MAX_NAME_LEN) {
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WARN("%s(): parent function name exceeds maximum length of %d characters",
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sym->name, MAX_NAME_LEN);
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return -1;
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}
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strncpy(pname, sym->name, pnamelen);
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pname[pnamelen] = '\0';
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pfunc = find_symbol_by_name(elf, pname);
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if (!pfunc) {
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WARN("%s(): can't find parent function",
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sym->name);
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return -1;
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}
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sym->pfunc = pfunc;
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pfunc->cfunc = sym;
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/*
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* Unfortunately, -fnoreorder-functions puts the child
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* inside the parent. Remove the overlap so we can
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* have sane assumptions.
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*
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* Note that pfunc->len now no longer matches
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* pfunc->sym.st_size.
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*/
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if (sym->sec == pfunc->sec &&
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sym->offset >= pfunc->offset &&
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sym->offset + sym->len == pfunc->offset + pfunc->len) {
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pfunc->len -= sym->len;
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}
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}
|
|
}
|
|
|
|
return 0;
|
|
|
|
err:
|
|
free(sym);
|
|
return -1;
|
|
}
|
|
|
|
void elf_add_reloc(struct elf *elf, struct reloc *reloc)
|
|
{
|
|
struct section *sec = reloc->sec;
|
|
|
|
list_add_tail(&reloc->list, &sec->reloc_list);
|
|
elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
|
|
}
|
|
|
|
static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
|
|
{
|
|
if (!gelf_getrel(sec->data, i, &reloc->rel)) {
|
|
WARN_ELF("gelf_getrel");
|
|
return -1;
|
|
}
|
|
reloc->type = GELF_R_TYPE(reloc->rel.r_info);
|
|
reloc->addend = 0;
|
|
reloc->offset = reloc->rel.r_offset;
|
|
*symndx = GELF_R_SYM(reloc->rel.r_info);
|
|
return 0;
|
|
}
|
|
|
|
static int read_rela_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
|
|
{
|
|
if (!gelf_getrela(sec->data, i, &reloc->rela)) {
|
|
WARN_ELF("gelf_getrela");
|
|
return -1;
|
|
}
|
|
reloc->type = GELF_R_TYPE(reloc->rela.r_info);
|
|
reloc->addend = reloc->rela.r_addend;
|
|
reloc->offset = reloc->rela.r_offset;
|
|
*symndx = GELF_R_SYM(reloc->rela.r_info);
|
|
return 0;
|
|
}
|
|
|
|
static int read_relocs(struct elf *elf)
|
|
{
|
|
struct section *sec;
|
|
struct reloc *reloc;
|
|
int i;
|
|
unsigned int symndx;
|
|
unsigned long nr_reloc, max_reloc = 0, tot_reloc = 0;
|
|
|
|
list_for_each_entry(sec, &elf->sections, list) {
|
|
if ((sec->sh.sh_type != SHT_RELA) &&
|
|
(sec->sh.sh_type != SHT_REL))
|
|
continue;
|
|
|
|
sec->base = find_section_by_index(elf, sec->sh.sh_info);
|
|
if (!sec->base) {
|
|
WARN("can't find base section for reloc section %s",
|
|
sec->name);
|
|
return -1;
|
|
}
|
|
|
|
sec->base->reloc = sec;
|
|
|
|
nr_reloc = 0;
|
|
for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
|
|
reloc = malloc(sizeof(*reloc));
|
|
if (!reloc) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
memset(reloc, 0, sizeof(*reloc));
|
|
switch (sec->sh.sh_type) {
|
|
case SHT_REL:
|
|
if (read_rel_reloc(sec, i, reloc, &symndx))
|
|
return -1;
|
|
break;
|
|
case SHT_RELA:
|
|
if (read_rela_reloc(sec, i, reloc, &symndx))
|
|
return -1;
|
|
break;
|
|
default: return -1;
|
|
}
|
|
|
|
reloc->sec = sec;
|
|
reloc->idx = i;
|
|
reloc->sym = find_symbol_by_index(elf, symndx);
|
|
if (!reloc->sym) {
|
|
WARN("can't find reloc entry symbol %d for %s",
|
|
symndx, sec->name);
|
|
return -1;
|
|
}
|
|
|
|
elf_add_reloc(elf, reloc);
|
|
nr_reloc++;
|
|
}
|
|
max_reloc = max(max_reloc, nr_reloc);
|
|
tot_reloc += nr_reloc;
|
|
}
|
|
|
|
if (stats) {
|
|
printf("max_reloc: %lu\n", max_reloc);
|
|
printf("tot_reloc: %lu\n", tot_reloc);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
struct elf *elf_open_read(const char *name, int flags)
|
|
{
|
|
struct elf *elf;
|
|
Elf_Cmd cmd;
|
|
|
|
elf_version(EV_CURRENT);
|
|
|
|
elf = malloc(sizeof(*elf));
|
|
if (!elf) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
memset(elf, 0, offsetof(struct elf, sections));
|
|
|
|
INIT_LIST_HEAD(&elf->sections);
|
|
|
|
elf_hash_init(elf->symbol_hash);
|
|
elf_hash_init(elf->symbol_name_hash);
|
|
elf_hash_init(elf->section_hash);
|
|
elf_hash_init(elf->section_name_hash);
|
|
elf_hash_init(elf->reloc_hash);
|
|
|
|
elf->fd = open(name, flags);
|
|
if (elf->fd == -1) {
|
|
fprintf(stderr, "objtool: Can't open '%s': %s\n",
|
|
name, strerror(errno));
|
|
goto err;
|
|
}
|
|
|
|
if ((flags & O_ACCMODE) == O_RDONLY)
|
|
cmd = ELF_C_READ_MMAP;
|
|
else if ((flags & O_ACCMODE) == O_RDWR)
|
|
cmd = ELF_C_RDWR;
|
|
else /* O_WRONLY */
|
|
cmd = ELF_C_WRITE;
|
|
|
|
elf->elf = elf_begin(elf->fd, cmd, NULL);
|
|
if (!elf->elf) {
|
|
WARN_ELF("elf_begin");
|
|
goto err;
|
|
}
|
|
|
|
if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
|
|
WARN_ELF("gelf_getehdr");
|
|
goto err;
|
|
}
|
|
|
|
if (read_sections(elf))
|
|
goto err;
|
|
|
|
if (read_symbols(elf))
|
|
goto err;
|
|
|
|
if (read_relocs(elf))
|
|
goto err;
|
|
|
|
return elf;
|
|
|
|
err:
|
|
elf_close(elf);
|
|
return NULL;
|
|
}
|
|
|
|
struct section *elf_create_section(struct elf *elf, const char *name,
|
|
unsigned int sh_flags, size_t entsize, int nr)
|
|
{
|
|
struct section *sec, *shstrtab;
|
|
size_t size = entsize * nr;
|
|
Elf_Scn *s;
|
|
Elf_Data *data;
|
|
|
|
sec = malloc(sizeof(*sec));
|
|
if (!sec) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
memset(sec, 0, sizeof(*sec));
|
|
|
|
INIT_LIST_HEAD(&sec->symbol_list);
|
|
INIT_LIST_HEAD(&sec->reloc_list);
|
|
|
|
s = elf_newscn(elf->elf);
|
|
if (!s) {
|
|
WARN_ELF("elf_newscn");
|
|
return NULL;
|
|
}
|
|
|
|
sec->name = strdup(name);
|
|
if (!sec->name) {
|
|
perror("strdup");
|
|
return NULL;
|
|
}
|
|
|
|
sec->idx = elf_ndxscn(s);
|
|
sec->len = size;
|
|
sec->changed = true;
|
|
|
|
sec->data = elf_newdata(s);
|
|
if (!sec->data) {
|
|
WARN_ELF("elf_newdata");
|
|
return NULL;
|
|
}
|
|
|
|
sec->data->d_size = size;
|
|
sec->data->d_align = 1;
|
|
|
|
if (size) {
|
|
sec->data->d_buf = malloc(size);
|
|
if (!sec->data->d_buf) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
memset(sec->data->d_buf, 0, size);
|
|
}
|
|
|
|
if (!gelf_getshdr(s, &sec->sh)) {
|
|
WARN_ELF("gelf_getshdr");
|
|
return NULL;
|
|
}
|
|
|
|
sec->sh.sh_size = size;
|
|
sec->sh.sh_entsize = entsize;
|
|
sec->sh.sh_type = SHT_PROGBITS;
|
|
sec->sh.sh_addralign = 1;
|
|
sec->sh.sh_flags = SHF_ALLOC | sh_flags;
|
|
|
|
|
|
/* Add section name to .shstrtab (or .strtab for Clang) */
|
|
shstrtab = find_section_by_name(elf, ".shstrtab");
|
|
if (!shstrtab)
|
|
shstrtab = find_section_by_name(elf, ".strtab");
|
|
if (!shstrtab) {
|
|
WARN("can't find .shstrtab or .strtab section");
|
|
return NULL;
|
|
}
|
|
|
|
s = elf_getscn(elf->elf, shstrtab->idx);
|
|
if (!s) {
|
|
WARN_ELF("elf_getscn");
|
|
return NULL;
|
|
}
|
|
|
|
data = elf_newdata(s);
|
|
if (!data) {
|
|
WARN_ELF("elf_newdata");
|
|
return NULL;
|
|
}
|
|
|
|
data->d_buf = sec->name;
|
|
data->d_size = strlen(name) + 1;
|
|
data->d_align = 1;
|
|
|
|
sec->sh.sh_name = shstrtab->len;
|
|
|
|
shstrtab->len += strlen(name) + 1;
|
|
shstrtab->changed = true;
|
|
|
|
list_add_tail(&sec->list, &elf->sections);
|
|
elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
|
|
elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
|
|
|
|
elf->changed = true;
|
|
|
|
return sec;
|
|
}
|
|
|
|
static struct section *elf_create_rel_reloc_section(struct elf *elf, struct section *base)
|
|
{
|
|
char *relocname;
|
|
struct section *sec;
|
|
|
|
relocname = malloc(strlen(base->name) + strlen(".rel") + 1);
|
|
if (!relocname) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
strcpy(relocname, ".rel");
|
|
strcat(relocname, base->name);
|
|
|
|
sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rel), 0);
|
|
free(relocname);
|
|
if (!sec)
|
|
return NULL;
|
|
|
|
base->reloc = sec;
|
|
sec->base = base;
|
|
|
|
sec->sh.sh_type = SHT_REL;
|
|
sec->sh.sh_addralign = 8;
|
|
sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
|
|
sec->sh.sh_info = base->idx;
|
|
sec->sh.sh_flags = SHF_INFO_LINK;
|
|
|
|
return sec;
|
|
}
|
|
|
|
static struct section *elf_create_rela_reloc_section(struct elf *elf, struct section *base)
|
|
{
|
|
char *relocname;
|
|
struct section *sec;
|
|
|
|
relocname = malloc(strlen(base->name) + strlen(".rela") + 1);
|
|
if (!relocname) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
strcpy(relocname, ".rela");
|
|
strcat(relocname, base->name);
|
|
|
|
sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rela), 0);
|
|
free(relocname);
|
|
if (!sec)
|
|
return NULL;
|
|
|
|
base->reloc = sec;
|
|
sec->base = base;
|
|
|
|
sec->sh.sh_type = SHT_RELA;
|
|
sec->sh.sh_addralign = 8;
|
|
sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
|
|
sec->sh.sh_info = base->idx;
|
|
sec->sh.sh_flags = SHF_INFO_LINK;
|
|
|
|
return sec;
|
|
}
|
|
|
|
struct section *elf_create_reloc_section(struct elf *elf,
|
|
struct section *base,
|
|
int reltype)
|
|
{
|
|
switch (reltype) {
|
|
case SHT_REL: return elf_create_rel_reloc_section(elf, base);
|
|
case SHT_RELA: return elf_create_rela_reloc_section(elf, base);
|
|
default: return NULL;
|
|
}
|
|
}
|
|
|
|
static int elf_rebuild_rel_reloc_section(struct section *sec, int nr)
|
|
{
|
|
struct reloc *reloc;
|
|
int idx = 0, size;
|
|
void *buf;
|
|
|
|
/* Allocate a buffer for relocations */
|
|
size = nr * sizeof(GElf_Rel);
|
|
buf = malloc(size);
|
|
if (!buf) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
|
|
sec->data->d_buf = buf;
|
|
sec->data->d_size = size;
|
|
sec->data->d_type = ELF_T_REL;
|
|
|
|
sec->sh.sh_size = size;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
reloc->rel.r_offset = reloc->offset;
|
|
reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
|
|
gelf_update_rel(sec->data, idx, &reloc->rel);
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int elf_rebuild_rela_reloc_section(struct section *sec, int nr)
|
|
{
|
|
struct reloc *reloc;
|
|
int idx = 0, size;
|
|
void *buf;
|
|
|
|
/* Allocate a buffer for relocations with addends */
|
|
size = nr * sizeof(GElf_Rela);
|
|
buf = malloc(size);
|
|
if (!buf) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
|
|
sec->data->d_buf = buf;
|
|
sec->data->d_size = size;
|
|
sec->data->d_type = ELF_T_RELA;
|
|
|
|
sec->sh.sh_size = size;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(reloc, &sec->reloc_list, list) {
|
|
reloc->rela.r_offset = reloc->offset;
|
|
reloc->rela.r_addend = reloc->addend;
|
|
reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
|
|
gelf_update_rela(sec->data, idx, &reloc->rela);
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
|
|
{
|
|
struct reloc *reloc;
|
|
int nr;
|
|
|
|
sec->changed = true;
|
|
elf->changed = true;
|
|
|
|
nr = 0;
|
|
list_for_each_entry(reloc, &sec->reloc_list, list)
|
|
nr++;
|
|
|
|
switch (sec->sh.sh_type) {
|
|
case SHT_REL: return elf_rebuild_rel_reloc_section(sec, nr);
|
|
case SHT_RELA: return elf_rebuild_rela_reloc_section(sec, nr);
|
|
default: return -1;
|
|
}
|
|
}
|
|
|
|
int elf_write_insn(struct elf *elf, struct section *sec,
|
|
unsigned long offset, unsigned int len,
|
|
const char *insn)
|
|
{
|
|
Elf_Data *data = sec->data;
|
|
|
|
if (data->d_type != ELF_T_BYTE || data->d_off) {
|
|
WARN("write to unexpected data for section: %s", sec->name);
|
|
return -1;
|
|
}
|
|
|
|
memcpy(data->d_buf + offset, insn, len);
|
|
elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);
|
|
|
|
elf->changed = true;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int elf_write_reloc(struct elf *elf, struct reloc *reloc)
|
|
{
|
|
struct section *sec = reloc->sec;
|
|
|
|
if (sec->sh.sh_type == SHT_REL) {
|
|
reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
|
|
reloc->rel.r_offset = reloc->offset;
|
|
|
|
if (!gelf_update_rel(sec->data, reloc->idx, &reloc->rel)) {
|
|
WARN_ELF("gelf_update_rel");
|
|
return -1;
|
|
}
|
|
} else {
|
|
reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
|
|
reloc->rela.r_addend = reloc->addend;
|
|
reloc->rela.r_offset = reloc->offset;
|
|
|
|
if (!gelf_update_rela(sec->data, reloc->idx, &reloc->rela)) {
|
|
WARN_ELF("gelf_update_rela");
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
elf->changed = true;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int elf_write(struct elf *elf)
|
|
{
|
|
struct section *sec;
|
|
Elf_Scn *s;
|
|
|
|
/* Update section headers for changed sections: */
|
|
list_for_each_entry(sec, &elf->sections, list) {
|
|
if (sec->changed) {
|
|
s = elf_getscn(elf->elf, sec->idx);
|
|
if (!s) {
|
|
WARN_ELF("elf_getscn");
|
|
return -1;
|
|
}
|
|
if (!gelf_update_shdr(s, &sec->sh)) {
|
|
WARN_ELF("gelf_update_shdr");
|
|
return -1;
|
|
}
|
|
|
|
sec->changed = false;
|
|
}
|
|
}
|
|
|
|
/* Make sure the new section header entries get updated properly. */
|
|
elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
|
|
|
|
/* Write all changes to the file. */
|
|
if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
|
|
WARN_ELF("elf_update");
|
|
return -1;
|
|
}
|
|
|
|
elf->changed = false;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void elf_close(struct elf *elf)
|
|
{
|
|
struct section *sec, *tmpsec;
|
|
struct symbol *sym, *tmpsym;
|
|
struct reloc *reloc, *tmpreloc;
|
|
|
|
if (elf->elf)
|
|
elf_end(elf->elf);
|
|
|
|
if (elf->fd > 0)
|
|
close(elf->fd);
|
|
|
|
list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
|
|
list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
|
|
list_del(&sym->list);
|
|
hash_del(&sym->hash);
|
|
free(sym);
|
|
}
|
|
list_for_each_entry_safe(reloc, tmpreloc, &sec->reloc_list, list) {
|
|
list_del(&reloc->list);
|
|
hash_del(&reloc->hash);
|
|
free(reloc);
|
|
}
|
|
list_del(&sec->list);
|
|
free(sec);
|
|
}
|
|
|
|
free(elf);
|
|
}
|