mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-31 16:38:12 +00:00
e463a09af2
Make use of an upcoming GCC feature to mitigate straight-line-speculation for x86: https://gcc.gnu.org/g:53a643f8568067d7700a9f2facc8ba39974973d3 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102952 https://bugs.llvm.org/show_bug.cgi?id=52323 It's built tested on x86_64-allyesconfig using GCC-12 and GCC-11. Maintenance overhead of this should be fairly low due to objtool validation. Size overhead of all these additional int3 instructions comes to: text data bss dec hex filename 22267751 6933356 2011368 31212475 1dc43bb defconfig-build/vmlinux 22804126 6933356 1470696 31208178 1dc32f2 defconfig-build/vmlinux.sls Or roughly 2.4% additional text. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20211204134908.140103474@infradead.org
680 lines
18 KiB
C
680 lines
18 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Dynamic function tracing support.
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*
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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*
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* Thanks goes to Ingo Molnar, for suggesting the idea.
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* Mathieu Desnoyers, for suggesting postponing the modifications.
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* Arjan van de Ven, for keeping me straight, and explaining to me
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* the dangers of modifying code on the run.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/spinlock.h>
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#include <linux/hardirq.h>
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <linux/percpu.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/memory.h>
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#include <linux/vmalloc.h>
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#include <trace/syscall.h>
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#include <asm/set_memory.h>
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#include <asm/kprobes.h>
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#include <asm/ftrace.h>
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#include <asm/nops.h>
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#include <asm/text-patching.h>
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#ifdef CONFIG_DYNAMIC_FTRACE
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static int ftrace_poke_late = 0;
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int ftrace_arch_code_modify_prepare(void)
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__acquires(&text_mutex)
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{
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/*
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* Need to grab text_mutex to prevent a race from module loading
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* and live kernel patching from changing the text permissions while
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* ftrace has it set to "read/write".
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*/
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mutex_lock(&text_mutex);
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ftrace_poke_late = 1;
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return 0;
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}
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int ftrace_arch_code_modify_post_process(void)
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__releases(&text_mutex)
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{
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/*
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* ftrace_make_{call,nop}() may be called during
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* module load, and we need to finish the text_poke_queue()
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* that they do, here.
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*/
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text_poke_finish();
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ftrace_poke_late = 0;
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mutex_unlock(&text_mutex);
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return 0;
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}
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static const char *ftrace_nop_replace(void)
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{
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return x86_nops[5];
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}
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static const char *ftrace_call_replace(unsigned long ip, unsigned long addr)
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{
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return text_gen_insn(CALL_INSN_OPCODE, (void *)ip, (void *)addr);
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}
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static int ftrace_verify_code(unsigned long ip, const char *old_code)
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{
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char cur_code[MCOUNT_INSN_SIZE];
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/*
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* Note:
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* We are paranoid about modifying text, as if a bug was to happen, it
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* could cause us to read or write to someplace that could cause harm.
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* Carefully read and modify the code with probe_kernel_*(), and make
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* sure what we read is what we expected it to be before modifying it.
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*/
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/* read the text we want to modify */
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if (copy_from_kernel_nofault(cur_code, (void *)ip, MCOUNT_INSN_SIZE)) {
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WARN_ON(1);
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return -EFAULT;
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}
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/* Make sure it is what we expect it to be */
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if (memcmp(cur_code, old_code, MCOUNT_INSN_SIZE) != 0) {
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WARN_ON(1);
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return -EINVAL;
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}
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return 0;
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}
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/*
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* Marked __ref because it calls text_poke_early() which is .init.text. That is
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* ok because that call will happen early, during boot, when .init sections are
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* still present.
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*/
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static int __ref
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ftrace_modify_code_direct(unsigned long ip, const char *old_code,
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const char *new_code)
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{
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int ret = ftrace_verify_code(ip, old_code);
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if (ret)
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return ret;
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/* replace the text with the new text */
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if (ftrace_poke_late)
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text_poke_queue((void *)ip, new_code, MCOUNT_INSN_SIZE, NULL);
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else
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text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE);
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return 0;
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}
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int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned long ip = rec->ip;
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const char *new, *old;
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old = ftrace_call_replace(ip, addr);
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new = ftrace_nop_replace();
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/*
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* On boot up, and when modules are loaded, the MCOUNT_ADDR
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* is converted to a nop, and will never become MCOUNT_ADDR
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* again. This code is either running before SMP (on boot up)
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* or before the code will ever be executed (module load).
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* We do not want to use the breakpoint version in this case,
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* just modify the code directly.
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*/
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if (addr == MCOUNT_ADDR)
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return ftrace_modify_code_direct(ip, old, new);
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/*
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* x86 overrides ftrace_replace_code -- this function will never be used
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* in this case.
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*/
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WARN_ONCE(1, "invalid use of ftrace_make_nop");
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return -EINVAL;
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}
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned long ip = rec->ip;
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const char *new, *old;
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old = ftrace_nop_replace();
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new = ftrace_call_replace(ip, addr);
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/* Should only be called when module is loaded */
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return ftrace_modify_code_direct(rec->ip, old, new);
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}
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/*
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* Should never be called:
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* As it is only called by __ftrace_replace_code() which is called by
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* ftrace_replace_code() that x86 overrides, and by ftrace_update_code()
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* which is called to turn mcount into nops or nops into function calls
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* but not to convert a function from not using regs to one that uses
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* regs, which ftrace_modify_call() is for.
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*/
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int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
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unsigned long addr)
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{
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WARN_ON(1);
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return -EINVAL;
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}
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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unsigned long ip;
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const char *new;
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ip = (unsigned long)(&ftrace_call);
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new = ftrace_call_replace(ip, (unsigned long)func);
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text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
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ip = (unsigned long)(&ftrace_regs_call);
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new = ftrace_call_replace(ip, (unsigned long)func);
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text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
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return 0;
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}
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void ftrace_replace_code(int enable)
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{
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struct ftrace_rec_iter *iter;
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struct dyn_ftrace *rec;
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const char *new, *old;
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int ret;
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for_ftrace_rec_iter(iter) {
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rec = ftrace_rec_iter_record(iter);
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switch (ftrace_test_record(rec, enable)) {
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case FTRACE_UPDATE_IGNORE:
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default:
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continue;
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case FTRACE_UPDATE_MAKE_CALL:
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old = ftrace_nop_replace();
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break;
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case FTRACE_UPDATE_MODIFY_CALL:
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case FTRACE_UPDATE_MAKE_NOP:
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old = ftrace_call_replace(rec->ip, ftrace_get_addr_curr(rec));
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break;
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}
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ret = ftrace_verify_code(rec->ip, old);
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if (ret) {
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ftrace_bug(ret, rec);
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return;
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}
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}
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for_ftrace_rec_iter(iter) {
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rec = ftrace_rec_iter_record(iter);
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switch (ftrace_test_record(rec, enable)) {
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case FTRACE_UPDATE_IGNORE:
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default:
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continue;
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case FTRACE_UPDATE_MAKE_CALL:
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case FTRACE_UPDATE_MODIFY_CALL:
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new = ftrace_call_replace(rec->ip, ftrace_get_addr_new(rec));
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break;
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case FTRACE_UPDATE_MAKE_NOP:
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new = ftrace_nop_replace();
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break;
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}
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text_poke_queue((void *)rec->ip, new, MCOUNT_INSN_SIZE, NULL);
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ftrace_update_record(rec, enable);
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}
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text_poke_finish();
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}
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void arch_ftrace_update_code(int command)
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{
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ftrace_modify_all_code(command);
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}
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/* Currently only x86_64 supports dynamic trampolines */
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#ifdef CONFIG_X86_64
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#ifdef CONFIG_MODULES
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#include <linux/moduleloader.h>
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/* Module allocation simplifies allocating memory for code */
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static inline void *alloc_tramp(unsigned long size)
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{
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return module_alloc(size);
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}
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static inline void tramp_free(void *tramp)
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{
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module_memfree(tramp);
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}
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#else
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/* Trampolines can only be created if modules are supported */
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static inline void *alloc_tramp(unsigned long size)
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{
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return NULL;
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}
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static inline void tramp_free(void *tramp) { }
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#endif
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/* Defined as markers to the end of the ftrace default trampolines */
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extern void ftrace_regs_caller_end(void);
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extern void ftrace_regs_caller_ret(void);
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extern void ftrace_caller_end(void);
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extern void ftrace_caller_op_ptr(void);
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extern void ftrace_regs_caller_op_ptr(void);
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extern void ftrace_regs_caller_jmp(void);
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/* movq function_trace_op(%rip), %rdx */
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/* 0x48 0x8b 0x15 <offset-to-ftrace_trace_op (4 bytes)> */
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#define OP_REF_SIZE 7
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/*
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* The ftrace_ops is passed to the function callback. Since the
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* trampoline only services a single ftrace_ops, we can pass in
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* that ops directly.
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*
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* The ftrace_op_code_union is used to create a pointer to the
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* ftrace_ops that will be passed to the callback function.
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*/
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union ftrace_op_code_union {
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char code[OP_REF_SIZE];
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struct {
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char op[3];
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int offset;
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} __attribute__((packed));
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};
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#define RET_SIZE 1 + IS_ENABLED(CONFIG_SLS)
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static unsigned long
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create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
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{
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unsigned long start_offset;
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unsigned long end_offset;
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unsigned long op_offset;
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unsigned long call_offset;
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unsigned long jmp_offset;
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unsigned long offset;
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unsigned long npages;
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unsigned long size;
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unsigned long retq;
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unsigned long *ptr;
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void *trampoline;
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void *ip;
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/* 48 8b 15 <offset> is movq <offset>(%rip), %rdx */
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unsigned const char op_ref[] = { 0x48, 0x8b, 0x15 };
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union ftrace_op_code_union op_ptr;
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int ret;
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if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
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start_offset = (unsigned long)ftrace_regs_caller;
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end_offset = (unsigned long)ftrace_regs_caller_end;
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op_offset = (unsigned long)ftrace_regs_caller_op_ptr;
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call_offset = (unsigned long)ftrace_regs_call;
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jmp_offset = (unsigned long)ftrace_regs_caller_jmp;
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} else {
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start_offset = (unsigned long)ftrace_caller;
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end_offset = (unsigned long)ftrace_caller_end;
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op_offset = (unsigned long)ftrace_caller_op_ptr;
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call_offset = (unsigned long)ftrace_call;
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jmp_offset = 0;
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}
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size = end_offset - start_offset;
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/*
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* Allocate enough size to store the ftrace_caller code,
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* the iret , as well as the address of the ftrace_ops this
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* trampoline is used for.
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*/
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trampoline = alloc_tramp(size + RET_SIZE + sizeof(void *));
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if (!trampoline)
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return 0;
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*tramp_size = size + RET_SIZE + sizeof(void *);
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npages = DIV_ROUND_UP(*tramp_size, PAGE_SIZE);
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/* Copy ftrace_caller onto the trampoline memory */
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ret = copy_from_kernel_nofault(trampoline, (void *)start_offset, size);
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if (WARN_ON(ret < 0))
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goto fail;
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ip = trampoline + size;
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/* The trampoline ends with ret(q) */
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retq = (unsigned long)ftrace_stub;
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ret = copy_from_kernel_nofault(ip, (void *)retq, RET_SIZE);
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if (WARN_ON(ret < 0))
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goto fail;
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/* No need to test direct calls on created trampolines */
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if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
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/* NOP the jnz 1f; but make sure it's a 2 byte jnz */
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ip = trampoline + (jmp_offset - start_offset);
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if (WARN_ON(*(char *)ip != 0x75))
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goto fail;
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ret = copy_from_kernel_nofault(ip, x86_nops[2], 2);
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if (ret < 0)
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goto fail;
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}
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/*
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* The address of the ftrace_ops that is used for this trampoline
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* is stored at the end of the trampoline. This will be used to
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* load the third parameter for the callback. Basically, that
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* location at the end of the trampoline takes the place of
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* the global function_trace_op variable.
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*/
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ptr = (unsigned long *)(trampoline + size + RET_SIZE);
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*ptr = (unsigned long)ops;
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op_offset -= start_offset;
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memcpy(&op_ptr, trampoline + op_offset, OP_REF_SIZE);
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/* Are we pointing to the reference? */
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if (WARN_ON(memcmp(op_ptr.op, op_ref, 3) != 0))
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goto fail;
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/* Load the contents of ptr into the callback parameter */
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offset = (unsigned long)ptr;
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offset -= (unsigned long)trampoline + op_offset + OP_REF_SIZE;
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op_ptr.offset = offset;
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/* put in the new offset to the ftrace_ops */
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memcpy(trampoline + op_offset, &op_ptr, OP_REF_SIZE);
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/* put in the call to the function */
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mutex_lock(&text_mutex);
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call_offset -= start_offset;
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memcpy(trampoline + call_offset,
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text_gen_insn(CALL_INSN_OPCODE,
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trampoline + call_offset,
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ftrace_ops_get_func(ops)), CALL_INSN_SIZE);
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mutex_unlock(&text_mutex);
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/* ALLOC_TRAMP flags lets us know we created it */
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ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
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set_vm_flush_reset_perms(trampoline);
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if (likely(system_state != SYSTEM_BOOTING))
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set_memory_ro((unsigned long)trampoline, npages);
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set_memory_x((unsigned long)trampoline, npages);
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return (unsigned long)trampoline;
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fail:
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tramp_free(trampoline);
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return 0;
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}
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void set_ftrace_ops_ro(void)
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{
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struct ftrace_ops *ops;
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unsigned long start_offset;
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unsigned long end_offset;
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unsigned long npages;
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unsigned long size;
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do_for_each_ftrace_op(ops, ftrace_ops_list) {
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if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
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continue;
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if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
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start_offset = (unsigned long)ftrace_regs_caller;
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end_offset = (unsigned long)ftrace_regs_caller_end;
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} else {
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start_offset = (unsigned long)ftrace_caller;
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end_offset = (unsigned long)ftrace_caller_end;
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}
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size = end_offset - start_offset;
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size = size + RET_SIZE + sizeof(void *);
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npages = DIV_ROUND_UP(size, PAGE_SIZE);
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set_memory_ro((unsigned long)ops->trampoline, npages);
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} while_for_each_ftrace_op(ops);
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}
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static unsigned long calc_trampoline_call_offset(bool save_regs)
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{
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unsigned long start_offset;
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unsigned long call_offset;
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if (save_regs) {
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start_offset = (unsigned long)ftrace_regs_caller;
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call_offset = (unsigned long)ftrace_regs_call;
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} else {
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start_offset = (unsigned long)ftrace_caller;
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call_offset = (unsigned long)ftrace_call;
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}
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return call_offset - start_offset;
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}
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void arch_ftrace_update_trampoline(struct ftrace_ops *ops)
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{
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ftrace_func_t func;
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unsigned long offset;
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unsigned long ip;
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unsigned int size;
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const char *new;
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if (!ops->trampoline) {
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ops->trampoline = create_trampoline(ops, &size);
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if (!ops->trampoline)
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return;
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ops->trampoline_size = size;
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return;
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}
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/*
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* The ftrace_ops caller may set up its own trampoline.
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* In such a case, this code must not modify it.
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*/
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if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
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return;
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offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS);
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ip = ops->trampoline + offset;
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func = ftrace_ops_get_func(ops);
|
|
|
|
mutex_lock(&text_mutex);
|
|
/* Do a safe modify in case the trampoline is executing */
|
|
new = ftrace_call_replace(ip, (unsigned long)func);
|
|
text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
|
|
mutex_unlock(&text_mutex);
|
|
}
|
|
|
|
/* Return the address of the function the trampoline calls */
|
|
static void *addr_from_call(void *ptr)
|
|
{
|
|
union text_poke_insn call;
|
|
int ret;
|
|
|
|
ret = copy_from_kernel_nofault(&call, ptr, CALL_INSN_SIZE);
|
|
if (WARN_ON_ONCE(ret < 0))
|
|
return NULL;
|
|
|
|
/* Make sure this is a call */
|
|
if (WARN_ON_ONCE(call.opcode != CALL_INSN_OPCODE)) {
|
|
pr_warn("Expected E8, got %x\n", call.opcode);
|
|
return NULL;
|
|
}
|
|
|
|
return ptr + CALL_INSN_SIZE + call.disp;
|
|
}
|
|
|
|
void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
|
|
unsigned long frame_pointer);
|
|
|
|
/*
|
|
* If the ops->trampoline was not allocated, then it probably
|
|
* has a static trampoline func, or is the ftrace caller itself.
|
|
*/
|
|
static void *static_tramp_func(struct ftrace_ops *ops, struct dyn_ftrace *rec)
|
|
{
|
|
unsigned long offset;
|
|
bool save_regs = rec->flags & FTRACE_FL_REGS_EN;
|
|
void *ptr;
|
|
|
|
if (ops && ops->trampoline) {
|
|
#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) && \
|
|
defined(CONFIG_FUNCTION_GRAPH_TRACER)
|
|
/*
|
|
* We only know about function graph tracer setting as static
|
|
* trampoline.
|
|
*/
|
|
if (ops->trampoline == FTRACE_GRAPH_ADDR)
|
|
return (void *)prepare_ftrace_return;
|
|
#endif
|
|
return NULL;
|
|
}
|
|
|
|
offset = calc_trampoline_call_offset(save_regs);
|
|
|
|
if (save_regs)
|
|
ptr = (void *)FTRACE_REGS_ADDR + offset;
|
|
else
|
|
ptr = (void *)FTRACE_ADDR + offset;
|
|
|
|
return addr_from_call(ptr);
|
|
}
|
|
|
|
void *arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec)
|
|
{
|
|
unsigned long offset;
|
|
|
|
/* If we didn't allocate this trampoline, consider it static */
|
|
if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
|
|
return static_tramp_func(ops, rec);
|
|
|
|
offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS);
|
|
return addr_from_call((void *)ops->trampoline + offset);
|
|
}
|
|
|
|
void arch_ftrace_trampoline_free(struct ftrace_ops *ops)
|
|
{
|
|
if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
|
|
return;
|
|
|
|
tramp_free((void *)ops->trampoline);
|
|
ops->trampoline = 0;
|
|
}
|
|
|
|
#endif /* CONFIG_X86_64 */
|
|
#endif /* CONFIG_DYNAMIC_FTRACE */
|
|
|
|
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
|
|
|
#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
|
|
extern void ftrace_graph_call(void);
|
|
static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
|
|
{
|
|
return text_gen_insn(JMP32_INSN_OPCODE, (void *)ip, (void *)addr);
|
|
}
|
|
|
|
static int ftrace_mod_jmp(unsigned long ip, void *func)
|
|
{
|
|
const char *new;
|
|
|
|
new = ftrace_jmp_replace(ip, (unsigned long)func);
|
|
text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
|
|
return 0;
|
|
}
|
|
|
|
int ftrace_enable_ftrace_graph_caller(void)
|
|
{
|
|
unsigned long ip = (unsigned long)(&ftrace_graph_call);
|
|
|
|
return ftrace_mod_jmp(ip, &ftrace_graph_caller);
|
|
}
|
|
|
|
int ftrace_disable_ftrace_graph_caller(void)
|
|
{
|
|
unsigned long ip = (unsigned long)(&ftrace_graph_call);
|
|
|
|
return ftrace_mod_jmp(ip, &ftrace_stub);
|
|
}
|
|
#else /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
|
|
int ftrace_enable_ftrace_graph_caller(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
int ftrace_disable_ftrace_graph_caller(void)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
|
|
#endif /* !CONFIG_DYNAMIC_FTRACE */
|
|
|
|
/*
|
|
* Hook the return address and push it in the stack of return addrs
|
|
* in current thread info.
|
|
*/
|
|
void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
|
|
unsigned long frame_pointer)
|
|
{
|
|
unsigned long return_hooker = (unsigned long)&return_to_handler;
|
|
int bit;
|
|
|
|
/*
|
|
* When resuming from suspend-to-ram, this function can be indirectly
|
|
* called from early CPU startup code while the CPU is in real mode,
|
|
* which would fail miserably. Make sure the stack pointer is a
|
|
* virtual address.
|
|
*
|
|
* This check isn't as accurate as virt_addr_valid(), but it should be
|
|
* good enough for this purpose, and it's fast.
|
|
*/
|
|
if (unlikely((long)__builtin_frame_address(0) >= 0))
|
|
return;
|
|
|
|
if (unlikely(ftrace_graph_is_dead()))
|
|
return;
|
|
|
|
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
|
|
return;
|
|
|
|
bit = ftrace_test_recursion_trylock(ip, *parent);
|
|
if (bit < 0)
|
|
return;
|
|
|
|
if (!function_graph_enter(*parent, ip, frame_pointer, parent))
|
|
*parent = return_hooker;
|
|
|
|
ftrace_test_recursion_unlock(bit);
|
|
}
|
|
|
|
#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
|
|
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
|
|
struct ftrace_ops *op, struct ftrace_regs *fregs)
|
|
{
|
|
struct pt_regs *regs = &fregs->regs;
|
|
unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs);
|
|
|
|
prepare_ftrace_return(ip, (unsigned long *)stack, 0);
|
|
}
|
|
#endif
|
|
|
|
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
|