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| author | Peter Zijlstra <peterz@infradead.org> | 2022-09-15 14:11:37 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-10-17 17:41:19 +0300 |
| commit | ee3e2469b3463d28ca4cde20e0283319ac6a562d (patch) | |
| tree | 958265de2b1865d821630bc175df913052ac7f25 /arch/x86/include/asm/nospec-branch.h | |
| parent | 36b64f101219dd9e6e4f0ea880b64e8a90da547b (diff) | |
| download | linux-ee3e2469b3463d28ca4cde20e0283319ac6a562d.tar.xz | |
x86/ftrace: Make it call depth tracking aware
Since ftrace has trampolines, don't use thunks for the __fentry__ site
but instead require that every function called from there includes
accounting. This very much includes all the direct-call functions.
Additionally, ftrace uses ROP tricks in two places:
- return_to_handler(), and
- ftrace_regs_caller() when pt_regs->orig_ax is set by a direct-call.
return_to_handler() already uses a retpoline to replace an
indirect-jump to defeat IBT, since this is a jump-type retpoline, make
sure there is no accounting done and ALTERNATIVE the RET into a ret.
ftrace_regs_caller() does much the same and gets the same treatment.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111148.927545073@infradead.org
Diffstat (limited to 'arch/x86/include/asm/nospec-branch.h')
| -rw-r--r-- | arch/x86/include/asm/nospec-branch.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 4771147c7c5a..82580adbca4b 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -343,6 +343,12 @@ static inline void x86_set_skl_return_thunk(void) { x86_return_thunk = &__x86_return_skl; } + +#define CALL_DEPTH_ACCOUNT \ + ALTERNATIVE("", \ + __stringify(INCREMENT_CALL_DEPTH), \ + X86_FEATURE_CALL_DEPTH) + #ifdef CONFIG_CALL_THUNKS_DEBUG DECLARE_PER_CPU(u64, __x86_call_count); DECLARE_PER_CPU(u64, __x86_ret_count); @@ -351,6 +357,9 @@ DECLARE_PER_CPU(u64, __x86_ctxsw_count); #endif #else static inline void x86_set_skl_return_thunk(void) {} + +#define CALL_DEPTH_ACCOUNT "" + #endif #ifdef CONFIG_RETPOLINE |