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| author | Peter Zijlstra <peterz@infradead.org> | 2022-09-15 13:11:25 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-10-17 16:41:14 +0200 |
| commit | 770ae1b709528a6a173b5c7b183818ee9b45e376 (patch) | |
| tree | 32e60c4fe4e050c253f981ed2ae7af00e2d51f77 /arch/x86/kernel/alternative.c | |
| parent | eaf44c816ed8d1ef94c354e3ed47d53cd5a5cb13 (diff) | |
| download | linux-770ae1b709528a6a173b5c7b183818ee9b45e376.tar.bz2 | |
x86/returnthunk: Allow different return thunks
In preparation for call depth tracking on Intel SKL CPUs, make it possible
to patch in a SKL specific return thunk.
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/20220915111147.680469665@infradead.org
Diffstat (limited to 'arch/x86/kernel/alternative.c')
| -rw-r--r-- | arch/x86/kernel/alternative.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 963872d17707..04d1e3d35b0e 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -518,6 +518,11 @@ void __init_or_module noinline apply_retpolines(s32 *start, s32 *end) } #ifdef CONFIG_RETHUNK + +#ifdef CONFIG_CALL_THUNKS +void (*x86_return_thunk)(void) __ro_after_init = &__x86_return_thunk; +#endif + /* * Rewrite the compiler generated return thunk tail-calls. * @@ -533,14 +538,18 @@ static int patch_return(void *addr, struct insn *insn, u8 *bytes) { int i = 0; - if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) - return -1; + if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) { + if (x86_return_thunk == __x86_return_thunk) + return -1; - bytes[i++] = RET_INSN_OPCODE; + i = JMP32_INSN_SIZE; + __text_gen_insn(bytes, JMP32_INSN_OPCODE, addr, x86_return_thunk, i); + } else { + bytes[i++] = RET_INSN_OPCODE; + } for (; i < insn->length;) bytes[i++] = INT3_INSN_OPCODE; - return i; } |