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| author |   Peter Zijlstra <peterz@infradead.org> | 2022-09-08 12:04:50 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-09-15 16:13:53 +0200 |
| commit | 8c03af3e090e9d57d90f482d344563dd4bae1e66 (patch) | |
| tree | 8d5a69ee1085ce310672ea551f78baa74ea25c66 /arch/x86/kernel/alternative.c | |
| parent | x86/earlyprintk: Clean up pciserial (diff) | |
| download | linux-dev-8c03af3e090e9d57d90f482d344563dd4bae1e66.tar.xz linux-dev-8c03af3e090e9d57d90f482d344563dd4bae1e66.zip | |
x86,retpoline: Be sure to emit INT3 after JMP *%\reg
Both AMD and Intel recommend using INT3 after an indirect JMP. Make sure
to emit one when rewriting the retpoline JMP irrespective of compiler
SLS options or even CONFIG_SLS.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Link: https://lkml.kernel.org/r/Yxm+QkFPOhrVSH6q@hirez.programming.kicks-ass.net
Diffstat (limited to 'arch/x86/kernel/alternative.c')
| -rw-r--r-- | arch/x86/kernel/alternative.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 62f6b8b7c4a5..68d84cf8e001 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -453,6 +453,15 @@ static int patch_retpoline(void *addr, struct insn *insn, u8 *bytes) return ret; i += ret; + /* + * The compiler is supposed to EMIT an INT3 after every unconditional + * JMP instruction due to AMD BTC. However, if the compiler is too old + * or SLS isn't enabled, we still need an INT3 after indirect JMPs + * even on Intel. + */ + if (op == JMP32_INSN_OPCODE && i < insn->length) + bytes[i++] = INT3_INSN_OPCODE; + for (; i < insn->length;) bytes[i++] = BYTES_NOP1; |