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| author | Peter Zijlstra <peterz@infradead.org> | 2023-06-14 16:35:50 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-06-14 19:02:54 +0200 |
| commit | 2bd4aa9325821551648cf9738d6aa3a49317d7e5 (patch) | |
| tree | 86d2e879140656fc0df9330afd349bf85490d4d7 | |
| parent | 9350a629e839ca1c2b529a83a916cf2370bd1c64 (diff) | |
| download | linux-stable-2bd4aa9325821551648cf9738d6aa3a49317d7e5.tar.gz linux-stable-2bd4aa9325821551648cf9738d6aa3a49317d7e5.tar.bz2 linux-stable-2bd4aa9325821551648cf9738d6aa3a49317d7e5.zip | |
x86/alternative: PAUSE is not a NOP
While chasing ghosts, I did notice that optimize_nops() was replacing
'REP NOP' aka 'PAUSE' with NOP2. This is clearly not right.
Fixes: 6c480f222128 ("x86/alternative: Rewrite optimize_nops() some")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/linux-next/20230524130104.GR83892@hirez.programming.kicks-ass.net/
| -rw-r--r-- | arch/x86/kernel/alternative.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index bbfbf7ad17ca..a7e1ec50ad29 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -169,9 +169,12 @@ void text_poke_early(void *addr, const void *opcode, size_t len); */ static bool insn_is_nop(struct insn *insn) { - if (insn->opcode.bytes[0] == 0x90) + /* Anything NOP, but no REP NOP */ + if (insn->opcode.bytes[0] == 0x90 && + (!insn->prefixes.nbytes || insn->prefixes.bytes[0] != 0xF3)) return true; + /* NOPL */ if (insn->opcode.bytes[0] == 0x0F && insn->opcode.bytes[1] == 0x1F) return true; |