diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2025-06-07 10:06:40 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2025-11-24 20:23:25 +0100 |
| commit | 860238af7a3348225de228dc0f33a7d631638333 (patch) | |
| tree | d9b6d53173913cb4953fe989bb76afc369ad6a0f /arch/x86/kernel/static_call.c | |
| parent | 11bb4944f014d756f35261f5afcb346901ef1efa (diff) | |
x86_64/bug: Inline the UD1
(Ab)use the static_call infrastructure to convert all:
call __WARN_trap
instances into the desired:
ud1 (%edx), %rdi
eliminating the CALL/RET, but more importantly, fixing the
fact that all WARNs will have:
RIP: 0010:__WARN_trap+0
Basically, by making it a static_call trampoline call, objtool will
collect the callsites, and then the inline rewrite will hit the
special case and replace the code with the magic instruction.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251110115758.456717741@infradead.org
Diffstat (limited to 'arch/x86/kernel/static_call.c')
| -rw-r--r-- | arch/x86/kernel/static_call.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c index 378c388d1b31..2892cdb14563 100644 --- a/arch/x86/kernel/static_call.c +++ b/arch/x86/kernel/static_call.c @@ -26,6 +26,11 @@ static const u8 xor5rax[] = { 0x2e, 0x2e, 0x2e, 0x31, 0xc0 }; static const u8 retinsn[] = { RET_INSN_OPCODE, 0xcc, 0xcc, 0xcc, 0xcc }; +/* + * ud1 (%edx),%rdi -- see __WARN_trap() / decode_bug() + */ +static const u8 warninsn[] = { 0x67, 0x48, 0x0f, 0xb9, 0x3a }; + static u8 __is_Jcc(u8 *insn) /* Jcc.d32 */ { u8 ret = 0; @@ -69,7 +74,10 @@ static void __ref __static_call_transform(void *insn, enum insn_type type, emulate = code; code = &xor5rax; } - + if (func == &__WARN_trap) { + emulate = code; + code = &warninsn; + } break; case NOP: @@ -128,7 +136,8 @@ static void __static_call_validate(u8 *insn, bool tail, bool tramp) } else { if (opcode == CALL_INSN_OPCODE || !memcmp(insn, x86_nops[5], 5) || - !memcmp(insn, xor5rax, 5)) + !memcmp(insn, xor5rax, 5) || + !memcmp(insn, warninsn, 5)) return; } |