Re: [PATCH v3 23/39] x86/alternative: Simplify int3_selftest_ip

Josh Poimboeuf
2022-03-04T18:02:40Z

On Thu, Mar 03, 2022 at 12:23:44PM +0100, Peter Zijlstra wrote:
> @@ -733,7 +733,7 @@ int3_exception_notify(struct notifier_bl
> if (val != DIE_INT3)
> return NOTIFY_DONE;
>
> - if (regs->ip - INT3_INSN_SIZE != int3_selftest_ip)
> + if (regs->ip - INT3_INSN_SIZE != (unsigned long)&int3_selftest_ip)
> return NOTIFY_DONE;
>
> int3_emulate_call(regs, (unsigned long)&int3_magic);
> @@ -757,14 +757,7 @@ static void __init int3_selftest(void)
> * then trigger the INT3, padded with NOPs to match a CALL instruction
> * length.
> */
> - asm volatile ("1: int3; nop; nop; nop; nop\n\t"
> - ".pushsection .init.data,\"aw\"\n\t"
> - ".align " __ASM_SEL(4, 8) "\n\t"
> - ".type int3_selftest_ip, @object\n\t"
> - ".size int3_selftest_ip, " __ASM_SEL(4, 8) "\n\t"
> - "int3_selftest_ip:\n\t"
> - __ASM_SEL(.long, .quad) " 1b\n\t"
> - ".popsection\n\t"
> + asm volatile ("int3_selftest_ip: int3; nop; nop; nop; nop\n\t"
> : ASM_CALL_CONSTRAINT
> : __ASM_SEL_RAW(a, D) (&val)
> : "memory");

Hm, why doesn't this need ANNOTATE_NOENDBR?

--
Josh