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

Josh Poimboeuf
2022-03-04T18:09:45Z

On Fri, Mar 04, 2022 at 10:02:23AM -0800, Josh Poimboeuf wrote:
> 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?

Never mind, I see it's added later... though I still have the same
comment about the ANNOTATE_ENDBR coming after the label.

--
Josh