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x86/alternative: Simplify int3_selftest_ip 

Similar to ibt_selftest_ip, apply the same pattern.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.700456643@infradead.org
This commit is contained in:
Peter Zijlstra 2022-03-08 16:30:37 +01:00
parent af22700390
commit 99c95c5d4f
1 changed files with 7 additions and 14 deletions
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21
arch/x86/kernel/alternative.c
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@ -719,7 +719,7 @@ asm (
" .popsection\n"
);
extern __initdata unsigned long int3_selftest_ip; /* defined in asm below */
extern void int3_selftest_ip(void); /* defined in asm below */
static int __init
int3_exception_notify(struct notifier_block *self, unsigned long val, void *data)
@ -733,14 +733,15 @@ int3_exception_notify(struct notifier_block *self, unsigned long val, void *data
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);
return NOTIFY_STOP;
}
static void __init int3_selftest(void)
/* Must be noinline to ensure uniqueness of int3_selftest_ip. */
static noinline void __init int3_selftest(void)
{
static __initdata struct notifier_block int3_exception_nb = {
.notifier_call = int3_exception_notify,
@ -753,18 +754,10 @@ static void __init int3_selftest(void)
/*
* Basically: int3_magic(&val); but really complicated :-)
*
* Stick the address of the INT3 instruction into int3_selftest_ip,
* then trigger the INT3, padded with NOPs to match a CALL instruction
* length.
* INT3 padded with NOP to CALL_INSN_SIZE. The int3_exception_nb
* notifier above will emulate CALL for us.
*/
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");