Commit 99c95c5d authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

x86/alternative: Simplify int3_selftest_ip 



Similar to ibt_selftest_ip, apply the same pattern.

Suggested-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.700456643@infradead.org
parent af227003

arch/x86/kernel/alternative.c

+7 −14
Original line number Diff line number Diff line
@@ -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");