Commit ef79ed20 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

x86/entry: Make sync_regs() invocation a tail call 



No point in having a call there. Spare the call/ret overhead.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111146.539578813@infradead.org
parent 5a9c361a

arch/x86/entry/entry_64.S

+2 −5
Original line number Diff line number Diff line
@@ -1062,11 +1062,8 @@ SYM_CODE_START_LOCAL(error_entry) 
	UNTRAIN_RET



	leaq	8(%rsp), %rdi			/* arg0 = pt_regs pointer */

.Lerror_entry_from_usermode_after_swapgs:



	/* Put us onto the real thread stack. */

	call	sync_regs

	RET

	jmp	sync_regs



	/*

	 * There are two places in the kernel that can potentially fault with
@@ -1124,7 +1121,7 @@ SYM_CODE_START_LOCAL(error_entry) 
	leaq	8(%rsp), %rdi			/* arg0 = pt_regs pointer */

	call	fixup_bad_iret

	mov	%rax, %rdi

	jmp	.Lerror_entry_from_usermode_after_swapgs

	jmp	sync_regs

SYM_CODE_END(error_entry)



SYM_CODE_START_LOCAL(error_return)