Commit 1b331eee authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Borislav Petkov
Browse files

x86/entry: Remove skip_r11rcx 



Yes, r11 and rcx have been restored previously, but since they're being
popped anyway (into rsi) might as well pop them into their own regs --
setting them to the value they already are.

Less magical code.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220506121631.365070674@infradead.org
parent 8c42819b

arch/x86/entry/calling.h

+1 −9
Original line number Diff line number Diff line
@@ -120,27 +120,19 @@ For 32-bit we have the following conventions - kernel is built with 
	CLEAR_REGS

.endm



.macro POP_REGS pop_rdi=1 skip_r11rcx=0

.macro POP_REGS pop_rdi=1

	popq %r15

	popq %r14

	popq %r13

	popq %r12

	popq %rbp

	popq %rbx

	.if \skip_r11rcx

	popq %rsi

	.else

	popq %r11

	.endif

	popq %r10

	popq %r9

	popq %r8

	popq %rax

	.if \skip_r11rcx

	popq %rsi

	.else

	popq %rcx

	.endif

	popq %rdx

	popq %rsi

	.if \pop_rdi

arch/x86/entry/entry_64.S

+1 −2
Original line number Diff line number Diff line
@@ -191,8 +191,7 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_hwframe, SYM_L_GLOBAL) 
	 * perf profiles. Nothing jumps here.

	 */

syscall_return_via_sysret:

	/* rcx and r11 are already restored (see code above) */

	POP_REGS pop_rdi=0 skip_r11rcx=1

	POP_REGS pop_rdi=0



	/*

	 * Now all regs are restored except RSP and RDI.