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x86/entry: Remove skip_r11rcx

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commit 1b331eeea7 upstream.

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: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220506121631.365070674@infradead.org
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Zijlstra 2022-05-06 14:14:35 +02:00 • committed by Justin Hammond
parent dc8bf07914
commit f80e90bfe5
2 changed files with 2 additions and 11 deletions
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10
arch/x86/entry/calling.h
View file

@ -119,27 +119,19 @@ 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

3
arch/x86/entry/entry_64.S
View file

@ -189,8 +189,7 @@ 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.