[PATCH 5.4 11/51] x86/entry: Remove skip_r11rcx

From: Greg Kroah-Hartman
Date: Wed Oct 05 2022 - 07:39:16 EST


From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

commit 1b331eeea7b8676fc5dbdf80d0a07e41be226177 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@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lore.kernel.org/r/20220506121631.365070674@xxxxxxxxxxxxx
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/entry/calling.h | 10 +---------
arch/x86/entry/entry_64.S | 3 +--
2 files changed, 2 insertions(+), 11 deletions(-)

--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -146,27 +146,19 @@ For 32-bit we have the following convent

.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
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -248,8 +248,7 @@ GLOBAL(entry_SYSCALL_64_after_hwframe)
* 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.