[PATCH 4/6] x86/entry: Remove skip_r11rcx

From: Peter Zijlstra
Date: Fri May 06 2022 - 08:21:08 EST


Yes, r11 and rcx have been restored previously, but since we're
popping them 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>
---
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
@@ -120,27 +120,19 @@ For 32-bit we have the following convent
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
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -191,8 +191,7 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_h
* 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.