[PATCH v4 13/17] x86/asm/entry/64: Simplify irq stack pt_regs handling

Andy Lutomirski
2015-06-29T19:37:29Z

There's no need for both rsi and rdi to point to the original stack.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/entry/entry_64.S | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 51d34fafe4c0..ce2c9049abef 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -506,8 +506,6 @@ END(irq_entries_start)
SAVE_C_REGS
SAVE_EXTRA_REGS

- movq %rsp,%rdi /* arg1 for \func (pointer to pt_regs) */
-
testb $3, CS(%rsp)
jz 1f
SWAPGS
@@ -519,14 +517,14 @@ END(irq_entries_start)
* a little cheaper to use a separate counter in the PDA (short of
* moving irq_enter into assembly, which would be too much work)
*/
- movq %rsp, %rsi
+ movq %rsp, %rdi
incl PER_CPU_VAR(irq_count)
cmovzq PER_CPU_VAR(irq_stack_ptr), %rsp
- pushq %rsi
+ pushq %rdi
/* We entered an interrupt context - irqs are off: */
TRACE_IRQS_OFF

- call \func
+ call \func /* rdi points to pt_regs */
.endm

/*
--
2.4.3