[tip:x86/asm] x86/asm/entry/64: Simplify IRQ stack pt_regs handling

tip-bot for Andy Lutomirski
2015-07-07T10:54:16Z

Commit-ID: a586f98e9767fb0dfdb989002866b4024f00ce08
Gitweb: http://git.kernel.org/tip/a586f98e9767fb0dfdb989002866b4024f00ce08
Author: Andy Lutomirski <luto@kernel.org>
AuthorDate: Fri, 3 Jul 2015 12:44:30 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 7 Jul 2015 10:59:08 +0200

x86/asm/entry/64: Simplify IRQ stack pt_regs handling

There's no need for both RSI and RDI to point to the original stack.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/3a0481f809dd340c7d3f54ce3fd6d66ef2a578cd.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@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 65029f4..83eb63d 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

/*