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Subject[PATCH V6 20/49] x86/entry: Move cld to the start of idtentry
Date
From: Lai Jiangshan <laijs@linux.alibaba.com>

Make it next to CLAC

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/entry/entry_64.S | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 4781ffbe39ba..09bd77e49249 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -356,6 +356,7 @@ SYM_CODE_END(ret_from_fork)
SYM_CODE_START(\asmsym)
UNWIND_HINT_IRET_REGS offset=\has_error_code*8
ASM_CLAC
+ cld

.if \has_error_code == 0
pushq $-1 /* ORIG_RAX: no syscall to restart */
@@ -423,6 +424,7 @@ SYM_CODE_END(\asmsym)
SYM_CODE_START(\asmsym)
UNWIND_HINT_IRET_REGS
ASM_CLAC
+ cld

pushq $-1 /* ORIG_RAX: no syscall to restart */

@@ -478,6 +480,7 @@ SYM_CODE_END(\asmsym)
SYM_CODE_START(\asmsym)
UNWIND_HINT_IRET_REGS
ASM_CLAC
+ cld

/*
* If the entry is from userspace, switch stacks and treat it as
@@ -539,6 +542,7 @@ SYM_CODE_END(\asmsym)
SYM_CODE_START(\asmsym)
UNWIND_HINT_IRET_REGS offset=8
ASM_CLAC
+ cld

/* paranoid_entry returns GS information for paranoid_exit in EBX. */
call paranoid_entry
@@ -853,7 +857,6 @@ SYM_CODE_END(xen_failsafe_callback)
*/
SYM_CODE_START_LOCAL(paranoid_entry)
UNWIND_HINT_FUNC
- cld
PUSH_AND_CLEAR_REGS save_ret=1
ENCODE_FRAME_POINTER 8

@@ -975,7 +978,6 @@ SYM_CODE_END(paranoid_exit)
*/
SYM_CODE_START_LOCAL(error_entry)
UNWIND_HINT_FUNC
- cld
testb $3, CS+8(%rsp)
jz .Lerror_kernelspace

@@ -1109,6 +1111,7 @@ SYM_CODE_START(asm_exc_nmi)
*/

ASM_CLAC
+ cld

/* Use %rdx as our temp variable throughout */
pushq %rdx
@@ -1128,7 +1131,6 @@ SYM_CODE_START(asm_exc_nmi)
*/

swapgs
- cld
FENCE_SWAPGS_USER_ENTRY
SWITCH_TO_KERNEL_CR3 scratch_reg=%rdx
movq %rsp, %rdx
--
2.19.1.6.gb485710b
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