Now that NT is filtered by the SYSENTER entry code, it is safe to skip saving
and
restoring flags on task switch. Also remove a leftover reset of flags on 64-bit
fork.
Signed-off-by: Brian Gerst
---
arch/x86/entry/entry_32.S| 4
arch/x86/entry/entry_64.S| 3 ---
arch/x86/include/asm/switch_to.h | 4 +---
3 files changed, 1 insertion(+), 10 deletions(-)
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 10868aa..c84d99b 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -209,8 +209,6 @@ ENTRY(ret_from_fork)
callschedule_tail
GET_THREAD_INFO(%ebp)
popl%eax
- pushl $0x0202 # Reset kernel eflags
- popfl
/* When we fork, we trace the syscall return in the child, too. */
movl%esp, %eax
@@ -223,8 +221,6 @@ ENTRY(ret_from_kernel_thread)
callschedule_tail
GET_THREAD_INFO(%ebp)
popl%eax
- pushl $0x0202 # Reset kernel eflags
- popfl
movlPT_EBP(%esp), %eax
call*PT_EBX(%esp)
movl$0, PT_EAX(%esp)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 6344629..9ee0da1 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -372,9 +372,6 @@ END(ptregs_\func)
ENTRY(ret_from_fork)
LOCK ; btr $TIF_FORK, TI_flags(%r8)
- pushq $0x0002
- popfq /* reset kernel eflags */
-
callschedule_tail /* rdi: 'prev' task parameter */
testb $3, CS(%rsp)/* from kernel_thread? */
diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h
index 751bf4b..8f321a1 100644
--- a/arch/x86/include/asm/switch_to.h
+++ b/arch/x86/include/asm/switch_to.h
@@ -39,8 +39,7 @@ do {
\
*/ \
unsigned long ebx, ecx, edx, esi, edi; \
\
- asm volatile("pushfl\n\t" /* saveflags */ \
-"pushl %%ebp\n\t" /* saveEBP */ \
+ asm volatile("pushl %%ebp\n\t" /* saveEBP */ \
"movl %%esp,%[prev_sp]\n\t"/* saveESP */ \
"movl %[next_sp],%%esp\n\t"/* restore ESP */ \
"movl $1f,%[prev_ip]\n\t" /* saveEIP */ \
@@ -49,7 +48,6 @@ do {
\
"jmp __switch_to\n"/* regparm call */ \
"1:\t" \
"popl %%ebp\n\t" /* restore EBP */ \
-"popfl\n" /* restore flags */ \
\
/* output parameters */\
: [prev_sp] "=m" (prev->thread.sp),\
--
2.5.5
