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authorDaniel Vetter <daniel.vetter@ffwll.ch>2015-11-23 09:04:05 +0100
committerDaniel Vetter <daniel.vetter@ffwll.ch>2015-11-23 09:04:05 +0100
commit92907cbbef8625bb3998d1eb385fc88f23c97a3f (patch)
tree15626ff9287e37c3cb81c7286d6db5a7fd77c854 /arch/x86/include/asm/switch_to.h
parent15fbfccfe92c62ae8d1ecc647c44157ed01ac02e (diff)
parent1ec218373b8ebda821aec00bb156a9c94fad9cd4 (diff)
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Merge tag 'v4.4-rc2' into drm-intel-next-queued
Linux 4.4-rc2 Backmerge to get at commit 1b0e3a049efe471c399674fd954500ce97438d30 Author: Imre Deak <imre.deak@intel.com> Date: Thu Nov 5 23:04:11 2015 +0200 drm/i915/skl: disable display side power well support for now so that we can proplery re-eanble skl power wells in -next. Conflicts are just adjacent lines changed, except for intel_fbdev.c where we need to interleave the changs. Nothing nefarious. Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Diffstat (limited to 'arch/x86/include/asm/switch_to.h')
-rw-r--r--arch/x86/include/asm/switch_to.h12
1 files changed, 8 insertions, 4 deletions
diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h
index d7f3b3b78ac3..751bf4b7bf11 100644
--- a/arch/x86/include/asm/switch_to.h
+++ b/arch/x86/include/asm/switch_to.h
@@ -79,12 +79,12 @@ do { \
#else /* CONFIG_X86_32 */
/* frame pointer must be last for get_wchan */
-#define SAVE_CONTEXT "pushf ; pushq %%rbp ; movq %%rsi,%%rbp\n\t"
-#define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp ; popf\t"
+#define SAVE_CONTEXT "pushq %%rbp ; movq %%rsi,%%rbp\n\t"
+#define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp\t"
#define __EXTRA_CLOBBER \
, "rcx", "rbx", "rdx", "r8", "r9", "r10", "r11", \
- "r12", "r13", "r14", "r15"
+ "r12", "r13", "r14", "r15", "flags"
#ifdef CONFIG_CC_STACKPROTECTOR
#define __switch_canary \
@@ -100,7 +100,11 @@ do { \
#define __switch_canary_iparam
#endif /* CC_STACKPROTECTOR */
-/* Save restore flags to clear handle leaking NT */
+/*
+ * There is no need to save or restore flags, because flags are always
+ * clean in kernel mode, with the possible exception of IOPL. Kernel IOPL
+ * has no effect.
+ */
#define switch_to(prev, next, last) \
asm volatile(SAVE_CONTEXT \
"movq %%rsp,%P[threadrsp](%[prev])\n\t" /* save RSP */ \