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| author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-01-20 14:01:31 -0300 |
|---|---|---|
| committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-01-20 14:01:31 -0300 |
| commit | b4b7ff4b08e691656c9d77c758fc355833128ac0 (patch) | |
| tree | 82fcb00e6b918026dc9f2d1f05ed8eee83874cc0 /arch/x86/include/asm/switch_to.h | |
| parent | 35acfa0fc609f2a2cd95cef4a6a9c3a5c38f1778 (diff) | |
Linux-libre 4.4-gnupck-4.4-gnu
Diffstat (limited to 'arch/x86/include/asm/switch_to.h')
| -rw-r--r-- | arch/x86/include/asm/switch_to.h | 12 |
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 d7f3b3b78..751bf4b7b 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 */ \ |