x86-64: remove locked instruction from switch_to()

[deliverable/linux.git] / arch / x86 / include / asm / system.h

diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
index 07c3e4048991c757663c3de65338a85259a0cd2a..fa47b1e6a86651872c98ce2e2c144f05ecda92d3 100644 (file)
--- a/arch/x86/include/asm/system.h
+++ b/arch/x86/include/asm/system.h
@@ -17,12 +17,12 @@
 # define AT_VECTOR_SIZE_ARCH 1
 #endif
 
-#ifdef CONFIG_X86_32
-
 struct task_struct; /* one of the stranger aspects of C forward declarations */
 struct task_struct *__switch_to(struct task_struct *prev,
                                struct task_struct *next);
 
+#ifdef CONFIG_X86_32
+
 /*
  * Saving eflags is important. It switches not only IOPL between tasks,
  * it also protects other tasks from NT leaking through sysenter etc.
@@ -96,15 +96,15 @@ do {                                                                        \
             "thread_return:\n\t"                                         \
             "movq %%gs:%P[pda_pcurrent],%%rsi\n\t"                       \
             "movq %P[thread_info](%%rsi),%%r8\n\t"                       \
-            LOCK_PREFIX "btr  %[tif_fork],%P[ti_flags](%%r8)\n\t"        \
             "movq %%rax,%%rdi\n\t"                                       \
-            "jc   ret_from_fork\n\t"                                     \
+            "testl  %[_tif_fork],%P[ti_flags](%%r8)\n\t"         \
+            "jnz   ret_from_fork\n\t"                                    \
             RESTORE_CONTEXT                                              \
             : "=a" (last)                                                \
             : [next] "S" (next), [prev] "D" (prev),                      \
               [threadrsp] "i" (offsetof(struct task_struct, thread.sp)), \
               [ti_flags] "i" (offsetof(struct thread_info, flags)),      \
-              [tif_fork] "i" (TIF_FORK),                                 \
+              [_tif_fork] "i" (_TIF_FORK),                               \
               [thread_info] "i" (offsetof(struct task_struct, stack)),   \
               [pda_pcurrent] "i" (offsetof(struct x8664_pda, pcurrent))  \
             : "memory", "cc" __EXTRA_CLOBBER)