1 files changed, 7 insertions, 1 deletions

diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h
index 49928eb33f8b..098bcee94e38 100644
--- a/include/asm-i386/system.h
+++ b/include/asm-i386/system.h
@@ -11,9 +11,14 @@
 struct task_struct;     /* one of the stranger aspects of C forward declarations.. */
 extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struct task_struct *next));
 
+/*
+ * Saving eflags is important. It switches not only IOPL between tasks,
+ * it also protects other tasks from NT leaking through sysenter etc.
+ */
 #define switch_to(prev,next,last) do {                                  \
         unsigned long esi,edi;                                          \
-        asm volatile("pushl %%ebp\n\t"                                  \
+        asm volatile("pushfl\n\t"               /* Save flags */        \
+                     "pushl %%ebp\n\t"                                  \
                      "movl %%esp,%0\n\t"        /* save ESP */          \
                      "movl %5,%%esp\n\t"        /* restore ESP */       \
                      "movl $1f,%1\n\t"          /* save EIP */          \
@@ -21,6 +26,7 @@ extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struc
                      "jmp __switch_to\n"                                \
                      "1:\t"                                             \
                      "popl %%ebp\n\t"                                   \
+                     "popfl"                                            \
                      :"=m" (prev->thread.esp),"=m" (prev->thread.eip),  \
                       "=a" (last),"=S" (esi),"=D" (edi)                 \
                      :"m" (next->thread.esp),"m" (next->thread.eip),    \