aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--arch/i386/kernel/entry.S4
-rw-r--r--include/asm-i386/system.h8
2 files changed, 11 insertions, 1 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 37a7d2eaf4a..87f9f60b803 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -209,6 +209,10 @@ ENTRY(ret_from_fork)
GET_THREAD_INFO(%ebp)
popl %eax
CFI_ADJUST_CFA_OFFSET -4
+ pushl $0x0202 # Reset kernel eflags
+ CFI_ADJUST_CFA_OFFSET 4
+ popfl
+ CFI_ADJUST_CFA_OFFSET -4
jmp syscall_exit
CFI_ENDPROC
diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h
index 49928eb33f8..098bcee94e3 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), \