---

yaml --- r: 33979 b: refs/heads/master c: 47a5c6f h: refs/heads/master i: 33977: bf524b4 33975: 7384516 v: v3
git-mirror · Sep 18, 2006 · b8043c4 · b8043c4
1 parent def3cac
commit b8043c4
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Showing 3 changed files with 12 additions and 2 deletions.
diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1d19f176a2884d31c4fe2c7018349ff884a819b1
+refs/heads/master: 47a5c6fa0e204a2b63309c648bb2fde36836c826
diff --git a/trunk/arch/i386/kernel/entry.S b/trunk/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/trunk/include/asm-i386/system.h b/trunk/include/asm-i386/system.h
@@ -11,16 +11,22 @@
 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 */		\
 		     "pushl %6\n\t"		/* restore EIP */	\
 		     "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),	\