Merge to Fedora kernel-2.6.18-1.2255_FC5-vs2.0.2.2-rc9 patched with stable patch...

[linux-2.6.git] / include / asm-i386 / mach-xen / asm / system.h

diff --git a/include/asm-i386/mach-xen/asm/system.h b/include/asm-i386/mach-xen/asm/system.h
index d8ca393..b126e23 100644 (file)
--- a/include/asm-i386/mach-xen/asm/system.h
+++ b/include/asm-i386/mach-xen/asm/system.h
@@ -19,6 +19,10 @@
 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("pushfl\n\t"               /* Save flags */        \