X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=include%2Fasm-i386%2Fmach-xen%2Fasm%2Fsystem.h;h=875fca7f9435d43e09a4cbd7da7c86e8b490a8f6;hb=refs%2Fheads%2Fvserver;hp=d8ca39352a9a180d099da4bc1a618529899d9e96;hpb=16c70f8c1b54b61c3b951b6fb220df250fe09b32;p=linux-2.6.git

diff --git a/include/asm-i386/mach-xen/asm/system.h b/include/asm-i386/mach-xen/asm/system.h
index d8ca39352..875fca7f9 100644
--- 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 */	\
@@ -92,6 +96,9 @@ __asm__ __volatile__ ("movw %%dx,%1\n\t" \
 #define savesegment(seg, value) \
 	asm volatile("mov %%" #seg ",%0":"=rm" (value))
 
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt.h>
+#else
 #define read_cr0() ({ \
 	unsigned int __dummy; \
 	__asm__ __volatile__( \
@@ -139,20 +146,21 @@ __asm__ __volatile__ ("movw %%dx,%1\n\t" \
 		: "=r" (__dummy): "0" (0));	      \
 	__dummy;				      \
 })
-
 #define write_cr4(x) \
 	__asm__ __volatile__("movl %0,%%cr4": :"r" (x))
-/*
- * Clear and set 'TS' bit respectively
- */
+
+#define wbinvd() \
+	__asm__ __volatile__ ("wbinvd": : :"memory")
+
+/* Clear the 'TS' bit */
 #define clts() (HYPERVISOR_fpu_taskswitch(0))
+#endif/* CONFIG_PARAVIRT */
+
+/* Set the 'TS' bit */
 #define stts() (HYPERVISOR_fpu_taskswitch(1))
 
 #endif	/* __KERNEL__ */
 
-#define wbinvd() \
-	__asm__ __volatile__ ("wbinvd": : :"memory")
-
 static inline unsigned long get_limit(unsigned long segment)
 {
 	unsigned long __limit;
@@ -270,6 +278,9 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz
 #define cmpxchg(ptr,o,n)\
 	((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
 					(unsigned long)(n),sizeof(*(ptr))))
+#define sync_cmpxchg(ptr,o,n)\
+	((__typeof__(*(ptr)))__sync_cmpxchg((ptr),(unsigned long)(o),\
+					(unsigned long)(n),sizeof(*(ptr))))
 #endif
 
 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
@@ -299,6 +310,39 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 	return old;
 }
 
+/*
+ * Always use locked operations when touching memory shared with a
+ * hypervisor, since the system may be SMP even if the guest kernel
+ * isn't.
+ */
+static inline unsigned long __sync_cmpxchg(volatile void *ptr,
+					    unsigned long old,
+					    unsigned long new, int size)
+{
+	unsigned long prev;
+	switch (size) {
+	case 1:
+		__asm__ __volatile__("lock; cmpxchgb %b1,%2"
+				     : "=a"(prev)
+				     : "q"(new), "m"(*__xg(ptr)), "0"(old)
+				     : "memory");
+		return prev;
+	case 2:
+		__asm__ __volatile__("lock; cmpxchgw %w1,%2"
+				     : "=a"(prev)
+				     : "r"(new), "m"(*__xg(ptr)), "0"(old)
+				     : "memory");
+		return prev;
+	case 4:
+		__asm__ __volatile__("lock; cmpxchgl %1,%2"
+				     : "=a"(prev)
+				     : "r"(new), "m"(*__xg(ptr)), "0"(old)
+				     : "memory");
+		return prev;
+	}
+	return old;
+}
+
 #ifndef CONFIG_X86_CMPXCHG
 /*
  * Building a kernel capable running on 80386. It may be necessary to