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 */ \
#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__( \
: "=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;
#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,
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