1 files changed, 293 insertions, 0 deletions

diff --git a/include/asm-i386/cmpxchg.h b/include/asm-i386/cmpxchg.h
new file mode 100644
index 000000000000..7adcef0cd53b
--- /dev/null
+++ b/include/asm-i386/cmpxchg.h
@@ -0,0 +1,293 @@
+#ifndef __ASM_CMPXCHG_H
+#define __ASM_CMPXCHG_H
+
+#include <linux/bitops.h> /* for LOCK_PREFIX */
+
+#define xchg(ptr,v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v),(ptr),sizeof(*(ptr))))
+
+struct __xchg_dummy { unsigned long a[100]; };
+#define __xg(x) ((struct __xchg_dummy *)(x))
+
+
+#ifdef CONFIG_X86_CMPXCHG64
+
+/*
+ * The semantics of XCHGCMP8B are a bit strange, this is why
+ * there is a loop and the loading of %%eax and %%edx has to
+ * be inside. This inlines well in most cases, the cached
+ * cost is around ~38 cycles. (in the future we might want
+ * to do an SIMD/3DNOW!/MMX/FPU 64-bit store here, but that
+ * might have an implicit FPU-save as a cost, so it's not
+ * clear which path to go.)
+ *
+ * cmpxchg8b must be used with the lock prefix here to allow
+ * the instruction to be executed atomically, see page 3-102
+ * of the instruction set reference 24319102.pdf. We need
+ * the reader side to see the coherent 64bit value.
+ */
+static inline void __set_64bit (unsigned long long * ptr,
+                unsigned int low, unsigned int high)
+{
+        __asm__ __volatile__ (
+                "\n1:\t"
+                "movl (%0), %%eax\n\t"
+                "movl 4(%0), %%edx\n\t"
+                "lock cmpxchg8b (%0)\n\t"
+                "jnz 1b"
+                : /* no outputs */
+                :       "D"(ptr),
+                        "b"(low),
+                        "c"(high)
+                :       "ax","dx","memory");
+}
+
+static inline void __set_64bit_constant (unsigned long long *ptr,
+                                                 unsigned long long value)
+{
+        __set_64bit(ptr,(unsigned int)(value), (unsigned int)((value)>>32ULL));
+}
+#define ll_low(x)       *(((unsigned int*)&(x))+0)
+#define ll_high(x)      *(((unsigned int*)&(x))+1)
+
+static inline void __set_64bit_var (unsigned long long *ptr,
+                         unsigned long long value)
+{
+        __set_64bit(ptr,ll_low(value), ll_high(value));
+}
+
+#define set_64bit(ptr,value) \
+(__builtin_constant_p(value) ? \
+ __set_64bit_constant(ptr, value) : \
+ __set_64bit_var(ptr, value) )
+
+#define _set_64bit(ptr,value) \
+(__builtin_constant_p(value) ? \
+ __set_64bit(ptr, (unsigned int)(value), (unsigned int)((value)>>32ULL) ) : \
+ __set_64bit(ptr, ll_low(value), ll_high(value)) )
+
+#endif
+
+/*
+ * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
+ * Note 2: xchg has side effect, so that attribute volatile is necessary,
+ *        but generally the primitive is invalid, *ptr is output argument. --ANK
+ */
+static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
+{
+        switch (size) {
+                case 1:
+                        __asm__ __volatile__("xchgb %b0,%1"
+                                :"=q" (x)
+                                :"m" (*__xg(ptr)), "0" (x)
+                                :"memory");
+                        break;
+                case 2:
+                        __asm__ __volatile__("xchgw %w0,%1"
+                                :"=r" (x)
+                                :"m" (*__xg(ptr)), "0" (x)
+                                :"memory");
+                        break;
+                case 4:
+                        __asm__ __volatile__("xchgl %0,%1"
+                                :"=r" (x)
+                                :"m" (*__xg(ptr)), "0" (x)
+                                :"memory");
+                        break;
+        }
+        return x;
+}
+
+/*
+ * Atomic compare and exchange.  Compare OLD with MEM, if identical,
+ * store NEW in MEM.  Return the initial value in MEM.  Success is
+ * indicated by comparing RETURN with OLD.
+ */
+
+#ifdef CONFIG_X86_CMPXCHG
+#define __HAVE_ARCH_CMPXCHG 1
+#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))))
+#define cmpxchg_local(ptr,o,n)\
+        ((__typeof__(*(ptr)))__cmpxchg_local((ptr),(unsigned long)(o),\
+                                        (unsigned long)(n),sizeof(*(ptr))))
+#endif
+
+static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
+                                      unsigned long new, int size)
+{
+        unsigned long prev;
+        switch (size) {
+        case 1:
+                __asm__ __volatile__(LOCK_PREFIX "cmpxchgb %b1,%2"
+                                     : "=a"(prev)
+                                     : "q"(new), "m"(*__xg(ptr)), "0"(old)
+                                     : "memory");
+                return prev;
+        case 2:
+                __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
+                                     : "=a"(prev)
+                                     : "r"(new), "m"(*__xg(ptr)), "0"(old)
+                                     : "memory");
+                return prev;
+        case 4:
+                __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %1,%2"
+                                     : "=a"(prev)
+                                     : "r"(new), "m"(*__xg(ptr)), "0"(old)
+                                     : "memory");
+                return prev;
+        }
+        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;
+}
+
+static inline unsigned long __cmpxchg_local(volatile void *ptr,
+                        unsigned long old, unsigned long new, int size)
+{
+        unsigned long prev;
+        switch (size) {
+        case 1:
+                __asm__ __volatile__("cmpxchgb %b1,%2"
+                                     : "=a"(prev)
+                                     : "q"(new), "m"(*__xg(ptr)), "0"(old)
+                                     : "memory");
+                return prev;
+        case 2:
+                __asm__ __volatile__("cmpxchgw %w1,%2"
+                                     : "=a"(prev)
+                                     : "r"(new), "m"(*__xg(ptr)), "0"(old)
+                                     : "memory");
+                return prev;
+        case 4:
+                __asm__ __volatile__("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
+ * simulate the cmpxchg on the 80386 CPU. For that purpose we define
+ * a function for each of the sizes we support.
+ */
+
+extern unsigned long cmpxchg_386_u8(volatile void *, u8, u8);
+extern unsigned long cmpxchg_386_u16(volatile void *, u16, u16);
+extern unsigned long cmpxchg_386_u32(volatile void *, u32, u32);
+
+static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old,
+                                      unsigned long new, int size)
+{
+        switch (size) {
+        case 1:
+                return cmpxchg_386_u8(ptr, old, new);
+        case 2:
+                return cmpxchg_386_u16(ptr, old, new);
+        case 4:
+                return cmpxchg_386_u32(ptr, old, new);
+        }
+        return old;
+}
+
+#define cmpxchg(ptr,o,n)                                                \
+({                                                                      \
+        __typeof__(*(ptr)) __ret;                                       \
+        if (likely(boot_cpu_data.x86 > 3))                              \
+                __ret = __cmpxchg((ptr), (unsigned long)(o),            \
+                                        (unsigned long)(n), sizeof(*(ptr))); \
+        else                                                            \
+                __ret = cmpxchg_386((ptr), (unsigned long)(o),          \
+                                        (unsigned long)(n), sizeof(*(ptr))); \
+        __ret;                                                          \
+})
+#define cmpxchg_local(ptr,o,n)                                          \
+({                                                                      \
+        __typeof__(*(ptr)) __ret;                                       \
+        if (likely(boot_cpu_data.x86 > 3))                              \
+                __ret = __cmpxchg_local((ptr), (unsigned long)(o),      \
+                                        (unsigned long)(n), sizeof(*(ptr))); \
+        else                                                            \
+                __ret = cmpxchg_386((ptr), (unsigned long)(o),          \
+                                        (unsigned long)(n), sizeof(*(ptr))); \
+        __ret;                                                          \
+})
+#endif
+
+#ifdef CONFIG_X86_CMPXCHG64
+
+static inline unsigned long long __cmpxchg64(volatile void *ptr, unsigned long long old,
+                                      unsigned long long new)
+{
+        unsigned long long prev;
+        __asm__ __volatile__(LOCK_PREFIX "cmpxchg8b %3"
+                             : "=A"(prev)
+                             : "b"((unsigned long)new),
+                               "c"((unsigned long)(new >> 32)),
+                               "m"(*__xg(ptr)),
+                               "0"(old)
+                             : "memory");
+        return prev;
+}
+
+static inline unsigned long long __cmpxchg64_local(volatile void *ptr,
+                        unsigned long long old, unsigned long long new)
+{
+        unsigned long long prev;
+        __asm__ __volatile__("cmpxchg8b %3"
+                             : "=A"(prev)
+                             : "b"((unsigned long)new),
+                               "c"((unsigned long)(new >> 32)),
+                               "m"(*__xg(ptr)),
+                               "0"(old)
+                             : "memory");
+        return prev;
+}
+
+#define cmpxchg64(ptr,o,n)\
+        ((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\
+                                        (unsigned long long)(n)))
+#define cmpxchg64_local(ptr,o,n)\
+        ((__typeof__(*(ptr)))__cmpxchg64_local((ptr),(unsigned long long)(o),\
+                                        (unsigned long long)(n)))
+#endif
+
+#endif