1 files changed, 68 insertions, 5 deletions

diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h
index acd5c26b69ba..772f85da1206 100644
--- a/include/asm-i386/system.h
+++ b/include/asm-i386/system.h
@@ -167,6 +167,8 @@ 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
@@ -221,6 +223,8 @@ static inline void __set_64bit_var (unsigned long long *ptr,
  __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,
@@ -259,6 +263,9 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz
 
 #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))))
 #endif
 
 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
@@ -275,22 +282,78 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
         case 2:
                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
                                      : "=a"(prev)
-                                     : "q"(new), "m"(*__xg(ptr)), "0"(old)
+                                     : "r"(new), "m"(*__xg(ptr)), "0"(old)
                                      : "memory");
                 return prev;
         case 4:
                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %1,%2"
                                      : "=a"(prev)
-                                     : "q"(new), "m"(*__xg(ptr)), "0"(old)
+                                     : "r"(new), "m"(*__xg(ptr)), "0"(old)
                                      : "memory");
                 return prev;
         }
         return old;
 }
 
-#define cmpxchg(ptr,o,n)\
-        ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
-                                        (unsigned long)(n),sizeof(*(ptr))))
+#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;                                                          \
+})
+#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;
+}
+
+#define cmpxchg64(ptr,o,n)\
+        ((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\
+                                        (unsigned long long)(n)))
+
+#endif
     
 #ifdef __KERNEL__
 struct alt_instr {