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-rw-r--r--arch/x86/include/asm/cmpxchg_32.h344
1 files changed, 344 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cmpxchg_32.h b/arch/x86/include/asm/cmpxchg_32.h
new file mode 100644
index 000000000000..0622e45cdf7c
--- /dev/null
+++ b/arch/x86/include/asm/cmpxchg_32.h
@@ -0,0 +1,344 @@
+#ifndef ASM_X86__CMPXCHG_32_H
+#define ASM_X86__CMPXCHG_32_H
+
+#include <linux/bitops.h> /* for LOCK_PREFIX */
+
+/*
+ * Note: if you use set64_bit(), __cmpxchg64(), or their variants, you
+ * you need to test for the feature in boot_cpu_data.
+ */
+
+#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))
+
+/*
+ * 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_PREFIX "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 >> 32));
+}
+
+#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) >> 32)) \
+ : __set_64bit(ptr, ll_low((value)), ll_high((value))))
+
+/*
+ * 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
+
+#ifdef CONFIG_X86_CMPXCHG64
+#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
+
+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;
+}
+
+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;
+}
+
+#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 = (__typeof__(*(ptr)))__cmpxchg((ptr), \
+ (unsigned long)(o), (unsigned long)(n), \
+ sizeof(*(ptr))); \
+ else \
+ __ret = (__typeof__(*(ptr)))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 = (__typeof__(*(ptr)))__cmpxchg_local((ptr), \
+ (unsigned long)(o), (unsigned long)(n), \
+ sizeof(*(ptr))); \
+ else \
+ __ret = (__typeof__(*(ptr)))cmpxchg_386((ptr), \
+ (unsigned long)(o), (unsigned long)(n), \
+ sizeof(*(ptr))); \
+ __ret; \
+})
+#endif
+
+#ifndef CONFIG_X86_CMPXCHG64
+/*
+ * Building a kernel capable running on 80386 and 80486. It may be necessary
+ * to simulate the cmpxchg8b on the 80386 and 80486 CPU.
+ */
+
+extern unsigned long long cmpxchg_486_u64(volatile void *, u64, u64);
+
+#define cmpxchg64(ptr, o, n) \
+({ \
+ __typeof__(*(ptr)) __ret; \
+ if (likely(boot_cpu_data.x86 > 4)) \
+ __ret = (__typeof__(*(ptr)))__cmpxchg64((ptr), \
+ (unsigned long long)(o), \
+ (unsigned long long)(n)); \
+ else \
+ __ret = (__typeof__(*(ptr)))cmpxchg_486_u64((ptr), \
+ (unsigned long long)(o), \
+ (unsigned long long)(n)); \
+ __ret; \
+})
+#define cmpxchg64_local(ptr, o, n) \
+({ \
+ __typeof__(*(ptr)) __ret; \
+ if (likely(boot_cpu_data.x86 > 4)) \
+ __ret = (__typeof__(*(ptr)))__cmpxchg64_local((ptr), \
+ (unsigned long long)(o), \
+ (unsigned long long)(n)); \
+ else \
+ __ret = (__typeof__(*(ptr)))cmpxchg_486_u64((ptr), \
+ (unsigned long long)(o), \
+ (unsigned long long)(n)); \
+ __ret; \
+})
+
+#endif
+
+#endif /* ASM_X86__CMPXCHG_32_H */
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