x86, um: ... and asm-x86 move

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

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 */