x86: partial unification of asm-x86/bitops.h

This unifies the set/clear/test bit functions of asm/bitops.h.

I have not attempted to merge the bit-finding functions, since they
rely on the machine word size and can't be easily restructured to work
generically without a lot of #ifdefs.  In particular, the 64-bit code
can assume the presence of conditional move instructions, whereas
32-bit needs to be more careful.

The inline assembly for the bit operations has been changed to remove
explicit sizing hints on the instructions, so the assembler will pick
the appropriate instruction forms depending on the architecture and
the context.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 315 insertions, 0 deletions

diff --git a/include/asm-x86/bitops.h b/include/asm-x86/bitops.h
index 07e3f6d4fe47..c6dd7e259b46 100644
--- a/include/asm-x86/bitops.h
+++ b/include/asm-x86/bitops.h
@@ -1,5 +1,320 @@
+#ifndef _ASM_X86_BITOPS_H
+#define _ASM_X86_BITOPS_H
+
+/*
+ * Copyright 1992, Linus Torvalds.
+ */
+
+#ifndef _LINUX_BITOPS_H
+#error only <linux/bitops.h> can be included directly
+#endif
+
+#include <linux/compiler.h>
+#include <asm/alternative.h>
+
+/*
+ * These have to be done with inline assembly: that way the bit-setting
+ * is guaranteed to be atomic. All bit operations return 0 if the bit
+ * was cleared before the operation and != 0 if it was not.
+ *
+ * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
+ */
+
+#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 1)
+/* Technically wrong, but this avoids compilation errors on some gcc
+   versions. */
+#define ADDR "=m" (*(volatile long *) addr)
+#else
+#define ADDR "+m" (*(volatile long *) addr)
+#endif
+
+/**
+ * set_bit - Atomically set a bit in memory
+ * @nr: the bit to set
+ * @addr: the address to start counting from
+ *
+ * This function is atomic and may not be reordered.  See __set_bit()
+ * if you do not require the atomic guarantees.
+ *
+ * Note: there are no guarantees that this function will not be reordered
+ * on non x86 architectures, so if you are writing portable code,
+ * make sure not to rely on its reordering guarantees.
+ *
+ * Note that @nr may be almost arbitrarily large; this function is not
+ * restricted to acting on a single-word quantity.
+ */
+static inline void set_bit(int nr, volatile unsigned long *addr)
+{
+        asm volatile(LOCK_PREFIX "bts %1,%0"
+                     : ADDR
+                     : "Ir" (nr) : "memory");
+}
+
+/**
+ * __set_bit - Set a bit in memory
+ * @nr: the bit to set
+ * @addr: the address to start counting from
+ *
+ * Unlike set_bit(), this function is non-atomic and may be reordered.
+ * If it's called on the same region of memory simultaneously, the effect
+ * may be that only one operation succeeds.
+ */
+static inline void __set_bit(int nr, volatile unsigned long *addr)
+{
+        asm volatile("bts %1,%0"
+                     : ADDR
+                     : "Ir" (nr) : "memory");
+}
+
+
+/**
+ * clear_bit - Clears a bit in memory
+ * @nr: Bit to clear
+ * @addr: Address to start counting from
+ *
+ * clear_bit() is atomic and may not be reordered.  However, it does
+ * not contain a memory barrier, so if it is used for locking purposes,
+ * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
+ * in order to ensure changes are visible on other processors.
+ */
+static inline void clear_bit(int nr, volatile unsigned long *addr)
+{
+        asm volatile(LOCK_PREFIX "btr %1,%0"
+                     : ADDR
+                     : "Ir" (nr));
+}
+
+/*
+ * clear_bit_unlock - Clears a bit in memory
+ * @nr: Bit to clear
+ * @addr: Address to start counting from
+ *
+ * clear_bit() is atomic and implies release semantics before the memory
+ * operation. It can be used for an unlock.
+ */
+static inline void clear_bit_unlock(unsigned nr, volatile unsigned long *addr)
+{
+        barrier();
+        clear_bit(nr, addr);
+}
+
+static inline void __clear_bit(int nr, volatile unsigned long *addr)
+{
+        asm volatile("btr %1,%0" : ADDR : "Ir" (nr));
+}
+
+/*
+ * __clear_bit_unlock - Clears a bit in memory
+ * @nr: Bit to clear
+ * @addr: Address to start counting from
+ *
+ * __clear_bit() is non-atomic and implies release semantics before the memory
+ * operation. It can be used for an unlock if no other CPUs can concurrently
+ * modify other bits in the word.
+ *
+ * No memory barrier is required here, because x86 cannot reorder stores past
+ * older loads. Same principle as spin_unlock.
+ */
+static inline void __clear_bit_unlock(unsigned nr, volatile unsigned long *addr)
+{
+        barrier();
+        __clear_bit(nr, addr);
+}
+
+#define smp_mb__before_clear_bit()      barrier()
+#define smp_mb__after_clear_bit()       barrier()
+
+/**
+ * __change_bit - Toggle a bit in memory
+ * @nr: the bit to change
+ * @addr: the address to start counting from
+ *
+ * Unlike change_bit(), this function is non-atomic and may be reordered.
+ * If it's called on the same region of memory simultaneously, the effect
+ * may be that only one operation succeeds.
+ */
+static inline void __change_bit(int nr, volatile unsigned long *addr)
+{
+        asm volatile("btc %1,%0" : ADDR : "Ir" (nr));
+}
+
+/**
+ * change_bit - Toggle a bit in memory
+ * @nr: Bit to change
+ * @addr: Address to start counting from
+ *
+ * change_bit() is atomic and may not be reordered.
+ * Note that @nr may be almost arbitrarily large; this function is not
+ * restricted to acting on a single-word quantity.
+ */
+static inline void change_bit(int nr, volatile unsigned long *addr)
+{
+        asm volatile(LOCK_PREFIX "btc %1,%0"
+                     : ADDR : "Ir" (nr));
+}
+
+/**
+ * test_and_set_bit - Set a bit and return its old value
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This operation is atomic and cannot be reordered.
+ * It also implies a memory barrier.
+ */
+static inline int test_and_set_bit(int nr, volatile unsigned long *addr)
+{
+        int oldbit;
+
+        asm volatile(LOCK_PREFIX "bts %2,%1\n\t"
+                     "sbb %0,%0"
+                     : "=r" (oldbit), ADDR
+                     : "Ir" (nr) : "memory");
+
+        return oldbit;
+}
+
+/**
+ * test_and_set_bit_lock - Set a bit and return its old value for lock
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This is the same as test_and_set_bit on x86.
+ */
+static inline int test_and_set_bit_lock(int nr, volatile unsigned long *addr)
+{
+        return test_and_set_bit(nr, addr);
+}
+
+/**
+ * __test_and_set_bit - Set a bit and return its old value
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This operation is non-atomic and can be reordered.
+ * If two examples of this operation race, one can appear to succeed
+ * but actually fail.  You must protect multiple accesses with a lock.
+ */
+static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
+{
+        int oldbit;
+
+        asm("bts %2,%1\n\t"
+            "sbb %0,%0"
+            : "=r" (oldbit), ADDR
+            : "Ir" (nr));
+        return oldbit;
+}
+
+/**
+ * test_and_clear_bit - Clear a bit and return its old value
+ * @nr: Bit to clear
+ * @addr: Address to count from
+ *
+ * This operation is atomic and cannot be reordered.
+ * It also implies a memory barrier.
+ */
+static inline int test_and_clear_bit(int nr, volatile unsigned long *addr)
+{
+        int oldbit;
+
+        asm volatile(LOCK_PREFIX "btr %2,%1\n\t"
+                     "sbb %0,%0"
+                     : "=r" (oldbit), ADDR
+                     : "Ir" (nr) : "memory");
+
+        return oldbit;
+}
+
+/**
+ * __test_and_clear_bit - Clear a bit and return its old value
+ * @nr: Bit to clear
+ * @addr: Address to count from
+ *
+ * This operation is non-atomic and can be reordered.
+ * If two examples of this operation race, one can appear to succeed
+ * but actually fail.  You must protect multiple accesses with a lock.
+ */
+static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
+{
+        int oldbit;
+
+        asm volatile("btr %2,%1\n\t"
+                     "sbb %0,%0"
+                     : "=r" (oldbit), ADDR
+                     : "Ir" (nr));
+        return oldbit;
+}
+
+/* WARNING: non atomic and it can be reordered! */
+static inline int __test_and_change_bit(int nr, volatile unsigned long *addr)
+{
+        int oldbit;
+
+        asm volatile("btc %2,%1\n\t"
+                     "sbb %0,%0"
+                     : "=r" (oldbit), ADDR
+                     : "Ir" (nr) : "memory");
+
+        return oldbit;
+}
+
+/**
+ * test_and_change_bit - Change a bit and return its old value
+ * @nr: Bit to change
+ * @addr: Address to count from
+ *
+ * This operation is atomic and cannot be reordered.
+ * It also implies a memory barrier.
+ */
+static inline int test_and_change_bit(int nr, volatile unsigned long *addr)
+{
+        int oldbit;
+
+        asm volatile(LOCK_PREFIX "btc %2,%1\n\t"
+                     "sbb %0,%0"
+                     : "=r" (oldbit), ADDR
+                     : "Ir" (nr) : "memory");
+
+        return oldbit;
+}
+
+static inline int constant_test_bit(int nr, const volatile unsigned long *addr)
+{
+        return ((1UL << (nr % BITS_PER_LONG)) & (addr[nr / BITS_PER_LONG])) != 0;
+}
+
+static inline int variable_test_bit(int nr, volatile const unsigned long *addr)
+{
+        int oldbit;
+
+        asm volatile("bt %2,%1\n\t"
+                     "sbb %0,%0"
+                     : "=r" (oldbit)
+                     : "m" (*addr), "Ir" (nr));
+
+        return oldbit;
+}
+
+#if 0 /* Fool kernel-doc since it doesn't do macros yet */
+/**
+ * test_bit - Determine whether a bit is set
+ * @nr: bit number to test
+ * @addr: Address to start counting from
+ */
+static int test_bit(int nr, const volatile unsigned long *addr);
+#endif
+
+#define test_bit(nr,addr)                       \
+        (__builtin_constant_p(nr) ?             \
+         constant_test_bit((nr),(addr)) :       \
+         variable_test_bit((nr),(addr)))
+
+#undef ADDR
+
 #ifdef CONFIG_X86_32
 # include "bitops_32.h"
 #else
 # include "bitops_64.h"
 #endif
+
+#endif  /* _ASM_X86_BITOPS_H */