alpha: xchg/cmpxchg cleanup and fixes
- "_local" versions of xchg/cmpxchg functions duplicate code
of non-local ones (quite a few pages of assembler), except
memory barriers. We can generate these two variants from a
single header file using simple macros;
- convert xchg macro back to inline function using always_inline
attribute;
- use proper argument types for cmpxchg_u8/u16 functions
to fix a problem with negative arguments.
Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/alpha/include/asm/xchg.h b/arch/alpha/include/asm/xchg.h
new file mode 100644
index 0000000..beba1b8
--- /dev/null
+++ b/arch/alpha/include/asm/xchg.h
@@ -0,0 +1,258 @@
+#ifndef __ALPHA_SYSTEM_H
+#error Do not include xchg.h directly!
+#else
+/*
+ * xchg/xchg_local and cmpxchg/cmpxchg_local share the same code
+ * except that local version do not have the expensive memory barrier.
+ * So this file is included twice from asm/system.h.
+ */
+
+/*
+ * Atomic exchange.
+ * Since it can be used to implement critical sections
+ * it must clobber "memory" (also for interrupts in UP).
+ */
+
+static inline unsigned long
+____xchg(_u8, volatile char *m, unsigned long val)
+{
+ unsigned long ret, tmp, addr64;
+
+ __asm__ __volatile__(
+ " andnot %4,7,%3\n"
+ " insbl %1,%4,%1\n"
+ "1: ldq_l %2,0(%3)\n"
+ " extbl %2,%4,%0\n"
+ " mskbl %2,%4,%2\n"
+ " or %1,%2,%2\n"
+ " stq_c %2,0(%3)\n"
+ " beq %2,2f\n"
+ __ASM__MB
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
+ : "r" ((long)m), "1" (val) : "memory");
+
+ return ret;
+}
+
+static inline unsigned long
+____xchg(_u16, volatile short *m, unsigned long val)
+{
+ unsigned long ret, tmp, addr64;
+
+ __asm__ __volatile__(
+ " andnot %4,7,%3\n"
+ " inswl %1,%4,%1\n"
+ "1: ldq_l %2,0(%3)\n"
+ " extwl %2,%4,%0\n"
+ " mskwl %2,%4,%2\n"
+ " or %1,%2,%2\n"
+ " stq_c %2,0(%3)\n"
+ " beq %2,2f\n"
+ __ASM__MB
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
+ : "r" ((long)m), "1" (val) : "memory");
+
+ return ret;
+}
+
+static inline unsigned long
+____xchg(_u32, volatile int *m, unsigned long val)
+{
+ unsigned long dummy;
+
+ __asm__ __volatile__(
+ "1: ldl_l %0,%4\n"
+ " bis $31,%3,%1\n"
+ " stl_c %1,%2\n"
+ " beq %1,2f\n"
+ __ASM__MB
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ : "=&r" (val), "=&r" (dummy), "=m" (*m)
+ : "rI" (val), "m" (*m) : "memory");
+
+ return val;
+}
+
+static inline unsigned long
+____xchg(_u64, volatile long *m, unsigned long val)
+{
+ unsigned long dummy;
+
+ __asm__ __volatile__(
+ "1: ldq_l %0,%4\n"
+ " bis $31,%3,%1\n"
+ " stq_c %1,%2\n"
+ " beq %1,2f\n"
+ __ASM__MB
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ : "=&r" (val), "=&r" (dummy), "=m" (*m)
+ : "rI" (val), "m" (*m) : "memory");
+
+ return val;
+}
+
+/* This function doesn't exist, so you'll get a linker error
+ if something tries to do an invalid xchg(). */
+extern void __xchg_called_with_bad_pointer(void);
+
+static __always_inline unsigned long
+____xchg(, volatile void *ptr, unsigned long x, int size)
+{
+ switch (size) {
+ case 1:
+ return ____xchg(_u8, ptr, x);
+ case 2:
+ return ____xchg(_u16, ptr, x);
+ case 4:
+ return ____xchg(_u32, ptr, x);
+ case 8:
+ return ____xchg(_u64, ptr, x);
+ }
+ __xchg_called_with_bad_pointer();
+ 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.
+ *
+ * The memory barrier should be placed in SMP only when we actually
+ * make the change. If we don't change anything (so if the returned
+ * prev is equal to old) then we aren't acquiring anything new and
+ * we don't need any memory barrier as far I can tell.
+ */
+
+static inline unsigned long
+____cmpxchg(_u8, volatile char *m, unsigned char old, unsigned char new)
+{
+ unsigned long prev, tmp, cmp, addr64;
+
+ __asm__ __volatile__(
+ " andnot %5,7,%4\n"
+ " insbl %1,%5,%1\n"
+ "1: ldq_l %2,0(%4)\n"
+ " extbl %2,%5,%0\n"
+ " cmpeq %0,%6,%3\n"
+ " beq %3,2f\n"
+ " mskbl %2,%5,%2\n"
+ " or %1,%2,%2\n"
+ " stq_c %2,0(%4)\n"
+ " beq %2,3f\n"
+ __ASM__MB
+ "2:\n"
+ ".subsection 2\n"
+ "3: br 1b\n"
+ ".previous"
+ : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
+ : "r" ((long)m), "Ir" (old), "1" (new) : "memory");
+
+ return prev;
+}
+
+static inline unsigned long
+____cmpxchg(_u16, volatile short *m, unsigned short old, unsigned short new)
+{
+ unsigned long prev, tmp, cmp, addr64;
+
+ __asm__ __volatile__(
+ " andnot %5,7,%4\n"
+ " inswl %1,%5,%1\n"
+ "1: ldq_l %2,0(%4)\n"
+ " extwl %2,%5,%0\n"
+ " cmpeq %0,%6,%3\n"
+ " beq %3,2f\n"
+ " mskwl %2,%5,%2\n"
+ " or %1,%2,%2\n"
+ " stq_c %2,0(%4)\n"
+ " beq %2,3f\n"
+ __ASM__MB
+ "2:\n"
+ ".subsection 2\n"
+ "3: br 1b\n"
+ ".previous"
+ : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
+ : "r" ((long)m), "Ir" (old), "1" (new) : "memory");
+
+ return prev;
+}
+
+static inline unsigned long
+____cmpxchg(_u32, volatile int *m, int old, int new)
+{
+ unsigned long prev, cmp;
+
+ __asm__ __volatile__(
+ "1: ldl_l %0,%5\n"
+ " cmpeq %0,%3,%1\n"
+ " beq %1,2f\n"
+ " mov %4,%1\n"
+ " stl_c %1,%2\n"
+ " beq %1,3f\n"
+ __ASM__MB
+ "2:\n"
+ ".subsection 2\n"
+ "3: br 1b\n"
+ ".previous"
+ : "=&r"(prev), "=&r"(cmp), "=m"(*m)
+ : "r"((long) old), "r"(new), "m"(*m) : "memory");
+
+ return prev;
+}
+
+static inline unsigned long
+____cmpxchg(_u64, volatile long *m, unsigned long old, unsigned long new)
+{
+ unsigned long prev, cmp;
+
+ __asm__ __volatile__(
+ "1: ldq_l %0,%5\n"
+ " cmpeq %0,%3,%1\n"
+ " beq %1,2f\n"
+ " mov %4,%1\n"
+ " stq_c %1,%2\n"
+ " beq %1,3f\n"
+ __ASM__MB
+ "2:\n"
+ ".subsection 2\n"
+ "3: br 1b\n"
+ ".previous"
+ : "=&r"(prev), "=&r"(cmp), "=m"(*m)
+ : "r"((long) old), "r"(new), "m"(*m) : "memory");
+
+ return prev;
+}
+
+/* This function doesn't exist, so you'll get a linker error
+ if something tries to do an invalid cmpxchg(). */
+extern void __cmpxchg_called_with_bad_pointer(void);
+
+static __always_inline unsigned long
+____cmpxchg(, volatile void *ptr, unsigned long old, unsigned long new,
+ int size)
+{
+ switch (size) {
+ case 1:
+ return ____cmpxchg(_u8, ptr, old, new);
+ case 2:
+ return ____cmpxchg(_u16, ptr, old, new);
+ case 4:
+ return ____cmpxchg(_u32, ptr, old, new);
+ case 8:
+ return ____cmpxchg(_u64, ptr, old, new);
+ }
+ __cmpxchg_called_with_bad_pointer();
+ return old;
+}
+
+#endif