Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/sh/include/asm/atomic-grb.h | 34 ++++++++++++++++++++++++++++++----
arch/sh/include/asm/atomic-irq.h | 31 +++++++++++++++++++++++++++----
arch/sh/include/asm/atomic-llsc.h | 32 ++++++++++++++++++++++++++++----
arch/sh/include/asm/atomic.h | 2 ++
4 files changed, 87 insertions(+), 12 deletions(-)
--- a/arch/sh/include/asm/atomic-grb.h
+++ b/arch/sh/include/asm/atomic-grb.h
@@ -43,16 +43,42 @@ static inline int atomic_##op##_return(i
return tmp; \
}
-#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
+#define ATOMIC_FETCH_OP(op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ int res, tmp; \
+ \
+ __asm__ __volatile__ ( \
+ " .align 2 \n\t" \
+ " mova 1f, r0 \n\t" /* r0 = end point */ \
+ " mov r15, r1 \n\t" /* r1 = saved sp */ \
+ " mov #-6, r15 \n\t" /* LOGIN: r15 = size */ \
+ " mov.l @%2, %0 \n\t" /* load old value */ \
+ " mov %0, %1 \n\t" /* save old value */ \
+ " " #op " %3, %0 \n\t" /* $op */ \
+ " mov.l %0, @%2 \n\t" /* store new value */ \
+ "1: mov r1, r15 \n\t" /* LOGOUT */ \
+ : "=&r" (tmp), "=&r" (res), "+r" (v) \
+ : "r" (i) \
+ : "memory" , "r0", "r1"); \
+ \
+ return res; \
+}
+
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op) ATOMIC_FETCH_OP(op)
ATOMIC_OPS(add)
ATOMIC_OPS(sub)
-ATOMIC_OP(and)
-ATOMIC_OP(or)
-ATOMIC_OP(xor)
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op)
+
+ATOMIC_OPS(and)
+ATOMIC_OPS(or)
+ATOMIC_OPS(xor)
#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
--- a/arch/sh/include/asm/atomic-irq.h
+++ b/arch/sh/include/asm/atomic-irq.h
@@ -33,15 +33,38 @@ static inline int atomic_##op##_return(i
return temp; \
}
-#define ATOMIC_OPS(op, c_op) ATOMIC_OP(op, c_op) ATOMIC_OP_RETURN(op, c_op)
+#define ATOMIC_FETCH_OP(op, c_op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ unsigned long temp, flags; \
+ \
+ raw_local_irq_save(flags); \
+ temp = v->counter; \
+ v->counter c_op i; \
+ raw_local_irq_restore(flags); \
+ \
+ return temp; \
+}
+
+#define ATOMIC_OPS(op, c_op) \
+ ATOMIC_OP(op, c_op) \
+ ATOMIC_OP_RETURN(op, c_op) \
+ ATOMIC_FETCH_OP(op, c_op)
ATOMIC_OPS(add, +=)
ATOMIC_OPS(sub, -=)
-ATOMIC_OP(and, &=)
-ATOMIC_OP(or, |=)
-ATOMIC_OP(xor, ^=)
#undef ATOMIC_OPS
+#define ATOMIC_OPS(op, c_op) \
+ ATOMIC_OP(op, c_op) \
+ ATOMIC_FETCH_OP(op, c_op)
+
+ATOMIC_OPS(and, &=)
+ATOMIC_OPS(or, |=)
+ATOMIC_OPS(xor, ^=)
+
+#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
--- a/arch/sh/include/asm/atomic-llsc.h
+++ b/arch/sh/include/asm/atomic-llsc.h
@@ -48,15 +48,39 @@ static inline int atomic_##op##_return(i
return temp; \
}
-#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
+#define ATOMIC_FETCH_OP(op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ unsigned long res, temp; \
+ \
+ __asm__ __volatile__ ( \
+"1: movli.l @%3, %0 ! atomic_fetch_" #op " \n" \
+" mov %0, %1 \n" \
+" " #op " %2, %0 \n" \
+" movco.l %0, @%3 \n" \
+" bf 1b \n" \
+" synco \n" \
+ : "=&z" (temp), "=&z" (res) \
+ : "r" (i), "r" (&v->counter) \
+ : "t"); \
+ \
+ return res; \
+}
+
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op) ATOMIC_FETCH_OP(op)
ATOMIC_OPS(add)
ATOMIC_OPS(sub)
-ATOMIC_OP(and)
-ATOMIC_OP(or)
-ATOMIC_OP(xor)
#undef ATOMIC_OPS
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op)
+
+ATOMIC_OPS(and)
+ATOMIC_OPS(or)
+ATOMIC_OPS(xor)
+
+#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
--- a/arch/sh/include/asm/atomic.h
+++ b/arch/sh/include/asm/atomic.h
@@ -25,6 +25,8 @@
#include <asm/atomic-irq.h>
#endif
+#define atomic_fetch_or atomic_fetch_or
+
#define atomic_add_negative(a, v) (atomic_add_return((a), (v)) < 0)
#define atomic_dec_return(v) atomic_sub_return(1, (v))
#define atomic_inc_return(v) atomic_add_return(1, (v))
--
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