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) <pet...@infradead.org>
---
arch/xtensa/include/asm/atomic.h | 54 ++++++++++++++++++++++++++++++++++++---
1 file changed, 50 insertions(+), 4 deletions(-)
--- a/arch/xtensa/include/asm/atomic.h
+++ b/arch/xtensa/include/asm/atomic.h
@@ -98,6 +98,26 @@ static inline int atomic_##op##_return(i
return result; \
}
+#define ATOMIC_FETCH_OP(op) \
+static inline int atomic_fetch_##op(int i, atomic_t * v) \
+{ \
+ unsigned long tmp; \
+ int result; \
+ \
+ __asm__ __volatile__( \
+ "1: l32i %1, %3, 0\n" \
+ " wsr %1, scompare1\n" \
+ " " #op " %0, %1, %2\n" \
+ " s32c1i %0, %3, 0\n" \
+ " bne %0, %1, 1b\n" \
+ : "=&a" (result), "=&a" (tmp) \
+ : "a" (i), "a" (v) \
+ : "memory" \
+ ); \
+ \
+ return result; \
+}
+
#else /* XCHAL_HAVE_S32C1I */
#define ATOMIC_OP(op) \
@@ -138,18 +158,44 @@ static inline int atomic_##op##_return(i
return vval; \
}
+#define ATOMIC_FETCH_OP(op) \
+static inline int atomic_fetch_##op(int i, atomic_t * v) \
+{ \
+ unsigned int tmp, vval; \
+ \
+ __asm__ __volatile__( \
+ " rsil a15,"__stringify(TOPLEVEL)"\n" \
+ " l32i %0, %3, 0\n" \
+ " " #op " %1, %0, %2\n" \
+ " s32i %1, %3, 0\n" \
+ " wsr a15, ps\n" \
+ " rsync\n" \
+ : "=&a" (vval), "=&a" (tmp) \
+ : "a" (i), "a" (v) \
+ : "a15", "memory" \
+ ); \
+ \
+ return vval; \
+}
+
#endif /* XCHAL_HAVE_S32C1I */
-#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op) ATOMIC_OP_RETURN(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)
+
+#define atomic_fetch_or atomic_fetch_or
+
+ATOMIC_OPS(and)
+ATOMIC_OPS(or)
+ATOMIC_OPS(xor)
#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
