On Wed, Dec 21, 2022 at 05:25:20PM -0800, Boqun Feng wrote:
quoted
+#define __CMPXCHG128(name, mb, cl...) \
+static __always_inline u128 \
+__lse__cmpxchg128##name(volatile u128 *ptr, u128 old, u128 new) \
+{ \
+ union __u128_halves r, o = { .full = (old) }, \
+ n = { .full = (new) }; \
+ register unsigned long x0 asm ("x0") = o.low; \
+ register unsigned long x1 asm ("x1") = o.high; \
+ register unsigned long x2 asm ("x2") = n.low; \
+ register unsigned long x3 asm ("x3") = n.high; \
+ register unsigned long x4 asm ("x4") = (unsigned long)ptr; \
+ \
+ asm volatile( \
+ __LSE_PREAMBLE \
+ " casp" #mb "\t%[old1], %[old2], %[new1], %[new2], %[v]\n"\
+ : [old1] "+&r" (x0), [old2] "+&r" (x1), \
+ [v] "+Q" (*(unsigned long *)ptr) \
+ : [new1] "r" (x2), [new2] "r" (x3), [ptr] "r" (x4), \
Issue #1: the line below can be removed, otherwise..
quoted
+ [oldval1] "r" (r.low), [oldval2] "r" (r.high) \
warning:
./arch/arm64/include/asm/atomic_lse.h: In function '__lse__cmpxchg128_mb':
./arch/arm64/include/asm/atomic_lse.h:309:27: warning: 'r.<U97b8>.low' is used uninitialized [-Wuninitialized]
309 | [oldval1] "r" (r.low), [oldval2] "r" (r.high)
quoted
+ : cl); \
+ \
+ r.low = x0; r.high = x1; \
+ \
+ return r.full; \
+}
+
+__CMPXCHG128( , )
+__CMPXCHG128(_mb, al, "memory")
+
+#undef __CMPXCHG128
+
#endif /* __ASM_ATOMIC_LSE_H */
--- a/arch/arm64/include/asm/cmpxchg.h
+++ b/arch/arm64/include/asm/cmpxchg.h
@@ -147,6 +147,19 @@ __CMPXCHG_DBL(_mb)
#undef __CMPXCHG_DBL
+#define __CMPXCHG128(name) \
+static inline long __cmpxchg128##name(volatile u128 *ptr, \
Issue #2: this should be
static inline u128 __cmpxchg128##name(..)
because cmpxchg* needs to return the old value.
Duh.. fixed both. Pushed out to queue/core/wip-u128. I'll probably
continue all this in two weeks (yay xmas break!).