Merge branch 'for-next/atomics' into for-next/core

* for-next/atomics: (10 commits)
  Rework LSE instruction selection to use static keys instead of alternatives

1 files changed, 121 insertions, 96 deletions

diff --git a/arch/arm64/include/asm/atomic_ll_sc.h b/arch/arm64/include/asm/atomic_ll_sc.h
index c8c850bc3dfb..7b012148bfd6 100644
--- a/arch/arm64/include/asm/atomic_ll_sc.h
+++ b/arch/arm64/include/asm/atomic_ll_sc.h
@@ -10,83 +10,92 @@
 #ifndef __ASM_ATOMIC_LL_SC_H
 #define __ASM_ATOMIC_LL_SC_H
 
-#ifndef __ARM64_IN_ATOMIC_IMPL
-#error "please don't include this file directly"
+#include <linux/stringify.h>
+
+#if IS_ENABLED(CONFIG_ARM64_LSE_ATOMICS) && IS_ENABLED(CONFIG_AS_LSE)
+#define __LL_SC_FALLBACK(asm_ops)					\
+"	b	3f\n"							\
+"	.subsection	1\n"						\
+"3:\n"									\
+asm_ops "\n"								\
+"	b	4f\n"							\
+"	.previous\n"							\
+"4:\n"
+#else
+#define __LL_SC_FALLBACK(asm_ops) asm_ops
+#endif
+
+#ifndef CONFIG_CC_HAS_K_CONSTRAINT
+#define K
 #endif
 
 /*
  * AArch64 UP and SMP safe atomic ops.  We use load exclusive and
  * store exclusive to ensure that these are atomic.  We may loop
  * to ensure that the update happens.
- *
- * NOTE: these functions do *not* follow the PCS and must explicitly
- * save any clobbered registers other than x0 (regardless of return
- * value).  This is achieved through -fcall-saved-* compiler flags for
- * this file, which unfortunately don't work on a per-function basis
- * (the optimize attribute silently ignores these options).
  */
 
-#define ATOMIC_OP(op, asm_op)						\
-__LL_SC_INLINE void							\
-__LL_SC_PREFIX(arch_atomic_##op(int i, atomic_t *v))			\
+#define ATOMIC_OP(op, asm_op, constraint)				\
+static inline void							\
+__ll_sc_atomic_##op(int i, atomic_t *v)					\
 {									\
 	unsigned long tmp;						\
 	int result;							\
 									\
 	asm volatile("// atomic_" #op "\n"				\
+	__LL_SC_FALLBACK(						\
 "	prfm	pstl1strm, %2\n"					\
 "1:	ldxr	%w0, %2\n"						\
 "	" #asm_op "	%w0, %w0, %w3\n"				\
 "	stxr	%w1, %w0, %2\n"						\
-"	cbnz	%w1, 1b"						\
+"	cbnz	%w1, 1b\n")						\
 	: "=&r" (result), "=&r" (tmp), "+Q" (v->counter)		\
-	: "Ir" (i));							\
-}									\
-__LL_SC_EXPORT(arch_atomic_##op);
+	: __stringify(constraint) "r" (i));				\
+}
 
-#define ATOMIC_OP_RETURN(name, mb, acq, rel, cl, op, asm_op)		\
-__LL_SC_INLINE int							\
-__LL_SC_PREFIX(arch_atomic_##op##_return##name(int i, atomic_t *v))	\
+#define ATOMIC_OP_RETURN(name, mb, acq, rel, cl, op, asm_op, constraint)\
+static inline int							\
+__ll_sc_atomic_##op##_return##name(int i, atomic_t *v)			\
 {									\
 	unsigned long tmp;						\
 	int result;							\
 									\
 	asm volatile("// atomic_" #op "_return" #name "\n"		\
+	__LL_SC_FALLBACK(						\
 "	prfm	pstl1strm, %2\n"					\
 "1:	ld" #acq "xr	%w0, %2\n"					\
 "	" #asm_op "	%w0, %w0, %w3\n"				\
 "	st" #rel "xr	%w1, %w0, %2\n"					\
 "	cbnz	%w1, 1b\n"						\
-"	" #mb								\
+"	" #mb )								\
 	: "=&r" (result), "=&r" (tmp), "+Q" (v->counter)		\
-	: "Ir" (i)							\
+	: __stringify(constraint) "r" (i)				\
 	: cl);								\
 									\
 	return result;							\
-}									\
-__LL_SC_EXPORT(arch_atomic_##op##_return##name);
+}
 
-#define ATOMIC_FETCH_OP(name, mb, acq, rel, cl, op, asm_op)		\
-__LL_SC_INLINE int							\
-__LL_SC_PREFIX(arch_atomic_fetch_##op##name(int i, atomic_t *v))	\
+#define ATOMIC_FETCH_OP(name, mb, acq, rel, cl, op, asm_op, constraint) \
+static inline int							\
+__ll_sc_atomic_fetch_##op##name(int i, atomic_t *v)			\
 {									\
 	unsigned long tmp;						\
 	int val, result;						\
 									\
 	asm volatile("// atomic_fetch_" #op #name "\n"			\
+	__LL_SC_FALLBACK(						\
 "	prfm	pstl1strm, %3\n"					\
 "1:	ld" #acq "xr	%w0, %3\n"					\
 "	" #asm_op "	%w1, %w0, %w4\n"				\
 "	st" #rel "xr	%w2, %w1, %3\n"					\
 "	cbnz	%w2, 1b\n"						\
-"	" #mb								\
+"	" #mb )								\
 	: "=&r" (result), "=&r" (val), "=&r" (tmp), "+Q" (v->counter)	\
-	: "Ir" (i)							\
+	: __stringify(constraint) "r" (i)				\
 	: cl);								\
 									\
 	return result;							\
-}									\
-__LL_SC_EXPORT(arch_atomic_fetch_##op##name);
+}
 
 #define ATOMIC_OPS(...)							\
 	ATOMIC_OP(__VA_ARGS__)						\
@@ -99,8 +108,8 @@ __LL_SC_EXPORT(arch_atomic_fetch_##op##name);
 	ATOMIC_FETCH_OP (_acquire,        , a,  , "memory", __VA_ARGS__)\
 	ATOMIC_FETCH_OP (_release,        ,  , l, "memory", __VA_ARGS__)
 
-ATOMIC_OPS(add, add)
-ATOMIC_OPS(sub, sub)
+ATOMIC_OPS(add, add, I)
+ATOMIC_OPS(sub, sub, J)
 
 #undef ATOMIC_OPS
 #define ATOMIC_OPS(...)							\
@@ -110,77 +119,82 @@ ATOMIC_OPS(sub, sub)
 	ATOMIC_FETCH_OP (_acquire,        , a,  , "memory", __VA_ARGS__)\
 	ATOMIC_FETCH_OP (_release,        ,  , l, "memory", __VA_ARGS__)
 
-ATOMIC_OPS(and, and)
-ATOMIC_OPS(andnot, bic)
-ATOMIC_OPS(or, orr)
-ATOMIC_OPS(xor, eor)
+ATOMIC_OPS(and, and, K)
+ATOMIC_OPS(or, orr, K)
+ATOMIC_OPS(xor, eor, K)
+/*
+ * GAS converts the mysterious and undocumented BIC (immediate) alias to
+ * an AND (immediate) instruction with the immediate inverted. We don't
+ * have a constraint for this, so fall back to register.
+ */
+ATOMIC_OPS(andnot, bic, )
 
 #undef ATOMIC_OPS
 #undef ATOMIC_FETCH_OP
 #undef ATOMIC_OP_RETURN
 #undef ATOMIC_OP
 
-#define ATOMIC64_OP(op, asm_op)						\
-__LL_SC_INLINE void							\
-__LL_SC_PREFIX(arch_atomic64_##op(s64 i, atomic64_t *v))		\
+#define ATOMIC64_OP(op, asm_op, constraint)				\
+static inline void							\
+__ll_sc_atomic64_##op(s64 i, atomic64_t *v)				\
 {									\
 	s64 result;							\
 	unsigned long tmp;						\
 									\
 	asm volatile("// atomic64_" #op "\n"				\
+	__LL_SC_FALLBACK(						\
 "	prfm	pstl1strm, %2\n"					\
 "1:	ldxr	%0, %2\n"						\
 "	" #asm_op "	%0, %0, %3\n"					\
 "	stxr	%w1, %0, %2\n"						\
-"	cbnz	%w1, 1b"						\
+"	cbnz	%w1, 1b")						\
 	: "=&r" (result), "=&r" (tmp), "+Q" (v->counter)		\
-	: "Ir" (i));							\
-}									\
-__LL_SC_EXPORT(arch_atomic64_##op);
+	: __stringify(constraint) "r" (i));				\
+}
 
-#define ATOMIC64_OP_RETURN(name, mb, acq, rel, cl, op, asm_op)		\
-__LL_SC_INLINE s64							\
-__LL_SC_PREFIX(arch_atomic64_##op##_return##name(s64 i, atomic64_t *v))\
+#define ATOMIC64_OP_RETURN(name, mb, acq, rel, cl, op, asm_op, constraint)\
+static inline long							\
+__ll_sc_atomic64_##op##_return##name(s64 i, atomic64_t *v)		\
 {									\
 	s64 result;							\
 	unsigned long tmp;						\
 									\
 	asm volatile("// atomic64_" #op "_return" #name "\n"		\
+	__LL_SC_FALLBACK(						\
 "	prfm	pstl1strm, %2\n"					\
 "1:	ld" #acq "xr	%0, %2\n"					\
 "	" #asm_op "	%0, %0, %3\n"					\
 "	st" #rel "xr	%w1, %0, %2\n"					\
 "	cbnz	%w1, 1b\n"						\
-"	" #mb								\
+"	" #mb )								\
 	: "=&r" (result), "=&r" (tmp), "+Q" (v->counter)		\
-	: "Ir" (i)							\
+	: __stringify(constraint) "r" (i)				\
 	: cl);								\
 									\
 	return result;							\
-}									\
-__LL_SC_EXPORT(arch_atomic64_##op##_return##name);
+}
 
-#define ATOMIC64_FETCH_OP(name, mb, acq, rel, cl, op, asm_op)		\
-__LL_SC_INLINE s64							\
-__LL_SC_PREFIX(arch_atomic64_fetch_##op##name(s64 i, atomic64_t *v))	\
+#define ATOMIC64_FETCH_OP(name, mb, acq, rel, cl, op, asm_op, constraint)\
+static inline long							\
+__ll_sc_atomic64_fetch_##op##name(s64 i, atomic64_t *v)		\
 {									\
 	s64 result, val;						\
 	unsigned long tmp;						\
 									\
 	asm volatile("// atomic64_fetch_" #op #name "\n"		\
+	__LL_SC_FALLBACK(						\
 "	prfm	pstl1strm, %3\n"					\
 "1:	ld" #acq "xr	%0, %3\n"					\
 "	" #asm_op "	%1, %0, %4\n"					\
 "	st" #rel "xr	%w2, %1, %3\n"					\
 "	cbnz	%w2, 1b\n"						\
-"	" #mb								\
+"	" #mb )								\
 	: "=&r" (result), "=&r" (val), "=&r" (tmp), "+Q" (v->counter)	\
-	: "Ir" (i)							\
+	: __stringify(constraint) "r" (i)				\
 	: cl);								\
 									\
 	return result;							\
-}									\
-__LL_SC_EXPORT(arch_atomic64_fetch_##op##name);
+}
 
 #define ATOMIC64_OPS(...)						\
 	ATOMIC64_OP(__VA_ARGS__)					\
@@ -193,8 +207,8 @@ __LL_SC_EXPORT(arch_atomic64_fetch_##op##name);
 	ATOMIC64_FETCH_OP (_acquire,, a,  , "memory", __VA_ARGS__)	\
 	ATOMIC64_FETCH_OP (_release,,  , l, "memory", __VA_ARGS__)
 
-ATOMIC64_OPS(add, add)
-ATOMIC64_OPS(sub, sub)
+ATOMIC64_OPS(add, add, I)
+ATOMIC64_OPS(sub, sub, J)
 
 #undef ATOMIC64_OPS
 #define ATOMIC64_OPS(...)						\
@@ -204,23 +218,29 @@ ATOMIC64_OPS(sub, sub)
 	ATOMIC64_FETCH_OP (_acquire,, a,  , "memory", __VA_ARGS__)	\
 	ATOMIC64_FETCH_OP (_release,,  , l, "memory", __VA_ARGS__)
 
-ATOMIC64_OPS(and, and)
-ATOMIC64_OPS(andnot, bic)
-ATOMIC64_OPS(or, orr)
-ATOMIC64_OPS(xor, eor)
+ATOMIC64_OPS(and, and, L)
+ATOMIC64_OPS(or, orr, L)
+ATOMIC64_OPS(xor, eor, L)
+/*
+ * GAS converts the mysterious and undocumented BIC (immediate) alias to
+ * an AND (immediate) instruction with the immediate inverted. We don't
+ * have a constraint for this, so fall back to register.
+ */
+ATOMIC64_OPS(andnot, bic, )
 
 #undef ATOMIC64_OPS
 #undef ATOMIC64_FETCH_OP
 #undef ATOMIC64_OP_RETURN
 #undef ATOMIC64_OP
 
-__LL_SC_INLINE s64
-__LL_SC_PREFIX(arch_atomic64_dec_if_positive(atomic64_t *v))
+static inline s64
+__ll_sc_atomic64_dec_if_positive(atomic64_t *v)
 {
 	s64 result;
 	unsigned long tmp;
 
 	asm volatile("// atomic64_dec_if_positive\n"
+	__LL_SC_FALLBACK(
 "	prfm	pstl1strm, %2\n"
 "1:	ldxr	%0, %2\n"
 "	subs	%0, %0, #1\n"
@@ -228,20 +248,19 @@ __LL_SC_PREFIX(arch_atomic64_dec_if_positive(atomic64_t *v))
 "	stlxr	%w1, %0, %2\n"
 "	cbnz	%w1, 1b\n"
 "	dmb	ish\n"
-"2:"
+"2:")
 	: "=&r" (result), "=&r" (tmp), "+Q" (v->counter)
 	:
 	: "cc", "memory");
 
 	return result;
 }
-__LL_SC_EXPORT(arch_atomic64_dec_if_positive);
 
-#define __CMPXCHG_CASE(w, sfx, name, sz, mb, acq, rel, cl)		\
-__LL_SC_INLINE u##sz							\
-__LL_SC_PREFIX(__cmpxchg_case_##name##sz(volatile void *ptr,		\
+#define __CMPXCHG_CASE(w, sfx, name, sz, mb, acq, rel, cl, constraint)	\
+static inline u##sz							\
+__ll_sc__cmpxchg_case_##name##sz(volatile void *ptr,			\
 					 unsigned long old,		\
-					 u##sz new))			\
+					 u##sz new)			\
 {									\
 	unsigned long tmp;						\
 	u##sz oldval;							\
@@ -255,6 +274,7 @@ __LL_SC_PREFIX(__cmpxchg_case_##name##sz(volatile void *ptr,		\
 		old = (u##sz)old;					\
 									\
 	asm volatile(							\
+	__LL_SC_FALLBACK(						\
 	"	prfm	pstl1strm, %[v]\n"				\
 	"1:	ld" #acq "xr" #sfx "\t%" #w "[oldval], %[v]\n"		\
 	"	eor	%" #w "[tmp], %" #w "[oldval], %" #w "[old]\n"	\
@@ -262,46 +282,51 @@ __LL_SC_PREFIX(__cmpxchg_case_##name##sz(volatile void *ptr,		\
 	"	st" #rel "xr" #sfx "\t%w[tmp], %" #w "[new], %[v]\n"	\
 	"	cbnz	%w[tmp], 1b\n"					\
 	"	" #mb "\n"						\
-	"2:"								\
+	"2:")								\
 	: [tmp] "=&r" (tmp), [oldval] "=&r" (oldval),			\
 	  [v] "+Q" (*(u##sz *)ptr)					\
-	: [old] "Kr" (old), [new] "r" (new)				\
+	: [old] __stringify(constraint) "r" (old), [new] "r" (new)	\
 	: cl);								\
 									\
 	return oldval;							\
-}									\
-__LL_SC_EXPORT(__cmpxchg_case_##name##sz);
+}
 
-__CMPXCHG_CASE(w, b,     ,  8,        ,  ,  ,         )
-__CMPXCHG_CASE(w, h,     , 16,        ,  ,  ,         )
-__CMPXCHG_CASE(w,  ,     , 32,        ,  ,  ,         )
-__CMPXCHG_CASE( ,  ,     , 64,        ,  ,  ,         )
-__CMPXCHG_CASE(w, b, acq_,  8,        , a,  , "memory")
-__CMPXCHG_CASE(w, h, acq_, 16,        , a,  , "memory")
-__CMPXCHG_CASE(w,  , acq_, 32,        , a,  , "memory")
-__CMPXCHG_CASE( ,  , acq_, 64,        , a,  , "memory")
-__CMPXCHG_CASE(w, b, rel_,  8,        ,  , l, "memory")
-__CMPXCHG_CASE(w, h, rel_, 16,        ,  , l, "memory")
-__CMPXCHG_CASE(w,  , rel_, 32,        ,  , l, "memory")
-__CMPXCHG_CASE( ,  , rel_, 64,        ,  , l, "memory")
-__CMPXCHG_CASE(w, b,  mb_,  8, dmb ish,  , l, "memory")
-__CMPXCHG_CASE(w, h,  mb_, 16, dmb ish,  , l, "memory")
-__CMPXCHG_CASE(w,  ,  mb_, 32, dmb ish,  , l, "memory")
-__CMPXCHG_CASE( ,  ,  mb_, 64, dmb ish,  , l, "memory")
+/*
+ * Earlier versions of GCC (no later than 8.1.0) appear to incorrectly
+ * handle the 'K' constraint for the value 4294967295 - thus we use no
+ * constraint for 32 bit operations.
+ */
+__CMPXCHG_CASE(w, b,     ,  8,        ,  ,  ,         , K)
+__CMPXCHG_CASE(w, h,     , 16,        ,  ,  ,         , K)
+__CMPXCHG_CASE(w,  ,     , 32,        ,  ,  ,         , K)
+__CMPXCHG_CASE( ,  ,     , 64,        ,  ,  ,         , L)
+__CMPXCHG_CASE(w, b, acq_,  8,        , a,  , "memory", K)
+__CMPXCHG_CASE(w, h, acq_, 16,        , a,  , "memory", K)
+__CMPXCHG_CASE(w,  , acq_, 32,        , a,  , "memory", K)
+__CMPXCHG_CASE( ,  , acq_, 64,        , a,  , "memory", L)
+__CMPXCHG_CASE(w, b, rel_,  8,        ,  , l, "memory", K)
+__CMPXCHG_CASE(w, h, rel_, 16,        ,  , l, "memory", K)
+__CMPXCHG_CASE(w,  , rel_, 32,        ,  , l, "memory", K)
+__CMPXCHG_CASE( ,  , rel_, 64,        ,  , l, "memory", L)
+__CMPXCHG_CASE(w, b,  mb_,  8, dmb ish,  , l, "memory", K)
+__CMPXCHG_CASE(w, h,  mb_, 16, dmb ish,  , l, "memory", K)
+__CMPXCHG_CASE(w,  ,  mb_, 32, dmb ish,  , l, "memory", K)
+__CMPXCHG_CASE( ,  ,  mb_, 64, dmb ish,  , l, "memory", L)
 
 #undef __CMPXCHG_CASE
 
 #define __CMPXCHG_DBL(name, mb, rel, cl)				\
-__LL_SC_INLINE long							\
-__LL_SC_PREFIX(__cmpxchg_double##name(unsigned long old1,		\
+static inline long							\
+__ll_sc__cmpxchg_double##name(unsigned long old1,			\
 				      unsigned long old2,		\
 				      unsigned long new1,		\
 				      unsigned long new2,		\
-				      volatile void *ptr))		\
+				      volatile void *ptr)		\
 {									\
 	unsigned long tmp, ret;						\
 									\
 	asm volatile("// __cmpxchg_double" #name "\n"			\
+	__LL_SC_FALLBACK(						\
 	"	prfm	pstl1strm, %2\n"				\
 	"1:	ldxp	%0, %1, %2\n"					\
 	"	eor	%0, %0, %3\n"					\
@@ -311,18 +336,18 @@ __LL_SC_PREFIX(__cmpxchg_double##name(unsigned long old1,		\
 	"	st" #rel "xp	%w0, %5, %6, %2\n"			\
 	"	cbnz	%w0, 1b\n"					\
 	"	" #mb "\n"						\
-	"2:"								\
+	"2:")								\
 	: "=&r" (tmp), "=&r" (ret), "+Q" (*(unsigned long *)ptr)	\
 	: "r" (old1), "r" (old2), "r" (new1), "r" (new2)		\
 	: cl);								\
 									\
 	return ret;							\
-}									\
-__LL_SC_EXPORT(__cmpxchg_double##name);
+}
 
 __CMPXCHG_DBL(   ,        ,  ,         )
 __CMPXCHG_DBL(_mb, dmb ish, l, "memory")
 
 #undef __CMPXCHG_DBL
+#undef K
 
 #endif	/* __ASM_ATOMIC_LL_SC_H */