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authorWill Deacon <will.deacon@arm.com>2015-02-03 11:26:53 +0000
committerWill Deacon <will.deacon@arm.com>2015-07-27 14:34:39 +0100
commitc275f76bb4ce16fd0205da1e15f31b875013678e (patch)
tree1d486f58d6af6dab18fe5cf5858260fd8d16043b /arch/arm64/include/asm/atomic_ll_sc.h
parent144e9697a9e70b5549fd52df90111f1410bcbfeb (diff)
downloadlinux-c275f76bb4ce16fd0205da1e15f31b875013678e.tar.gz
arm64: atomics: move ll/sc atomics into separate header file
In preparation for the Large System Extension (LSE) atomic instructions introduced by ARM v8.1, move the current exclusive load/store (LL/SC) atomics into their own header file. Reviewed-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/atomic_ll_sc.h')
-rw-r--r--arch/arm64/include/asm/atomic_ll_sc.h215
1 files changed, 215 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/atomic_ll_sc.h b/arch/arm64/include/asm/atomic_ll_sc.h
new file mode 100644
index 000000000000..66e992a58f6b
--- /dev/null
+++ b/arch/arm64/include/asm/atomic_ll_sc.h
@@ -0,0 +1,215 @@
+/*
+ * Based on arch/arm/include/asm/atomic.h
+ *
+ * Copyright (C) 1996 Russell King.
+ * Copyright (C) 2002 Deep Blue Solutions Ltd.
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __ASM_ATOMIC_LL_SC_H
+#define __ASM_ATOMIC_LL_SC_H
+
+/*
+ * 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).
+ */
+
+#ifndef __LL_SC_INLINE
+#define __LL_SC_INLINE static inline
+#endif
+
+#ifndef __LL_SC_PREFIX
+#define __LL_SC_PREFIX(x) x
+#endif
+
+#define ATOMIC_OP(op, asm_op) \
+__LL_SC_INLINE void \
+__LL_SC_PREFIX(atomic_##op(int i, atomic_t *v)) \
+{ \
+ unsigned long tmp; \
+ int result; \
+ \
+ asm volatile("// atomic_" #op "\n" \
+"1: ldxr %w0, %2\n" \
+" " #asm_op " %w0, %w0, %w3\n" \
+" stxr %w1, %w0, %2\n" \
+" cbnz %w1, 1b" \
+ : "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
+ : "Ir" (i)); \
+} \
+
+#define ATOMIC_OP_RETURN(op, asm_op) \
+__LL_SC_INLINE int \
+__LL_SC_PREFIX(atomic_##op##_return(int i, atomic_t *v)) \
+{ \
+ unsigned long tmp; \
+ int result; \
+ \
+ asm volatile("// atomic_" #op "_return\n" \
+"1: ldxr %w0, %2\n" \
+" " #asm_op " %w0, %w0, %w3\n" \
+" stlxr %w1, %w0, %2\n" \
+" cbnz %w1, 1b" \
+ : "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
+ : "Ir" (i) \
+ : "memory"); \
+ \
+ smp_mb(); \
+ return result; \
+}
+
+#define ATOMIC_OPS(op, asm_op) \
+ ATOMIC_OP(op, asm_op) \
+ ATOMIC_OP_RETURN(op, asm_op)
+
+ATOMIC_OPS(add, add)
+ATOMIC_OPS(sub, sub)
+
+ATOMIC_OP(and, and)
+ATOMIC_OP(andnot, bic)
+ATOMIC_OP(or, orr)
+ATOMIC_OP(xor, eor)
+
+#undef ATOMIC_OPS
+#undef ATOMIC_OP_RETURN
+#undef ATOMIC_OP
+
+__LL_SC_INLINE int
+__LL_SC_PREFIX(atomic_cmpxchg(atomic_t *ptr, int old, int new))
+{
+ unsigned long tmp;
+ int oldval;
+
+ smp_mb();
+
+ asm volatile("// atomic_cmpxchg\n"
+"1: ldxr %w1, %2\n"
+" cmp %w1, %w3\n"
+" b.ne 2f\n"
+" stxr %w0, %w4, %2\n"
+" cbnz %w0, 1b\n"
+"2:"
+ : "=&r" (tmp), "=&r" (oldval), "+Q" (ptr->counter)
+ : "Ir" (old), "r" (new)
+ : "cc");
+
+ smp_mb();
+ return oldval;
+}
+
+#define ATOMIC64_OP(op, asm_op) \
+__LL_SC_INLINE void \
+__LL_SC_PREFIX(atomic64_##op(long i, atomic64_t *v)) \
+{ \
+ long result; \
+ unsigned long tmp; \
+ \
+ asm volatile("// atomic64_" #op "\n" \
+"1: ldxr %0, %2\n" \
+" " #asm_op " %0, %0, %3\n" \
+" stxr %w1, %0, %2\n" \
+" cbnz %w1, 1b" \
+ : "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
+ : "Ir" (i)); \
+} \
+
+#define ATOMIC64_OP_RETURN(op, asm_op) \
+__LL_SC_INLINE long \
+__LL_SC_PREFIX(atomic64_##op##_return(long i, atomic64_t *v)) \
+{ \
+ long result; \
+ unsigned long tmp; \
+ \
+ asm volatile("// atomic64_" #op "_return\n" \
+"1: ldxr %0, %2\n" \
+" " #asm_op " %0, %0, %3\n" \
+" stlxr %w1, %0, %2\n" \
+" cbnz %w1, 1b" \
+ : "=&r" (result), "=&r" (tmp), "+Q" (v->counter) \
+ : "Ir" (i) \
+ : "memory"); \
+ \
+ smp_mb(); \
+ return result; \
+}
+
+#define ATOMIC64_OPS(op, asm_op) \
+ ATOMIC64_OP(op, asm_op) \
+ ATOMIC64_OP_RETURN(op, asm_op)
+
+ATOMIC64_OPS(add, add)
+ATOMIC64_OPS(sub, sub)
+
+ATOMIC64_OP(and, and)
+ATOMIC64_OP(andnot, bic)
+ATOMIC64_OP(or, orr)
+ATOMIC64_OP(xor, eor)
+
+#undef ATOMIC64_OPS
+#undef ATOMIC64_OP_RETURN
+#undef ATOMIC64_OP
+
+__LL_SC_INLINE long
+__LL_SC_PREFIX(atomic64_cmpxchg(atomic64_t *ptr, long old, long new))
+{
+ long oldval;
+ unsigned long res;
+
+ smp_mb();
+
+ asm volatile("// atomic64_cmpxchg\n"
+"1: ldxr %1, %2\n"
+" cmp %1, %3\n"
+" b.ne 2f\n"
+" stxr %w0, %4, %2\n"
+" cbnz %w0, 1b\n"
+"2:"
+ : "=&r" (res), "=&r" (oldval), "+Q" (ptr->counter)
+ : "Ir" (old), "r" (new)
+ : "cc");
+
+ smp_mb();
+ return oldval;
+}
+
+__LL_SC_INLINE long
+__LL_SC_PREFIX(atomic64_dec_if_positive(atomic64_t *v))
+{
+ long result;
+ unsigned long tmp;
+
+ asm volatile("// atomic64_dec_if_positive\n"
+"1: ldxr %0, %2\n"
+" subs %0, %0, #1\n"
+" b.mi 2f\n"
+" stlxr %w1, %0, %2\n"
+" cbnz %w1, 1b\n"
+" dmb ish\n"
+"2:"
+ : "=&r" (result), "=&r" (tmp), "+Q" (v->counter)
+ :
+ : "cc", "memory");
+
+ return result;
+}
+
+#endif /* __ASM_ATOMIC_LL_SC_H */