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-rw-r--r--arch/arc/include/asm/cmpxchg.h143
1 files changed, 143 insertions, 0 deletions
diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
new file mode 100644
index 0000000000..e138fde067
--- /dev/null
+++ b/arch/arc/include/asm/cmpxchg.h
@@ -0,0 +1,143 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ */
+
+#ifndef __ASM_ARC_CMPXCHG_H
+#define __ASM_ARC_CMPXCHG_H
+
+#include <linux/build_bug.h>
+#include <linux/types.h>
+
+#include <asm/barrier.h>
+#include <asm/smp.h>
+
+#ifdef CONFIG_ARC_HAS_LLSC
+
+/*
+ * if (*ptr == @old)
+ * *ptr = @new
+ */
+#define __cmpxchg(ptr, old, new) \
+({ \
+ __typeof__(*(ptr)) _prev; \
+ \
+ __asm__ __volatile__( \
+ "1: llock %0, [%1] \n" \
+ " brne %0, %2, 2f \n" \
+ " scond %3, [%1] \n" \
+ " bnz 1b \n" \
+ "2: \n" \
+ : "=&r"(_prev) /* Early clobber prevent reg reuse */ \
+ : "r"(ptr), /* Not "m": llock only supports reg */ \
+ "ir"(old), \
+ "r"(new) /* Not "ir": scond can't take LIMM */ \
+ : "cc", \
+ "memory"); /* gcc knows memory is clobbered */ \
+ \
+ _prev; \
+})
+
+#define arch_cmpxchg_relaxed(ptr, old, new) \
+({ \
+ __typeof__(ptr) _p_ = (ptr); \
+ __typeof__(*(ptr)) _o_ = (old); \
+ __typeof__(*(ptr)) _n_ = (new); \
+ __typeof__(*(ptr)) _prev_; \
+ \
+ switch(sizeof((_p_))) { \
+ case 4: \
+ _prev_ = __cmpxchg(_p_, _o_, _n_); \
+ break; \
+ default: \
+ BUILD_BUG(); \
+ } \
+ _prev_; \
+})
+
+#else
+
+#define arch_cmpxchg(ptr, old, new) \
+({ \
+ volatile __typeof__(ptr) _p_ = (ptr); \
+ __typeof__(*(ptr)) _o_ = (old); \
+ __typeof__(*(ptr)) _n_ = (new); \
+ __typeof__(*(ptr)) _prev_; \
+ unsigned long __flags; \
+ \
+ BUILD_BUG_ON(sizeof(_p_) != 4); \
+ \
+ /* \
+ * spin lock/unlock provide the needed smp_mb() before/after \
+ */ \
+ atomic_ops_lock(__flags); \
+ _prev_ = *_p_; \
+ if (_prev_ == _o_) \
+ *_p_ = _n_; \
+ atomic_ops_unlock(__flags); \
+ _prev_; \
+})
+
+#endif
+
+/*
+ * xchg
+ */
+#ifdef CONFIG_ARC_HAS_LLSC
+
+#define __arch_xchg(ptr, val) \
+({ \
+ __asm__ __volatile__( \
+ " ex %0, [%1] \n" /* set new value */ \
+ : "+r"(val) \
+ : "r"(ptr) \
+ : "memory"); \
+ _val_; /* get old value */ \
+})
+
+#define arch_xchg_relaxed(ptr, val) \
+({ \
+ __typeof__(ptr) _p_ = (ptr); \
+ __typeof__(*(ptr)) _val_ = (val); \
+ \
+ switch(sizeof(*(_p_))) { \
+ case 4: \
+ _val_ = __arch_xchg(_p_, _val_); \
+ break; \
+ default: \
+ BUILD_BUG(); \
+ } \
+ _val_; \
+})
+
+#else /* !CONFIG_ARC_HAS_LLSC */
+
+/*
+ * EX instructions is baseline and present in !LLSC too. But in this
+ * regime it still needs use @atomic_ops_lock spinlock to allow interop
+ * with cmpxchg() which uses spinlock in !LLSC
+ * (llist.h use xchg and cmpxchg on sama data)
+ */
+
+#define arch_xchg(ptr, val) \
+({ \
+ __typeof__(ptr) _p_ = (ptr); \
+ __typeof__(*(ptr)) _val_ = (val); \
+ \
+ unsigned long __flags; \
+ \
+ atomic_ops_lock(__flags); \
+ \
+ __asm__ __volatile__( \
+ " ex %0, [%1] \n" \
+ : "+r"(_val_) \
+ : "r"(_p_) \
+ : "memory"); \
+ \
+ atomic_ops_unlock(__flags); \
+ _val_; \
+})
+
+#endif
+
+#endif