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-rw-r--r--include/asm-generic/cmpxchg-local.h68
1 files changed, 68 insertions, 0 deletions
diff --git a/include/asm-generic/cmpxchg-local.h b/include/asm-generic/cmpxchg-local.h
new file mode 100644
index 000000000..380cdc824
--- /dev/null
+++ b/include/asm-generic/cmpxchg-local.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_GENERIC_CMPXCHG_LOCAL_H
+#define __ASM_GENERIC_CMPXCHG_LOCAL_H
+
+#include <linux/types.h>
+#include <linux/irqflags.h>
+
+extern unsigned long wrong_size_cmpxchg(volatile void *ptr)
+ __noreturn;
+
+/*
+ * Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned
+ * long parameter, supporting various types of architectures.
+ */
+static inline unsigned long __generic_cmpxchg_local(volatile void *ptr,
+ unsigned long old, unsigned long new, int size)
+{
+ unsigned long flags, prev;
+
+ /*
+ * Sanity checking, compile-time.
+ */
+ if (size == 8 && sizeof(unsigned long) != 8)
+ wrong_size_cmpxchg(ptr);
+
+ raw_local_irq_save(flags);
+ switch (size) {
+ case 1: prev = *(u8 *)ptr;
+ if (prev == old)
+ *(u8 *)ptr = (u8)new;
+ break;
+ case 2: prev = *(u16 *)ptr;
+ if (prev == old)
+ *(u16 *)ptr = (u16)new;
+ break;
+ case 4: prev = *(u32 *)ptr;
+ if (prev == old)
+ *(u32 *)ptr = (u32)new;
+ break;
+ case 8: prev = *(u64 *)ptr;
+ if (prev == old)
+ *(u64 *)ptr = (u64)new;
+ break;
+ default:
+ wrong_size_cmpxchg(ptr);
+ }
+ raw_local_irq_restore(flags);
+ return prev;
+}
+
+/*
+ * Generic version of __cmpxchg64_local. Takes an u64 parameter.
+ */
+static inline u64 __generic_cmpxchg64_local(volatile void *ptr,
+ u64 old, u64 new)
+{
+ u64 prev;
+ unsigned long flags;
+
+ raw_local_irq_save(flags);
+ prev = *(u64 *)ptr;
+ if (prev == old)
+ *(u64 *)ptr = new;
+ raw_local_irq_restore(flags);
+ return prev;
+}
+
+#endif