v4.19.13 snapshot.
diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h
new file mode 100644
index 0000000..89e9fb7
--- /dev/null
+++ b/arch/mips/include/asm/cmpxchg.h
@@ -0,0 +1,214 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2003, 06, 07 by Ralf Baechle (ralf@linux-mips.org)
+ */
+#ifndef __ASM_CMPXCHG_H
+#define __ASM_CMPXCHG_H
+
+#include <linux/bug.h>
+#include <linux/irqflags.h>
+#include <asm/compiler.h>
+#include <asm/war.h>
+
+/*
+ * Using a branch-likely instruction to check the result of an sc instruction
+ * works around a bug present in R10000 CPUs prior to revision 3.0 that could
+ * cause ll-sc sequences to execute non-atomically.
+ */
+#if R10000_LLSC_WAR
+# define __scbeqz "beqzl"
+#else
+# define __scbeqz "beqz"
+#endif
+
+/*
+ * These functions doesn't exist, so if they are called you'll either:
+ *
+ * - Get an error at compile-time due to __compiletime_error, if supported by
+ * your compiler.
+ *
+ * or:
+ *
+ * - Get an error at link-time due to the call to the missing function.
+ */
+extern unsigned long __cmpxchg_called_with_bad_pointer(void)
+ __compiletime_error("Bad argument size for cmpxchg");
+extern unsigned long __xchg_called_with_bad_pointer(void)
+ __compiletime_error("Bad argument size for xchg");
+
+#define __xchg_asm(ld, st, m, val) \
+({ \
+ __typeof(*(m)) __ret; \
+ \
+ if (kernel_uses_llsc) { \
+ __asm__ __volatile__( \
+ " .set push \n" \
+ " .set noat \n" \
+ " .set " MIPS_ISA_ARCH_LEVEL " \n" \
+ "1: " ld " %0, %2 # __xchg_asm \n" \
+ " .set mips0 \n" \
+ " move $1, %z3 \n" \
+ " .set " MIPS_ISA_ARCH_LEVEL " \n" \
+ " " st " $1, %1 \n" \
+ "\t" __scbeqz " $1, 1b \n" \
+ " .set pop \n" \
+ : "=&r" (__ret), "=" GCC_OFF_SMALL_ASM() (*m) \
+ : GCC_OFF_SMALL_ASM() (*m), "Jr" (val) \
+ : "memory"); \
+ } else { \
+ unsigned long __flags; \
+ \
+ raw_local_irq_save(__flags); \
+ __ret = *m; \
+ *m = val; \
+ raw_local_irq_restore(__flags); \
+ } \
+ \
+ __ret; \
+})
+
+extern unsigned long __xchg_small(volatile void *ptr, unsigned long val,
+ unsigned int size);
+
+static inline unsigned long __xchg(volatile void *ptr, unsigned long x,
+ int size)
+{
+ switch (size) {
+ case 1:
+ case 2:
+ return __xchg_small(ptr, x, size);
+
+ case 4:
+ return __xchg_asm("ll", "sc", (volatile u32 *)ptr, x);
+
+ case 8:
+ if (!IS_ENABLED(CONFIG_64BIT))
+ return __xchg_called_with_bad_pointer();
+
+ return __xchg_asm("lld", "scd", (volatile u64 *)ptr, x);
+
+ default:
+ return __xchg_called_with_bad_pointer();
+ }
+}
+
+#define xchg(ptr, x) \
+({ \
+ __typeof__(*(ptr)) __res; \
+ \
+ smp_mb__before_llsc(); \
+ \
+ __res = (__typeof__(*(ptr))) \
+ __xchg((ptr), (unsigned long)(x), sizeof(*(ptr))); \
+ \
+ smp_llsc_mb(); \
+ \
+ __res; \
+})
+
+#define __cmpxchg_asm(ld, st, m, old, new) \
+({ \
+ __typeof(*(m)) __ret; \
+ \
+ if (kernel_uses_llsc) { \
+ __asm__ __volatile__( \
+ " .set push \n" \
+ " .set noat \n" \
+ " .set "MIPS_ISA_ARCH_LEVEL" \n" \
+ "1: " ld " %0, %2 # __cmpxchg_asm \n" \
+ " bne %0, %z3, 2f \n" \
+ " .set mips0 \n" \
+ " move $1, %z4 \n" \
+ " .set "MIPS_ISA_ARCH_LEVEL" \n" \
+ " " st " $1, %1 \n" \
+ "\t" __scbeqz " $1, 1b \n" \
+ " .set pop \n" \
+ "2: \n" \
+ : "=&r" (__ret), "=" GCC_OFF_SMALL_ASM() (*m) \
+ : GCC_OFF_SMALL_ASM() (*m), "Jr" (old), "Jr" (new) \
+ : "memory"); \
+ } else { \
+ unsigned long __flags; \
+ \
+ raw_local_irq_save(__flags); \
+ __ret = *m; \
+ if (__ret == old) \
+ *m = new; \
+ raw_local_irq_restore(__flags); \
+ } \
+ \
+ __ret; \
+})
+
+extern unsigned long __cmpxchg_small(volatile void *ptr, unsigned long old,
+ unsigned long new, unsigned int size);
+
+static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
+ unsigned long new, unsigned int size)
+{
+ switch (size) {
+ case 1:
+ case 2:
+ return __cmpxchg_small(ptr, old, new, size);
+
+ case 4:
+ return __cmpxchg_asm("ll", "sc", (volatile u32 *)ptr,
+ (u32)old, new);
+
+ case 8:
+ /* lld/scd are only available for MIPS64 */
+ if (!IS_ENABLED(CONFIG_64BIT))
+ return __cmpxchg_called_with_bad_pointer();
+
+ return __cmpxchg_asm("lld", "scd", (volatile u64 *)ptr,
+ (u64)old, new);
+
+ default:
+ return __cmpxchg_called_with_bad_pointer();
+ }
+}
+
+#define cmpxchg_local(ptr, old, new) \
+ ((__typeof__(*(ptr))) \
+ __cmpxchg((ptr), \
+ (unsigned long)(__typeof__(*(ptr)))(old), \
+ (unsigned long)(__typeof__(*(ptr)))(new), \
+ sizeof(*(ptr))))
+
+#define cmpxchg(ptr, old, new) \
+({ \
+ __typeof__(*(ptr)) __res; \
+ \
+ smp_mb__before_llsc(); \
+ __res = cmpxchg_local((ptr), (old), (new)); \
+ smp_llsc_mb(); \
+ \
+ __res; \
+})
+
+#ifdef CONFIG_64BIT
+#define cmpxchg64_local(ptr, o, n) \
+ ({ \
+ BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
+ cmpxchg_local((ptr), (o), (n)); \
+ })
+
+#define cmpxchg64(ptr, o, n) \
+ ({ \
+ BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
+ cmpxchg((ptr), (o), (n)); \
+ })
+#else
+#include <asm-generic/cmpxchg-local.h>
+#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
+#ifndef CONFIG_SMP
+#define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n))
+#endif
+#endif
+
+#undef __scbeqz
+
+#endif /* __ASM_CMPXCHG_H */