MIPS: Fall back to generic implementation of cmpxchg64 on 32-bit platforms

This is in preparation of adding HAVE_VIRT_CPU_ACCOUNTING_GEN support in
the next patch.

Without having cmpxchg64 to use the generic implementation, kernel linking
will complain:

kernel/built-in.o: In function `cputime_adjust':
cputime.c:(.text+0x33748): undefined reference to `__cmpxchg_called_with_bad_pointer'
cputime.c:(.text+0x33810): undefined reference to `__cmpxchg_called_with_bad_pointer'
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9474/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/cmpxchg.h

@@ -229,21 +229,22 @@ extern void __cmpxchg_called_with_bad_pointer(void);
 #define cmpxchg(ptr, old, new)		__cmpxchg(ptr, old, new, smp_mb__before_llsc(), smp_llsc_mb())
 #define cmpxchg_local(ptr, old, new)	__cmpxchg(ptr, old, new, , )
 
-#define cmpxchg64(ptr, o, n)						\
+#ifdef CONFIG_64BIT
+#define cmpxchg64_local(ptr, o, n)					\
   ({									\
 	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
-	cmpxchg((ptr), (o), (n));					\
+	cmpxchg_local((ptr), (o), (n));					\
   })
 
-#ifdef CONFIG_64BIT
-#define cmpxchg64_local(ptr, o, n)					\
+#define cmpxchg64(ptr, o, n)						\
   ({									\
 	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
-	cmpxchg_local((ptr), (o), (n));					\
+	cmpxchg((ptr), (o), (n));					\
   })
 #else
 #include <asm-generic/cmpxchg-local.h>
 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
+#define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n))
 #endif
 
 #endif /* __ASM_CMPXCHG_H */