[linux-next:master 2555/3220] arch/csky/include/asm/cmpxchg.h:138:25: error: implicit declaration of function 'cmpxchg_emu_u8'

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   c0b832517f627ead3388c6f0c74e8ac10ad5774b
commit: ea7f9bb7268e89fff8590ab5a360f5b27a0fc19a [2555/3220] csky: Emulate one-byte and two-byte cmpxchg
config: csky-randconfig-r012-20230202 (https://download.01.org/0day-ci/archive/20240402/202404022106.mYwpypit-lkp@intel.com/config)
compiler: csky-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240402/202404022106.mYwpypit-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404022106.mYwpypit-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from arch/csky/include/asm/atomic.h:9,
                    from include/linux/atomic.h:7,
                    from include/asm-generic/bitops/lock.h:5,
                    from arch/csky/include/asm/bitops.h:69,
                    from include/linux/bitops.h:68,
                    from include/linux/log2.h:12,
                    from kernel/bounds.c:13:
   include/linux/atomic/atomic-arch-fallback.h: In function 'raw_atomic_cmpxchg':
>> arch/csky/include/asm/cmpxchg.h:138:25: error: implicit declaration of function 'cmpxchg_emu_u8' [-Werror=implicit-function-declaration]
     138 |                 __ret = cmpxchg_emu_u8((volatile u8 *)__ptr, __old, __new); \
         |                         ^~~~~~~~~~~~~~
   arch/csky/include/asm/cmpxchg.h:165:10: note: in expansion of macro '__cmpxchg'
     165 |         (__cmpxchg((ptr), (o), (n), sizeof(*(ptr))))
         |          ^~~~~~~~~
   include/linux/atomic/atomic-arch-fallback.h:55:21: note: in expansion of macro 'arch_cmpxchg'
      55 | #define raw_cmpxchg arch_cmpxchg
         |                     ^~~~~~~~~~~~
   include/linux/atomic/atomic-arch-fallback.h:2026:16: note: in expansion of macro 'raw_cmpxchg'
    2026 |         return raw_cmpxchg(&v->counter, old, new);
         |                ^~~~~~~~~~~
>> arch/csky/include/asm/cmpxchg.h:141:25: error: implicit declaration of function 'cmpxchg_emu_u16' [-Werror=implicit-function-declaration]
     141 |                 __ret = cmpxchg_emu_u16((volatile u16 *)__ptr, __old, __new); \
         |                         ^~~~~~~~~~~~~~~
   arch/csky/include/asm/cmpxchg.h:165:10: note: in expansion of macro '__cmpxchg'
     165 |         (__cmpxchg((ptr), (o), (n), sizeof(*(ptr))))
         |          ^~~~~~~~~
   include/linux/atomic/atomic-arch-fallback.h:55:21: note: in expansion of macro 'arch_cmpxchg'
      55 | #define raw_cmpxchg arch_cmpxchg
         |                     ^~~~~~~~~~~~
   include/linux/atomic/atomic-arch-fallback.h:2026:16: note: in expansion of macro 'raw_cmpxchg'
    2026 |         return raw_cmpxchg(&v->counter, old, new);
         |                ^~~~~~~~~~~
   cc1: some warnings being treated as errors
   make[3]: *** [scripts/Makefile.build:117: kernel/bounds.s] Error 1
   make[3]: Target 'prepare' not remade because of errors.
   make[2]: *** [Makefile:1197: prepare0] Error 2
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:240: __sub-make] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:240: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +/cmpxchg_emu_u8 +138 arch/csky/include/asm/cmpxchg.h

   125	
   126	#define arch_cmpxchg_acquire(ptr, o, n) \
   127		(__cmpxchg_acquire((ptr), (o), (n), sizeof(*(ptr))))
   128	
   129	#define __cmpxchg(ptr, old, new, size)				\
   130	({								\
   131		__typeof__(ptr) __ptr = (ptr);				\
   132		__typeof__(new) __new = (new);				\
   133		__typeof__(new) __tmp;					\
   134		__typeof__(old) __old = (old);				\
   135		__typeof__(*(ptr)) __ret;				\
   136		switch (size) {						\
   137		case 1:							\
 > 138			__ret = cmpxchg_emu_u8((volatile u8 *)__ptr, __old, __new); \
   139			break;						\
   140		case 2:							\
 > 141			__ret = cmpxchg_emu_u16((volatile u16 *)__ptr, __old, __new); \
   142			break;						\
   143		case 4:							\
   144			asm volatile (					\
   145			RELEASE_FENCE					\
   146			"1:	ldex.w		%0, (%3) \n"		\
   147			"	cmpne		%0, %4   \n"		\
   148			"	bt		2f       \n"		\
   149			"	mov		%1, %2   \n"		\
   150			"	stex.w		%1, (%3) \n"		\
   151			"	bez		%1, 1b   \n"		\
   152			FULL_FENCE					\
   153			"2:				 \n"		\
   154				: "=&r" (__ret), "=&r" (__tmp)		\
   155				: "r" (__new), "r"(__ptr), "r"(__old)	\
   156				:);					\
   157			break;						\
   158		default:						\
   159			BUILD_BUG();					\
   160		}							\
   161		__ret;							\
   162	})
   163	

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