[linux-next:master 4535/6266] arch/arc/include/asm/cmpxchg.h:73:27: 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:   6bd343537461b57f3efe5dfc5fc193a232dfef1e
commit: d4f26ed66a53be57567bf71d60e80a116cec34e1 [4535/6266] ARC: Emulate one-byte cmpxchg
config: arc-randconfig-r016-20230816 (https://download.01.org/0day-ci/archive/20240416/202404160503.zFIp77TO-lkp@intel.com/config)
compiler: arceb-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240416/202404160503.zFIp77TO-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/202404160503.zFIp77TO-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from include/linux/bitops.h:68,
                    from include/linux/log2.h:12,
                    from kernel/bounds.c:13:
   arch/arc/include/asm/bitops.h: In function '__fls':
   arch/arc/include/asm/bitops.h:137:17: error: implicit declaration of function '__builtin_arc_fls'; did you mean '__builtin_arc_flag'? [-Werror=implicit-function-declaration]
     137 |         return  __builtin_arc_fls(x);
         |                 ^~~~~~~~~~~~~~~~~
         |                 __builtin_arc_flag
   In file included from arch/arc/include/asm/atomic.h:31,
                    from include/linux/atomic.h:7,
                    from include/asm-generic/bitops/lock.h:5,
                    from arch/arc/include/asm/bitops.h:188:
   arch/arc/include/asm/atomic64-arcv2.h: At top level:
   arch/arc/include/asm/atomic64-arcv2.h:13:3: error: conflicting types for 'atomic64_t'; have 'struct <anonymous>'
      13 | } atomic64_t;
         |   ^~~~~~~~~~
   In file included from include/linux/page-flags.h:9,
                    from kernel/bounds.c:10:
   include/linux/types.h:184:3: note: previous declaration of 'atomic64_t' with type 'atomic64_t'
     184 | } atomic64_t;
         |   ^~~~~~~~~~
   In file included from arch/arc/include/asm/atomic.h:13:
   include/linux/atomic/atomic-arch-fallback.h: In function 'raw_atomic_cmpxchg':
>> arch/arc/include/asm/cmpxchg.h:73:27: error: implicit declaration of function 'cmpxchg_emu_u8' [-Werror=implicit-function-declaration]
      73 |                 __flags = cmpxchg_emu_u8((volatile u8 *)_p_, _o_, _n_); \
         |                           ^~~~~~~~~~~~~~
   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);
         |                ^~~~~~~~~~~
   In file included from arch/arc/include/uapi/asm/byteorder.h:14,
                    from include/asm-generic/bitops/le.h:6,
                    from arch/arc/include/asm/bitops.h:192:
   include/linux/byteorder/big_endian.h: At top level:
   include/linux/byteorder/big_endian.h:8:2: warning: #warning inconsistent configuration, needs CONFIG_CPU_BIG_ENDIAN [-Wcpp]
       8 | #warning inconsistent configuration, needs CONFIG_CPU_BIG_ENDIAN
         |  ^~~~~~~
   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 +73 arch/arc/include/asm/cmpxchg.h

    62	
    63	#define arch_cmpxchg(ptr, old, new)				        \
    64	({									\
    65		volatile __typeof__(ptr) _p_ = (ptr);				\
    66		__typeof__(*(ptr)) _o_ = (old);					\
    67		__typeof__(*(ptr)) _n_ = (new);					\
    68		__typeof__(*(ptr)) _prev_;					\
    69		unsigned long __flags;						\
    70										\
    71		switch(sizeof((_p_))) {						\
    72		case 1:								\
  > 73			__flags = cmpxchg_emu_u8((volatile u8 *)_p_, _o_, _n_);	\
    74			_prev_ = (__typeof__(*(ptr)))__flags;			\
    75			break;							\
    76			break;							\
    77		case 4:								\
    78			/*							\
    79			 * spin lock/unlock provide the needed smp_mb()		\
    80			 * before/after						\
    81			 */							\
    82			atomic_ops_lock(__flags);				\
    83			_prev_ = *_p_;						\
    84			if (_prev_ == _o_)					\
    85				*_p_ = _n_;					\
    86			atomic_ops_unlock(__flags);				\
    87			break;							\
    88		default:							\
    89			BUILD_BUG();						\
    90		}								\
    91										\
    92		_prev_;								\
    93	})
    94	

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