[viro-vfs:misc.cmpxchg 4/8] arch/sparc/include/asm/cmpxchg_32.h:51:61: sparse: sparse: cast truncates bits from constant value (eb9f becomes 9f)

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

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git misc.cmpxchg
head:   9e2f22ef1ae21b949a3903727d7e7cd5eb48810f
commit: 1b2857f7277164d8bed4e831e3c3696572a51f0b [4/8] sparc32: add __cmpxchg_u{8,16}() and teach __cmpxchg() to handle those sizes
config: sparc-randconfig-r132-20240403 (https://download.01.org/0day-ci/archive/20240403/202404030332.d8MKrNbM-lkp@intel.com/config)
compiler: sparc-linux-gcc (GCC) 13.2.0
reproduce: (https://download.01.org/0day-ci/archive/20240403/202404030332.d8MKrNbM-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/202404030332.d8MKrNbM-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   kernel/bpf/helpers.c:2157:18: sparse: sparse: symbol 'bpf_task_release_dtor' was not declared. Should it be static?
   kernel/bpf/helpers.c:2187:18: sparse: sparse: symbol 'bpf_cgroup_release_dtor' was not declared. Should it be static?
   kernel/bpf/helpers.c: note: in included file (through arch/sparc/include/asm/cmpxchg.h, arch/sparc/include/asm/atomic_32.h, arch/sparc/include/asm/atomic.h, ...):
>> arch/sparc/include/asm/cmpxchg_32.h:51:61: sparse: sparse: cast truncates bits from constant value (eb9f becomes 9f)
   kernel/bpf/helpers.c: note: in included file (through include/linux/timer.h, include/linux/workqueue.h, include/linux/bpf.h):
   include/linux/list.h:83:21: sparse: sparse: self-comparison always evaluates to true
   include/linux/list.h:83:21: sparse: sparse: self-comparison always evaluates to true
   kernel/bpf/helpers.c: note: in included file (through arch/sparc/include/asm/cmpxchg.h, arch/sparc/include/asm/atomic_32.h, arch/sparc/include/asm/atomic.h, ...):
>> arch/sparc/include/asm/cmpxchg_32.h:51:61: sparse: sparse: cast truncates bits from constant value (eb9f becomes 9f)
   kernel/bpf/helpers.c:2495:18: sparse: sparse: context imbalance in 'bpf_rcu_read_lock' - wrong count at exit
   kernel/bpf/helpers.c:2500:18: sparse: sparse: context imbalance in 'bpf_rcu_read_unlock' - unexpected unlock

vim +51 arch/sparc/include/asm/cmpxchg_32.h

    44	
    45	/* don't worry...optimizer will get rid of most of this */
    46	static inline unsigned long
    47	__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
    48	{
    49		switch (size) {
    50		case 1:
  > 51			return __cmpxchg_u8((u8 *)ptr, (u8)old, (u8)new_);
    52		case 2:
    53			return __cmpxchg_u16((u16 *)ptr, (u16)old, (u16)new_);
    54		case 4:
    55			return __cmpxchg_u32((u32 *)ptr, (u32)old, (u32)new_);
    56		default:
    57			__cmpxchg_called_with_bad_pointer();
    58			break;
    59		}
    60		return old;
    61	}
    62	

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