[jgunthorpe:iommu_pt_arm64 19/37] include/linux/bitops.h:279:19: sparse: sparse: cast truncates bits from constant value (fffffffffffe0 becomes ffffffe0)

[jgunthorpe:iommu_pt_arm64 19/37] include/linux/bitops.h:279:19: sparse: sparse: cast truncates bits from constant value (fffffffffffe0 becomes ffffffe0)

[kernel test robot]

tree:   https://github.com/jgunthorpe/linux iommu_pt_arm64
head:   ec570e1cdbc0f03b5f4f9940802c7579d913e1ce
commit: c5d3121e6ad2a22ea8059b1ef203c86fd1649625 [19/37] iommupt/armv8: Implement the iommu specific components
config: um-randconfig-r134-20260820 (https://download.01.org/0day-ci/archive/20260820/202608201925.v1ShtOtY-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260820/202608201925.v1ShtOtY-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/202608201925.v1ShtOtY-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   drivers/iommu/generic_pt/fmt/iommu_armv8.c: note: in included file (through drivers/iommu/generic_pt/fmt/../pt_log2.h, drivers/iommu/generic_pt/fmt/../pt_defs.h, drivers/iommu/generic_pt/fmt/iommu_template.h):
>> include/linux/bitops.h:279:19: sparse: sparse: cast truncates bits from constant value (fffffffffffe0 becomes ffffffe0)
   include/linux/bitops.h:284:16: sparse: sparse: cast truncates bits from constant value (fffffffffffe0 becomes ffffffe0)
>> include/linux/bitops.h:279:19: sparse: sparse: cast truncates bits from constant value (fffffffffffe0 becomes ffffffe0)
   include/linux/bitops.h:284:16: sparse: sparse: cast truncates bits from constant value (fffffffffffe0 becomes ffffffe0)

vim +279 include/linux/bitops.h

c320592f3f2a1e6 Wolfram Sang       2025-01-07  267  
952043ac12a117d Steven Whitehouse  2009-04-23  268  /**
952043ac12a117d Steven Whitehouse  2009-04-23  269   * __ffs64 - find first set bit in a 64 bit word
952043ac12a117d Steven Whitehouse  2009-04-23  270   * @word: The 64 bit word
952043ac12a117d Steven Whitehouse  2009-04-23  271   *
4945cca232ce8bc Geert Uytterhoeven 2021-02-25  272   * On 64 bit arches this is a synonym for __ffs
952043ac12a117d Steven Whitehouse  2009-04-23  273   * The result is not defined if no bits are set, so check that @word
952043ac12a117d Steven Whitehouse  2009-04-23  274   * is non-zero before calling this.
952043ac12a117d Steven Whitehouse  2009-04-23  275   */
6606c8c7e818865 Kees Cook          2025-08-04  276  static inline __attribute_const__ unsigned int __ffs64(u64 word)
952043ac12a117d Steven Whitehouse  2009-04-23  277  {
952043ac12a117d Steven Whitehouse  2009-04-23  278  #if BITS_PER_LONG == 32
952043ac12a117d Steven Whitehouse  2009-04-23 @279  	if (((u32)word) == 0UL)
952043ac12a117d Steven Whitehouse  2009-04-23  280  		return __ffs((u32)(word >> 32)) + 32;
952043ac12a117d Steven Whitehouse  2009-04-23  281  #elif BITS_PER_LONG != 64
952043ac12a117d Steven Whitehouse  2009-04-23  282  #error BITS_PER_LONG not 32 or 64
952043ac12a117d Steven Whitehouse  2009-04-23  283  #endif
952043ac12a117d Steven Whitehouse  2009-04-23  284  	return __ffs((unsigned long)word);
952043ac12a117d Steven Whitehouse  2009-04-23  285  }
952043ac12a117d Steven Whitehouse  2009-04-23  286  

:::::: The code at line 279 was first introduced by commit
:::::: 952043ac12a117d8e94bddd9088338d7ad20ca7d bitops: Add __ffs64 bitop

:::::: TO: Steven Whitehouse <swhiteho@redhat.com>
:::::: CC: Steven Whitehouse <swhiteho@redhat.com>

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