Re: [PATCH] perf arm_spe: Fix bitfield dependency failure

[Leo Yan <leo.yan@arm.com>]

On Fri, Jan 23, 2026 at 02:03:17PM +0000, David Laight wrote:

[...]

> > bitfield.h is a common header so I did not change it.  I digged a bit
> > and found diverage between kernel's bitfield.h and tool's bitfield.h.
> > 
> > 1) The kernel's bitfield.h includes asm/byteorder.h, and finally it
> >    includes linux/byteorder/generic.h, cpu_to_le{16|32|64} are defined
> >    in this file.
> > 
> > 2) The tool's bitfield.h will includes asm/byteorder.h, but this hooks
> >    to the headers provided by the toolchain.  cpu_to_le{16|32|64} are
> >    not C lib API, they are defined in tool's kernel.h.
> 
> Perhaps cpu_to_le16() and friends should be defined in the tools
> asm/byteorder.h rather than its kernel.h.

This will override the toolchain's asm/byteorder.h.

Another issue is:

  $ git grep -l cpu_to_le tools/
  tools/arch/x86/include/asm/insn.h
  tools/include/asm-generic/io.h
  tools/include/linux/bitfield.h
  tools/include/linux/kernel.h
  tools/include/linux/unaligned.h
  tools/perf/util/intel-pt.c
  tools/testing/cxl/test/mem.c
  tools/testing/nvdimm/test/ndtest.c
  tools/testing/selftests/arm64/fp/fp-ptrace.c
  tools/testing/selftests/kvm/include/arm64/processor.h
  tools/testing/selftests/kvm/lib/arm64/gic_v3_its.c
  tools/usb/ffs-aio-example/simple/device_app/aio_simple.c
  tools/usb/ffs-test.c

I assume these programs include kernel.h for calling cpu_to_le(), if
move cpu_to_le() out from kernel.h, it will break build for these
programs.

Thanks,
Leo