Re: [thomas-weissschuh:b4/module-hashes 9/9] llvm-objcopy: error: '.tmp_module_hashes.o': The file was not recognized as a valid object file

[Nathan Chancellor <nathan@kernel.org>]

On Tue, Mar 11, 2025 at 09:58:06PM +0100, Thomas Weißschuh wrote:
> Hi Nathan,
> 
> On 2025-03-11 20:49:40+0100, Nathan Chancellor wrote:
> > On Tue, Mar 11, 2025 at 08:14:14PM +0800, kernel test robot wrote:
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/thomas.weissschuh/linux.git b4/module-hashes
> > > head:   8ab7849599f74e8492224b62d852cd9affecea7c
> > > commit: 8ab7849599f74e8492224b62d852cd9affecea7c [9/9] module: Introduce hash-based integrity checking
> > > config: x86_64-randconfig-005-20250311 (https://download.01.org/0day-ci/archive/20250311/202503112010.RsM1bgi6-lkp@intel.com/config)
> > > compiler: clang version 19.1.7 (https://github.com/llvm/llvm-project cd708029e0b2869e80abe31ddb175f7c35361f90)
> > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250311/202503112010.RsM1bgi6-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/202503112010.RsM1bgi6-lkp@intel.com/
> > > 
> > > All errors (new ones prefixed by >>):
> > > 
> > > >> llvm-objcopy: error: '.tmp_module_hashes.o': The file was not recognized as a valid object file
> > 
> > I suspect this happens because LTO is enabled for this configuration (so
> > -flto will be in KBUILD_CFLAGS), which generates an LLVM bitcode object
> > file instead of an ELF one.
> 
> Thanks for the hint!
> 
> The following diff seems to fix the issue and quick testing indicates
> that it should work with the different supported compilers.
> Any objections?

Nope, I think that should work fine.

> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 2add7eb950a0..f8d87a2ae74b 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -324,7 +324,7 @@ if is_enabled CONFIG_MODULE_HASHES; then
>         ${srctree}/scripts/module-hashes.sh > .tmp_module_hashes.c
>         info CC ${module_hashes_o}
>         ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} ${KBUILD_CFLAGS} \
> -               ${KBUILD_CFLAGS_KERNEL} -c -o "${module_hashes_o}" ".tmp_module_hashes.c"
> +               ${KBUILD_CFLAGS_KERNEL} -fno-lto -c -o "${module_hashes_o}" ".tmp_module_hashes.c"
>         ${OBJCOPY} --dump-section .module_hashes=.tmp_module_hashes.bin ${module_hashes_o}
>         ${OBJCOPY} --update-section .module_hashes=.tmp_module_hashes.bin vmlinux
>  fi