[PATCH v2] kbuild: userprogs: use correct linker when mixing clang and GNU ld

[PATCH v2] kbuild: userprogs: use correct linker when mixing clang and GNU ld

[Thomas Weißschuh]

The userprogs infrastructure does not expect clang being used with GNU ld
and in that case uses /usr/bin/ld for linking, not the configured $(LD).
This fallback is problematic as it will break when cross-compiling.
Mixing clang and GNU ld is used for example when building for SPARC64,
as ld.lld is not sufficient; see Documentation/kbuild/llvm.rst.

Relax the check around --ld-path so it gets used for all linkers.

Fixes: dfc1b168a8c4 ("kbuild: userprogs: use correct lld when linking through clang")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
---
Changes in v2:
- Use plain ifdef instead of ifneq
- Rebase onto v6.16
- Pick up review tag from Nathan
- Link to v1: https://lore.kernel.org/r/20250724-userprogs-clang-gnu-ld-v1-1-3d3d071e53a7@linutronix.de
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 478f2004602da03c9039044e3288f24a13833cc7..7d24245d118c0e903119263b871d2e5c2759f48a 100644
--- a/Makefile
+++ b/Makefile
@@ -1134,7 +1134,7 @@ KBUILD_USERCFLAGS  += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD
 KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
 
 # userspace programs are linked via the compiler, use the correct linker
-ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_LD_IS_LLD),yy)
+ifdef CONFIG_CC_IS_CLANG
 KBUILD_USERLDFLAGS += --ld-path=$(LD)
 endif
 

---
base-commit: 038d61fd642278bab63ee8ef722c50d10ab01e8f
change-id: 20250723-userprogs-clang-gnu-ld-7a1c16fc852d

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@linutronix.de>

Re: [PATCH v2] kbuild: userprogs: use correct linker when mixing clang and GNU ld

[Masahiro Yamada]

On Mon, Jul 28, 2025 at 10:50 PM Thomas Weißschuh
<thomas.weissschuh@linutronix.de> wrote:
>
> The userprogs infrastructure does not expect clang being used with GNU ld
> and in that case uses /usr/bin/ld for linking, not the configured $(LD).
> This fallback is problematic as it will break when cross-compiling.
> Mixing clang and GNU ld is used for example when building for SPARC64,
> as ld.lld is not sufficient; see Documentation/kbuild/llvm.rst.
>
> Relax the check around --ld-path so it gets used for all linkers.
>
> Fixes: dfc1b168a8c4 ("kbuild: userprogs: use correct lld when linking through clang")
> Cc: stable@vger.kernel.org
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> ---

Applied to linux-kbuild.
Thanks.


> Changes in v2:
> - Use plain ifdef instead of ifneq
> - Rebase onto v6.16
> - Pick up review tag from Nathan
> - Link to v1: https://lore.kernel.org/r/20250724-userprogs-clang-gnu-ld-v1-1-3d3d071e53a7@linutronix.de
> ---
>  Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index 478f2004602da03c9039044e3288f24a13833cc7..7d24245d118c0e903119263b871d2e5c2759f48a 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1134,7 +1134,7 @@ KBUILD_USERCFLAGS  += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD
>  KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
>
>  # userspace programs are linked via the compiler, use the correct linker
> -ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_LD_IS_LLD),yy)
> +ifdef CONFIG_CC_IS_CLANG
>  KBUILD_USERLDFLAGS += --ld-path=$(LD)
>  endif
>
>
> ---
> base-commit: 038d61fd642278bab63ee8ef722c50d10ab01e8f
> change-id: 20250723-userprogs-clang-gnu-ld-7a1c16fc852d
>
> Best regards,
> --
> Thomas Weißschuh <thomas.weissschuh@linutronix.de>
>


-- 
Best Regards
Masahiro Yamada