Re: [PATCH v3 1/7] tools build: Add feature check for elfutils libasm

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] ASMLIBS is missing the -ldl dependency for static builds.
- [Medium] Passing NULL to an integer/boolean argument in disasm_begin triggers implicit pointer-to-integer conversion errors.
--

commit 9ca40464008d6c950047c60bdb1b0966c47a038d
Author: Ian Rogers <irogers@google.com>

tools build: Add feature check for elfutils libasm

This commit introduces a build-time feature test for the elfutils libasm
library in the shared tools/build system. It adds the test program and
updates the Makefiles to attempt building it to detect support.

> diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
> index 62909a9c799d3..f0f39a2ab2035 100644
> --- a/tools/build/feature/Makefile
> +++ b/tools/build/feature/Makefile

[ ... ]

> @@ -184,6 +185,11 @@ ifeq ($(findstring -static,${LDFLAGS}),-static)
>    DWARFLIBS += -ldl
>  endif
>  
> +ASMLIBS := -lasm -ldw -lelf
> +ifeq ($(findstring -static,${LDFLAGS}),-static)
> +  ASMLIBS += -lz -llzma -lbz2 -lzstd
> +endif

[Severity: Medium]
Will this fail to link during static builds?  Since libdw dynamically
loads backend modules via dlopen, it requires libdl.  DWARFLIBS above
correctly adds -ldl for static builds, but ASMLIBS omits it, which might
cause the feature test to fail and spuriously report libasm as unsupported.

> +
>  $(OUTPUT)test-libdw.bin:
>  	$(BUILD) $(DWLIBS)
>  

[ ... ]

> diff --git a/tools/build/feature/test-libasm.c b/tools/build/feature/test-libasm.c
> new file mode 100644
> index 0000000000000..928fc46ecc755
> --- /dev/null
> +++ b/tools/build/feature/test-libasm.c

[ ... ]

> @@ -0,0 +1,20 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <stddef.h>
> +#include <elfutils/libasm.h>
> +#include <gelf.h>
> +
> +struct ebl;
> +extern struct ebl *ebl_openbackend(Elf *elf);
> +extern void ebl_closebackend(struct ebl *ebl);
> +
> +int main(void)
> +{
> +	Elf *elf = elf_begin(0, ELF_C_READ, NULL);
> +	struct ebl *ebl = ebl_openbackend(elf);
> +	DisasmCtx_t *ctx = disasm_begin(ebl, elf, NULL);

[Severity: Medium]
Will this fail to build on modern compilers?  The third argument to
disasm_begin() is typically a boolean or integer type (like show_bytes or
fd), but NULL is passed here.  This causes a -Wint-conversion warning,
which compilers like GCC 14 elevate to a hard error by default.  This
could cause the feature test to unconditionally fail.

> +
> +	disasm_end(ctx);
> +	ebl_closebackend(ebl);
> +	elf_end(elf);
> +	return 0;
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260609182108.975586-1-irogers@google.com?part=1