Re: [PATCH v4 3/4] tools/build: Allow versioning LLVM readelf

[Ihor Solodrai <ihor.solodrai@linux.dev>]

On 7/15/26 7:53 AM, James Clark wrote:
> Documentation/kbuild/llvm.rst mentions that readelf is included in the
> LLVM toolchain, but it's not currently included in this block.
> 
> Add it so that LLVM=... options also apply to readelf. Users in tools/
> were Perf which was hardcoding it, and another was the BPF makefile.
> Both already include Makefile.include so convert them to use the new
> variables.
> 
> Where readelf wasn't doing anything arch specific, use HOSTREADELF
> because it's more likely to be installed.
> 
> Reviewed-by: Ian Rogers <irogers@google.com>
> Signed-off-by: James Clark <james.clark@linaro.org>
> ---
>  tools/lib/bpf/Makefile         | 8 ++++----
>  tools/perf/Makefile.perf       | 1 -
>  tools/scripts/Makefile.include | 4 ++++
>  3 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index eca584fb061e16013e76827e4203f6be0477a73e..269fe21fc8da73083367b3c122bdd2b718e12bc5 100644
> --- a/tools/lib/bpf/Makefile
> +++ b/tools/lib/bpf/Makefile
> @@ -115,12 +115,12 @@ PC_FILE		:= $(addprefix $(OUTPUT),$(PC_FILE))
>  
>  TAGS_PROG := $(if $(shell which etags 2>/dev/null),etags,ctags)
>  
> -GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \
> +GLOBAL_SYM_COUNT = $(shell $(HOSTREADELF) -s --wide $(BPF_IN_SHARED) | \
>  			   cut -d "@" -f1 | sed 's/_v[0-9]_[0-9]_[0-9].*//' | \
>  			   sed 's/\[.*\]//' | \
>  			   awk '/GLOBAL/ && /DEFAULT/ && !/UND|ABS/ {print $$NF}' | \
>  			   sort -u | wc -l)
> -VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
> +VERSIONED_SYM_COUNT = $(shell $(HOSTREADELF) --dyn-syms --wide $(OUTPUT)libbpf.so | \
>  			      sed 's/\[.*\]//' | \
>  			      awk '/GLOBAL/ && /DEFAULT/ && !/UND|ABS/ {print $$NF}' | \
>  			      grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
> @@ -183,12 +183,12 @@ check_abi: $(OUTPUT)libbpf.so $(VERSION_SCRIPT)
>  		     "versioned symbols in $^ ($(VERSIONED_SYM_COUNT))." \
>  		     "Please make sure all LIBBPF_API symbols are"	 \
>  		     "versioned in $(VERSION_SCRIPT)." >&2;		 \
> -		readelf -s --wide $(BPF_IN_SHARED) |			 \
> +		$(HOSTREADELF) -s --wide $(BPF_IN_SHARED) |		 \
>  		    cut -d "@" -f1 | sed 's/_v[0-9]_[0-9]_[0-9].*//' |	 \
>  		    sed 's/\[.*\]//' |					 \
>  		    awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'|  \
>  		    sort -u > $(OUTPUT)libbpf_global_syms.tmp;		 \
> -		readelf --dyn-syms --wide $(OUTPUT)libbpf.so |		 \
> +		$(HOSTREADELF) --dyn-syms --wide $(OUTPUT)libbpf.so |	 \

Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>

Thanks!

>  		    sed 's/\[.*\]//' |					 \
>  		    awk '/GLOBAL/ && /DEFAULT/ && !/UND|ABS/ {print $$NF}'|  \
>  		    grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 |		 \
> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf> index 476b8dcaef58cb1f3fa75f46a647c2cfe2352767..4d0d7ae02e06b117487a17691c4e62a138428ac5 100644
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -215,7 +215,6 @@ FLEX    ?= flex
>  BISON   ?= bison
>  STRIP   = strip
>  AWK     = awk
> -READELF ?= readelf
>  
>  # include Makefile.config by default and rule out
>  # non-config cases
> diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
> index e81e5b479c563321e458b2a7ad8fca2b4607a254..46a3872b87624a7bf475d9b42a3e471f36789dfd 100644
> --- a/tools/scripts/Makefile.include
> +++ b/tools/scripts/Makefile.include
> @@ -73,6 +73,8 @@ ifneq ($(LLVM),)
>    $(call allow-override,LLC,$(LLVM_PREFIX)llc$(LLVM_SUFFIX))
>    $(call allow-override,LLVM_CONFIG,$(LLVM_PREFIX)llvm-config$(LLVM_SUFFIX))
>    $(call allow-override,LLVM_OBJCOPY,$(LLVM_PREFIX)llvm-objcopy$(LLVM_SUFFIX))
> +  $(call allow-override,READELF,$(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX))
> +  $(call allow-override,HOSTREADELF,$(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX))
>  else
>    # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
>    $(call allow-override,CC,$(CROSS_COMPILE)gcc)
> @@ -80,11 +82,13 @@ else
>    $(call allow-override,LD,$(CROSS_COMPILE)ld)
>    $(call allow-override,CXX,$(CROSS_COMPILE)g++)
>    $(call allow-override,STRIP,$(CROSS_COMPILE)strip)
> +  $(call allow-override,READELF,$(CROSS_COMPILE)readelf)
>  
>    # Host versions aren't prefixed
>    $(call allow-override,HOSTAR,ar)
>    $(call allow-override,HOSTCC,gcc)
>    $(call allow-override,HOSTLD,ld)
> +  $(call allow-override,HOSTREADELF,readelf)
>  
>    # Some tools still require Clang, LLC and/or LLVM utils
>    $(call allow-override,CLANG,clang)
>