[PATCH v2 0/6] tools/build: Allow versioning of all LLVM tools

[PATCH v2 0/6] tools/build: Allow versioning of all LLVM tools

[James Clark]

I ran into the build issue mentioned in the first commit, because using
an option like LLVM=-15 is a documented way to build [1], but only
some of the LLVM tools defined in tools/ support this.

After fixing that, a lot of other tidyups fell out. I didn't go too far,
for example some selftests include tools/testing/selftests/lib.mk which
reimplements some of the LLVM_SUFFIX stuff, but other selftests include
tools/scripts/Makefile.include and I stopped before touching the former.
Some other non build scripts hard code toolchains and I didn't touch
those either, this change is only focused on things that already
include Makefile.include.

[1]: Documentation/kbuild/llvm.rst

Signed-off-by: James Clark <james.clark@linaro.org>
---
Changes in v2:
- Fix selftests/bpf build. LLD needs to take the full path to be used
  with -fuse-ld=
- Link to v1: https://lore.kernel.org/r/20260514-james-perf-llvm-version-v1-0-6cac1a9a4c8d@linaro.org

---
James Clark (6):
      tools/build: Allow versioning of all LLVM tools defined in Makefile.include
      tools/build: Indent if else blocks
      selftests: Remove unused LLD variable
      tools/build: Allow versioning LLVM readelf
      tools/build: selftests: Allow versioning LLVM lld
      tools/build: selftests: Remove some duplicate toolchain definitions

 tools/bpf/resolve_btfids/Makefile    |  3 --
 tools/lib/api/Makefile               |  4 --
 tools/lib/bpf/Makefile               |  8 ++--
 tools/lib/subcmd/Makefile            |  4 --
 tools/lib/symbol/Makefile            |  4 --
 tools/perf/Makefile.perf             |  7 ----
 tools/scripts/Makefile.include       | 77 ++++++++++++++++++++----------------
 tools/testing/selftests/bpf/Makefile |  9 ++---
 tools/testing/selftests/hid/Makefile |  7 ----
 9 files changed, 50 insertions(+), 73 deletions(-)
---
base-commit: 09d355618f7ccc27ffc7fc668b2e232872962079
change-id: 20260511-james-perf-llvm-version-43ab1cb5bc7d

Best regards,
-- 
James Clark <james.clark@linaro.org>

[PATCH v2 1/6] tools/build: Allow versioning of all LLVM tools defined in Makefile.include

[James Clark]

The version of LLVM tools can be given on the build command with
LLVM=-15, but this isn't applied to all tools. For example $(CC) gets
versioned, but $(CLANG) doesn't. This causes a Perf build with LTO=1 to
fail with an error about mixed clang versions:

 ld.lld: error: libperf/core.o: Unknown attribute kind (86)
   (Producer: 'LLVM18.1.8' Reader: 'LLVM 15.0.7')

This file has two "ifneq ($(LLVM),)" blocks adjacent to each other, so
merge these blocks making it obvious that all tools should be versioned
consistently and there is nothing special about each block.

This also reveals that ?= and "allow-override" are used inconsistently
between the blocks. "allow-override" is technically only required for
builtin variables, but isn't only used on them, and doesn't do any harm
if used on a non-builtin. Make them all "allow-override" for
consistency. The only functional difference this will cause is if there
is a file level definition of one of the variables followed by an
"#include of Makefile.include" which will now overwrite. But this isn't
done and in a later commit some of the duplicate definitions will be
removed for good measure.

There are also some other LLVM tools that are not defined here and will
be moved in a later commit.

Signed-off-by: James Clark <james.clark@linaro.org>
---
 tools/scripts/Makefile.include | 37 ++++++++++++++++++++-----------------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
index 41971a68972d..7022e78208a2 100644
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -61,10 +61,18 @@ $(error Invalid value for LLVM, see Documentation/kbuild/llvm.rst)
 endif
 
 $(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
+$(call allow-override,CLANG,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
+$(call allow-override,HOSTCC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
 $(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
+$(call allow-override,HOSTAR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
 $(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
+$(call allow-override,HOSTLD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
 $(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX))
 $(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
+$(call allow-override,LLVM_STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
+$(call allow-override,LLC,$(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))
 else
 # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
 $(call allow-override,CC,$(CROSS_COMPILE)gcc)
@@ -72,26 +80,21 @@ $(call allow-override,AR,$(CROSS_COMPILE)ar)
 $(call allow-override,LD,$(CROSS_COMPILE)ld)
 $(call allow-override,CXX,$(CROSS_COMPILE)g++)
 $(call allow-override,STRIP,$(CROSS_COMPILE)strip)
-endif
-
-CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
 
-ifneq ($(LLVM),)
-HOSTAR  ?= $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)
-HOSTCC  ?= $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
-HOSTLD  ?= $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)
-else
-HOSTAR  ?= ar
-HOSTCC  ?= gcc
-HOSTLD  ?= ld
+# Host versions aren't prefixed
+$(call allow-override,HOSTAR,ar)
+$(call allow-override,HOSTCC,gcc)
+$(call allow-override,HOSTLD,ld)
+
+# Some tools still require Clang, LLC and/or LLVM utils
+$(call allow-override,CLANG,clang)
+$(call allow-override,LLC,llc)
+$(call allow-override,LLVM_CONFIG,llvm-config)
+$(call allow-override,LLVM_OBJCOPY,llvm-objcopy)
+$(call allow-override,LLVM_STRIP,llvm-strip)
 endif
 
-# Some tools require Clang, LLC and/or LLVM utils
-CLANG		?= clang
-LLC		?= llc
-LLVM_CONFIG	?= llvm-config
-LLVM_OBJCOPY	?= llvm-objcopy
-LLVM_STRIP	?= llvm-strip
+CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
 
 # Some tools require bpftool
 SYSTEM_BPFTOOL	?= bpftool

-- 
2.34.1

[PATCH v2 2/6] tools/build: Indent if else blocks

[James Clark]

These blocks are quite big and unreadable without indentation. Indent
them.

No functional changes intended.

Signed-off-by: James Clark <james.clark@linaro.org>
---
 tools/scripts/Makefile.include | 76 +++++++++++++++++++++---------------------
 1 file changed, 38 insertions(+), 38 deletions(-)

diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
index 7022e78208a2..e81e5b479c56 100644
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -52,46 +52,46 @@ define allow-override
 endef
 
 ifneq ($(LLVM),)
-ifneq ($(filter %/,$(LLVM)),)
-LLVM_PREFIX := $(LLVM)
-else ifneq ($(filter -%,$(LLVM)),)
-LLVM_SUFFIX := $(LLVM)
-else ifneq ($(LLVM),1)
-$(error Invalid value for LLVM, see Documentation/kbuild/llvm.rst)
-endif
+  ifneq ($(filter %/,$(LLVM)),)
+    LLVM_PREFIX := $(LLVM)
+  else ifneq ($(filter -%,$(LLVM)),)
+    LLVM_SUFFIX := $(LLVM)
+  else ifneq ($(LLVM),1)
+    $(error Invalid value for LLVM, see Documentation/kbuild/llvm.rst)
+  endif
 
-$(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
-$(call allow-override,CLANG,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
-$(call allow-override,HOSTCC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
-$(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
-$(call allow-override,HOSTAR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
-$(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
-$(call allow-override,HOSTLD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
-$(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX))
-$(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
-$(call allow-override,LLVM_STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
-$(call allow-override,LLC,$(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))
+  $(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
+  $(call allow-override,CLANG,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
+  $(call allow-override,HOSTCC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
+  $(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
+  $(call allow-override,HOSTAR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
+  $(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
+  $(call allow-override,HOSTLD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
+  $(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX))
+  $(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
+  $(call allow-override,LLVM_STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
+  $(call allow-override,LLC,$(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$(LLVM_SUFFIX))
 else
-# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
-$(call allow-override,CC,$(CROSS_COMPILE)gcc)
-$(call allow-override,AR,$(CROSS_COMPILE)ar)
-$(call allow-override,LD,$(CROSS_COMPILE)ld)
-$(call allow-override,CXX,$(CROSS_COMPILE)g++)
-$(call allow-override,STRIP,$(CROSS_COMPILE)strip)
-
-# Host versions aren't prefixed
-$(call allow-override,HOSTAR,ar)
-$(call allow-override,HOSTCC,gcc)
-$(call allow-override,HOSTLD,ld)
-
-# Some tools still require Clang, LLC and/or LLVM utils
-$(call allow-override,CLANG,clang)
-$(call allow-override,LLC,llc)
-$(call allow-override,LLVM_CONFIG,llvm-config)
-$(call allow-override,LLVM_OBJCOPY,llvm-objcopy)
-$(call allow-override,LLVM_STRIP,llvm-strip)
+  # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
+  $(call allow-override,CC,$(CROSS_COMPILE)gcc)
+  $(call allow-override,AR,$(CROSS_COMPILE)ar)
+  $(call allow-override,LD,$(CROSS_COMPILE)ld)
+  $(call allow-override,CXX,$(CROSS_COMPILE)g++)
+  $(call allow-override,STRIP,$(CROSS_COMPILE)strip)
+
+  # Host versions aren't prefixed
+  $(call allow-override,HOSTAR,ar)
+  $(call allow-override,HOSTCC,gcc)
+  $(call allow-override,HOSTLD,ld)
+
+  # Some tools still require Clang, LLC and/or LLVM utils
+  $(call allow-override,CLANG,clang)
+  $(call allow-override,LLC,llc)
+  $(call allow-override,LLVM_CONFIG,llvm-config)
+  $(call allow-override,LLVM_OBJCOPY,llvm-objcopy)
+  $(call allow-override,LLVM_STRIP,llvm-strip)
 endif
 
 CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)

-- 
2.34.1

[PATCH v2 3/6] selftests: Remove unused LLD variable

[James Clark]

This file was mostly copied from selftests/bpf/Makefile, but the LLD
variable is not used here. Also, this copied block didn't get the same
fixes as the original one did later.

Remove it to avoid confusion and so future fixes don't have to be in two
places.

Signed-off-by: James Clark <james.clark@linaro.org>
---
 tools/testing/selftests/hid/Makefile | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/tools/testing/selftests/hid/Makefile b/tools/testing/selftests/hid/Makefile
index 50ec9e0406ab..96071b4800e8 100644
--- a/tools/testing/selftests/hid/Makefile
+++ b/tools/testing/selftests/hid/Makefile
@@ -105,13 +105,6 @@ $(MAKE_DIRS):
 	$(call msg,MKDIR,,$@)
 	$(Q)mkdir -p $@
 
-# LLVM's ld.lld doesn't support all the architectures, so use it only on x86
-ifeq ($(SRCARCH),x86)
-LLD := lld
-else
-LLD := ld
-endif
-
 DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool
 
 TEST_GEN_PROGS_EXTENDED += $(DEFAULT_BPFTOOL)

-- 
2.34.1

Re: [PATCH v2 3/6] selftests: Remove unused LLD variable

[Benjamin Tissoires]

On May 18 2026, James Clark wrote:
> This file was mostly copied from selftests/bpf/Makefile, but the LLD
> variable is not used here. Also, this copied block didn't get the same
> fixes as the original one did later.
> 
> Remove it to avoid confusion and so future fixes don't have to be in two
> places.
> 
> Signed-off-by: James Clark <james.clark@linaro.org>
> ---

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/hid/hid.git (for-7.2/bpf), thanks!

[3/6] selftests: Remove unused LLD variable
      https://git.kernel.org/hid/hid/c/08918b98b02b

Cheers,
Benjamin


>  tools/testing/selftests/hid/Makefile | 7 -------
>  1 file changed, 7 deletions(-)
> 
> diff --git a/tools/testing/selftests/hid/Makefile b/tools/testing/selftests/hid/Makefile
> index 50ec9e0406ab..96071b4800e8 100644
> --- a/tools/testing/selftests/hid/Makefile
> +++ b/tools/testing/selftests/hid/Makefile
> @@ -105,13 +105,6 @@ $(MAKE_DIRS):
>  	$(call msg,MKDIR,,$@)
>  	$(Q)mkdir -p $@
>  
> -# LLVM's ld.lld doesn't support all the architectures, so use it only on x86
> -ifeq ($(SRCARCH),x86)
> -LLD := lld
> -else
> -LLD := ld
> -endif
> -
>  DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool
>  
>  TEST_GEN_PROGS_EXTENDED += $(DEFAULT_BPFTOOL)
> 
> -- 
> 2.34.1
> 

[PATCH v2 4/6] tools/build: Allow versioning LLVM readelf

[James Clark]

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
variable.

It also didn't have the cross compile prefix, so either readelf didn't
mind opening cross binaries, or it wasn't working for cross builds.

Signed-off-by: James Clark <james.clark@linaro.org>
---
 tools/lib/bpf/Makefile         | 8 ++++----
 tools/perf/Makefile.perf       | 1 -
 tools/scripts/Makefile.include | 2 ++
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 168140f8e646..180dca9c57c8 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -114,12 +114,12 @@ 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 $(READELF) -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 $(READELF) --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)
@@ -182,12 +182,12 @@ 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) |			 \
+		$(READELF) -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 |		 \
+		$(READELF) --dyn-syms --wide $(OUTPUT)libbpf.so |		 \
 		    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 0aba14f22a06..63276bf55856 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 e81e5b479c56..380ad84ac51e 100644
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -73,6 +73,7 @@ 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))
 else
   # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
   $(call allow-override,CC,$(CROSS_COMPILE)gcc)
@@ -80,6 +81,7 @@ 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)

-- 
2.34.1

Re: [PATCH v2 4/6] tools/build: Allow versioning LLVM readelf

[Ian Rogers]

On Mon, May 18, 2026 at 2:04 AM James Clark <james.clark@linaro.org> 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
> variable.
>
> It also didn't have the cross compile prefix, so either readelf didn't
> mind opening cross binaries, or it wasn't working for cross builds.
>
> Signed-off-by: James Clark <james.clark@linaro.org>

For the tools/perf/Makefile.perf part of this change.

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks for the cleanup!
Ian

> ---
>  tools/lib/bpf/Makefile         | 8 ++++----
>  tools/perf/Makefile.perf       | 1 -
>  tools/scripts/Makefile.include | 2 ++
>  3 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index 168140f8e646..180dca9c57c8 100644
> --- a/tools/lib/bpf/Makefile
> +++ b/tools/lib/bpf/Makefile
> @@ -114,12 +114,12 @@ 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 $(READELF) -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 $(READELF) --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)
> @@ -182,12 +182,12 @@ 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) |                     \
> +               $(READELF) -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 |           \
> +               $(READELF) --dyn-syms --wide $(OUTPUT)libbpf.so |                \
>                     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 0aba14f22a06..63276bf55856 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 e81e5b479c56..380ad84ac51e 100644
> --- a/tools/scripts/Makefile.include
> +++ b/tools/scripts/Makefile.include
> @@ -73,6 +73,7 @@ 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))
>  else
>    # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
>    $(call allow-override,CC,$(CROSS_COMPILE)gcc)
> @@ -80,6 +81,7 @@ 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)
>
> --
> 2.34.1
>

[PATCH v2 5/6] tools/build: selftests: Allow versioning LLVM lld

[James Clark]

Building with LLVM=... could result in a different version of lld being
used than the main toolchain for liburandom_read.so because it's
hardcoded to "lld" in this makefile.

Make it consistent with the rest of the LLVM toolchain by adding an LLD
variable to Makefile.include. Keep the fallback for other architectures
in tools/testing/selftests/bpf/Makefile as it seems like it's something
specific to this make rule and shouldn't be global.

Clang only accepts either a full path to "/x/x/ld.lld" or "lld-15" style
inputs to "-fuse-ld=", so the only way to make it work with both
prefixed and postfixed paths is to always take the full path. Also I
don't think the original use of "lld" over "ld.lld" was significant as
this is always a linux build, so that can be changed to make it work in
both cases.

Signed-off-by: James Clark <james.clark@linaro.org>
---
 tools/scripts/Makefile.include       | 2 ++
 tools/testing/selftests/bpf/Makefile | 8 ++++----
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
index 380ad84ac51e..5c2d505cba62 100644
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -67,6 +67,7 @@ ifneq ($(LLVM),)
   $(call allow-override,HOSTAR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
   $(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
   $(call allow-override,HOSTLD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
+  $(call allow-override,LLD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
   $(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX))
   $(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
   $(call allow-override,LLVM_STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
@@ -91,6 +92,7 @@ else
   # Some tools still require Clang, LLC and/or LLVM utils
   $(call allow-override,CLANG,clang)
   $(call allow-override,LLC,llc)
+  $(call allow-override,LLD,ld.lld)
   $(call allow-override,LLVM_CONFIG,llvm-config)
   $(call allow-override,LLVM_OBJCOPY,llvm-objcopy)
   $(call allow-override,LLVM_STRIP,llvm-strip)
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 6ef6872adbc3..836e783f0170 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -245,9 +245,9 @@ $(OUTPUT)/%:%.c
 
 # LLVM's ld.lld doesn't support all the architectures, so use it only on x86
 ifeq ($(SRCARCH),$(filter $(SRCARCH),x86 riscv))
-LLD := lld
+USE_LD := $(shell command -v $(LLD))
 else
-LLD := $(shell command -v $(LD))
+USE_LD := $(shell command -v $(LD))
 endif
 
 # Filter out -static for liburandom_read.so and its dependent targets so that static builds
@@ -258,7 +258,7 @@ $(OUTPUT)/liburandom_read.so: urandom_read_lib1.c urandom_read_lib2.c liburandom
 		     $(filter-out -static,$(CFLAGS) $(LDFLAGS)) \
 		     $(filter %.c,$^) $(filter-out -static,$(LDLIBS)) \
 		     -Wno-unused-command-line-argument \
-		     -fuse-ld=$(LLD) -Wl,-znoseparate-code -Wl,--build-id=sha1 \
+		     -fuse-ld=$(USE_LD) -Wl,-znoseparate-code -Wl,--build-id=sha1 \
 		     -Wl,--version-script=liburandom_read.map \
 		     -fPIC -shared -o $@
 
@@ -268,7 +268,7 @@ $(OUTPUT)/urandom_read: urandom_read.c urandom_read_aux.c $(OUTPUT)/liburandom_r
 		     $(filter-out -static,$(CFLAGS) $(LDFLAGS)) $(filter %.c,$^) \
 		     -Wno-unused-command-line-argument \
 		     -lurandom_read $(filter-out -static,$(LDLIBS)) -L$(OUTPUT) \
-		     -fuse-ld=$(LLD) -Wl,-znoseparate-code -Wl,--build-id=sha1 \
+		     -fuse-ld=$(USE_LD) -Wl,-znoseparate-code -Wl,--build-id=sha1 \
 		     -Wl,-rpath=. -o $@
 
 $(OUTPUT)/sign-file: ../../../../scripts/sign-file.c

-- 
2.34.1

Re: [PATCH v2 5/6] tools/build: selftests: Allow versioning LLVM lld

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Empty USE_LD variable causes clang build failure in selftests when ld.lld is not in PATH.
--

commit 371ca22c55bb0fa6502ac06f7b33d63418ad16ff
Author: James Clark <james.clark@linaro.org>

tools/build: selftests: Allow versioning LLVM lld

This commit adds an LLD variable to Makefile.include to allow versioning of
LLVM's linker, keeping it consistent with the rest of the LLVM toolchain. It
modifies the BPF selftests Makefile to resolve the full path of the linker
using the command -v shell utility.

> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index 6ef6872adbc3e..836e783f0170e 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile

[ ... ]

> @@ -245,9 +245,9 @@ $(OUTPUT)/%:%.c
>  
>  # LLVM's ld.lld doesn't support all the architectures, so use it only on x86
>  ifeq ($(SRCARCH),$(filter $(SRCARCH),x86 riscv))
> -LLD := lld
> +USE_LD := $(shell command -v $(LLD))

Does this cause the build to fail if the toolchain directory is not in the
system PATH?

If a user explicitly specifies the compiler using an absolute path like
CLANG=/path/to/clang, but does not add the toolchain directory to their PATH,
the command -v utility will return an empty string.

This would cause USE_LD to be empty, leading to a malformed argument like
-fuse-ld= being passed to clang later in the Makefile, which then fails with
an invalid linker name error.

Previously, passing the hardcoded lld allowed clang to natively resolve the
linker relative to its own binary location. Is there a way to support both
versioned linker names and absolute compiler paths without relying entirely
on the system PATH?

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260518-james-perf-llvm-version-v2-0-f12cc4f031d8@linaro.org?part=5

Re: [PATCH v2 5/6] tools/build: selftests: Allow versioning LLVM lld

[James Clark]

On 18/05/2026 10:32 am, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] Empty USE_LD variable causes clang build failure in selftests when ld.lld is not in PATH.
> --
> 
> commit 371ca22c55bb0fa6502ac06f7b33d63418ad16ff
> Author: James Clark <james.clark@linaro.org>
> 
> tools/build: selftests: Allow versioning LLVM lld
> 
> This commit adds an LLD variable to Makefile.include to allow versioning of
> LLVM's linker, keeping it consistent with the rest of the LLVM toolchain. It
> modifies the BPF selftests Makefile to resolve the full path of the linker
> using the command -v shell utility.
> 
>> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
>> index 6ef6872adbc3e..836e783f0170e 100644
>> --- a/tools/testing/selftests/bpf/Makefile
>> +++ b/tools/testing/selftests/bpf/Makefile
> 
> [ ... ]
> 
>> @@ -245,9 +245,9 @@ $(OUTPUT)/%:%.c
>>   
>>   # LLVM's ld.lld doesn't support all the architectures, so use it only on x86
>>   ifeq ($(SRCARCH),$(filter $(SRCARCH),x86 riscv))
>> -LLD := lld
>> +USE_LD := $(shell command -v $(LLD))
> 
> Does this cause the build to fail if the toolchain directory is not in the
> system PATH?
> 
> If a user explicitly specifies the compiler using an absolute path like
> CLANG=/path/to/clang, but does not add the toolchain directory to their PATH,
> the command -v utility will return an empty string.

If they don't use LLVM= and use CLANG= with an absolute path then they 
need to set all the tools with an absolute path. That's the problem that 
setting the path with a prefix for all tools with LLVM= solved.

I suppose this could _technically_ be a regression, but so could adding 
any new build rule that added a new tool that wouldn't be set in 
someones existing build command. Being that strict would mean we can't 
ever add new tools so I don't think this is an issue. And I don't think 
there's a way to solve this and also respect the documented rules of LLVM=

> 
> This would cause USE_LD to be empty, leading to a malformed argument like
> -fuse-ld= being passed to clang later in the Makefile, which then fails with
> an invalid linker name error.
> 
> Previously, passing the hardcoded lld allowed clang to natively resolve the
> linker relative to its own binary location. Is there a way to support both
> versioned linker names and absolute compiler paths without relying entirely
> on the system PATH?
> 
> [ ... ]
> 

Re: [PATCH v2 5/6] tools/build: selftests: Allow versioning LLVM lld

[Arnaldo Carvalho de Melo]

On Mon, May 18, 2026 at 10:47:53AM +0100, James Clark wrote:
> 
> 
> On 18/05/2026 10:32 am, sashiko-bot@kernel.org wrote:
> > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> > - [Medium] Empty USE_LD variable causes clang build failure in selftests when ld.lld is not in PATH.
> > --
> > 
> > commit 371ca22c55bb0fa6502ac06f7b33d63418ad16ff
> > Author: James Clark <james.clark@linaro.org>
> > 
> > tools/build: selftests: Allow versioning LLVM lld
> > 
> > This commit adds an LLD variable to Makefile.include to allow versioning of
> > LLVM's linker, keeping it consistent with the rest of the LLVM toolchain. It
> > modifies the BPF selftests Makefile to resolve the full path of the linker
> > using the command -v shell utility.
> > 
> > > diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> > > index 6ef6872adbc3e..836e783f0170e 100644
> > > --- a/tools/testing/selftests/bpf/Makefile
> > > +++ b/tools/testing/selftests/bpf/Makefile
> > 
> > [ ... ]
> > 
> > > @@ -245,9 +245,9 @@ $(OUTPUT)/%:%.c
> > >   # LLVM's ld.lld doesn't support all the architectures, so use it only on x86
> > >   ifeq ($(SRCARCH),$(filter $(SRCARCH),x86 riscv))
> > > -LLD := lld
> > > +USE_LD := $(shell command -v $(LLD))
> > 
> > Does this cause the build to fail if the toolchain directory is not in the
> > system PATH?
> > 
> > If a user explicitly specifies the compiler using an absolute path like
> > CLANG=/path/to/clang, but does not add the toolchain directory to their PATH,
> > the command -v utility will return an empty string.
> 
> If they don't use LLVM= and use CLANG= with an absolute path then they need
> to set all the tools with an absolute path. That's the problem that setting
> the path with a prefix for all tools with LLVM= solved.
> 
> I suppose this could _technically_ be a regression, but so could adding any
> new build rule that added a new tool that wouldn't be set in someones
> existing build command. Being that strict would mean we can't ever add new
> tools so I don't think this is an issue. And I don't think there's a way to
> solve this and also respect the documented rules of LLVM=

Hey, this touches several tools and libs, did you get acks besides the
one from Ian?

- Arnaldo

Re: [PATCH v2 5/6] tools/build: selftests: Allow versioning LLVM lld

[James Clark]

On 20/05/2026 8:50 pm, Arnaldo Carvalho de Melo wrote:
> On Mon, May 18, 2026 at 10:47:53AM +0100, James Clark wrote:
>>
>>
>> On 18/05/2026 10:32 am, sashiko-bot@kernel.org wrote:
>>> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
>>> - [Medium] Empty USE_LD variable causes clang build failure in selftests when ld.lld is not in PATH.
>>> --
>>>
>>> commit 371ca22c55bb0fa6502ac06f7b33d63418ad16ff
>>> Author: James Clark <james.clark@linaro.org>
>>>
>>> tools/build: selftests: Allow versioning LLVM lld
>>>
>>> This commit adds an LLD variable to Makefile.include to allow versioning of
>>> LLVM's linker, keeping it consistent with the rest of the LLVM toolchain. It
>>> modifies the BPF selftests Makefile to resolve the full path of the linker
>>> using the command -v shell utility.
>>>
>>>> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
>>>> index 6ef6872adbc3e..836e783f0170e 100644
>>>> --- a/tools/testing/selftests/bpf/Makefile
>>>> +++ b/tools/testing/selftests/bpf/Makefile
>>>
>>> [ ... ]
>>>
>>>> @@ -245,9 +245,9 @@ $(OUTPUT)/%:%.c
>>>>    # LLVM's ld.lld doesn't support all the architectures, so use it only on x86
>>>>    ifeq ($(SRCARCH),$(filter $(SRCARCH),x86 riscv))
>>>> -LLD := lld
>>>> +USE_LD := $(shell command -v $(LLD))
>>>
>>> Does this cause the build to fail if the toolchain directory is not in the
>>> system PATH?
>>>
>>> If a user explicitly specifies the compiler using an absolute path like
>>> CLANG=/path/to/clang, but does not add the toolchain directory to their PATH,
>>> the command -v utility will return an empty string.
>>
>> If they don't use LLVM= and use CLANG= with an absolute path then they need
>> to set all the tools with an absolute path. That's the problem that setting
>> the path with a prefix for all tools with LLVM= solved.
>>
>> I suppose this could _technically_ be a regression, but so could adding any
>> new build rule that added a new tool that wouldn't be set in someones
>> existing build command. Being that strict would mean we can't ever add new
>> tools so I don't think this is an issue. And I don't think there's a way to
>> solve this and also respect the documented rules of LLVM=
> 
> Hey, this touches several tools and libs, did you get acks besides the
> one from Ian?
> 
> - Arnaldo

Only the build bpf failure report from Ihor on V1 but nothing from 
anyone on V2. Ihor did you get a chance to look at this version?

Thanks
James

[PATCH v2 6/6] tools/build: selftests: Remove some duplicate toolchain definitions

[James Clark]

Try to remove some, but not all duplicate toolchain definitions. In
these instances, their makefiles already include
tools/scripts/Makefile.include which defines these in a consistent way.

STRIP is the only one that was set with an '=', but I don't think it
was significant so that difference can be dropped.

Signed-off-by: James Clark <james.clark@linaro.org>
---
 tools/bpf/resolve_btfids/Makefile    | 3 ---
 tools/lib/api/Makefile               | 4 ----
 tools/lib/subcmd/Makefile            | 4 ----
 tools/lib/symbol/Makefile            | 4 ----
 tools/perf/Makefile.perf             | 6 ------
 tools/testing/selftests/bpf/Makefile | 1 -
 6 files changed, 22 deletions(-)

diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
index 7672208f65e4..6fdb6302e0a2 100644
--- a/tools/bpf/resolve_btfids/Makefile
+++ b/tools/bpf/resolve_btfids/Makefile
@@ -20,9 +20,6 @@ HOST_OVERRIDES := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH)
 		  CROSS_COMPILE="" CLANG_CROSS_FLAGS="" EXTRA_CFLAGS="$(HOSTCFLAGS)"
 
 RM      ?= rm
-HOSTCC  ?= gcc
-HOSTLD  ?= ld
-HOSTAR  ?= ar
 HOSTPKG_CONFIG ?= pkg-config
 CROSS_COMPILE =
 
diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile
index 8665c799e0fa..a228fdb5adba 100644
--- a/tools/lib/api/Makefile
+++ b/tools/lib/api/Makefile
@@ -9,10 +9,6 @@ srctree := $(patsubst %/,%,$(dir $(srctree)))
 #$(info Determined 'srctree' to be $(srctree))
 endif
 
-CC ?= $(CROSS_COMPILE)gcc
-AR ?= $(CROSS_COMPILE)ar
-LD ?= $(CROSS_COMPILE)ld
-
 MAKEFLAGS += --no-print-directory
 
 INSTALL = install
diff --git a/tools/lib/subcmd/Makefile b/tools/lib/subcmd/Makefile
index 8703ab487b68..9f1ddcf0504d 100644
--- a/tools/lib/subcmd/Makefile
+++ b/tools/lib/subcmd/Makefile
@@ -9,10 +9,6 @@ srctree := $(patsubst %/,%,$(dir $(srctree)))
 #$(info Determined 'srctree' to be $(srctree))
 endif
 
-CC ?= $(CROSS_COMPILE)gcc
-LD ?= $(CROSS_COMPILE)ld
-AR ?= $(CROSS_COMPILE)ar
-
 RM = rm -f
 
 MAKEFLAGS += --no-print-directory
diff --git a/tools/lib/symbol/Makefile b/tools/lib/symbol/Makefile
index 426b845edfac..d692abe8add6 100644
--- a/tools/lib/symbol/Makefile
+++ b/tools/lib/symbol/Makefile
@@ -9,10 +9,6 @@ srctree := $(patsubst %/,%,$(dir $(srctree)))
 #$(info Determined 'srctree' to be $(srctree))
 endif
 
-CC ?= $(CROSS_COMPILE)gcc
-AR ?= $(CROSS_COMPILE)ar
-LD ?= $(CROSS_COMPILE)ld
-
 MAKEFLAGS += --no-print-directory
 
 INSTALL = install
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 63276bf55856..948abfd2ee8d 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -174,11 +174,6 @@ endef
 
 LD += $(EXTRA_LDFLAGS)
 
-HOSTCC  ?= gcc
-HOSTLD  ?= ld
-HOSTAR  ?= ar
-CLANG   ?= clang
-
 # Some distros provide the command $(CROSS_COMPILE)pkg-config for
 # searching packges installed with Multiarch. Use it for cross
 # compilation if it is existed.
@@ -213,7 +208,6 @@ FIND    = find
 INSTALL = install
 FLEX    ?= flex
 BISON   ?= bison
-STRIP   = strip
 AWK     = awk
 
 # include Makefile.config by default and rule out
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 836e783f0170..f038642b283f 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -3,7 +3,6 @@ include ../../../build/Build.include
 include ../../../scripts/Makefile.arch
 include ../../../scripts/Makefile.include
 
-CXX ?= $(CROSS_COMPILE)g++
 OBJCOPY ?= $(CROSS_COMPILE)objcopy
 
 CURDIR := $(abspath .)

-- 
2.34.1