tools build: bpf: Append EXTRA_CFLAGS and HOST_EXTRACFLAGS by kernel-patches-daemon-bpf[bot] · Pull Request #12293 · kernel-patches/bpf

kernel-patches-daemon-bpf · 2026-06-02T15:01:28Z

Pull request for series with
subject: tools build: bpf: Append EXTRA_CFLAGS and HOST_EXTRACFLAGS
version: 2
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693

kernel-patches-daemon-bpf · 2026-06-02T15:01:31Z

Upstream branch: b93c55b
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-review-bot · 2026-06-02T15:16:07Z

commit 19bc0e37b0e2f9bb9d4b1d2e59228c83b7d10f54
Author: Leo Yan <leo.yan@arm.com>

selftests/bpf: Use common CFLAGS for urandom_read

The urandom_read helper and its shared library are built with $(CLANG)
directly rather than through the normal selftest $(CC) rules. The CFLAGS
variable can contain specific flags only for $(CC) but might be
imcompatible for $(CLANG) and those flags are not necessarily valid for
the clang-only urandom_read build. Split the BPF selftest local flags
into COMMON_CFLAGS and append them to CFLAGS for the normal build path.
Use COMMON_CFLAGS directly for urandom_read and liburandom_read.so, while
still filtering out -static as before.

> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index bc049620c774..1e47e29ba421 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -51,7 +51,7 @@ srctree := $(patsubst %/,%,$(dir $(srctree)))
>  srctree := $(patsubst %/,%,$(dir $(srctree)))
>  endif
>
> -CFLAGS += -g $(OPT_FLAGS) -rdynamic -std=gnu11				\
> +COMMON_CFLAGS = -g $(OPT_FLAGS) -rdynamic -std=gnu11				\
>  	  -Wall -Werror -fno-omit-frame-pointer				\
>  	  -Wno-unused-but-set-variable					\
>  	  $(GENFLAGS) $(SAN_CFLAGS) $(LIBELF_CFLAGS)			\
> @@ -64,7 +64,7 @@ LDLIBS += $(LIBELF_LIBS) -lz -lrt -lpthread
>  PCAP_CFLAGS	:= $(shell $(PKG_CONFIG) --cflags libpcap 2>/dev/null && echo "-DTRAFFIC_MONITOR=1")
>  PCAP_LIBS	:= $(shell $(PKG_CONFIG) --libs libpcap 2>/dev/null)
>  LDLIBS += $(PCAP_LIBS)
> -CFLAGS += $(PCAP_CFLAGS)
> +CFLAGS += $(COMMON_CFLAGS) $(PCAP_CFLAGS)

Ian Rogers raised a concern in v4 that COMMON_CFLAGS is being assigned
before 'include ../lib.mk' (which happens later around line 165).

The ../lib.mk include appends important flags to CFLAGS, such as
-D_GNU_SOURCE=. Since COMMON_CFLAGS uses recursive assignment (=), these
flags added by lib.mk should be available when COMMON_CFLAGS expands.
However, COMMON_CFLAGS references $(GENFLAGS), $(SAN_CFLAGS), and
$(LIBELF_CFLAGS) which are defined before lib.mk, but lib.mk may also
modify CFLAGS directly with additional flags.

Will urandom_read miss any flags that lib.mk adds to CFLAGS but that
aren't captured in the variables referenced by COMMON_CFLAGS? Ian
suggested moving these assignments below the include to ensure all
lib.mk-added flags are captured.

Reference:
https://lore.kernel.org/all/CAP-5=fXjd15e5YpCM9KMjEhpjLxvxc6qUk0g7BprCfkzcRZ5_g@mail.gmail.com/

>
>  # Some utility functions use LLVM libraries
>  jit_disasm_helpers.c-CFLAGS = $(LLVM_CFLAGS)

[ ... ]

> @@ -261,7 +261,7 @@ endif
>  $(OUTPUT)/liburandom_read.so: urandom_read_lib1.c urandom_read_lib2.c liburandom_read.map
>  	$(call msg,LIB,,$@)
>  	$(Q)$(CLANG) $(CLANG_TARGET_ARCH) \
> -		     $(filter-out -static,$(CFLAGS) $(LDFLAGS)) \
> +		     $(filter-out -static,$(COMMON_CFLAGS) $(LDFLAGS)) \
>  		     $(filter %.c,$^) $(filter-out -static,$(LDLIBS)) \
>  		     -Wno-unused-command-line-argument \
>  		     -fuse-ld=$(LLD) -Wl,-znoseparate-code -Wl,--build-id=sha1 \

[ ... ]

> @@ -271,7 +271,7 @@ $(OUTPUT)/liburandom_read.so: urandom_read_lib1.c urandom_read_lib2.c liburandom
>  $(OUTPUT)/urandom_read: urandom_read.c urandom_read_aux.c $(OUTPUT)/liburandom_read.so
>  	$(call msg,BINARY,,$@)
>  	$(Q)$(CLANG) $(CLANG_TARGET_ARCH) \
> -		     $(filter-out -static,$(CFLAGS) $(LDFLAGS)) $(filter %.c,$^) \
> +		     $(filter-out -static,$(COMMON_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 \

AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

In-Reply-To-Subject: selftests/bpf: Use common CFLAGS for urandom_read
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/26828477669

kernel-patches-daemon-bpf · 2026-06-02T15:32:58Z

Forwarding comment 4603866551 via email
In-Reply-To: 20260602-tools_build_fix_zero_init_bpf_only-v2-7-c76e5250ea1c@arm.com
Patch: https://patchwork.kernel.org/project/netdevbpf/patch/20260602-tools_build_fix_zero_init_bpf_only-v2-7-c76e5250ea1c@arm.com/

kernel-patches-daemon-bpf · 2026-06-02T16:56:59Z

Upstream branch: 04de7bc
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-daemon-bpf · 2026-06-02T19:11:56Z

Upstream branch: c169a2a
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-daemon-bpf · 2026-06-03T09:35:06Z

Upstream branch: c169a2a
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-daemon-bpf · 2026-06-03T22:37:54Z

Upstream branch: 8a7f2bf
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-daemon-bpf · 2026-06-04T17:01:45Z

Upstream branch: bf29346
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-daemon-bpf · 2026-06-05T15:14:38Z

Upstream branch: 390dc36
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-daemon-bpf · 2026-06-05T15:32:32Z

Upstream branch: f64c723
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-daemon-bpf · 2026-06-09T18:19:09Z

Upstream branch: 68f4e48
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-daemon-bpf · 2026-06-09T19:52:20Z

Upstream branch: c15261b
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-daemon-bpf · 2026-06-10T04:32:07Z

Upstream branch: 140fa23
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

kernel-patches-daemon-bpf · 2026-06-10T16:31:11Z

Upstream branch: 2e8ad1f
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

bpftool builds a bootstrap libbpf with HOSTCC, but the libbpf submake can still inherit target build flags through CFLAGS. This can break cross builds when host objects are compiled with target-only options. Since HOST_CFLAGS contains warning options that are not suitable for building libbpf, use LIBBPF_BOOTSTRAP_CFLAGS with the warning options removed to build the bootstrap libbpf. Clear EXTRA_CFLAGS so target extra flags are not mixed into the host bootstrap libbpf build. Signed-off-by: Leo Yan <leo.yan@arm.com> Acked-by: Quentin Monnet <qmo@kernel.org>

Prepare for future changes where EXTRA_CFLAGS may include flags not applicable to the host compiler. Move the HOST_CFLAGS assignment before appending EXTRA_CFLAGS to CFLAGS so that HOST_CFLAGS does not inherit flags from EXTRA_CFLAGS. Acked-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Leo Yan <leo.yan@arm.com>

Append HOST_EXTRACFLAGS to HOST_CFLAGS so that additional flags can be applied to the host compiler. Acked-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Leo Yan <leo.yan@arm.com>

kernel-patches-daemon-bpf · 2026-06-10T23:27:11Z

Upstream branch: 30dee2c
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1104693
version: 2

tools/scripts/Makefile.include may expand EXTRA_CFLAGS in a future change. This could alter the initialization of CFLAGS, as the default options "-g -O2" would never be set once EXTRA_CFLAGS is expanded. Prepare for this by moving the CFLAGS initialization before including tools/scripts/Makefile.include, so it is not affected by the extended EXTRA_CFLAGS. Append EXTRA_CFLAGS to CFLAGS only after including Makefile.include and place it last so that the extra flags propagate properly and can override the default options. tools/scripts/Makefile.include already appends $(CLANG_CROSS_FLAGS) to CFLAGS, the Makefile appends $(CLANG_CROSS_FLAGS) again, remove the redundant append. Signed-off-by: Leo Yan <leo.yan@arm.com> Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>

Append EXTRA_CFLAGS to CFLAGS so that additional flags can be applied to the compiler. Signed-off-by: Leo Yan <leo.yan@arm.com>

ASAN reports stack-buffer-overflow due to the uninitialized op_name. Initialize it to fix the issue. Fixes: 054b6c7 ("selftests/bpf: Add verifier log tests for BPF_BTF_LOAD command") Signed-off-by: Leo Yan <leo.yan@arm.com>

The urandom_read helper and its shared library are built with $(CLANG) directly rather than through the normal selftest $(CC) rules. The CFLAGS variable can contain specific flags only for $(CC) but might be imcompatible for $(CLANG) and those flags are not necessarily valid for the clang-only urandom_read build. Split the BPF selftest local flags into COMMON_CFLAGS and append them to CFLAGS for the normal build path. Use COMMON_CFLAGS directly for urandom_read and liburandom_read.so, while still filtering out -static as before. Signed-off-by: Leo Yan <leo.yan@arm.com>

The BPF selftests prefer static LLVM linking, which works for native builds but can break cross builds. Its --link-static output may include host-only libraries that are unavailable for the cross compilation, causing link failures. Avoid static LLVM linking for cross builds and use shared LLVM libraries instead. Native builds keep the existing behavior. Signed-off-by: Leo Yan <leo.yan@arm.com>

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Leo-Yan added 3 commits June 10, 2026 16:27

bpftool: Append extra host flags

8665159

Append HOST_EXTRACFLAGS to HOST_CFLAGS so that additional flags can be applied to the host compiler. Acked-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Leo Yan <leo.yan@arm.com>

Leo-Yan added 5 commits June 10, 2026 16:27

tools/bpf: build: Append extra cflags

5797662

Append EXTRA_CFLAGS to CFLAGS so that additional flags can be applied to the compiler. Signed-off-by: Leo Yan <leo.yan@arm.com>

selftests/bpf: Initialize operation name before use

b96c79d

ASAN reports stack-buffer-overflow due to the uninitialized op_name. Initialize it to fix the issue. Fixes: 054b6c7 ("selftests/bpf: Add verifier log tests for BPF_BTF_LOAD command") Signed-off-by: Leo Yan <leo.yan@arm.com>

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