From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794376893; b=A9GcMI+ylIaR4zYOX/q9Z9xKJF76yna8K6sS8ClMs7hW67maSawZTIED5OyPMvcoIT10 iDhDaa5EAY6vT8LPdU8VxCTvP5Xtyke2H5242GCV7d+kON/IHZiv2mlQoJ7npBeCx+F7Y 0LvhRDzLRSXoOws68nOdT6zEI1e24kuvElIzMKK9AvxmgubZVpxycK2Rkv0j9LSaNvcmI UNax+eRhPGYnB0lzLYCi4Kp/3gtEzOgGCfLO70ca/0TNxGL7Khjgmqs6ztPx7+Xk4Omcw JR0jEITIhX1A0QkwNwBsoGrRrW83iwlKEgqSjO2iluLSoZymeiQBTDBt80zGtV2zvHw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794376893; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=dINrgosS+w8IkLAmH96/TOQITM9xe5YuD9KyLFCdOco=; b=sqOkNWyKcAzCgJghZ2xze08DrULPP20J64ZKJEYZ1X3GkR8Bkf59Mj0EoSKqLOyxbIig wtaUcgXJgIWjBG1+QOUYs7MdIVR3RQNWUtfWABEPFlNrhDC4BMIQTvTFNJqKl5ysDGtOh qd7lkdivSzjsY+Oj3V8eRwJiOSGQGxHXsfSo3d6SZSNDfiL7vncMGc2ENfTNyw7pFwb7N RQQXsuhTB+yQ7Vb3Us2GTi3OCfB1+PTMMjYFqvQSpvrAfuhKgnez7kcTAHMtC5Mik5Y/s ZUqzd3Wd5S5eH2/DlzPxqPtVl+toBMAttl/jJz+4lQwrabfU0G4+TJujRNArzL0B4mQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="KwQ/VKxu"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 600AB606A31C; Wed, 11 Nov 2026 06:01:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=KwQ/VKxu Received: by smtp.kernel.org (Postfix) with ESMTPSA id 70B171F00A05; Wed, 11 Nov 2026 06:01:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794376892; bh=dINrgosS+w8IkLAmH96/TOQITM9xe5YuD9KyLFCdOco=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=KwQ/VKxucDt0SWejmeNXKDSQf3YC6HUG38pU9ANO+/OdMs8Xh/AWgdOP3fo218H1O qARaOqrKverYF8BWeBUEaBMp7ZFBC/1YEoBMqel4sWbLzEzZNt4SdNlSDIer2S+TU5 02Xk5jIVOOO4ADOHHCJiga8n1jle8qZp1w5oR+SJU7AxPwm1RZHlHeWTC09BpUWgS7 wpOtiDVPCFrpgxvz5PjyYlsChyEn+dATBVcomUXvjXBy9ZgcEvpurU+7WLh5NaVen4 9VPGCpYDymgC2OkFZuXfRAUdyfg4ZPXBZvpW91lSGVblCYxaYO2LGhrxlqxMpwu3wH YUcMM2rlkG7yA== Date: Tue, 10 Nov 2026 22:01:30 -0800 From: Namhyung Kim To: Ian Rogers Cc: acme@kernel.org, cupertino.miranda@oracle.com, jose.marchesi@oracle.com, adrian.hunter@intel.com, andrii@kernel.org, eddyz87@gmail.com, james.clark@linaro.org, jolsa@kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, yonghong.song@linux.dev Subject: Re: [PATCH v3 1/2] perf build: Support building BPF skeletons with bpf-gcc Message-ID: References: <20261013231430.2163505-1-irogers@google.com> <20261022204627.1813821-1-irogers@google.com> <20261022204627.1813821-2-irogers@google.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20261022204627.1813821-2-irogers@google.com> On Thu, Oct 22, 2026 at 01:46:26PM -0700, Ian Rogers wrote: > Support building perf BPF skeletons with bpf-gcc (>= 14.0.0) in addition > to clang (>= 12.0.1), similar to tools/testing/selftests/bpf/Makefile. > > When building perf with GCC (CC_NO_CLANG=1), prefer bpf-gcc and fall > back to clang if bpf-gcc is unavailable or too old. When building with > Clang/LLVM (CC_NO_CLANG=0), prefer clang and fall back to bpf-gcc. > Explicit command-line overrides via BPF_GCC=... or CLANG=... are > respected, and setting BPF_GCC= or CLANG= to empty disables that > compiler. > > In bpf_skel.mak, pass the bpf-gcc flags (-mcpu=v3, -fno-ident, > -DBPF_NO_PRESERVE_ACCESS_INDEX, -Wno-attributes, > -D__TARGET_ARCH_$(SRCARCH), and target endianness) and query system > include paths from $(CC). > > Also update version-ge3 and version-lt3 in tools/scripts/utilities.mak > to split the two version arguments separately in awk so empty or > fewer-than-3-component version strings do not shift fields across > arguments. Sorry for the delay. But can you please split this part from the bpf-gcc changes? Thanks, Namhyung > > Assisted-by: Antigravity:gemini-3.1-pro > Signed-off-by: Ian Rogers > --- > tools/perf/Makefile.config | 83 +++++++++++++++++++++++++++------- > tools/perf/Makefile.perf | 8 +++- > tools/perf/bpf_skel.mak | 36 ++++++++++----- > tools/scripts/Makefile.include | 1 + > tools/scripts/utilities.mak | 4 +- > 5 files changed, 101 insertions(+), 31 deletions(-) > > diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config > index cafc7be79643..ca045f7ff01d 100644 > --- a/tools/perf/Makefile.config > +++ b/tools/perf/Makefile.config > @@ -662,27 +662,78 @@ ifeq ($(BUILD_BPF_SKEL),1) > else ifeq ($(filter -DHAVE_LIBOPENSSL_SUPPORT, $(CFLAGS)),) > $(warning Warning: Disabled BPF skeletons as libopenssl is required) > BUILD_BPF_SKEL := 0 > - else ifeq ($(call get-executable,$(CLANG)),) > - $(warning Warning: Disabled BPF skeletons as clang ($(CLANG)) is missing) > - BUILD_BPF_SKEL := 0 > - else > - CLANG_VERSION := $(shell $(CLANG) --version | head -1 | sed 's/.*clang version \([[:digit:]]\+.[[:digit:]]\+.[[:digit:]]\+\).*/\1/g') > - ifeq ($(call version-lt3,$(CLANG_VERSION),12.0.1),1) > - $(warning Warning: Disabled BPF skeletons as reliable BTF generation needs at least $(CLANG) version 12.0.1) > - BUILD_BPF_SKEL := 0 > - endif > endif > ifeq ($(BUILD_BPF_SKEL),1) > - $(call feature_check,clang-bpf-co-re) > - ifeq ($(feature-clang-bpf-co-re), 0) > - $(warning Warning: Disabled BPF skeletons as clang is too old) > + # Prefer bpf-gcc when building with gcc (CC_NO_CLANG=1) and clang when > + # building with clang, unless CLANG or BPF_GCC was explicitly specified on > + # the command line. Fall back to whichever compiler is available. > + prefer_bpf_gcc := $(CC_NO_CLANG) > + ifeq ($(origin BPF_GCC),command line) > + ifneq ($(BPF_GCC),) > + prefer_bpf_gcc := 1 > + endif > + else ifeq ($(origin CLANG),command line) > + ifneq ($(CLANG),) > + prefer_bpf_gcc := 0 > + endif > + endif > + > + have_bpf_gcc := 0 > + have_clang_bpf := 0 > + > + define check_bpf_gcc > + ifneq ($$(call get-executable,$$(BPF_GCC)),) > + BPF_GCC_VERSION := $$(shell $$(BPF_GCC) -dumpfullversion 2>/dev/null) > + ifneq ($$(BPF_GCC_VERSION),) > + ifneq ($$(call version-lt3,$$(BPF_GCC_VERSION),14.0.0),1) > + have_bpf_gcc := 1 > + endif > + endif > + endif > + endef > + > + ifeq ($(prefer_bpf_gcc),1) > + $(eval $(check_bpf_gcc)) > + endif > + > + ifeq ($(have_bpf_gcc),0) > + ifneq ($(call get-executable,$(CLANG)),) > + CLANG_VERSION := $(shell $(CLANG) --version | head -1 | sed 's/.*clang version \([[:digit:]]\+.[[:digit:]]\+.[[:digit:]]\+\).*/\1/g') > + ifneq ($(call version-lt3,$(CLANG_VERSION),12.0.1),1) > + $(call feature_check,clang-bpf-co-re) > + ifneq ($(feature-clang-bpf-co-re), 0) > + have_clang_bpf := 1 > + endif > + endif > + endif > + endif > + > + ifeq ($(prefer_bpf_gcc)$(have_clang_bpf),00) > + $(eval $(check_bpf_gcc)) > + endif > + > + ifeq ($(have_bpf_gcc),1) > + $(call detected,CONFIG_PERF_BPF_SKEL_BPF_GCC) > + $(call detected,CONFIG_PERF_BPF_SKEL) > + CFLAGS += -DHAVE_BPF_SKEL > + else ifeq ($(have_clang_bpf),1) > + $(call detected,CONFIG_PERF_BPF_SKEL) > + CFLAGS += -DHAVE_BPF_SKEL > + else > + ifeq ($(call get-executable,$(CLANG))$(call get-executable,$(BPF_GCC)),) > + $(warning Warning: Disabled BPF skeletons as clang ($(CLANG)) and bpf-gcc ($(BPF_GCC)) are missing) > + else ifneq ($(call get-executable,$(CLANG)),) > + ifeq ($(call version-lt3,$(CLANG_VERSION),12.0.1),1) > + $(warning Warning: Disabled BPF skeletons as reliable BTF generation needs at least $(CLANG) version 12.0.1) > + else > + $(warning Warning: Disabled BPF skeletons as clang is too old) > + endif > + else > + $(warning Warning: Disabled BPF skeletons as bpf-gcc ($(BPF_GCC)) needs at least version 14.0.0) > + endif > BUILD_BPF_SKEL := 0 > endif > endif > - ifeq ($(BUILD_BPF_SKEL),1) > - $(call detected,CONFIG_PERF_BPF_SKEL) > - CFLAGS += -DHAVE_BPF_SKEL > - endif > endif > > ifndef GEN_VMLINUX_H > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf > index 2d9379fea267..4061a79cae54 100644 > --- a/tools/perf/Makefile.perf > +++ b/tools/perf/Makefile.perf > @@ -37,6 +37,9 @@ include ../scripts/utilities.mak > # Define EXTRA_BPF_FLAGS="--sysroot=" or other custom include paths for > # cross-compiling BPF skeletons > # > +# Define BPF_GCC to point to the bpf-gcc binary if the default `bpf-gcc' is not > +# correct, or set BPF_GCC= to disable using bpf-gcc for BPF skeletons. > +# > # Define EXCLUDE_EXTLIBS=-lmylib to exclude libmylib from the auto-generated > # EXTLIBS. > # > @@ -208,6 +211,7 @@ FIND = find > INSTALL = install > FLEX ?= flex > BISON ?= bison > +BPF_GCC ?= bpf-gcc > AWK = awk > > # include Makefile.config by default and rule out > @@ -321,8 +325,8 @@ ifneq ($(force_fixdep),1) > endif > endif > > -export srctree OUTPUT RM CC CXX RUSTC CLANG LD AR CFLAGS CXXFLAGS RUST_FLAGS V BISON FLEX AWK LIBBPF READELF > -export HOSTCC HOSTLD HOSTAR HOSTCFLAGS SHELLCHECK MYPY PYLINT CONFIG_PERF_BPF_SKEL > +export srctree OUTPUT RM CC CXX RUSTC CLANG BPF_GCC LD AR CFLAGS CXXFLAGS RUST_FLAGS V BISON FLEX AWK LIBBPF READELF > +export HOSTCC HOSTLD HOSTAR HOSTCFLAGS SHELLCHECK MYPY PYLINT CONFIG_PERF_BPF_SKEL CONFIG_PERF_BPF_SKEL_BPF_GCC > > include $(srctree)/tools/build/Makefile.include > > diff --git a/tools/perf/bpf_skel.mak b/tools/perf/bpf_skel.mak > index f2559de39f96..7b7edf506509 100644 > --- a/tools/perf/bpf_skel.mak > +++ b/tools/perf/bpf_skel.mak > @@ -22,21 +22,35 @@ bpf-skel-prepare: $(BPFTOOL) $(VMLINUX_H) > define get_sys_includes > $(shell $(1) $(2) -v -E - &1 \ > | sed -n '/<...> search starts here:/,/End of search list./{ s| \(/.*\)|-idirafter \1|p }') \ > -$(shell $(1) $(2) -dM -E - +$(shell $(1) $(2) -dM -E - +$(shell $(1) $(2) -dM -E - +$(shell $(1) $(2) -dM -E - endef > > -ifneq ($(CROSS_COMPILE),) > -CLANG_TARGET_ARCH = --target=$(notdir $(CROSS_COMPILE:%-=%)) > +ifeq ($(CONFIG_PERF_BPF_SKEL_BPF_GCC),y) > + BPF_CC := $(BPF_GCC) > + QUIET_BPF_CC = $(QUIET_BPF_GCC) > + IS_LITTLE_ENDIAN := $(shell $(CC) -dM -E - + grep 'define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__') > + BPF_OPTIONS = -Wall -mcpu=v3 -fno-ident -DBPF_NO_PRESERVE_ACCESS_INDEX -Wno-attributes \ > + -D__TARGET_ARCH_$(SRCARCH) $(if $(IS_LITTLE_ENDIAN),-mlittle-endian,-mbig-endian) > + BPF_SYS_INCLUDES = $(call get_sys_includes,$(CC),) > +else > + BPF_CC := $(CLANG) > + QUIET_BPF_CC = $(QUIET_CLANG) > + ifneq ($(CROSS_COMPILE),) > + CLANG_TARGET_ARCH = --target=$(notdir $(CROSS_COMPILE:%-=%)) > + endif > + BPF_OPTIONS = -Wall -mcpu=v3 -fno-stack-protector --target=bpf -Wno-microsoft-anon-tag > + BPF_SYS_INCLUDES = $(call get_sys_includes,$(CLANG),$(CLANG_TARGET_ARCH)) > endif > > -CLANG_OPTIONS = -Wall -mcpu=v3 > -CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG),$(CLANG_TARGET_ARCH)) > LIBBPF_INCLUDE := $(abspath $(or $(OUTPUT),.))/libbpf/include > -BPF_INCLUDE := -I$(SKEL_TMP_OUT)/.. -I$(SKEL_TOOL_OUT) -I$(LIBBPF_INCLUDE) $(CLANG_SYS_INCLUDES) > +BPF_INCLUDE := -I$(SKEL_TMP_OUT)/.. -I$(SKEL_TOOL_OUT) -I$(LIBBPF_INCLUDE) $(BPF_SYS_INCLUDES) > TOOLS_UAPI_INCLUDE := -I$(srctree)/tools/include/uapi > > ifneq ($(WERROR),0) > - CLANG_OPTIONS += -Werror > + BPF_OPTIONS += -Werror > endif > > $(BPFTOOL): > @@ -83,11 +97,11 @@ endif > # Consolidated Pattern rule for $(dir)/bpf_skel/ > $(SKEL_TMP_OUT)/%.bpf.o: $(srctree)/tools/perf/$(dir)/bpf_skel/%.bpf.c $(LIBBPF) $(VMLINUX_H) $(OUTPUT)PERF-VERSION-FILE util/bpf_skel/perf_version.h > $(call rule_mkdir) > - $(QUIET_CLANG) > - $(Q)$(CLANG) -g -O2 -fno-stack-protector --target=bpf \ > - $(CLANG_OPTIONS) $(EXTRA_BPF_FLAGS) $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ > + $(QUIET_BPF_CC) > + $(Q)$(BPF_CC) -g -O2 \ > + $(BPF_OPTIONS) $(EXTRA_BPF_FLAGS) $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ > -include $(OUTPUT)PERF-VERSION-FILE -include util/bpf_skel/perf_version.h \ > - -fms-extensions -Wno-microsoft-anon-tag \ > + -fms-extensions \ > -c $< -o $@ > > $(SKEL_OUT)/%.skel.h: $(SKEL_TMP_OUT)/%.bpf.o $(BPFTOOL) > diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include > index 378387f62960..9967210b2928 100644 > --- a/tools/scripts/Makefile.include > +++ b/tools/scripts/Makefile.include > @@ -217,6 +217,7 @@ ifneq ($(silent),1) > QUIET_CC = @echo ' CC '$@; > QUIET_CC_FPIC = @echo ' CC FPIC '$@; > QUIET_CLANG = @echo ' CLANG '$@; > + QUIET_BPF_GCC = @echo ' BPF_GCC '$@; > QUIET_AR = @echo ' AR '$@; > QUIET_LINK = @echo ' LINK '$@; > QUIET_MKDIR = @echo ' MKDIR '$@; > diff --git a/tools/scripts/utilities.mak b/tools/scripts/utilities.mak > index d69d0345cc23..746aaf6e5145 100644 > --- a/tools/scripts/utilities.mak > +++ b/tools/scripts/utilities.mak > @@ -186,7 +186,7 @@ _gea_err = $(if $(1),$(error Please set '$(1)' appropriately)) > # was to check the flex version to see if we can use compiler warnings as > # errors for one of the cases flex generates code C compilers complains about. > > -version-ge3 = $(shell echo "$(1).$(2)" | awk -F'.' '{ printf("%d\n", (10000000 * $$1 + 10000 * $$2 + $$3) >= (10000000 * $$4 + 10000 * $$5 + $$6)) }') > +version-ge3 = $(shell awk -v v1="$(1)" -v v2="$(2)" 'BEGIN { split(v1, a, "."); split(v2, b, "."); printf("%d\n", (10000000 * a[1] + 10000 * a[2] + a[3]) >= (10000000 * b[1] + 10000 * b[2] + b[3])) }') > > # version-lt3 > # > @@ -196,4 +196,4 @@ version-ge3 = $(shell echo "$(1).$(2)" | awk -F'.' '{ printf("%d\n", (10000000 * > # check the flex version to see if we can use compiler warnings as errors for > # one of the cases flex generates code C compilers complains about. > > -version-lt3 = $(shell echo "$(1).$(2)" | awk -F'.' '{ printf("%d\n", (10000000 * $$1 + 10000 * $$2 + $$3) < (10000000 * $$4 + 10000 * $$5 + $$6)) }') > +version-lt3 = $(shell awk -v v1="$(1)" -v v2="$(2)" 'BEGIN { split(v1, a, "."); split(v2, b, "."); printf("%d\n", (10000000 * a[1] + 10000 * a[2] + a[3]) < (10000000 * b[1] + 10000 * b[2] + b[3])) }') > -- > 2.56.0.307.g5fe7bd680c-goog >