[RFC 1/2] perf: support build BPF skeletons with perf
From: Song Liu
Date: Wed Nov 18 2020 - 23:59:01 EST
BPF programs are useful in perf to profile BPF programs. BPF skeleton is
by far the easiest way to write BPF tools. Enable building BPF skeletons
in util/bpf_skel. A dummy bpf skeleton is added. More bpf skeletons will
be added for different use cases.
Signed-off-by: Song Liu <songliubraving@xxxxxx>
---
tools/build/Makefile.feature | 3 +-
tools/perf/Makefile.config | 7 +++
tools/perf/Makefile.perf | 15 +++++-
tools/perf/util/bpf_skel/.gitignore | 3 ++
tools/perf/util/bpf_skel/Makefile | 71 ++++++++++++++++++++++++++++
tools/perf/util/bpf_skel/dummy.bpf.c | 19 ++++++++
6 files changed, 115 insertions(+), 3 deletions(-)
create mode 100644 tools/perf/util/bpf_skel/.gitignore
create mode 100644 tools/perf/util/bpf_skel/Makefile
create mode 100644 tools/perf/util/bpf_skel/dummy.bpf.c
diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 97cbfb31b7625..95a58b5564218 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -70,7 +70,8 @@ FEATURE_TESTS_BASIC := \
libaio \
libzstd \
disassembler-four-args \
- file-handle
+ file-handle \
+ clang-bpf-co-re
# FEATURE_TESTS_BASIC + FEATURE_TESTS_EXTRA is the complete list
# of all feature tests
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index ce8516e4de34f..1c2c0f4badd85 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -619,6 +619,13 @@ ifndef NO_LIBBPF
msg := $(warning BPF API too old. Please install recent kernel headers. BPF support in 'perf record' is disabled.)
NO_LIBBPF := 1
endif
+
+ ifndef NO_BPF_SKEL
+ ifeq ($(feature-clang-bpf-co-re), 1)
+ BUILD_BPF_SKEL := 1
+ $(call detected,CONFIG_PERF_BPF_SKEL)
+ endif
+ endif
endif
dwarf-post-unwind := 1
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 7ce3f2e8b9c74..9a9fc71e2ffa4 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -126,6 +126,8 @@ include ../scripts/utilities.mak
#
# Define NO_LIBDEBUGINFOD if you do not want support debuginfod
#
+# Define NO_BPF_SKEL if you do not want build BPF skeletons
+#
# As per kernel Makefile, avoid funny character set dependencies
unexport LC_ALL
@@ -735,7 +737,8 @@ prepare: $(OUTPUT)PERF-VERSION-FILE $(OUTPUT)common-cmds.h archheaders $(drm_ioc
$(x86_arch_prctl_code_array) \
$(rename_flags_array) \
$(arch_errno_name_array) \
- $(sync_file_range_arrays)
+ $(sync_file_range_arrays) \
+ bpf-skel
$(OUTPUT)%.o: %.c prepare FORCE
$(Q)$(MAKE) -f $(srctree)/tools/build/Makefile.build dir=$(build-dir) $@
@@ -1008,7 +1011,15 @@ config-clean:
python-clean:
$(python-clean)
+ifdef BUILD_BPF_SKEL
+bpf-skel:
+ $(Q)$(MAKE) -C util/bpf_skel
+else
+bpf-skel:
+endif
+
clean:: $(LIBTRACEEVENT)-clean $(LIBAPI)-clean $(LIBBPF)-clean $(LIBSUBCMD)-clean $(LIBPERF)-clean config-clean fixdep-clean python-clean
+ $(call descend,util/bpf_skel,clean)
$(call QUIET_CLEAN, core-objs) $(RM) $(LIBPERF_A) $(OUTPUT)perf-archive $(OUTPUT)perf-with-kcore $(LANG_BINDINGS)
$(Q)find $(if $(OUTPUT),$(OUTPUT),.) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
$(Q)$(RM) $(OUTPUT).config-detected
@@ -1071,7 +1082,7 @@ endif
FORCE:
-.PHONY: all install clean config-clean strip install-gtk
+.PHONY: all install clean config-clean strip install-gtk bpf-skel
.PHONY: shell_compatibility_test please_set_SHELL_PATH_to_a_more_modern_shell
.PHONY: $(GIT-HEAD-PHONY) TAGS tags cscope FORCE prepare
.PHONY: libtraceevent_plugins archheaders
diff --git a/tools/perf/util/bpf_skel/.gitignore b/tools/perf/util/bpf_skel/.gitignore
new file mode 100644
index 0000000000000..5263e9e6c5d83
--- /dev/null
+++ b/tools/perf/util/bpf_skel/.gitignore
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+.tmp
+*.skel.h
\ No newline at end of file
diff --git a/tools/perf/util/bpf_skel/Makefile b/tools/perf/util/bpf_skel/Makefile
new file mode 100644
index 0000000000000..853bece088f4b
--- /dev/null
+++ b/tools/perf/util/bpf_skel/Makefile
@@ -0,0 +1,71 @@
+# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+SKEL_OUTPUT := $(abspath .)
+TMP_OUTPUT := $(abspath .tmp)
+CLANG ?= clang
+LLC ?= llc
+LLVM_STRIP ?= llvm-strip
+DEFAULT_BPFTOOL := $(TMP_OUTPUT)/sbin/bpftool
+BPFTOOL ?= $(DEFAULT_BPFTOOL)
+LIBBPF_SRC := $(abspath ../../../lib/bpf)
+BPFOBJ := $(TMP_OUTPUT)/libbpf.a
+BPF_INCLUDE := $(TMP_OUTPUT)
+INCLUDES := -I$(TMP_OUTPUT) -I$(BPF_INCLUDE) -I$(abspath ../../../lib) \
+ -I$(abspath ../../../include/uapi)
+CFLAGS := -g -Wall
+
+# Try to detect best kernel BTF source
+KERNEL_REL := $(shell uname -r)
+VMLINUX_BTF_PATHS := /sys/kernel/btf/vmlinux /boot/vmlinux-$(KERNEL_REL)
+VMLINUX_BTF_PATH := $(or $(VMLINUX_BTF),$(firstword \
+ $(wildcard $(VMLINUX_BTF_PATHS))))
+ifeq ($(V),1)
+Q =
+msg =
+else
+Q = @
+msg = @printf ' %-8s %s%s\n' "$(1)" "$(notdir $(2))" "$(if $(3), $(3))";
+MAKEFLAGS += --no-print-directory
+submake_extras := feature_display=0
+endif
+
+SKELETONS := $(SKEL_OUTPUT)/dummy.skel.h
+
+.DELETE_ON_ERROR:
+
+.PHONY: all clean
+all: $(SKELETONS)
+
+clean:
+ $(call msg,CLEAN,bpf_skel)
+ $(Q)rm -rf $(TMP_OUTPUT) $(SKELETONS)
+
+$(SKEL_OUTPUT)/%.skel.h: $(TMP_OUTPUT)/%.bpf.o | $(BPFTOOL)
+ $(call msg,GEN-SKEL,$@)
+ $(Q)$(BPFTOOL) gen skeleton $< > $@
+
+$(TMP_OUTPUT)/%.bpf.o: %.bpf.c $(TMP_OUTPUT)/vmlinux.h $(BPFOBJ) | $(TMP_OUTPUT)
+ $(call msg,BPF,$@)
+ $(Q)$(CLANG) -g -O2 -target bpf $(INCLUDES) \
+ -c $(filter %.c,$^) -o $@ && \
+ $(LLVM_STRIP) -g $@
+
+$(TMP_OUTPUT):
+ $(call msg,MKDIR,$@)
+ $(Q)mkdir -p $(TMP_OUTPUT)
+
+$(TMP_OUTPUT)/vmlinux.h: $(VMLINUX_BTF_PATH) | $(TMP_OUTPUT) $(BPFTOOL)
+ $(call msg,GEN,$@)
+ $(Q)if [ ! -e "$(VMLINUX_BTF_PATH)" ] ; then \
+ echo "Couldn't find kernel BTF; set VMLINUX_BTF to" \
+ "specify its location." >&2; \
+ exit 1;\
+ fi
+ $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@
+
+$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(TMP_OUTPUT)
+ $(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) \
+ OUTPUT=$(abspath $(dir $@))/ $(abspath $@)
+
+$(DEFAULT_BPFTOOL): | $(TMP_OUTPUT)
+ $(Q)$(MAKE) $(submake_extras) -C ../../../bpf/bpftool \
+ prefix= OUTPUT=$(TMP_OUTPUT)/ DESTDIR=$(TMP_OUTPUT) install
diff --git a/tools/perf/util/bpf_skel/dummy.bpf.c b/tools/perf/util/bpf_skel/dummy.bpf.c
new file mode 100644
index 0000000000000..085fcee1f52cf
--- /dev/null
+++ b/tools/perf/util/bpf_skel/dummy.bpf.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+// Copyright (c) 2020 Facebook
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+ __uint(key_size, sizeof(u32));
+ __uint(value_size, sizeof(u64));
+} counts SEC(".maps");
+
+SEC("fentry/dummy")
+int BPF_PROG(fentry_dummy)
+{
+ return 0;
+}
+
+char LICENSE[] SEC("license") = "Dual BSD/GPL";
--
2.24.1