perf build: Add ability to build with a generated vmlinux.h

Commit a887466562b4 ("perf bpf skels: Stop using vmlinux.h generated
from BTF, use subset of used structs + CO-RE") made it so that
vmlinux.h was uncondtionally included from
tools/perf/util/vmlinux.h. This change reverts part of that change (so
that vmlinux.h is once again generated) and makes it so that the
vmlinux.h used at build time is selected from the VMLINUX_H
variable. By default the VMLINUX_H variable is set to the vmlinux.h
added in change a887466562b4, but if GEN_VMLINUX_H=1 is passed on the
build command line then the previous generation behavior kicks in.

The build with GEN_VMLINUX_H=1 currently fails with:

    util/bpf_skel/lock_contention.bpf.c:419:8: error: redefinition of 'rq'
    struct rq {};
           ^
    /tmp/perf/util/bpf_skel/.tmp/../vmlinux.h:45630:8: note: previous definition is here
    struct rq {
           ^
    1 error generated.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: James Clark <james.clark@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230623041405.4039475-2-irogers@google.com
[ Format the error message and add a comment for GEN_VMLINUX_H ]
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 9c5aa14a44cf49a50c1b2d7ef2fc73dbfc765438..78411252b72a8fac82e233ace35a26a522b76ff6 100644 (file)
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -680,6 +680,10 @@ ifdef BUILD_BPF_SKEL
   CFLAGS += -DHAVE_BPF_SKEL
 endif
 
+ifndef GEN_VMLINUX_H
+  VMLINUX_H=$(src-perf)/util/bpf_skel/vmlinux/vmlinux.h
+endif
+
 dwarf-post-unwind := 1
 dwarf-post-unwind-text := BUG
 

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index b1e62a621f92a71624cf3862499068f09831964a..a49eded5cc4f99dbc0ba7d822474a5b8c26c8f18 100644 (file)
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -132,6 +132,8 @@ include ../scripts/utilities.mak
 # Define EXTRA_TESTS to enable building extra tests useful mainly to perf
 # developers, such as:
 #      x86 instruction decoder - new instructions test
+#
+# Define GEN_VMLINUX_H to generate vmlinux.h from the BTF.
 
 # As per kernel Makefile, avoid funny character set dependencies
 unexport LC_ALL
@@ -1084,7 +1086,21 @@ $(BPFTOOL): | $(SKEL_TMP_OUT)
        $(Q)CFLAGS= $(MAKE) -C ../bpf/bpftool \
                OUTPUT=$(SKEL_TMP_OUT)/ bootstrap
 
-$(SKEL_TMP_OUT)/%.bpf.o: util/bpf_skel/%.bpf.c $(LIBBPF) | $(SKEL_TMP_OUT)
+VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux)                           \
+                    $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux)    \
+                    ../../vmlinux                                      \
+                    /sys/kernel/btf/vmlinux                            \
+                    /boot/vmlinux-$(shell uname -r)
+VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
+
+$(SKEL_OUT)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL)
+ifeq ($(VMLINUX_H),)
+       $(QUIET_GEN)$(BPFTOOL) btf dump file $< format c > $@
+else
+       $(Q)cp "$(VMLINUX_H)" $@
+endif
+
+$(SKEL_TMP_OUT)/%.bpf.o: util/bpf_skel/%.bpf.c $(LIBBPF) $(SKEL_OUT)/vmlinux.h | $(SKEL_TMP_OUT)
        $(QUIET_CLANG)$(CLANG) -g -O2 -target bpf -Wall -Werror $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \
          -c $(filter util/bpf_skel/%.bpf.c,$^) -o $@
 

diff --git a/tools/perf/util/bpf_skel/.gitignore b/tools/perf/util/bpf_skel/.gitignore
index 7a1c832825de8445c9d25798ed050f29199c9740..cd01455e1b53c3d997238d5058ec96de1774f15b 100644 (file)
--- a/tools/perf/util/bpf_skel/.gitignore
+++ b/tools/perf/util/bpf_skel/.gitignore
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 .tmp
 *.skel.h
+vmlinux.h

diff --git a/tools/perf/util/bpf_skel/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
similarity index 100%
rename from tools/perf/util/bpf_skel/vmlinux.h
rename to tools/perf/util/bpf_skel/vmlinux/vmlinux.h