linux-kernel - Re: [PATCH v3 1/2] perf: support build BPF skeletons with perf

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Date:   Wed, 9 Dec 2020 18:03:55 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Song Liu <songliubraving@...com>
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com,
        peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        namhyung@...nel.org
Subject: Re: [PATCH v3 1/2] perf: support build BPF skeletons with perf

On Tue, Dec 08, 2020 at 10:16:45AM -0800, Song Liu wrote:
> 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@...com>

one nit below, but other than that:

Acked-by: Jiri Olsa <jolsa@...hat.com>

thanks,
jirka

> ---
>  tools/bpf/bpftool/Makefile          |  3 ++
>  tools/build/Makefile.feature        |  4 ++-
>  tools/perf/Makefile.config          |  9 ++++++
>  tools/perf/Makefile.perf            | 48 +++++++++++++++++++++++++++--
>  tools/perf/util/bpf_skel/.gitignore |  3 ++
>  tools/scripts/Makefile.include      |  1 +
>  6 files changed, 65 insertions(+), 3 deletions(-)
>  create mode 100644 tools/perf/util/bpf_skel/.gitignore
> 
> diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
> index f897cb5fb12d0..390af1a52601e 100644
> --- a/tools/bpf/bpftool/Makefile
> +++ b/tools/bpf/bpftool/Makefile
> @@ -139,6 +139,9 @@ endif
>  BPFTOOL_BOOTSTRAP := $(BOOTSTRAP_OUTPUT)bpftool
>  
>  BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o)
> +
> +bootstrap: $(BPFTOOL_BOOTSTRAP)
> +
>  OBJS = $(patsubst %.c,$(OUTPUT)%.o,$(SRCS)) $(OUTPUT)disasm.o
>  
>  VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux)				\
> diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
> index 97cbfb31b7625..74e255d58d8d0 100644
> --- a/tools/build/Makefile.feature
> +++ b/tools/build/Makefile.feature
> @@ -99,7 +99,9 @@ FEATURE_TESTS_EXTRA :=                  \
>           clang                          \
>           libbpf                         \
>           libpfm4                        \
> -         libdebuginfod
> +         libdebuginfod			\
> +         clang-bpf-co-re
> +
>  
>  FEATURE_TESTS ?= $(FEATURE_TESTS_BASIC)
>  
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index ce8516e4de34f..fe234b8bfeefb 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -621,6 +621,15 @@ ifndef NO_LIBBPF
>    endif
>  endif
>  
> +ifdef BUILD_BPF_SKEL
> +  $(call feature_check,clang-bpf-co-re)
> +  ifeq ($(feature-clang-bpf-co-re), 0)
> +    dummy := $(error Error: clang too old. Please install recent clang)
> +  endif
> +  $(call detected,CONFIG_PERF_BPF_SKEL)
> +  CFLAGS += -DBUILD_BPF_SKEL

sorry I did not notice before, but we use HAVE_* name style for these C macros 

HAVE_BPF_SKEL should fit

> +endif
> +
>  dwarf-post-unwind := 1
>  dwarf-post-unwind-text := BUG
>  
> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> index 62f3deb1d3a8b..9ea9047a621bc 100644
> --- a/tools/perf/Makefile.perf

SNIP