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SubjectRe: [PATCH] perf tools: Convert legacy map definition to BTF-defined
Em Wed, Jun 29, 2022 at 09:43:17AM -0700, Ian Rogers escreveu:
> On Wed, Jun 29, 2022 at 4:27 AM Jiri Olsa <jolsa@kernel.org> wrote:
> > The libbpf is switching off support for legacy map definitions [1],
> > which will break the perf llvm tests.
> >
> > Moving the base source map definition to BTF-defined, so we need
> > to use -g compile option for to add debug/BTF info.
> >
> > [1] https://lore.kernel.org/bpf/20220627211527.2245459-1-andrii@kernel.org/
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> > tools/perf/tests/bpf-script-example.c | 15 +++++++++------
> > tools/perf/util/llvm-utils.c | 2 +-
> > 2 files changed, 10 insertions(+), 7 deletions(-)
> >
> > diff --git a/tools/perf/tests/bpf-script-example.c b/tools/perf/tests/bpf-script-example.c
> > index ab4b98b3165d..065a4ac5d8e5 100644
> > --- a/tools/perf/tests/bpf-script-example.c
> > +++ b/tools/perf/tests/bpf-script-example.c
> > @@ -24,13 +24,16 @@ struct bpf_map_def {
> > unsigned int max_entries;
> > };
> >
> > +#define __uint(name, val) int (*name)[val]
> > +#define __type(name, val) typeof(val) *name
>
> This is probably worth a comment, reading it hurts :-) I expect that
> libbpf provides a definition that the rest of the world uses.
>
> Fwiw, the pre bpf counters BPF in perf needs a good overhaul. Arnaldo
> mentioned switching perf trace's BPF to use BPF skeletons in another
> post. The tests we have on event filters are flaky. One fewer bpf.h in
> the world seems like a service to humanity (I'm looking at you
> tools/perf/include/bpf/bpf.h).

Yeah, bring perf trace to the modern world :-)

- Arnaldo

> Thanks,
> Ian
>
> > +
> > #define SEC(NAME) __attribute__((section(NAME), used))
> > -struct bpf_map_def SEC("maps") flip_table = {
> > - .type = BPF_MAP_TYPE_ARRAY,
> > - .key_size = sizeof(int),
> > - .value_size = sizeof(int),
> > - .max_entries = 1,
> > -};
> > +struct {
> > + __uint(type, BPF_MAP_TYPE_ARRAY);
> > + __uint(max_entries, 1);
> > + __type(key, int);
> > + __type(value, int);
> > +} flip_table SEC(".maps");
> >
> > SEC("func=do_epoll_wait")
> > int bpf_func__SyS_epoll_pwait(void *ctx)
> > diff --git a/tools/perf/util/llvm-utils.c b/tools/perf/util/llvm-utils.c
> > index 96c8ef60f4f8..2dc797007419 100644
> > --- a/tools/perf/util/llvm-utils.c
> > +++ b/tools/perf/util/llvm-utils.c
> > @@ -25,7 +25,7 @@
> > "$CLANG_OPTIONS $PERF_BPF_INC_OPTIONS $KERNEL_INC_OPTIONS " \
> > "-Wno-unused-value -Wno-pointer-sign " \
> > "-working-directory $WORKING_DIR " \
> > - "-c \"$CLANG_SOURCE\" -target bpf $CLANG_EMIT_LLVM -O2 -o - $LLVM_OPTIONS_PIPE"
> > + "-c \"$CLANG_SOURCE\" -target bpf $CLANG_EMIT_LLVM -g -O2 -o - $LLVM_OPTIONS_PIPE"
> >
> > struct llvm_param llvm_param = {
> > .clang_path = "clang",
> > --
> > 2.35.3
> >

--

- Arnaldo

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