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perf bpf: Fix build with libbpf 0.7.0 by checking if bpf_program__set_insns() is available

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During the transition to libbpf 1.0 some functions that perf used were
deprecated and finally removed from libbpf, so bpf_program__set_insns()
was introduced for perf to continue to use its bpf loader.

But when build with LIBBPF_DYNAMIC=1 we now need to check if that
function is available so that perf can build with older libbpf versions,
even if the end result is emitting a warning to the user that the use
of the perf BPF loader requires a newer libbpf, since bpf_program__set_insns()
touches libbpf objects internal state.

This affects only 'perf trace' when using bpf C code or pre-compiled
bytecode as an event.

Noticed on RHEL9, that has libbpf 0.7.0, where bpf_program__set_insns()
isn't available.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2022-10-19 08:44:17 -04:00
parent 409fb6bdd6
commit f1bdebbb67
5 changed files with 36 additions and 0 deletions
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1
tools/build/Makefile.feature
View File

@ -103,6 +103,7 @@ FEATURE_TESTS_EXTRA := \
libbpf-bpf_prog_load \
libbpf-bpf_object__next_program \
libbpf-bpf_object__next_map \
libbpf-bpf_program__set_insns \
libbpf-bpf_create_map \
libpfm4 \
libdebuginfod \

4
tools/build/feature/Makefile
View File

@ -63,6 +63,7 @@ FILES= \
test-libbpf-bpf_map_create.bin \
test-libbpf-bpf_object__next_program.bin \
test-libbpf-bpf_object__next_map.bin \
test-libbpf-bpf_program__set_insns.bin \
test-libbpf-btf__raw_data.bin \
test-get_cpuid.bin \
test-sdt.bin \
@ -316,6 +317,9 @@ $(OUTPUT)test-libbpf-bpf_object__next_program.bin:
$(OUTPUT)test-libbpf-bpf_object__next_map.bin:
$(BUILD) -lbpf
$(OUTPUT)test-libbpf-bpf_program__set_insns.bin:
$(BUILD) -lbpf
$(OUTPUT)test-libbpf-btf__raw_data.bin:
$(BUILD) -lbpf

8
tools/build/feature/test-libbpf-bpf_program__set_insns.c Normal file
View File

@ -0,0 +1,8 @@
// SPDX-License-Identifier: GPL-2.0
#include <bpf/libbpf.h>
int main(void)
{
bpf_program__set_insns(NULL /* prog */, NULL /* new_insns */, 0 /* new_insn_cnt */);
return 0;
}

5
tools/perf/Makefile.config
View File

@ -588,6 +588,10 @@ ifndef NO_LIBELF
ifeq ($(feature-libbpf-bpf_object__next_map), 1)
CFLAGS += -DHAVE_LIBBPF_BPF_OBJECT__NEXT_MAP
endif
$(call feature_check,libbpf-bpf_program__set_insns)
ifeq ($(feature-libbpf-bpf_program__set_insns), 1)
CFLAGS += -DHAVE_LIBBPF_BPF_PROGRAM__SET_INSNS
endif
$(call feature_check,libbpf-btf__raw_data)
ifeq ($(feature-libbpf-btf__raw_data), 1)
CFLAGS += -DHAVE_LIBBPF_BTF__RAW_DATA
@ -604,6 +608,7 @@ ifndef NO_LIBELF
CFLAGS += -DHAVE_LIBBPF_BPF_PROG_LOAD
CFLAGS += -DHAVE_LIBBPF_BPF_OBJECT__NEXT_PROGRAM
CFLAGS += -DHAVE_LIBBPF_BPF_OBJECT__NEXT_MAP
CFLAGS += -DHAVE_LIBBPF_BPF_PROGRAM__SET_INSNS
CFLAGS += -DHAVE_LIBBPF_BTF__RAW_DATA
CFLAGS += -DHAVE_LIBBPF_BPF_MAP_CREATE
endif

18
tools/perf/util/bpf-loader.c
View File

@ -36,6 +36,24 @@
#include <internal/xyarray.h>
#ifndef HAVE_LIBBPF_BPF_PROGRAM__SET_INSNS
int bpf_program__set_insns(struct bpf_program *prog __maybe_unused,
struct bpf_insn *new_insns __maybe_unused, size_t new_insn_cnt __maybe_unused)
{
pr_err("%s: not support, update libbpf\n", __func__);
return -ENOTSUP;
}
int libbpf_register_prog_handler(const char *sec __maybe_unused,
enum bpf_prog_type prog_type __maybe_unused,
enum bpf_attach_type exp_attach_type __maybe_unused,
const struct libbpf_prog_handler_opts *opts __maybe_unused)
{
pr_err("%s: not support, update libbpf\n", __func__);
return -ENOTSUP;
}
#endif
/* temporarily disable libbpf deprecation warnings */
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"