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

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>

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 57619f240b5604f8a76f9abaa95288dca64d1df5..38f8851bd7cbdb0e3f706a35bd2e0bfba70e0561 100644 (file)
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -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                 \

diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 04b07ff8823487a0f3e083f4d4aded7c0316607a..690fe97be190439952f178576a8cb66d82a5352b 100644 (file)
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -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
 

diff --git a/tools/build/feature/test-libbpf-bpf_program__set_insns.c b/tools/build/feature/test-libbpf-bpf_program__set_insns.c
new file mode 100644 (file)
index 0000000..f3b7f18
--- /dev/null
+++ b/tools/build/feature/test-libbpf-bpf_program__set_insns.c
@@ -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;
+}

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 6fd4b1384b975880c299e4263c8276d28ea0552d..898226ea8cadc570560386dcaa2d183cf43c1243 100644 (file)
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -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

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index d657594894cf6d1a225965e7476c7feb6af57cb7..f4adeccdbbcb4aef54e4b23dc9cf56880768cb40 100644 (file)
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -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"