Commit 739c9180 authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
Browse files

perf build: Stop using __weak bpf_object__next_map() to handle older libbpf versions 



By adding a feature test for bpf_object__next_map() and providing a fallback if
it isn't present in older versions of libbpf.

Committer testing:

  $ rpm -q libbpf-devel
  libbpf-devel-0.4.0-2.fc35.x86_64
  $ make -C tools/perf LIBBPF_DYNAMIC=1 O=/tmp/build/perf install-bin
  $ cat /tmp/build/perf/feature/test-libbpf-bpf_object__next_map.make.output
  test-libbpf-bpf_object__next_map.c: In function ‘main’:
  test-libbpf-bpf_object__next_map.c:6:9: error: implicit declaration of function ‘bpf_object__next_map’; did you mean ‘bpf_object__next’? [-Werror=implicit-function-declaration]
      6 |         bpf_object__next_map(NULL /* obj */, NULL /* prev */);
        |         ^~~~~~~~~~~~~~~~~~~~
        |         bpf_object__next
    cc1: all warnings being treated as errors
  $
  $ objdump -dS /tmp/build/perf/perf | grep '<bpf_object__next_map>:' -A20
  00000000005b2e00 <bpf_object__next_map>:
  {
    5b2e00:	55                   	push   %rbp
    5b2e01:	48 89 e5             	mov    %rsp,%rbp
    5b2e04:	48 83 ec 10          	sub    $0x10,%rsp
    5b2e08:	64 48 8b 04 25 28 00 	mov    %fs:0x28,%rax
    5b2e0f:	00 00
    5b2e11:	48 89 45 f8          	mov    %rax,-0x8(%rbp)
    5b2e15:	31 c0                	xor    %eax,%eax
	  return bpf_map__next(prev, obj);
    5b2e17:	48 8b 45 f8          	mov    -0x8(%rbp),%rax
    5b2e1b:	64 48 2b 04 25 28 00 	sub    %fs:0x28,%rax
    5b2e22:	00 00
    5b2e24:	75 0f                	jne    5b2e35 <bpf_object__next_map+0x35>
  }
    5b2e26:	c9                   	leave
    5b2e27:	49 89 f8             	mov    %rdi,%r8
    5b2e2a:	48 89 f7             	mov    %rsi,%rdi
	  return bpf_map__next(prev, obj);
    5b2e2d:	4c 89 c6             	mov    %r8,%rsi
    5b2e30:	e9 cb b1 e5 ff       	jmp    40e000 <bpf_map__next@plt>
  $

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/linux-perf-users/YozLKby7ITEtchC9@krava


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 8916d725

tools/build/Makefile.feature

+1 −0
Original line number Diff line number Diff line
@@ -101,6 +101,7 @@ FEATURE_TESTS_EXTRA := \ 
         libbpf-btf__load_from_kernel_by_id \

         libbpf-bpf_prog_load           \

         libbpf-bpf_object__next_program \

         libbpf-bpf_object__next_map    \

         libpfm4                        \

         libdebuginfod			\

         clang-bpf-co-re

tools/build/feature/Makefile

+4 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ FILES= \ 
         test-libbpf-btf__load_from_kernel_by_id.bin	\

         test-libbpf-bpf_prog_load.bin          \

         test-libbpf-bpf_object__next_program.bin \

         test-libbpf-bpf_object__next_map.bin   \

         test-get_cpuid.bin                     \

         test-sdt.bin                           \

         test-cxx.bin                           \
@@ -299,6 +300,9 @@ $(OUTPUT)test-libbpf-bpf_prog_load.bin: 
$(OUTPUT)test-libbpf-bpf_object__next_program.bin:

	$(BUILD) -lbpf



$(OUTPUT)test-libbpf-bpf_object__next_map.bin:

	$(BUILD) -lbpf



$(OUTPUT)test-sdt.bin:

	$(BUILD)

tools/build/feature/test-libbpf-bpf_object__next_map.c

0 → 100644
+8 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <bpf/libbpf.h>



int main(void)

{

	bpf_object__next_map(NULL /* obj */, NULL /* prev */);

	return 0;

}

tools/perf/Makefile.config

+5 −0
Original line number Diff line number Diff line
@@ -581,6 +581,10 @@ ifndef NO_LIBELF 
          ifeq ($(feature-libbpf-bpf_object__next_program), 1)

            CFLAGS += -DHAVE_LIBBPF_BPF_OBJECT__NEXT_PROGRAM

          endif

          $(call feature_check,libbpf-bpf_object__next_map)

          ifeq ($(feature-libbpf-bpf_object__next_map), 1)

            CFLAGS += -DHAVE_LIBBPF_BPF_OBJECT__NEXT_MAP

          endif

        else

          dummy := $(error Error: No libbpf devel library found, please install libbpf-devel);

        endif
@@ -588,6 +592,7 @@ ifndef NO_LIBELF 
	CFLAGS += -DHAVE_LIBBPF_BTF__LOAD_FROM_KERNEL_BY_ID

        CFLAGS += -DHAVE_LIBBPF_BPF_PROG_LOAD

        CFLAGS += -DHAVE_LIBBPF_BPF_OBJECT__NEXT_PROGRAM

        CFLAGS += -DHAVE_LIBBPF_BPF_OBJECT__NEXT_MAP

      endif

    endif

tools/perf/util/bpf-event.c

+3 −1
Original line number Diff line number Diff line
@@ -61,7 +61,8 @@ bpf_object__next_program(const struct bpf_object *obj, struct bpf_program *prev) 
}

#endif



struct bpf_map * __weak

#ifndef HAVE_LIBBPF_BPF_OBJECT__NEXT_MAP

struct bpf_map *

bpf_object__next_map(const struct bpf_object *obj, const struct bpf_map *prev)

{

#pragma GCC diagnostic push
@@ -69,6 +70,7 @@ bpf_object__next_map(const struct bpf_object *obj, const struct bpf_map *prev) 
	return bpf_map__next(prev, obj);

#pragma GCC diagnostic pop

}

#endif



const void * __weak

btf__raw_data(const struct btf *btf_ro, __u32 *size)