Commit 1d0654b7 authored by Blake Jones's avatar Blake Jones Committed by Namhyung Kim
Browse files

perf build: detect support for libbpf's emit_strings option 

This creates a config option that detects libbpf's ability to display
character arrays as strings, which was just added to the BPF tree
(https://git.kernel.org/bpf/bpf-next/c/87c9c79a02b4

).

To test this change, I built perf (from later in this patch set) with:

 - static libbpf (default, using source from kernel tree)
 - dynamic libbpf (LIBBPF_DYNAMIC=1 LIBBPF_INCLUDE=/usr/local/include)

For both the static and dynamic versions, I used headers with and without
the ".emit_strings" option.

I verified that of the four resulting binaries, the two with
".emit_strings" would successfully record BPF_METADATA events, and the two
without wouldn't.  All four binaries would successfully display
BPF_METADATA events, because the relevant bit of libbpf code is only used
during "perf record".

Signed-off-by: default avatarBlake Jones <blakejones@google.com>
Link: https://lore.kernel.org/r/20250612194939.162730-2-blakejones@google.com


Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
parent 13b38e6b

tools/build/Makefile.feature

+1 −0
Original line number Diff line number Diff line
@@ -126,6 +126,7 @@ FEATURE_TESTS_EXTRA := \ 
         llvm                           \

         clang                          \

         libbpf                         \

         libbpf-strings                 \

         libpfm4                        \

         libdebuginfod			\

         clang-bpf-co-re		\

tools/build/feature/Makefile

+4 −0
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ FILES= \ 
         test-lzma.bin                          \

         test-bpf.bin                           \

         test-libbpf.bin                        \

         test-libbpf-strings.bin                \

         test-get_cpuid.bin                     \

         test-sdt.bin                           \

         test-cxx.bin                           \
@@ -339,6 +340,9 @@ $(OUTPUT)test-bpf.bin: 
$(OUTPUT)test-libbpf.bin:

	$(BUILD) -lbpf



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

	$(BUILD)



$(OUTPUT)test-sdt.bin:

	$(BUILD)

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

0 → 100644
+10 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <bpf/btf.h>



int main(void)

{

	struct btf_dump_type_data_opts opts;



	opts.emit_strings = 0;

	return opts.emit_strings;

}

tools/perf/Documentation/perf-check.txt

+1 −0
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ feature:: 
                dwarf-unwind            /  HAVE_DWARF_UNWIND_SUPPORT

                auxtrace                /  HAVE_AUXTRACE_SUPPORT

                libbfd                  /  HAVE_LIBBFD_SUPPORT

                libbpf-strings          /  HAVE_LIBBPF_STRINGS_SUPPORT

                libcapstone             /  HAVE_LIBCAPSTONE_SUPPORT

                libcrypto               /  HAVE_LIBCRYPTO_SUPPORT

                libdw-dwarf-unwind      /  HAVE_LIBDW_SUPPORT

tools/perf/Makefile.config

+8 −0
Original line number Diff line number Diff line
@@ -595,8 +595,16 @@ ifndef NO_LIBELF 
          LIBBPF_STATIC := 1

          $(call detected,CONFIG_LIBBPF)

          CFLAGS += -DHAVE_LIBBPF_SUPPORT

	  LIBBPF_INCLUDE = $(LIBBPF_DIR)/..

        endif

      endif



      FEATURE_CHECK_CFLAGS-libbpf-strings="-I$(LIBBPF_INCLUDE)"

      $(call feature_check,libbpf-strings)

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

        $(call detected,CONFIG_LIBBPF_STRINGS)

        CFLAGS += -DHAVE_LIBBPF_STRINGS_SUPPORT

      endif

    endif

  endif # NO_LIBBPF

endif # NO_LIBELF