perf build-ids: Fall back to debuginfod query if debuginfo not found

During a perf-record, use the -ldebuginfod API to query a debuginfod
server, should the debug data not be found in the usual system
locations.  If successful, the usual $HOME/.debug dir is populated.

Tested with:

  $ find .
  .
  ./ctags-debuginfo-5.8-26.fc31.x86_64.rpm
  ./usr
  ./usr/lib
  ./usr/lib/debug
  ./usr/lib/debug/.build-id
  ./usr/lib/debug/.build-id/ca
  ./usr/lib/debug/.build-id/ca/46f6ae6a0cee57d85abc1d461c49074248908d
  ./usr/lib/debug/.build-id/ca/46f6ae6a0cee57d85abc1d461c49074248908d.debug
  ./usr/lib/debug/usr
  ./usr/lib/debug/usr/bin
  ./usr/lib/debug/usr/bin/ctags-5.8-26.fc31.x86_64.debug

  $ debuginfod  -F .
  ...

  $ rm -rf ~/.debug/ ; mkdir ~/.debug

  $ perf record make tags
    BUILD:   Doing 'make -j8' parallel build
    GEN      tags
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.107 MB perf.data (1483 samples) ]

  $ find ~/.debug | grep ctags
  /home/jolsa/.debug/usr/bin/ctags
  /home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d
  /home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d/elf
  /home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d/probes

  $ rm -rf ~/.debug/ ; mkdir ~/.debug

  $ DEBUGINFOD_URLS=http://localhost:8002 perf record make tags
    BUILD:   Doing 'make -j8' parallel build
    GEN      tags
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.108 MB perf.data (1531 samples) ]

  $ find ~/.debug | grep ctag
  /home/jolsa/.debug/usr/bin/ctags
  /home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d
  /home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d/debug
  /home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d/elf
  /home/jolsa/.debug/usr/bin/ctags/ca46f6ae6a0cee57d85abc1d461c49074248908d/probes

Note the 'debug' file is created in the last run.

Note that currently the debuginfo data are downloaded only on record path,
we still need add this support to perf build-id/report.. and test ;-)

Tested-by: Jiri Olsa <[email protected]>
Signed-off-by: Jiri Olsa <[email protected]>
Signed-off-by: Frank Ch. Eigler <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index e7818b44b48eef61c8821a50acbd53d8a28ed946..c1daf4d57518c5790cd295aa013a55f4fe629560 100644 (file)
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -98,7 +98,8 @@ FEATURE_TESTS_EXTRA :=                  \
          llvm-version                   \
          clang                          \
          libbpf                         \
-         libpfm4
+         libpfm4                        \
+         libdebuginfod
 
 FEATURE_TESTS ?= $(FEATURE_TESTS_BASIC)
 

diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 846ee1341a5cc21cd0f6d3e66a3434664b6124c9..d220fe952747053a80b7c2a4096cedd8baf886d2 100644 (file)
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -26,6 +26,7 @@ FILES=                                          \
          test-libelf-gelf_getnote.bin           \
          test-libelf-getshdrstrndx.bin          \
          test-libelf-mmap.bin                   \
+         test-libdebuginfod.bin                 \
          test-libnuma.bin                       \
          test-numa_num_possible_cpus.bin        \
          test-libperl.bin                       \
@@ -157,6 +158,9 @@ $(OUTPUT)test-libelf-gelf_getnote.bin:
 $(OUTPUT)test-libelf-getshdrstrndx.bin:
        $(BUILD) -lelf
 
+$(OUTPUT)test-libdebuginfod.bin:
+       $(BUILD) -ldebuginfod
+
 $(OUTPUT)test-libnuma.bin:
        $(BUILD) -lnuma
 

diff --git a/tools/build/feature/test-libdebuginfod.c b/tools/build/feature/test-libdebuginfod.c
new file mode 100644 (file)
index 0000000..da22548
--- /dev/null
+++ b/tools/build/feature/test-libdebuginfod.c
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <elfutils/debuginfod.h>
+
+int main(void)
+{
+       debuginfod_client* c = debuginfod_begin();
+       return (long)c;
+}

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 513633809c81ef7c6fc75211400ebc769f6ba1ea..190be4fa5c2187f37d37e7b3f4e66fcb392a6f6b 100644 (file)
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -501,6 +501,14 @@ ifndef NO_LIBELF
     CFLAGS += -DHAVE_ELF_GETSHDRSTRNDX_SUPPORT
   endif
 
+  ifndef NO_LIBDEBUGINFOD
+    $(call feature_check,libdebuginfod)
+    ifeq ($(feature-libdebuginfod), 1)
+      CFLAGS += -DHAVE_DEBUGINFOD_SUPPORT
+      EXTLIBS += -ldebuginfod
+    endif
+  endif
+
   ifndef NO_DWARF
     ifeq ($(origin PERF_HAVE_DWARF_REGS), undefined)
       msg := $(warning DWARF register mappings have not been defined for architecture $(SRCARCH), DWARF support disabled);

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index e339e225410c85435d342c624834b3407b4d2d39..6031167939ae609f613b8dfc71ac3314d38ead8e 100644 (file)
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -124,6 +124,8 @@ include ../scripts/utilities.mak
 #
 # Define LIBPFM4 to enable libpfm4 events extension.
 #
+# Define NO_LIBDEBUGINFOD if you do not want support debuginfod
+#
 
 # As per kernel Makefile, avoid funny character set dependencies
 unexport LC_ALL

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index c076fc7fe02530873169ea6d4577aa73091159c6..31207b6e20667cff26c1c2c50c716c04e737a20f 100644 (file)
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -31,6 +31,10 @@
 #include "probe-file.h"
 #include "strlist.h"
 
+#ifdef HAVE_DEBUGINFOD_SUPPORT
+#include <elfutils/debuginfod.h>
+#endif
+
 #include <linux/ctype.h>
 #include <linux/zalloc.h>
 
@@ -636,6 +640,21 @@ static char *build_id_cache__find_debug(const char *sbuild_id,
        if (realname && access(realname, R_OK))
                zfree(&realname);
        nsinfo__mountns_exit(&nsc);
+
+#ifdef HAVE_DEBUGINFOD_SUPPORT
+        if (realname == NULL) {
+                debuginfod_client* c = debuginfod_begin();
+                if (c != NULL) {
+                        int fd = debuginfod_find_debuginfo(c,
+                                                           (const unsigned char*)sbuild_id, 0,
+                                                           &realname);
+                        if (fd >= 0)
+                                close(fd); /* retaining reference by realname */
+                        debuginfod_end(c);
+                }
+        }
+#endif
+
 out:
        free(debugfile);
        return realname;