[PATCH v1 7/9] perf symbol: Use fallbacks for filename__read_debuglink

Ian Rogers
2025-11-23T02:32:42Z

Try libbfd and then libelf in symbol.c. Remove the non-existent
symbol-minimal version.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/perf-libelf.c | 52 +++++++++++++++++++++++++++++
tools/perf/util/perf-libelf.h | 10 ++++++
tools/perf/util/symbol-elf.c | 56 --------------------------------
tools/perf/util/symbol-minimal.c | 9 -----
tools/perf/util/symbol.c | 10 ++++++
5 files changed, 72 insertions(+), 65 deletions(-)

diff --git a/tools/perf/util/perf-libelf.c b/tools/perf/util/perf-libelf.c
index c7fa08a177d0..a8a8c39056da 100644
--- a/tools/perf/util/perf-libelf.c
+++ b/tools/perf/util/perf-libelf.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#include "perf-libelf.h"

+#include <fcntl.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
@@ -143,3 +144,54 @@ int libelf__read_build_id(int _fd, const char *filename, struct build_id *bid)
out:
return err;
}
+
+int libelf_filename__read_debuglink(const char *filename, char *debuglink, size_t size)
+{
+ int fd, err = -1;
+ Elf *elf;
+ GElf_Ehdr ehdr;
+ GElf_Shdr shdr;
+ Elf_Data *data;
+ Elf_Scn *sec;
+ Elf_Kind ek;
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0)
+ goto out;
+
+ elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
+ if (elf == NULL) {
+ pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
+ goto out_close;
+ }
+
+ ek = elf_kind(elf);
+ if (ek != ELF_K_ELF)
+ goto out_elf_end;
+
+ if (gelf_getehdr(elf, &ehdr) == NULL) {
+ pr_err("%s: cannot get elf header.\n", __func__);
+ goto out_elf_end;
+ }
+
+ sec = elf_section_by_name(elf, &ehdr, &shdr,
+ ".gnu_debuglink", NULL);
+ if (sec == NULL)
+ goto out_elf_end;
+
+ data = elf_getdata(sec, NULL);
+ if (data == NULL)
+ goto out_elf_end;
+
+ /* the start of this section is a zero-terminated string */
+ strncpy(debuglink, data->d_buf, size);
+
+ err = 0;
+
+out_elf_end:
+ elf_end(elf);
+out_close:
+ close(fd);
+out:
+ return err;
+}
diff --git a/tools/perf/util/perf-libelf.h b/tools/perf/util/perf-libelf.h
index 931597493b1f..167679f9fc9b 100644
--- a/tools/perf/util/perf-libelf.h
+++ b/tools/perf/util/perf-libelf.h
@@ -2,6 +2,8 @@
#ifndef __PERF_LIBELF_H
#define __PERF_LIBELF_H

+#include <stddef.h>
+
struct build_id;

#ifdef HAVE_LIBELF_SUPPORT
@@ -30,6 +32,7 @@ Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep, GElf_Shdr *shp, const char
int __libelf__read_build_id(Elf *elf, void *bf, size_t size);

int libelf__read_build_id(int _fd, const char *filename, struct build_id *bid);
+int libelf_filename__read_debuglink(const char *filename, char *debuglink, size_t size);

#else // !defined(HAVE_LIBELF_SUPPORT)

@@ -40,6 +43,13 @@ static inline int libelf__read_build_id(int fd __always_unused,
return -1;
}

+static inline int libelf_filename__read_debuglink(const char *filename __always_unused,
+ char *debuglink __always_unused,
+ size_t size __always_unused)
+{
+ return -1;
+}
+
#endif // defined(HAVE_LIBELF_SUPPORT)

#endif /* __PERF_LIBELF_H */
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index b301f1263ecc..d4a1b01010c1 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -801,62 +801,6 @@ int sysfs__read_build_id(const char *filename, struct build_id *bid)
return err;
}

-int filename__read_debuglink(const char *filename, char *debuglink,
- size_t size)
-{
- int fd, err = -1;
- Elf *elf;
- GElf_Ehdr ehdr;
- GElf_Shdr shdr;
- Elf_Data *data;
- Elf_Scn *sec;
- Elf_Kind ek;
-
- err = libbfd_filename__read_debuglink(filename, debuglink, size);
- if (err >= 0)
- goto out;
-
- fd = open(filename, O_RDONLY);
- if (fd < 0)
- goto out;
-
- elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
- if (elf == NULL) {
- pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
- goto out_close;
- }
-
- ek = elf_kind(elf);
- if (ek != ELF_K_ELF)
- goto out_elf_end;
-
- if (gelf_getehdr(elf, &ehdr) == NULL) {
- pr_err("%s: cannot get elf header.\n", __func__);
- goto out_elf_end;
- }
-
- sec = elf_section_by_name(elf, &ehdr, &shdr,
- ".gnu_debuglink", NULL);
- if (sec == NULL)
- goto out_elf_end;
-
- data = elf_getdata(sec, NULL);
- if (data == NULL)
- goto out_elf_end;
-
- /* the start of this section is a zero-terminated string */
- strncpy(debuglink, data->d_buf, size);
-
- err = 0;
-
-out_elf_end:
- elf_end(elf);
-out_close:
- close(fd);
-out:
- return err;
-}
-
bool symsrc__possibly_runtime(struct symsrc *ss)
{
return ss->dynsym || ss->opdsec;
diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index f9adeb09ef00..8700c0628437 100644
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -77,15 +77,6 @@ static int read_build_id(void *note_data, size_t note_len, struct build_id *bid,
return -1;
}

-#ifndef HAVE_LIBELF_SUPPORT
-int filename__read_debuglink(const char *filename __maybe_unused,
- char *debuglink __maybe_unused,
- size_t size __maybe_unused)
-{
- return -1;
-}
-#endif
-
/*
* Just try PT_NOTE header otherwise fails
*/
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index c8795e1da2df..1152d11a0366 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -2049,6 +2049,16 @@ int filename__read_build_id(const char *filename, struct build_id *bid, bool blo
return err;
}

+int filename__read_debuglink(const char *filename, char *debuglink, size_t size)
+{
+ int err = libbfd_filename__read_debuglink(filename, debuglink, size);
+
+ if (err == 0)
+ return 0;
+
+ return libelf_filename__read_debuglink(filename, debuglink, size);
+}
+
static char *dso__find_kallsyms(struct dso *dso, struct map *map)
{
struct build_id bid = { .size = 0, };
--
2.52.0.rc2.455.g230fcf2819-goog