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Message-ID: <20251201205509.195451-1-irogers@google.com>
Date: Mon, 1 Dec 2025 12:54:59 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
Suzuki K Poulose <suzuki.poulose@....com>, Mike Leach <mike.leach@...aro.org>,
James Clark <james.clark@...aro.org>, John Garry <john.g.garry@...cle.com>,
Will Deacon <will@...nel.org>, Leo Yan <leo.yan@...ux.dev>,
Athira Rajeev <atrajeev@...ux.ibm.com>, tanze <tanze@...inos.cn>,
Stephen Brennan <stephen.s.brennan@...cle.com>, Andi Kleen <ak@...ux.intel.com>,
Chun-Tse Shao <ctshao@...gle.com>, Thomas Falcon <thomas.falcon@...el.com>,
Dapeng Mi <dapeng1.mi@...ux.intel.com>, "Dr. David Alan Gilbert" <linux@...blig.org>,
Christophe Leroy <christophe.leroy@...roup.eu>,
"Krzysztof Łopatowski" <krzysztof.m.lopatowski@...il.com>,
"Masami Hiramatsu (Google)" <mhiramat@...nel.org>, Alexandre Ghiti <alexghiti@...osinc.com>,
Haibo Xu <haibo1.xu@...el.com>, Sergei Trofimovich <slyich@...il.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org
Subject: [PATCH v2 00/10] perf: Refactor/add fallbacks for reading build-id
and debuglink
This cleans up some tech debt mentioned in the thread:
https://lore.kernel.org/lkml/aQt66zhfxSA80xwt@gentoo.org/
The perf tool has fallbacks for objdump but not in the case of
build-id and debuglink reading. Refactor the code so that in the case
of read_build_id it now looks like:
```
...
int filename__read_build_id(const char *filename, struct build_id *bid)
{
struct kmod_path m = { .name = NULL, };
char path[PATH_MAX];
int err, fd;
if (!filename)
return -EFAULT;
if (!is_regular_file(filename))
return -EWOULDBLOCK;
err = kmod_path__parse(&m, filename);
if (err)
return -1;
if (m.comp) {
int error = 0;
fd = filename__decompress(filename, path, sizeof(path), m.comp, &error);
if (fd < 0) {
pr_debug("Failed to decompress (error %d) %s\n",
error, filename);
return -1;
}
lseek(fd, 0, SEEK_SET);
filename = path;
} else {
fd = open(filename, O_RDONLY);
if (fd < 0) {
pr_debug("Failed to open %s\n", filename);
return -1;
}
}
err = libbfd__read_build_id(fd, filename, bid);
if (err == 0)
goto out;
err = libelf__read_build_id(fd, filename, bid);
if (err == 0)
goto out;
err = sym_min__read_build_id(fd, filename, bid);
out:
close(fd);
if (m.comp)
unlink(filename);
return err;
}
...
```
That is what was previously symbol-elf decompression code is now made
common for all cases of reading. The handling of "is_regular_file" is
now common. There is a clear fallback from libbfd to libelf to the
symbol-minimal (sym_min) versions of the functions.
To support this there is refactoring of code into a perf-libelf.c
file, to follow patterns established for the capstone, LLVM and libbfd
code.
v2: Rebase, resolving merge conflict with James' removal of the block
argument:
https://lore.kernel.org/lkml/20251121-james-perf-non-block-v1-1-6ab2702ab573@linaro.org/
Add a patch fixing an issue with return values from
filename__read_build_id. Some tweaks to the PPC arch__sym_update
patch commit message and make it 64-bit only. Change the
sysfs__read_build_id code combining the libelf and minimal
implementations but avoiding the memory read overhead, avoiding a
potential buffer overrun if the descsz was particularly large in a
build ID note, avoid reads and just using seeks.
v1: https://lore.kernel.org/lkml/20251123023225.8069-1-irogers@google.com/
Ian Rogers (10):
perf symbol: Reduce scope of elf__needs_adjust_symbols
perf symbol: Reduce scope of arch__sym_update
perf symbol: Move libelf code to its own file/header
perf symbol: Remove unused includes
perf symbol: Move dso__load_bfd_symbols out of symbol.h
perf symbol: Use fallbacks with filename__read_build_id
perf symbol: Use fallbacks for filename__read_debuglink
perf symbol: Make a common sysfs__read_build_id
perf dso: Move type helpers out of symbol and use fallbacks
perf symbol: Fix ENOENT case for filename__read_build_id
tools/perf/arch/powerpc/util/sym-handling.c | 7 -
tools/perf/builtin-annotate.c | 47 +--
tools/perf/builtin-buildid-cache.c | 6 +-
tools/perf/builtin-c2c.c | 58 +--
tools/perf/builtin-diff.c | 22 +-
tools/perf/builtin-inject.c | 19 +-
tools/perf/builtin-kmem.c | 41 ++-
tools/perf/builtin-kwork.c | 9 +-
tools/perf/builtin-mem.c | 16 +-
tools/perf/builtin-report.c | 76 ++--
tools/perf/builtin-sched.c | 50 ++-
tools/perf/builtin-script.c | 89 ++---
tools/perf/builtin-timechart.c | 34 +-
tools/perf/builtin-top.c | 85 +++--
tools/perf/builtin-trace.c | 82 ++---
.../scripts/python/Perf-Trace-Util/Context.c | 11 +-
tools/perf/tests/code-reading.c | 1 +
tools/perf/tests/hists_cumulate.c | 1 +
tools/perf/tests/hists_filter.c | 1 +
tools/perf/tests/hists_link.c | 1 +
tools/perf/tests/hists_output.c | 1 +
tools/perf/tests/mmap-thread-lookup.c | 1 +
tools/perf/tests/pe-file-parsing.c | 5 +-
tools/perf/util/Build | 6 +-
tools/perf/util/annotate-data.c | 7 +-
tools/perf/util/auxtrace.h | 1 +
tools/perf/util/block-info.c | 11 +-
tools/perf/util/build-id.c | 28 +-
tools/perf/util/callchain.c | 1 +
tools/perf/util/cs-etm.c | 1 +
tools/perf/util/data-convert-json.c | 30 +-
tools/perf/util/db-export.c | 16 +-
tools/perf/util/dlfilter.c | 11 +-
tools/perf/util/dlfilter.h | 1 +
tools/perf/util/dso.c | 57 +--
tools/perf/util/event.c | 41 ++-
tools/perf/util/evsel_fprintf.c | 14 +-
tools/perf/util/hist.c | 29 +-
tools/perf/util/intel-pt.c | 35 +-
tools/perf/util/kvm-stat.h | 5 +-
tools/perf/util/libbfd.c | 9 +-
tools/perf/util/libbfd.h | 12 +-
tools/perf/util/machine.c | 34 +-
tools/perf/util/perf-libelf.c | 235 ++++++++++++
tools/perf/util/perf-libelf.h | 58 +++
tools/perf/util/print_insn.c | 14 +-
tools/perf/util/probe-event.c | 1 +
tools/perf/util/probe-finder.c | 1 +
.../util/scripting-engines/trace-event-perl.c | 1 +
.../scripting-engines/trace-event-python.c | 1 +
tools/perf/util/symbol-elf.c | 338 +-----------------
tools/perf/util/symbol-minimal.c | 166 +++++----
tools/perf/util/symbol-minimal.h | 13 +
tools/perf/util/symbol.c | 107 +++++-
tools/perf/util/symbol.h | 44 +--
tools/perf/util/symbol_fprintf.c | 1 +
tools/perf/util/thread-stack.c | 12 +-
tools/perf/util/thread.c | 18 +-
tools/perf/util/unwind-libdw.c | 15 +-
59 files changed, 1079 insertions(+), 958 deletions(-)
create mode 100644 tools/perf/util/perf-libelf.c
create mode 100644 tools/perf/util/perf-libelf.h
create mode 100644 tools/perf/util/symbol-minimal.h
--
2.52.0.158.g65b55ccf14-goog
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