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Message-ID: <aOQMzhBqoL8qs5t2@x1>
Date: Mon, 6 Oct 2025 15:39:10 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
Bill Wendling <morbo@...gle.com>,
Justin Stitt <justinstitt@...gle.com>,
Charlie Jenkins <charlie@...osinc.com>,
Eric Biggers <ebiggers@...nel.org>,
"Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
James Clark <james.clark@...aro.org>,
Collin Funk <collin.funk1@...il.com>,
"Dr. David Alan Gilbert" <linux@...blig.org>,
Li Huafei <lihuafei1@...wei.com>,
Athira Rajeev <atrajeev@...ux.ibm.com>,
Stephen Brennan <stephen.s.brennan@...cle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Alexandre Ghiti <alexghiti@...osinc.com>,
Haibo Xu <haibo1.xu@...el.com>, Andi Kleen <ak@...ux.intel.com>,
linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
bpf@...r.kernel.org, llvm@...ts.linux.dev,
Song Liu <song@...nel.org>
Subject: Re: [PATCH v7 00/11] Capstone/llvm improvements + dlopen support
On Sun, Oct 05, 2025 at 02:22:01PM -0700, Ian Rogers wrote:
> Linking against libcapstone and libLLVM can be a significant increase
> in dependencies and file size if building statically. For something
> like `perf record` the disassembler and addr2line functionality won't
> be used. Support dynamically loading these libraries using dlopen and
> then calling the appropriate functions found using dlsym.
>
> The patch series:
> 1) feature check libLLVM support and avoid always reinitializing the
> disassembler.
> 2) adds BPF JIT disassembly support to in memory disassemblers (LLVM
> and capstone) by just directing them at the BPF info linear JIT
> instructions (note this doesn't support source lines);
> 3) adds fallback to srcline's addr2line so that llvm_addr2line is
> tried first, then the deprecated libbfd and then the forked command
> tried next, moving the code for forking out of the main srcline.c
> file in the process.
> 4) adds perf_ variants of the capstone/llvm functions that will either
> directly call the function or use dlsym to discover it;
>
> The addr2line LLVM functionality is written in C++. To avoid linking
> against libLLVM for this, a new LIBLLVM_DYNAMIC option is added where
> the C++ code with the libLLVM dependency will be built into a
> libperf-llvm.so and that dlsym-ed and called against. Ideally LLVM
> would extend their C API to avoid this.
>
> v7: Refactor now the first 5 patches, that largely moved code around,
> have landed. Move the dlopen code to the end of the series so that
> the first 8 patches can be picked improving capstone/LLVM support
So I tentatively picked the first 8 patches, will test it now, hopefully
we can go with it to have BPF annotation...
Wait, will try to fix this one:
⬢ [acme@...lbx perf-tools-next]$ git log --oneline -1 ; time make -C tools/perf build-test
make_static: cd . && make LDFLAGS=-static NO_PERF_READ_VDSO32=1 NO_PERF_READ_VDSOX32=1 NO_JVMTI=1 NO_LIBTRACEEVENT=1 NO_LIBELF=1 -j32 DESTDIR=/tmp/tmp.w26bDGykTM
cd . && make LDFLAGS=-static NO_PERF_READ_VDSO32=1 NO_PERF_READ_VDSOX32=1 NO_JVMTI=1 NO_LIBTRACEEVENT=1 NO_LIBELF=1 -j32 DESTDIR=/tmp/tmp.w26bDGykTM
BUILD: Doing 'make -j32' parallel build
<SNIP>
Auto-detecting system features:
... libdw: [ OFF ]
... glibc: [ on ]
... libelf: [ OFF ]
... libnuma: [ OFF ]
... numa_num_possible_cpus: [ OFF ]
... libpython: [ OFF ]
... libcapstone: [ OFF ]
... llvm-perf: [ OFF ]
... zlib: [ OFF ]
... lzma: [ OFF ]
... get_cpuid: [ on ]
... bpf: [ on ]
... libaio: [ on ]
... libzstd: [ OFF ]
<SNIP>
CC tests/api-io.o
CC util/sha1.o
CC util/smt.o
LD util/intel-pt-decoder/perf-util-in.o
CC tests/demangle-java-test.o
CC util/strbuf.o
CC util/string.o
CC tests/demangle-ocaml-test.o
CC util/strlist.o
CC tests/demangle-rust-v0-test.o
CC tests/pfm.o
CC tests/parse-metric.o
CC util/strfilter.o
CC tests/pe-file-parsing.o
util/llvm.c: In function ‘init_llvm’:
util/llvm.c:78:17: error: implicit declaration of function ‘LLVMInitializeAllTargetInfos’ [-Wimplicit-function-declaration]
78 | LLVMInitializeAllTargetInfos();
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
util/llvm.c:79:17: error: implicit declaration of function ‘LLVMInitializeAllTargetMCs’ [-Wimplicit-function-declaration]
79 | LLVMInitializeAllTargetMCs();
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
util/llvm.c:80:17: error: implicit declaration of function ‘LLVMInitializeAllDisassemblers’ [-Wimplicit-function-declaration]
80 | LLVMInitializeAllDisassemblers();
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
util/llvm.c: At top level:
util/llvm.c:73:13: error: ‘init_llvm’ defined but not used [-Werror=unused-function]
73 | static void init_llvm(void)
| ^~~~~~~~~
cc1: all warnings being treated as errors
CC tests/expand-cgroup.o
CC util/top.o
CC tests/perf-time-to-tsc.o
CC util/usage.o
make[6]: *** [/home/acme/git/perf-tools-next/tools/build/Makefile.build:86: util/llvm.o] Error 1
make[6]: *** Waiting for unfinished jobs....
CC tests/dlfilter-test.o
CC tests/sigtrap.o
CC tests/event_groups.o
> without adding the dlopen code. Rename the cover letter and
> disassembler cleanup patches.
> v6: Refactor the libbfd along with capstone and LLVM, previous patch
> series had tried to avoid this by just removing the deprecated
> BUILD_NONDISTRO code. Remove the libtracefs removal into its own
> patch.
> v5: Rebase and comment typo fix.
> v4: Rebase and addition of a patch removing an unused struct variable.
> v3: Add srcline addr2line fallback trying LLVM first then forking a
> process. This came up in conversation with Steinar Gunderson
> <sesse@...gle.com>.
> Tweak the cover letter message to try to address Andi Kleen's
> <ak@...ux.intel.com> feedback that the series doesn't really
> achieve anything.
> v2: Add mangling of the function names in libperf-llvm.so to avoid
> potential infinite recursion. Add BPF JIT disassembly support to
> LLVM and capstone. Add/rebase the BUILD_NONDISTRO cleanup onto the
> series from:
> https://lore.kernel.org/lkml/20250111202851.1075338-1-irogers@google.com/
> Some other minor additional clean up.
>
> Ian Rogers (11):
> perf check: Add libLLVM feature
> perf llvm: Reduce LLVM initialization
> perf dso: Move read_symbol from llvm/capstone to dso
> perf dso: Support BPF programs in dso__read_symbol
> perf dso: Clean up read_symbol error handling
> perf disasm: Make ins__scnprintf and ins__is_nop static
> perf srcline: Fallback between addr2line implementations
> perf disasm: Remove unused evsel from annotate_args
> perf capstone: Support for dlopen-ing libcapstone.so
> perf llvm: Support for dlopen-ing libLLVM.so
> perf llvm: Mangle libperf-llvm.so function names
>
> tools/perf/Documentation/perf-check.txt | 1 +
> tools/perf/Makefile.config | 13 +
> tools/perf/Makefile.perf | 24 +-
> tools/perf/builtin-check.c | 1 +
> tools/perf/tests/make | 2 +
> tools/perf/util/Build | 3 +-
> tools/perf/util/addr2line.c | 439 +++++++++++++++++++++
> tools/perf/util/addr2line.h | 20 +
> tools/perf/util/annotate.c | 1 -
> tools/perf/util/capstone.c | 352 ++++++++++++-----
> tools/perf/util/config.c | 2 +-
> tools/perf/util/disasm.c | 18 +-
> tools/perf/util/disasm.h | 4 -
> tools/perf/util/dso.c | 112 ++++++
> tools/perf/util/dso.h | 4 +
> tools/perf/util/libbfd.c | 4 +-
> tools/perf/util/libbfd.h | 6 +-
> tools/perf/util/llvm-c-helpers.cpp | 120 +++++-
> tools/perf/util/llvm-c-helpers.h | 24 +-
> tools/perf/util/llvm.c | 374 +++++++++++++-----
> tools/perf/util/llvm.h | 3 -
> tools/perf/util/srcline.c | 495 ++----------------------
> tools/perf/util/srcline.h | 1 -
> 23 files changed, 1314 insertions(+), 709 deletions(-)
> create mode 100644 tools/perf/util/addr2line.c
> create mode 100644 tools/perf/util/addr2line.h
>
> --
> 2.51.0.618.g983fd99d29-goog
>
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