From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 352FA3624C5; Tue, 27 Jan 2026 17:12:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769533969; cv=none; b=DkNAB4TXJ5Yj/PD16hpSuAlw4UXHXZvO4W2NotowDsMqTNw689qvIw8HYReOtS/uC/q1SHEMGwSqXLzv9kwbNE27TfUzNEG58fjjGZObl03qkPNbxoByCWhZ3dKpARGEji8+/LjX0qH0/cgPJ1mrgWfAvAuj+rnsZ79U9EOjbWU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769533969; c=relaxed/simple; bh=es7Lzi+GLpreS3paNVEOSrq0wFpglPAFO/+T/8F9y4Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=rfsB5GR6NpBg8Uzo0msXmTtGp+xCkVtC79r0yrYslKz5VW13okDXiKKPl1MEkhzbjR/qk1KDgImMPl8VGhl7x7XxF80dvnOwpgIKKOPnjOeOAOxWbSLhiFFxsi09tbjTreL+tHiqkY8C7D+Gp7mxuM+T9Cp51m1TXt4qYtAkAGo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bgA2EBOW; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bgA2EBOW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45C49C116C6; Tue, 27 Jan 2026 17:12:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769533968; bh=es7Lzi+GLpreS3paNVEOSrq0wFpglPAFO/+T/8F9y4Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bgA2EBOWzd4zlvhbfAZOHLgja7/mlc+pOtcKyw7PGj8HKRHlW25GFZb+/thcTdEz4 JtRGWBiCe8OBRGnsfnVK2Bu5Bzyb/CVAd6fPY33kN5dMXtlJoCPbvIAR1sEWLd1tT6 u2JDC2Dow3V+Yt2JthmvwYNOQonOUcBsM3TKnixAqax3umM69h4nFU7J57RcE2GEfu N7y8YTQV/AGUbzICEPuvx8Dq5ZkTXI/+GYui+62HH1jE27ywVEMnhFV4Bvqmbh0msk O+IUeyy0KMEPU9l4pfW9uAyJKj6V3XWsP06J49DsSBllwWjRFOLdJ7RkYXl6OGT4vb wqKCQHGD6iN6A== Date: Tue, 27 Jan 2026 14:12:45 -0300 From: Arnaldo Carvalho de Melo To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Namhyung Kim , Alexander Shishkin , Jiri Olsa , Adrian Hunter , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Charlie Jenkins , "Masami Hiramatsu (Google)" , James Clark , Collin Funk , Dmitry Vyukov , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v9 0/3] Capstone/llvm dlopen support Message-ID: References: <20260127062302.544809-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260127062302.544809-1-irogers@google.com> On Mon, Jan 26, 2026 at 10:22:59PM -0800, Ian Rogers wrote: > Linking against libcapstone and libLLVM can be a significant increase > in dependencies and file size if building statically. The dependencies > are also quite cumbersome if bringing perf into a distribution. For > something like `perf record` the disassembler and addr2line > functionality of libcapstone and libLLVM won't be used. These patches > support dynamically loading these libraries using dlopen and then > calling the appropriate functions found using dlsym. Using dlopen > allows libcapstone and libLLVM to be installed separately to perf and > when that's done the performance will improve as separate commands for > objdump and addr2line won't be invoked. > > The patch series adds perf_ variants of the capstone/llvm functions > that will either directly call the function or (NO_CAPSTONE=1 and > NO_LIBLLVM=1 cases) use dlopen/dlsym to discover and then call the > function. To support the function signatures when > HAVE_LIBCAPSTONE_SUPPORT and HAVE_LIBLLVM_SUPPORT aren't defined > prototypes generated using pahole are given. This avoids requiring > libcapstone or libLLVM for the sake of the header files. It also > avoids having a build where neither dlopen or dynamic linking against > libcapstone or libLLVM is supported. There are other possibilities in > how to organize this, but the chosen approach was done so for the > simplicity and cleanliness of the code. > > 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. > > v9: Rebase. Thanks, applied locally, will test this after lunch. - Arnaldo > v8: Rebase down to 3 patches. Update commit and cover messages. > 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 > 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 > . > Tweak the cover letter message to try to address Andi Kleen's > 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 (3): > 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/Makefile.config | 13 ++ > tools/perf/Makefile.perf | 24 ++- > tools/perf/tests/make | 2 + > tools/perf/util/Build | 2 +- > tools/perf/util/capstone.c | 285 +++++++++++++++++++++++++---- > tools/perf/util/llvm-c-helpers.cpp | 120 +++++++++++- > tools/perf/util/llvm-c-helpers.h | 24 ++- > tools/perf/util/llvm.c | 273 ++++++++++++++++++++++++--- > 8 files changed, 660 insertions(+), 83 deletions(-) > > -- > 2.52.0.457.g6b5491de43-goog >