From patchwork Sun Oct 3 22:36:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Pinchart X-Patchwork-Id: 14028 Return-Path: X-Original-To: parsemail@patchwork.libcamera.org Delivered-To: parsemail@patchwork.libcamera.org Received: from lancelot.ideasonboard.com (lancelot.ideasonboard.com [92.243.16.209]) by patchwork.libcamera.org (Postfix) with ESMTPS id BEAEBC3243 for ; Sun, 3 Oct 2021 22:36:17 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id 2E986691C2; Mon, 4 Oct 2021 00:36:17 +0200 (CEST) Authentication-Results: lancelot.ideasonboard.com; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="fkMk2Dz0"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 15C56691AB for ; Mon, 4 Oct 2021 00:36:15 +0200 (CEST) Received: from pendragon.lan (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 97B58BBE for ; Mon, 4 Oct 2021 00:36:14 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1633300574; bh=khgFm8zw3UkfDQoi7PC5aiZoF4KM6T1HhcidNZwiCJc=; h=From:To:Subject:Date:In-Reply-To:References:From; b=fkMk2Dz0WRIJZYresQhtxMy2rbpaA7LfcvRusX/pOxC3Xr1h2L+Jb0ujgwbspiuW5 yCIUae0K/eFDbf00CTou/j5QdajrHbJP14xkbu4af/wA6XRmP+bw1GhacJB2rHe6QQ 2Stc8qZaD3mkzXGvbTwwP66G1iXUkiWZFdmvmvH8= From: Laurent Pinchart To: libcamera-devel@lists.libcamera.org Date: Mon, 4 Oct 2021 01:36:03 +0300 Message-Id: <20211003223606.20016-2-laurent.pinchart@ideasonboard.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211003223606.20016-1-laurent.pinchart@ideasonboard.com> References: <20211003223606.20016-1-laurent.pinchart@ideasonboard.com> MIME-Version: 1.0 Subject: [libcamera-devel] [PATCH v2 1/4] libcamera: base: Add Backtrace class X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" Create a new class to abstract generation and access to call stack backtraces. The current implementation depends on the glibc backtrace() implementation and is copied from the logger. Future development will bring support for libunwind, transparently for the users of the class. The logger backtrace implementation is dropped, replaced by usage of the new Backtrace class. Signed-off-by: Laurent Pinchart Reviewed-by: Kieran Bingham Reviewed-by: Paul Elder --- Changes since v1: - Print message when backtrace isn't available --- include/libcamera/base/backtrace.h | 34 +++++++++ include/libcamera/base/meson.build | 1 + meson.build | 4 -- src/libcamera/base/backtrace.cpp | 107 +++++++++++++++++++++++++++++ src/libcamera/base/log.cpp | 27 +++----- src/libcamera/base/meson.build | 5 ++ 6 files changed, 155 insertions(+), 23 deletions(-) create mode 100644 include/libcamera/base/backtrace.h create mode 100644 src/libcamera/base/backtrace.cpp diff --git a/include/libcamera/base/backtrace.h b/include/libcamera/base/backtrace.h new file mode 100644 index 000000000000..aefc76defa83 --- /dev/null +++ b/include/libcamera/base/backtrace.h @@ -0,0 +1,34 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2021, Ideas on Board Oy + * + * backtrace.h - Call stack backtraces + */ +#ifndef __LIBCAMERA_BASE_BACKTRACE_H__ +#define __LIBCAMERA_BASE_BACKTRACE_H__ + +#include +#include + +#include + +#include + +namespace libcamera { + +class Backtrace +{ +public: + Backtrace(); + + std::string toString(unsigned int skipLevels = 0) const; + +private: + LIBCAMERA_DISABLE_COPY(Backtrace) + + std::vector backtrace_; +}; + +} /* namespace libcamera */ + +#endif /* __LIBCAMERA_BASE_BACKTRACE_H__ */ diff --git a/include/libcamera/base/meson.build b/include/libcamera/base/meson.build index 9feb4b9346d5..525aba9d2919 100644 --- a/include/libcamera/base/meson.build +++ b/include/libcamera/base/meson.build @@ -3,6 +3,7 @@ libcamera_base_include_dir = libcamera_include_dir / 'base' libcamera_base_headers = files([ + 'backtrace.h', 'bound_method.h', 'class.h', 'event_dispatcher.h', diff --git a/meson.build b/meson.build index a49c484fe64e..dfed01ba26bc 100644 --- a/meson.build +++ b/meson.build @@ -29,10 +29,6 @@ cc = meson.get_compiler('c') cxx = meson.get_compiler('cpp') config_h = configuration_data() -if cc.has_header_symbol('execinfo.h', 'backtrace') - config_h.set('HAVE_BACKTRACE', 1) -endif - if cc.has_header_symbol('unistd.h', 'issetugid') config_h.set('HAVE_ISSETUGID', 1) endif diff --git a/src/libcamera/base/backtrace.cpp b/src/libcamera/base/backtrace.cpp new file mode 100644 index 000000000000..c010a7e42e4d --- /dev/null +++ b/src/libcamera/base/backtrace.cpp @@ -0,0 +1,107 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2021, Ideas on Board Oy + * + * backtrace.h - Call stack backtraces + */ + +#include + +#if HAVE_BACKTRACE +#include +#include +#endif + +#include + +#include + +/** + * \file backtrace.h + * \brief Generate call stack backtraces + */ + +namespace libcamera { + +/** + * \class Backtrace + * \brief Representation of a call stack backtrace + * + * The Backtrace class represents a function call stack. Constructing an + * instance captures the call stack at the point the instance is constructed. + * The instance can later be used to access the call stack and to generate a + * human-readable representation with the toString() function. + * + * Depending on the platform, different backends can be used to generate the + * backtrace. The Backtrace class provides a best effort to capture accurate + * backtraces, but doesn't offer any guarantee of a particular backtrace format. + */ + +/** + * \brief Construct a backtrace + * + * The backtrace captures the call stack at the point where it is constructed. + * It can later be converted to a string with toString(). + */ +Backtrace::Backtrace() +{ +#if HAVE_BACKTRACE + backtrace_.resize(32); + + int num_entries = backtrace(backtrace_.data(), backtrace_.size()); + if (num_entries < 0) { + backtrace_.clear(); + return; + } + + backtrace_.resize(num_entries); +#endif +} + +/** + * \brief Convert a backtrace to a string representation + * \param[in] skipLevels Number of initial levels to skip in the backtrace + * + * The string representation of the backtrace is a multi-line string, with one + * line per call stack entry. The format of the entries isn't specified and is + * platform-dependent. + * + * The \a skipLevels parameter indicates how many initial entries to skip from + * the backtrace. This can be used to hide functions that wrap the construction + * of the Backtrace instance from the call stack. The Backtrace constructor + * itself is automatically skipped and never shown in the backtrace. + * + * If backtrace generation fails for any reason (usually because the platform + * doesn't support this feature), an empty string is returned. + * + * \return A string representation of the backtrace, or an empty string if + * backtrace generation isn't possible + */ +std::string Backtrace::toString(unsigned int skipLevels) const +{ + /* Skip the first entry, corresponding to the Backtrace construction. */ + skipLevels += 1; + + if (backtrace_.size() <= skipLevels) + return std::string(); + +#if HAVE_BACKTRACE + Span trace{ backtrace_ }; + trace = trace.subspan(skipLevels); + + char **strings = backtrace_symbols(trace.data(), trace.size()); + if (strings) { + std::ostringstream msg; + + for (unsigned int i = 0; i < trace.size(); ++i) + msg << strings[i] << std::endl; + + free(strings); + return msg.str(); + } +#endif + + return std::string(); +} + +} /* namespace libcamera */ diff --git a/src/libcamera/base/log.cpp b/src/libcamera/base/log.cpp index a3e3f9ea2712..64813b6607c5 100644 --- a/src/libcamera/base/log.cpp +++ b/src/libcamera/base/log.cpp @@ -8,9 +8,6 @@ #include #include -#if HAVE_BACKTRACE -#include -#endif #include #include #include @@ -23,6 +20,7 @@ #include +#include #include #include @@ -418,31 +416,22 @@ void Logger::write(const LogMessage &msg) */ void Logger::backtrace() { -#if HAVE_BACKTRACE std::shared_ptr output = std::atomic_load(&output_); if (!output) return; - void *buffer[32]; - int num_entries = ::backtrace(buffer, std::size(buffer)); - char **strings = backtrace_symbols(buffer, num_entries); - if (!strings) - return; - - std::ostringstream msg; - msg << "Backtrace:" << std::endl; - /* * Skip the first two entries that correspond to this function and * ~LogMessage(). */ - for (int i = 2; i < num_entries; ++i) - msg << strings[i] << std::endl; + std::string backtrace = Backtrace().toString(2); + if (backtrace.empty()) { + output->write("Backtrace not available\n"); + return; + } - output->write(msg.str()); - - free(strings); -#endif + output->write("Backtrace:\n"); + output->write(backtrace); } /** diff --git a/src/libcamera/base/meson.build b/src/libcamera/base/meson.build index d17249a023e1..fc00296dfa8a 100644 --- a/src/libcamera/base/meson.build +++ b/src/libcamera/base/meson.build @@ -1,6 +1,7 @@ # SPDX-License-Identifier: CC0-1.0 libcamera_base_sources = files([ + 'backtrace.cpp', 'class.cpp', 'bound_method.cpp', 'event_dispatcher.cpp', @@ -18,6 +19,10 @@ libcamera_base_sources = files([ 'utils.cpp', ]) +if cc.has_header_symbol('execinfo.h', 'backtrace') + config_h.set('HAVE_BACKTRACE', 1) +endif + libcamera_base_deps = [ dependency('threads'), libatomic,