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{
    "id": 13922,
    "url": "https://patchwork.libcamera.org/api/1.1/patches/13922/?format=api",
    "web_url": "https://patchwork.libcamera.org/patch/13922/",
    "project": {
        "id": 1,
        "url": "https://patchwork.libcamera.org/api/1.1/projects/1/?format=api",
        "name": "libcamera",
        "link_name": "libcamera",
        "list_id": "libcamera_core",
        "list_email": "libcamera-devel@lists.libcamera.org",
        "web_url": "",
        "scm_url": "",
        "webscm_url": ""
    },
    "msgid": "<20210924102323.26787-4-laurent.pinchart@ideasonboard.com>",
    "date": "2021-09-24T10:23:22",
    "name": "[libcamera-devel,v1,3/4] libcamera: base: backtrace: Use libunwind when available",
    "commit_ref": null,
    "pull_url": null,
    "state": "accepted",
    "archived": false,
    "hash": "4ee8b784944b4d8cc1b5d6ba6cb9f420e1a93a13",
    "submitter": {
        "id": 2,
        "url": "https://patchwork.libcamera.org/api/1.1/people/2/?format=api",
        "name": "Laurent Pinchart",
        "email": "laurent.pinchart@ideasonboard.com"
    },
    "delegate": null,
    "mbox": "https://patchwork.libcamera.org/patch/13922/mbox/",
    "series": [
        {
            "id": 2562,
            "url": "https://patchwork.libcamera.org/api/1.1/series/2562/?format=api",
            "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=2562",
            "date": "2021-09-24T10:23:19",
            "name": "libcamera: Improve backtraces",
            "version": 1,
            "mbox": "https://patchwork.libcamera.org/series/2562/mbox/"
        }
    ],
    "comments": "https://patchwork.libcamera.org/api/patches/13922/comments/",
    "check": "pending",
    "checks": "https://patchwork.libcamera.org/api/patches/13922/checks/",
    "tags": {},
    "headers": {
        "Return-Path": "<libcamera-devel-bounces@lists.libcamera.org>",
        "X-Original-To": "parsemail@patchwork.libcamera.org",
        "Delivered-To": "parsemail@patchwork.libcamera.org",
        "Received": [
            "from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 1FFD0BDC71\n\tfor <parsemail@patchwork.libcamera.org>;\n\tFri, 24 Sep 2021 10:23:36 +0000 (UTC)",
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        ],
        "Authentication-Results": "lancelot.ideasonboard.com;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"G/M8QDbw\"; dkim-atps=neutral",
        "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1632479010;\n\tbh=evYR6+uZ6P7pXUXp9HzemyUQDU+nfKG1LrzBvG6LjtI=;\n\th=From:To:Subject:Date:In-Reply-To:References:From;\n\tb=G/M8QDbwS9x7NtGDx3eR8fpcAulbvG23ef+FsPsB/I7FYz73KhQadrMGKrgGBBt7v\n\tP17128+SwwxhNSBahTRX5DcM6eFPnpNFpYcm7gdW+YjhBgNCMUb2zNV6RAYcodTbrW\n\taEPRpOVe8QCMRtxf07ffLe9Hi+On79s6dzQUgrhk=",
        "From": "Laurent Pinchart <laurent.pinchart@ideasonboard.com>",
        "To": "libcamera-devel@lists.libcamera.org",
        "Date": "Fri, 24 Sep 2021 13:23:22 +0300",
        "Message-Id": "<20210924102323.26787-4-laurent.pinchart@ideasonboard.com>",
        "X-Mailer": "git-send-email 2.32.0",
        "In-Reply-To": "<20210924102323.26787-1-laurent.pinchart@ideasonboard.com>",
        "References": "<20210924102323.26787-1-laurent.pinchart@ideasonboard.com>",
        "MIME-Version": "1.0",
        "Content-Transfer-Encoding": "8bit",
        "Subject": "[libcamera-devel] [PATCH v1 3/4] libcamera: base: backtrace: Use\n\tlibunwind when available",
        "X-BeenThere": "libcamera-devel@lists.libcamera.org",
        "X-Mailman-Version": "2.1.29",
        "Precedence": "list",
        "List-Id": "<libcamera-devel.lists.libcamera.org>",
        "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>",
        "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>",
        "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>",
        "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>",
        "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>",
        "Errors-To": "libcamera-devel-bounces@lists.libcamera.org",
        "Sender": "\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>"
    },
    "content": "libunwind is an alternative to glibc's backtrace() to extract a\nbacktrace. Use it when available to extend backtrace support to more\nplatforms.\n\nSigned-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>\n---\n include/libcamera/base/backtrace.h |  3 ++\n src/libcamera/base/backtrace.cpp   | 61 ++++++++++++++++++++++++++++--\n src/libcamera/base/meson.build     |  6 +++\n 3 files changed, 67 insertions(+), 3 deletions(-)",
    "diff": "diff --git a/include/libcamera/base/backtrace.h b/include/libcamera/base/backtrace.h\nindex aefc76defa83..58ccc14c8f81 100644\n--- a/include/libcamera/base/backtrace.h\n+++ b/include/libcamera/base/backtrace.h\n@@ -26,6 +26,9 @@ public:\n private:\n \tLIBCAMERA_DISABLE_COPY(Backtrace)\n \n+\tbool backtraceTrace();\n+\tbool unwindTrace();\n+\n \tstd::vector<void *> backtrace_;\n };\n \ndiff --git a/src/libcamera/base/backtrace.cpp b/src/libcamera/base/backtrace.cpp\nindex 011f2e428d5d..40fa60d0f9bf 100644\n--- a/src/libcamera/base/backtrace.cpp\n+++ b/src/libcamera/base/backtrace.cpp\n@@ -18,6 +18,15 @@\n #include <unistd.h>\n #endif\n \n+#if HAVE_UNWIND\n+/*\n+ * Disable support for remote unwinding to enable a more optimized\n+ * implementation.\n+ */\n+#define UNW_LOCAL_ONLY\n+#include <libunwind.h>\n+#endif\n+\n #include <sstream>\n \n #include <libcamera/base/span.h>\n@@ -146,6 +155,15 @@ std::string DwflParser::stackEntry(const void *ip)\n  * It can later be converted to a string with toString().\n  */\n Backtrace::Backtrace()\n+{\n+\t/* Try libunwind first and fall back to backtrace() if it fails. */\n+\tif (unwindTrace())\n+\t\treturn;\n+\n+\tbacktraceTrace();\n+}\n+\n+bool Backtrace::backtraceTrace()\n {\n #if HAVE_BACKTRACE\n \tbacktrace_.resize(32);\n@@ -153,10 +171,44 @@ Backtrace::Backtrace()\n \tint num_entries = backtrace(backtrace_.data(), backtrace_.size());\n \tif (num_entries < 0) {\n \t\tbacktrace_.clear();\n-\t\treturn;\n+\t\treturn false;\n \t}\n \n \tbacktrace_.resize(num_entries);\n+\n+\treturn true;\n+#else\n+\treturn false;\n+#endif\n+}\n+\n+bool Backtrace::unwindTrace()\n+{\n+#if HAVE_UNWIND\n+\tunw_context_t uc;\n+\tint ret = unw_getcontext(&uc);\n+\tif (ret)\n+\t\treturn false;\n+\n+\tunw_cursor_t cursor;\n+\tret = unw_init_local(&cursor, &uc);\n+\tif (ret)\n+\t\treturn false;\n+\n+\tdo {\n+\t\tunw_word_t ip;\n+\t\tret = unw_get_reg(&cursor, UNW_REG_IP, &ip);\n+\t\tif (ret) {\n+\t\t\tbacktrace_.push_back(nullptr);\n+\t\t\tcontinue;\n+\t\t}\n+\n+\t\tbacktrace_.push_back(reinterpret_cast<void *>(ip));\n+\t} while (unw_step(&cursor) > 0);\n+\n+\treturn true;\n+#else\n+\treturn false;\n #endif\n }\n \n@@ -181,8 +233,11 @@ Backtrace::Backtrace()\n  */\n std::string Backtrace::toString(unsigned int skipLevels) const\n {\n-\t/* Skip the first entry, corresponding to the Backtrace construction. */\n-\tskipLevels += 1;\n+\t/*\n+\t * Skip the first two entries, corresponding to the Backtrace\n+\t * construction.\n+\t */\n+\tskipLevels += 2;\n \n \tif (backtrace_.size() <= skipLevels)\n \t\treturn std::string();\ndiff --git a/src/libcamera/base/meson.build b/src/libcamera/base/meson.build\nindex 1fa894cf1896..8d14a65648fc 100644\n--- a/src/libcamera/base/meson.build\n+++ b/src/libcamera/base/meson.build\n@@ -20,6 +20,7 @@ libcamera_base_sources = files([\n ])\n \n libdw = cc.find_library('libdw', required : false)\n+libunwind = cc.find_library('libunwind', required : false)\n \n if cc.has_header_symbol('execinfo.h', 'backtrace')\n     config_h.set('HAVE_BACKTRACE', 1)\n@@ -29,10 +30,15 @@ if libdw.found()\n     config_h.set('HAVE_DW', 1)\n endif\n \n+if libunwind.found()\n+    config_h.set('HAVE_UNWIND', 1)\n+endif\n+\n libcamera_base_deps = [\n     dependency('threads'),\n     libatomic,\n     libdw,\n+    libunwind,\n ]\n \n # Internal components must use the libcamera_base_private dependency to enable\n",
    "prefixes": [
        "libcamera-devel",
        "v1",
        "3/4"
    ]
}