Enable libunwind stacktrace printing with additional debug informatio…

…n (1014) (#1015) * Enable libunwind stacktrace printing with additional debug information (1014) * it will also print command to fetch function and line from external debug symbols file * logging agent version, improved labels and fixed logging in case of error
elastic · Jul 5, 2023 · 5257f69 · 5257f69
1 parent 8650c9c
commit 5257f69
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Showing 3 changed files with 53 additions and 23 deletions.
diff --git a/agent/native/ext/CMakeLists.txt b/agent/native/ext/CMakeLists.txt
@@ -35,14 +35,20 @@ foreach(_php_version ${_supported_php_versions})
                 "PHP_ATOM_INC"
                 "PHP_ABI=${CMAKE_C_COMPILER_ABI}")
 
+    if(MUSL_BUILD)
+        target_compile_definitions(${_Target}
+                PRIVATE
+                "__ELASTIC_LIBC_MUSL__"
+        )
+    endif()
+
     target_include_directories(${_Target} PUBLIC "${CONAN_INCLUDE_DIRS_PHP-HEADERS-${_php_version}}"
                                                 "${CONAN_INCLUDE_DIRS_PHP-HEADERS-${_php_version}}/ext"
                                                 "${CONAN_INCLUDE_DIRS_PHP-HEADERS-${_php_version}}/main"
                                                 "${CONAN_INCLUDE_DIRS_PHP-HEADERS-${_php_version}}/TSRM"
                                                 "${CONAN_INCLUDE_DIRS_PHP-HEADERS-${_php_version}}/Zend"
                                                 "${CONAN_INCLUDE_DIRS_LIBCURL}"
                                                 "${CONAN_INCLUDE_DIRS_LIBUNWIND}"
-
                                             )
 
     target_link_libraries(${_Target}

diff --git a/agent/native/ext/platform.c b/agent/native/ext/platform.c
@@ -18,6 +18,7 @@
  */
 
 #include "platform.h"
+#include "elastic_apm_version.h"
 #include <limits.h>
 #include <string.h>
 #include <stdlib.h>
@@ -36,6 +37,8 @@
 #   include <syslog.h>
 #   include <signal.h>
 #   include <errno.h>
+#define __USE_GNU
+#include <dlfcn.h>
 #endif
 
 #if defined( ELASTIC_APM_PLATFORM_HAS_LIBUNWIND )
@@ -378,30 +381,43 @@ void iterateOverCStackTraceLibUnwind( size_t numberOfFramesToSkip, IterateOverCS
     for (;; ++frameIndex)
     {
         // +1 is for this function frame
-        if ( frameIndex >= numberOfFramesToSkip + 1 )
-        {
-            // https://www.nongnu.org/libunwind/man/unw_get_proc_name(3).html
-            int getProcNameRetVal = unw_get_proc_name( &unwindCursor, funcNameBuffer, funcNameBufferSize, &offsetInsideFunc );
+        if ( frameIndex >= numberOfFramesToSkip + 1 ) {
             textOutputStreamRewind( &txtOutStream );
-            switch ( getProcNameRetVal ) // https://www.nongnu.org/libunwind/man/unw_get_proc_name(3).html
-            {
-                case 0: // On successful completion, unw_get_proc_name() returns 0
-                    callback( streamPrintf( &txtOutStream, "%s + 0x%X", funcNameBuffer, (unsigned int)offsetInsideFunc ), callbackCtx );
-                    break;
-                case UNW_EUNSPEC: // An unspecified error occurred.
-                    logErrorCallback( streamPrintf( &txtOutStream, "unw_get_proc_name call failed with return value UNW_EUNSPEC - stopping iteration over call stack" ), callbackCtx );
-                    return;
-                case UNW_ENOINFO: // Libunwind was unable to determine the name of the procedure.
-                    callback( NULL, callbackCtx );
-                    break;
-                case UNW_ENOMEM: // The procedure name is too long to fit in the buffer provided. A truncated version of the name has been returned.
-                    callback( streamPrintf( &txtOutStream, "%s (truncated) + 0x%X", funcNameBuffer, (unsigned int)offsetInsideFunc ), callbackCtx );
-                    break;
-                default:
-                    logErrorCallback( streamPrintf( &txtOutStream, "unw_get_proc_name call failed with an unexpected return value (%d) - stopping iteration over call stack", getProcNameRetVal ), callbackCtx );
-                    return;
+            unw_proc_info_t pi;
+            if (unw_get_proc_info(&unwindCursor, &pi) == 0) {
+                *funcNameBuffer = 0;
+                offsetInsideFunc = 0;
+                int getProcNameRetVal = unw_get_proc_name( &unwindCursor, funcNameBuffer, funcNameBufferSize, &offsetInsideFunc );
+                if (getProcNameRetVal != UNW_ESUCCESS && getProcNameRetVal != -UNW_ENOMEM) {
+                    strcpy(funcNameBuffer, "???");
+                    unw_word_t  pc;
+                    unw_get_reg(&unwindCursor, UNW_REG_IP, &pc);
+                    offsetInsideFunc = pc - pi.start_ip;
+                }
+
+                Dl_info dlInfo;
+                if (dladdr((const void *)pi.gp, &dlInfo)) {
+                    callback( streamPrintf( &txtOutStream, 
+                        "%s(%s+0x%lx) ModuleBase: %p FuncStart: 0x%lx FuncEnd: 0x%lx FuncStartRelative: 0x%lx FuncOffsetRelative: 0x%lx\n\t'addr2line -afCp -e \"%s\" %lx'\n",
+                        dlInfo.dli_fname ? dlInfo.dli_fname : "???",
+                        dlInfo.dli_sname ? dlInfo.dli_sname : funcNameBuffer,
+                        offsetInsideFunc,
+                        dlInfo.dli_fbase,
+                        pi.start_ip,
+                        pi.end_ip,
+                        (void*)pi.start_ip -  dlInfo.dli_fbase,
+                        (void*)pi.start_ip -  dlInfo.dli_fbase + offsetInsideFunc,
+                        dlInfo.dli_fname ? dlInfo.dli_fname : "???",
+                        (void*)pi.start_ip -  dlInfo.dli_fbase + offsetInsideFunc
+                        ), callbackCtx );
+                } else {
+                    logErrorCallback( streamPrintf( &txtOutStream, "dladdr failed on frame %zu", frameIndex), callbackCtx );
+                }
+            } else {
+                logErrorCallback( streamPrintf( &txtOutStream, "unw_get_proc_info failed on frame %zu", frameIndex), callbackCtx );
             }
         }
+
         int unwindStepRetVal = 0;
         ELASTIC_APM_LIBUNWIND_CALL_RETURN_ON_ERROR( unwindStepRetVal = unw_step( &unwindCursor ) );
         if ( unwindStepRetVal == 0 )
@@ -532,7 +548,13 @@ OsSignalHandler g_oldSignalHandler = NULL;
 
 void handleOsSignalLinux( int signalId )
 {
-    ELASTIC_APM_LOG_FROM_CRASH_SIGNAL_HANDLER( "Received signal %d (%s)", signalId, osSignalIdToName( signalId ) );
+#ifdef __ELASTIC_LIBC_MUSL__
+    #define LIBC_IMPL "musl"
+#else
+    #define LIBC_IMPL ""
+#endif
+
+    ELASTIC_APM_LOG_FROM_CRASH_SIGNAL_HANDLER( "Received signal %d (%s). Agent version: " PHP_ELASTIC_APM_VERSION " " LIBC_IMPL, signalId, osSignalIdToName( signalId ) );
     handleOsSignalLinux_writeStackTraceToSyslog();
 
     /* Call the default signal handler to have core dump generated... */

diff --git a/agent/native/ext/unit_tests/CMakeLists.txt b/agent/native/ext/unit_tests/CMakeLists.txt
@@ -111,6 +111,8 @@ LIST( APPEND source_files ${src_ext_dir}/time_util.h ${src_ext_dir}/time_util.c
 LIST( APPEND source_files ${src_ext_dir}/Tracer.h ${src_ext_dir}/Tracer.c )
 LIST( APPEND source_files ${src_ext_dir}/Tracer.h ${src_ext_dir}/util.c )
 
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libgcc -static-libstdc++ -pthread -ldl")
+
 IF ( NOT WIN32 )
     ADD_LINK_OPTIONS( -rdynamic )
 ENDIF()