# Copyright 2014 the V8 project authors. All rights reserved. # Use of this source code is governed by a BSD-style license that can be # found in the LICENSE file. # Print tagged object. define job call (void) _v8_internal_Print_Object((void*)($arg0)) end document job Print a v8 JavaScript object Usage: job tagged_ptr end # Print content of v8::internal::Handle. define jh call (void) _v8_internal_Print_Object(*((v8::internal::Object**)($arg0).location_)) end document jh Print content of a v8::internal::Handle Usage: jh internal_handle end # Print content of v8::Local handle. define jlh call (void) _v8_internal_Print_Object(*((v8::internal::Object**)($arg0).val_)) end document jlh Print content of a v8::Local handle Usage: jlh local_handle end # Print Code objects containing given PC. define jco call (void) _v8_internal_Print_Code((void*)($arg0)) end document jco Print a v8 Code object from an internal code address Usage: jco pc end # Print LayoutDescriptor. define jld call (void) _v8_internal_Print_LayoutDescriptor((void*)($arg0)) end document jld Print a v8 LayoutDescriptor object Usage: jld tagged_ptr end # Print TransitionTree. define jtt call (void) _v8_internal_Print_TransitionTree((void*)($arg0)) end document jtt Print the complete transition tree of the given v8 Map. Usage: jtt tagged_ptr end # Print JavaScript stack trace. define jst call (void) _v8_internal_Print_StackTrace() end document jst Print the current JavaScript stack trace Usage: jst end # Print TurboFan graph node. define pn call _v8_internal_Node_Print((void*)($arg0)) end document pn Print a v8 TurboFan graph node Usage: pn node_address end # Skip the JavaScript stack. define jss set $js_entry_sp=v8::internal::Isolate::Current()->thread_local_top()->js_entry_sp_ set $rbp=*(void**)$js_entry_sp set $rsp=$js_entry_sp + 2*sizeof(void*) set $pc=*(void**)($js_entry_sp+sizeof(void*)) end document jss Skip the jitted stack on x64 to where we entered JS last. Usage: jss end # Print stack trace with assertion scopes. define bta python import re frame_re = re.compile("^#(\d+)\s*(?:0x[a-f\d]+ in )?(.+) \(.+ at (.+)") assert_re = re.compile("^\s*(\S+) = .+") btl = gdb.execute("backtrace full", to_string = True).splitlines() for l in btl: match = frame_re.match(l) if match: print("[%-2s] %-60s %-40s" % (match.group(1), match.group(2), match.group(3))) match = assert_re.match(l) if match: if match.group(3) == "false": prefix = "Disallow" color = "\033[91m" else: prefix = "Allow" color = "\033[92m" print("%s -> %s %s (%s)\033[0m" % (color, prefix, match.group(2), match.group(1))) end end document bta Print stack trace with assertion scopes Usage: bta end # Search for a pointer inside all valid pages. define space_find set $space = $arg0 set $current_page = $space->first_page() while ($current_page != 0) printf "# Searching in %p - %p\n", $current_page->area_start(), $current_page->area_end()-1 find $current_page->area_start(), $current_page->area_end()-1, $arg1 set $current_page = $current_page->next_page() end end define heap_find set $heap = v8::internal::Isolate::Current()->heap() printf "# Searching for %p in old_space ===============================\n", $arg0 space_find $heap->old_space() ($arg0) printf "# Searching for %p in map_space ===============================\n", $arg0 space_find $heap->map_space() $arg0 printf "# Searching for %p in code_space ===============================\n", $arg0 space_find $heap->code_space() $arg0 end document heap_find Find the location of a given address in V8 pages. Usage: heap_find address end # The 'disassembly-flavor' command is only available on i386 and x84_64. python try: gdb.execute("set disassembly-flavor intel") except gdb.error: pass end set disable-randomization off # Install a handler whenever the debugger stops due to a signal. It walks up the # stack looking for V8_Dcheck and moves the frame to the one above it so it's # immediately at the line of code that triggered the DCHECK. python def dcheck_stop_handler(event): frame = gdb.selected_frame() select_frame = None message = None count = 0 # limit stack scanning since they're usually shallow and otherwise stack # overflows can be very slow. while frame is not None and count < 7: count += 1 if frame.name() == 'V8_Dcheck': frame_message = gdb.lookup_symbol('message', frame.block())[0] if frame_message: message = frame_message.value(frame).string() select_frame = frame.older() break if frame.name() is not None and frame.name().startswith('V8_Fatal'): select_frame = frame.older() frame = frame.older() if select_frame is not None: select_frame.select() gdb.execute('frame') if message: print('DCHECK error: {}'.format(message)) gdb.events.stop.connect(dcheck_stop_handler) end # Code imported from chromium/src/tools/gdb/gdbinit python import os import subprocess import sys compile_dirs = set() def get_current_debug_file_directories(): dir = gdb.execute("show debug-file-directory", to_string=True) dir = dir[ len('The directory where separate debug symbols are searched for is "' ):-len('".') - 1] return set(dir.split(":")) def add_debug_file_directory(dir): # gdb has no function to add debug-file-directory, simulates that by using # `show debug-file-directory` and `set debug-file-directory `. current_dirs = get_current_debug_file_directories() current_dirs.add(dir) gdb.execute( "set debug-file-directory %s" % ":".join(current_dirs), to_string=True) def newobj_handler(event): global compile_dirs compile_dir = os.path.dirname(event.new_objfile.filename) if not compile_dir: return if compile_dir in compile_dirs: return compile_dirs.add(compile_dir) # Add source path gdb.execute("dir %s" % compile_dir) # Need to tell the location of .dwo files. # https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html # https://crbug.com/603286#c35 add_debug_file_directory(compile_dir) # Event hook for newly loaded objfiles. # https://sourceware.org/gdb/onlinedocs/gdb/Events-In-Python.html gdb.events.new_objfile.connect(newobj_handler) gdb.execute("set environment V8_GDBINIT_SOURCED=1") end