diagnose_unwind.py revision 297fc67ce9907e4ccbc2a1a013bd4c593c1c9b3d
13c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# This implements the "diagnose-unwind" command, usually installed 23c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# in the debug session like 33c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# command script import lldb.diagnose 43c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# it is used when lldb's backtrace fails -- it collects and prints 53c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# information about the stack frames, and tries an alternate unwind 63c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# algorithm, that will help to understand why lldb's unwind algorithm 73c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# did not succeed. 83c827367444ee418f129b2c238299f49d3264554Jarkko Poyry 93c827367444ee418f129b2c238299f49d3264554Jarkko Poyryimport optparse 103c827367444ee418f129b2c238299f49d3264554Jarkko Poyryimport lldb 113c827367444ee418f129b2c238299f49d3264554Jarkko Poyryimport re 123c827367444ee418f129b2c238299f49d3264554Jarkko Poyryimport shlex 133c827367444ee418f129b2c238299f49d3264554Jarkko Poyry 143c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# Print the frame number, pc, frame pointer, module UUID and function name 153c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# Returns the SBModule that contains the PC, if it could be found 163c827367444ee418f129b2c238299f49d3264554Jarkko Poyrydef backtrace_print_frame (target, frame_num, addr, fp): 173c827367444ee418f129b2c238299f49d3264554Jarkko Poyry process = target.GetProcess() 183c827367444ee418f129b2c238299f49d3264554Jarkko Poyry addr_for_printing = addr 193c827367444ee418f129b2c238299f49d3264554Jarkko Poyry addr_width = process.GetAddressByteSize() * 2 203c827367444ee418f129b2c238299f49d3264554Jarkko Poyry if frame_num > 0: 213c827367444ee418f129b2c238299f49d3264554Jarkko Poyry addr = addr - 1 223c827367444ee418f129b2c238299f49d3264554Jarkko Poyry 233c827367444ee418f129b2c238299f49d3264554Jarkko Poyry sbaddr = lldb.SBAddress() 243c827367444ee418f129b2c238299f49d3264554Jarkko Poyry try: 253c827367444ee418f129b2c238299f49d3264554Jarkko Poyry sbaddr.SetLoadAddress(addr, target) 263c827367444ee418f129b2c238299f49d3264554Jarkko Poyry module_description = "" 273c827367444ee418f129b2c238299f49d3264554Jarkko Poyry if sbaddr.GetModule(): 283c827367444ee418f129b2c238299f49d3264554Jarkko Poyry module_filename = "" 293c827367444ee418f129b2c238299f49d3264554Jarkko Poyry module_uuid_str = sbaddr.GetModule().GetUUIDString() 303c827367444ee418f129b2c238299f49d3264554Jarkko Poyry if module_uuid_str == None: 313c827367444ee418f129b2c238299f49d3264554Jarkko Poyry module_uuid_str = "" 323c827367444ee418f129b2c238299f49d3264554Jarkko Poyry if sbaddr.GetModule().GetFileSpec(): 333c827367444ee418f129b2c238299f49d3264554Jarkko Poyry module_filename = sbaddr.GetModule().GetFileSpec().GetFilename() 343c827367444ee418f129b2c238299f49d3264554Jarkko Poyry if module_filename == None: 353c827367444ee418f129b2c238299f49d3264554Jarkko Poyry module_filename = "" 363c827367444ee418f129b2c238299f49d3264554Jarkko Poyry if module_uuid_str != "" or module_filename != "": 373c827367444ee418f129b2c238299f49d3264554Jarkko Poyry module_description = '%s %s' % (module_filename, module_uuid_str) 383c827367444ee418f129b2c238299f49d3264554Jarkko Poyry except Exception: 393c827367444ee418f129b2c238299f49d3264554Jarkko Poyry print '%2d: pc==0x%-*x fp==0x%-*x' % (frame_num, addr_width, addr_for_printing, addr_width, fp) 403c827367444ee418f129b2c238299f49d3264554Jarkko Poyry return 413c827367444ee418f129b2c238299f49d3264554Jarkko Poyry 423c827367444ee418f129b2c238299f49d3264554Jarkko Poyry sym_ctx = target.ResolveSymbolContextForAddress(sbaddr, lldb.eSymbolContextEverything) 433c827367444ee418f129b2c238299f49d3264554Jarkko Poyry if sym_ctx.IsValid() and sym_ctx.GetSymbol().IsValid(): 443c827367444ee418f129b2c238299f49d3264554Jarkko Poyry function_start = sym_ctx.GetSymbol().GetStartAddress().GetLoadAddress(target) 453c827367444ee418f129b2c238299f49d3264554Jarkko Poyry offset = addr - function_start 463c827367444ee418f129b2c238299f49d3264554Jarkko Poyry print '%2d: pc==0x%-*x fp==0x%-*x %s %s + %d' % (frame_num, addr_width, addr_for_printing, addr_width, fp, module_description, sym_ctx.GetSymbol().GetName(), offset) 473c827367444ee418f129b2c238299f49d3264554Jarkko Poyry else: 483c827367444ee418f129b2c238299f49d3264554Jarkko Poyry print '%2d: pc==0x%-*x fp==0x%-*x %s' % (frame_num, addr_width, addr_for_printing, addr_width, fp, module_description) 493c827367444ee418f129b2c238299f49d3264554Jarkko Poyry return sbaddr.GetModule() 503c827367444ee418f129b2c238299f49d3264554Jarkko Poyry 513c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# A simple stack walk algorithm that follows the frame chain. 523c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# Returns a two-element list; the first element is a list of modules 533c827367444ee418f129b2c238299f49d3264554Jarkko Poyry# seen and the second element is a list of addresses seen during the backtrace. 543c827367444ee418f129b2c238299f49d3264554Jarkko Poyrydef simple_backtrace(debugger): 55 target = debugger.GetSelectedTarget() 56 process = target.GetProcess() 57 cur_thread = process.GetSelectedThread() 58 59 initial_fp = cur_thread.GetFrameAtIndex(0).GetFP() 60 61 # If the pseudoreg "fp" isn't recognized, on arm hardcode to r7 which is correct for Darwin programs. 62 if initial_fp == lldb.LLDB_INVALID_ADDRESS and target.triple[0:3] == "arm": 63 for reggroup in cur_thread.GetFrameAtIndex(1).registers: 64 if reggroup.GetName() == "General Purpose Registers": 65 for reg in reggroup: 66 if reg.GetName() == "r7": 67 initial_fp = int (reg.GetValue(), 16) 68 69 module_list = [] 70 address_list = [cur_thread.GetFrameAtIndex(0).GetPC()] 71 this_module = backtrace_print_frame (target, 0, cur_thread.GetFrameAtIndex(0).GetPC(), initial_fp) 72 if this_module != None: 73 module_list.append (this_module) 74 if cur_thread.GetNumFrames() < 2: 75 return [module_list, address_list] 76 77 cur_fp = process.ReadPointerFromMemory (initial_fp, lldb.SBError()) 78 cur_pc = process.ReadPointerFromMemory (initial_fp + process.GetAddressByteSize(), lldb.SBError()) 79 80 frame_num = 1 81 82 while cur_pc != 0 and cur_fp != 0 and cur_pc != lldb.LLDB_INVALID_ADDRESS and cur_fp != lldb.LLDB_INVALID_ADDRESS: 83 address_list.append (cur_pc) 84 this_module = backtrace_print_frame (target, frame_num, cur_pc, cur_fp) 85 print_stack_frame (process, cur_fp) 86 print "" 87 if this_module != None: 88 module_list.append (this_module) 89 frame_num = frame_num + 1 90 next_pc = 0 91 next_fp = 0 92 if target.triple[0:6] == "x86_64" or target.triple[0:4] == "i386" or target.triple[0:3] == "arm": 93 error = lldb.SBError() 94 next_pc = process.ReadPointerFromMemory(cur_fp + process.GetAddressByteSize(), error) 95 if not error.Success(): 96 next_pc = 0 97 next_fp = process.ReadPointerFromMemory(cur_fp, error) 98 if not error.Success(): 99 next_fp = 0 100 # Clear the 0th bit for arm frames - this indicates it is a thumb frame 101 if target.triple[0:3] == "arm" and (next_pc & 1) == 1: 102 next_pc = next_pc & ~1 103 cur_pc = next_pc 104 cur_fp = next_fp 105 this_module = backtrace_print_frame (target, frame_num, cur_pc, cur_fp) 106 print_stack_frame (process, cur_fp) 107 print "" 108 if this_module != None: 109 module_list.append (this_module) 110 return [module_list, address_list] 111 112def print_stack_frame(process, fp): 113 if fp == 0 or fp == lldb.LLDB_INVALID_ADDRESS or fp == 1: 114 return 115 addr_size = process.GetAddressByteSize() 116 addr = fp - (2 * addr_size) 117 i = 0 118 outline = "Stack frame from $fp-%d: " % (2 * addr_size) 119 error = lldb.SBError() 120 try: 121 while i < 5 and error.Success(): 122 address = process.ReadPointerFromMemory(addr + (i * addr_size), error) 123 outline += " 0x%x" % address 124 i += 1 125 print outline 126 except Exception: 127 return 128 129def diagnose_unwind(debugger, command, result, dict): 130 """ 131Gather diagnostic information to help debug incorrect unwind (backtrace) 132behavior in lldb. When there is a backtrace that doesn't look 133correct, run this command with the correct thread selected and a 134large amount of diagnostic information will be printed, it is likely 135to be helpful when reporting the problem. 136 """ 137 138 command_args = shlex.split(command) 139 parser = create_diagnose_unwind_options() 140 try: 141 (options, args) = parser.parse_args(command_args) 142 except: 143 return 144 target = debugger.GetSelectedTarget() 145 if target: 146 process = target.GetProcess() 147 if process: 148 thread = process.GetSelectedThread() 149 if thread: 150 lldb_versions_match = re.search(r'[lL][lL][dD][bB]-(\d+)([.](\d+))?([.](\d+))?', debugger.GetVersionString()) 151 lldb_version = 0 152 lldb_minor = 0 153 if len(lldb_versions_match.groups()) >= 1 and lldb_versions_match.groups()[0]: 154 lldb_major = int(lldb_versions_match.groups()[0]) 155 if len(lldb_versions_match.groups()) >= 5 and lldb_versions_match.groups()[4]: 156 lldb_minor = int(lldb_versions_match.groups()[4]) 157 158 modules_seen = [] 159 addresses_seen = [] 160 161 print 'LLDB version %s' % debugger.GetVersionString() 162 print 'Unwind diagnostics for thread %d' % thread.GetIndexID() 163 print "" 164 print "=============================================================================================" 165 print "" 166 print "OS plugin setting:" 167 debugger.HandleCommand("settings show target.process.python-os-plugin-path") 168 print "" 169 print "Live register context:" 170 thread.SetSelectedFrame(0) 171 debugger.HandleCommand("register read") 172 print "" 173 print "=============================================================================================" 174 print "" 175 print "lldb's unwind algorithm:" 176 print "" 177 frame_num = 0 178 for frame in thread.frames: 179 if not frame.IsInlined(): 180 this_module = backtrace_print_frame (target, frame_num, frame.GetPC(), frame.GetFP()) 181 print_stack_frame (process, frame.GetFP()) 182 print "" 183 if this_module != None: 184 modules_seen.append (this_module) 185 addresses_seen.append (frame.GetPC()) 186 frame_num = frame_num + 1 187 print "" 188 print "=============================================================================================" 189 print "" 190 print "Simple stack walk algorithm:" 191 print "" 192 (module_list, address_list) = simple_backtrace(debugger) 193 if module_list and module_list != None: 194 modules_seen += module_list 195 if address_list and address_list != None: 196 addresses_seen = set(addresses_seen) 197 addresses_seen.update(set(address_list)) 198 199 print "" 200 print "=============================================================================================" 201 print "" 202 print "Modules seen in stack walks:" 203 print "" 204 modules_already_seen = set() 205 for module in modules_seen: 206 if module != None and module.GetFileSpec().GetFilename() != None: 207 if not module.GetFileSpec().GetFilename() in modules_already_seen: 208 debugger.HandleCommand('image list %s' % module.GetFileSpec().GetFilename()) 209 modules_already_seen.add(module.GetFileSpec().GetFilename()) 210 211 print "" 212 print "=============================================================================================" 213 print "" 214 print "Disassembly ofaddresses seen in stack walks:" 215 print "" 216 additional_addresses_to_disassemble = addresses_seen 217 for frame in thread.frames: 218 if not frame.IsInlined(): 219 print "--------------------------------------------------------------------------------------" 220 print "" 221 print "Disassembly of %s, frame %d, address 0x%x" % (frame.GetFunctionName(), frame.GetFrameID(), frame.GetPC()) 222 print "" 223 if target.triple[0:6] == "x86_64" or target.triple[0:4] == "i386": 224 debugger.HandleCommand('disassemble -F att -a 0x%x' % frame.GetPC()) 225 else: 226 debugger.HandleCommand('disassemble -a 0x%x' % frame.GetPC()) 227 if frame.GetPC() in additional_addresses_to_disassemble: 228 additional_addresses_to_disassemble.remove (frame.GetPC()) 229 230 for address in list(additional_addresses_to_disassemble): 231 print "--------------------------------------------------------------------------------------" 232 print "" 233 print "Disassembly of 0x%x" % address 234 print "" 235 if target.triple[0:6] == "x86_64" or target.triple[0:4] == "i386": 236 debugger.HandleCommand('disassemble -F att -a 0x%x' % address) 237 else: 238 debugger.HandleCommand('disassemble -a 0x%x' % address) 239 240 print "" 241 print "=============================================================================================" 242 print "" 243 additional_addresses_to_show_unwind = addresses_seen 244 for frame in thread.frames: 245 if not frame.IsInlined(): 246 print "--------------------------------------------------------------------------------------" 247 print "" 248 print "Unwind instructions for %s, frame %d" % (frame.GetFunctionName(), frame.GetFrameID()) 249 print "" 250 debugger.HandleCommand('image show-unwind -a "0x%x"' % frame.GetPC()) 251 if frame.GetPC() in additional_addresses_to_show_unwind: 252 additional_addresses_to_show_unwind.remove (frame.GetPC()) 253 254 for address in list(additional_addresses_to_show_unwind): 255 print "--------------------------------------------------------------------------------------" 256 print "" 257 print "Unwind instructions for 0x%x" % address 258 print "" 259 debugger.HandleCommand('image show-unwind -a "0x%x"' % address) 260 261def create_diagnose_unwind_options(): 262 usage = "usage: %prog" 263 description='''Print diagnostic information about a thread backtrace which will help to debug unwind problems''' 264 parser = optparse.OptionParser(description=description, prog='diagnose_unwind',usage=usage) 265 return parser 266 267lldb.debugger.HandleCommand('command script add -f %s.diagnose_unwind diagnose-unwind' % __name__) 268print 'The "diagnose-unwind" command has been installed, type "help diagnose-unwind" for detailed help.' 269