| """ |
| In asm code, out-of-bounds heap accesses cause segfaults, which the engine |
| handles internally. Make GDB ignore them. |
| """ |
| |
| import gdb |
| |
| SIGSEGV = 11 |
| |
| # A sigaction buffer for each inferior process. |
| sigaction_buffers = {} |
| |
| def on_stop(event): |
| if isinstance(event, gdb.SignalEvent) and event.stop_signal == 'SIGSEGV': |
| # Allocate memory for sigaction, once per js shell process. |
| process = gdb.selected_inferior() |
| buf = sigaction_buffers.get(process) |
| if buf is None: |
| buf = gdb.parse_and_eval("(struct sigaction *) malloc(sizeof(struct sigaction))") |
| sigaction_buffers[process] = buf |
| |
| # See if AsmJSFaultHandler is installed as the SIGSEGV signal action. |
| sigaction_fn = gdb.parse_and_eval('__sigaction') |
| sigaction_fn(SIGSEGV, 0, buf) |
| AsmJSFaultHandler = gdb.parse_and_eval("AsmJSFaultHandler") |
| if buf['__sigaction_handler']['sa_handler'] == AsmJSFaultHandler: |
| # Advise the user that magic is happening. |
| print("js/src/gdb/mozilla/asmjs.py: Allowing AsmJSFaultHandler to run.") |
| |
| # If AsmJSFaultHandler doesn't handle this segfault, it will unhook |
| # itself and re-raise. |
| gdb.execute("continue") |
| |
| def on_exited(event): |
| if event.inferior in sigaction_buffers: |
| del sigaction_buffers[event.inferior] |
| |
| def install(): |
| gdb.events.stop.connect(on_stop) |
| gdb.events.exited.connect(on_exited) |