jasonmolenda created this revision.
jasonmolenda added a reviewer: kastiglione.
jasonmolenda added a project: LLDB.
Herald added subscribers: JDevlieghere, kristof.beyls.
Herald added a project: All.
jasonmolenda requested review of this revision.
Herald added a subscriber: lldb-commits.
A common crash is calling through a null function pointer and trying to execute
an instruction at address 0. lldb's backtracer special cases this, but the
macOS crash tracer algorithm does not; crash reports will have a stack frame at
0 and then skip the calling stack frame, assuming a stack frame was set up. On
arm64, the caller function is likely available in $lr, so let's insert a stack
frame with that return pc value.
Also fix a little bug where register names without a "prefix" would get "None"
prepended, so "Nonepc", "Nonelr" etc.
rdar://92631787
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D125042
Files:
lldb/examples/python/crashlog.py
Index: lldb/examples/python/crashlog.py
===================================================================
--- lldb/examples/python/crashlog.py
+++ lldb/examples/python/crashlog.py
@@ -516,6 +516,22 @@
image_addr = self.get_used_image(image_id)['base']
pc = image_addr + frame_offset
thread.frames.append(self.crashlog.Frame(idx, pc, frame_offset))
+
+ # on arm64 systems, if jump through a null function pointer,
+ # we end up at address 0 and the crash reporter unwinder
+ # misses the frame that actually faulted.
+ # But $lr can tell us where the last BL/BLR instruction used
+ # was at, so insert that address as the caller stack frame.
+ if idx == 0 and pc == 0 and "lr" in thread.registers:
+ pc = thread.registers["lr"]
+ for image in self.data['usedImages']:
+ text_lo = image['base']
+ text_hi = text_lo + image['size']
+ if text_lo <= pc < text_hi:
+ idx += 1
+ frame_offset = pc - text_lo
+ thread.frames.append(self.crashlog.Frame(idx, pc,
frame_offset))
+
idx += 1
def parse_threads(self, json_threads):
@@ -551,7 +567,7 @@
continue
try:
value = int(state['value'])
- registers["{}{}".format(prefix,key)] = value
+ registers["{}{}".format(prefix or '',key)] = value
except (KeyError, ValueError, TypeError):
pass
return registers
Index: lldb/examples/python/crashlog.py
===================================================================
--- lldb/examples/python/crashlog.py
+++ lldb/examples/python/crashlog.py
@@ -516,6 +516,22 @@
image_addr = self.get_used_image(image_id)['base']
pc = image_addr + frame_offset
thread.frames.append(self.crashlog.Frame(idx, pc, frame_offset))
+
+ # on arm64 systems, if jump through a null function pointer,
+ # we end up at address 0 and the crash reporter unwinder
+ # misses the frame that actually faulted.
+ # But $lr can tell us where the last BL/BLR instruction used
+ # was at, so insert that address as the caller stack frame.
+ if idx == 0 and pc == 0 and "lr" in thread.registers:
+ pc = thread.registers["lr"]
+ for image in self.data['usedImages']:
+ text_lo = image['base']
+ text_hi = text_lo + image['size']
+ if text_lo <= pc < text_hi:
+ idx += 1
+ frame_offset = pc - text_lo
+ thread.frames.append(self.crashlog.Frame(idx, pc, frame_offset))
+
idx += 1
def parse_threads(self, json_threads):
@@ -551,7 +567,7 @@
continue
try:
value = int(state['value'])
- registers["{}{}".format(prefix,key)] = value
+ registers["{}{}".format(prefix or '',key)] = value
except (KeyError, ValueError, TypeError):
pass
return registers
_______________________________________________
lldb-commits mailing list
lldb-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
