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jpolo1224
7daa89e0e7
Arkham City dies of SIGSEGV about 140ms after the game writes PS3Progress_Frame_1,
on both the Qualcomm driver and Turnip, with the database on or off, Multithreaded
RSX on or off, and the RSX profiler on or off. A table of ten runs showed no setting
correlates with it.
The reason it took so long to even establish that it WAS a segfault: nothing records
it. No tombstone (/data/tombstones is root-only, so its emptiness proves nothing), no
logcat crash-buffer entry, and no line from our own handler. The single witness
anywhere is Zygote:
I Zygote : Process <pid> exited due to signal 11 (Segmentation fault)
That combination is what a stack overflow looks like here. The handler is installed
with SA_SIGINFO alone, so it runs on the faulting thread's own stack; if that stack is
what overflowed there is nowhere to run, it faults again immediately, and the kernel
applies the default action having written nothing.
So: an alternate signal stack per thread in thread_base::initialize, and SA_ONSTACK on
the handler. Thread-local rather than shared, because two threads can fault at once and
a shared stack would corrupt whichever report lost the race.
This does not fix the fault. It makes the fault reportable, which is the thing that has
been missing all along: the next occurrence should log where it came from instead of
vanishing. Android only.