The special object contained the string "kernel-error" which were used
to tag VM errors. But it is simplier and removes a little complexity to
just tag them with a fixnum constant.
No need for a special out of memory function -- it's just a kind of
fatal error. Also make fatal_error() call dump_memory_layout() for
easier debugging.
If we got here from memory_protection_error(), then the stack pointer
has been fiddled with and the elements of these vectors, which address
stack-allocated objects, are bogus and needs to be resetted.
Revert "errors.cpp: general_error() throws away its args when it calls compact_gc() when compiled with DEBUG=1. Save the args as data_roots instead. Fixes#615. See #620."
This reverts commit dc46297050.
* Clear faulting_p from a safepoint rather than inside general_error, because jumping into unwind-native-frames could blow up.
* Handle multiple faults from fatal_error by breakpointing. Is there anything else we can safely do at that point?
* Verify memory protection faults in the top half of the signal handlers because signal dispatch could fault. Treat memory faults during gc or fep as fatal errors.
* Add a function factor_vm::abort() that restores the default SIGABRT handler and ::abort()s. Use it from fatal_error() so we get useful context from gdb and so the user gets feedback from the system crash reporter that Factor blew up and didn't just disappear.
* In factorbug(), don't proceed with .s .r .c if it would be unsafe to do so.
* Don't pile on signals if we've already called fatal_error().
On OS X it appears the mach exception thread and libdispatch queue threads occasionally get the SIGALRM from the itimer. Count those as foreign_thread_samples instead of letting the signal kill the process.
Set up the state necessary to collect samples. We still need to add GC support for walking the sample set, and the compiler needs to register GC roots before safepoints as well. We also need primitives to expose the data to Factor for reporting.
This will let us safely unguard the callstack overflow guard page as a grace page so the callstack overflow handler can do its business without discarding frames.
Also rename "q" to "c" because it "c"ontinues, remove the useless "im" command, and rename the less useful "t" to "trim" so we can use "t" to mean "throw"
Björn Lindqvist
Alexander Iljin
John Benediktsson
Doug Coleman
Erik Charlebois
Joe Groff