🚀 go-pugleaf

In article <2203@tivoli.UUCP> bjv@shasta.tivoli.com (Brian Vetter) writes:
>I am working on a program that creates its own lightweight threads (must manage
>the stacks).  To detect stack overflow, I am using the mprotect() system
>call to create a guard page at the end of the stack.  Instead of just dumping
>core when the stack overflows, I want to exit the failed thread (the others
>get to keep running).
>
>My idea is to use setjmp() at the beginning of each thread to provide a "place"
>to come back, and to call longjmp() from the bus error handler.  To do this,
>I have to have a separate signal stack (using sigstack() and sigvec()).
>
>The guard page works (I get my bus error), but I can't unwind the stack
>using longjmp().  I'm doing this on a Sun4 (ELC), and I suspect that there
>is some register window weirdness going on.
>
>The function calling setjmp gets control after the longjmp but it gets a
>bus error as soon as it returns to its caller.  The $i7 and $fp registers
>are foobar when the function calling setjmp() gets control.  I tried the
>#pragma unknown_control_flow for my function but it still doesn't get
>the correct $i7 and $fp.  (If I set them to their correct values by hand
>in the debugger, everything works ok).
>
>After disassembling the setjmp/longjmp code in the library, I'm wondering
>how they ever work with long stack depths with the register windows.
>
>Does anyone know what I'm doing incorrectly?  Or am I faced with a
>bug in SunOS (the rev. is 4.1.1)?

There is a techinical report on wuarchive.wustl.edu entitled
"Register Windows and User-Space Threads on the SPARC*"
by David Keppel.  It's number is #91-08-01.


It's available from FTP, or:

Department of Computer Science and Engineering
University of Washington
Seattle, Washington 98195



					Terry Lambert
					terry_lambert@gateway.novell.com
					terry@icarus.weber.edu
---
Disclaimer:  Any opinions in this posting are my own and not those of
my present or previous employers.