The syscall problem indeed wasn't the problem - or even a#

Sun, 17 Aug 2003 03:43:17 +0000

The syscall problem indeed wasn't the problem - or even a problem.

The real problem was that we weren't saving/restoring a pile of stuff (most immediately obvious gap: floating point modes) that we should have been. This was fixed by calling callintolisp(function) instead of function directly. And a certain amount of messing around with our fake stack to make it both correct and intelligible to SBCL's backtrace

The non-problem was that during an interrupted select() call, eax was changing from -514 (as seen by ptrace when the signal went off) to -4 (as seen in the signal handler). The former is -ERESTARTNOHAND, the latter is -EINTR. It's kind of interesting that ptrace() gets to see (what as far as I can tell is) the kernel-internal value of eax, but I can't right now think of any way this might be exploited, so oh well.

returntolispfunction (soon to be renamed arrangereturntolisp_function) is now in CVS.