Signal callstack question

Jim Nance (jnance@nortelnetworks.com)
Tue, 30 Nov 1999 08:09:40 -0500


Hello All,
I am writting a little profiling tool which uses a timer to signal my
process, and then, in the signal handler it walks the call stack to see
where it is. My problem is that if I have a call stack like this:

main() -> f1() -> f2() -> f3()

and I get a signal while I am in f3(), when I walk the call stack it looks
like this:

main() -> f1() -> f2() -> __restore -> signalHandler()

Since this is a profiler, it would really be nice to know that I am in the
f3() function, but I can not figure out how to get this information. I took
a look at __restore and it is a little bit of code that calls the sigrestore()
system call. I assume that sigrestore() cleans up and puts f3() back onto
the call stack. Does anyone know how I can figure out the name of the
function that was executing when I caught the signal? The best I can come
up with is to go back to f2() and try to disassemble the function call
instruction, but I dont really like that approach (particularly since I don't
know intel assembly).

Incidently, if a program longjmp()s out of a signal handler, and thus never
calls sigrestore(), does this break anything (like queued signal delivery)?

Thanks,

Jim

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