Berkeley CSUA MOTD:Entry 33811
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2025/07/10 [General] UID:1000 Activity:popular
7/10    

2004/9/28 [Computer/SW/OS/Linux] UID:33811 Activity:high
9/28    I am trying to get fault address and ip(instruction pointer)
        information in a signal handler under Linux.  I know how to
        do this, but it doesn't seem to work under linux (redhat 7 & 8).
        Are there any special tricks?  --jwm
        \_ The code I am using to test is in ~jwm/sigtest.c --jwm
        \_ I use the following to get the instruction pointer for an
           timer based profiler I had to write:
           void profile_handler(int sig, siginfo_t *info, void *uap) {
                // grab the old pc from the user context
                // this is x86 linux specific crap
                ucontext_t *context = (ucontext_t *)uap;
                greg_t pc = context->uc_mcontext.gregs[REG_EIP];
                ...
            }

            I know this works on debian and some variants of redhat.
            I hope this helps. --twohey.
            \_ I should add that I setup the signal handler using sigemptyset,
               sigaddset, and sigaction. --twohey
            \_ This is perfect, thank you.  --jwm
2025/07/10 [General] UID:1000 Activity:popular
7/10    

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