Re: [Fwd: sigcontext on Linux-ppc in user space]

From: jekacur@ca.ibm.com
Date: Thu Jan 25 2001 - 10:09:07 EST

John Kacur/Toronto/IBM@IBMCA
jekacur@ca.ibm.com
(416) 448-2584 (phone)
778-2584 (tie line)

---------------------- Forwarded by John Kacur/Toronto/IBM on 01/25/2001
10:06 AM ---------------------------

John Kacur
01/24/2001 04:47 PM

To: aj@suse.de
cc: aj@arthur.inka.de
From: John Kacur/Toronto/IBM@IBMCA
Subject: Re: [Fwd: sigcontext on Linux-ppc in user space] (Document link:
      John Kacur)

Thanks for your reply. Yes, you are right I shouldn't include kernel files
in user space programs, and signal.h will contain what I need anyway. But I
still can't get at the sigcontext.c on Linux Powerpc. For example, this
simple program gives me a segmentation fault. (Linux ppc, suse 6.4, kernel
2.2.14

#include <stdio.h>
#include <signal.h>

/* Function Prototypes */
void install_sigusr1_handler(void);
void sigusr_handler(int , siginfo_t *, struct sigcontext * scp);

int main(void)
{
        install_sigusr1_handler();
        printf("SIGUSR1 = %d\n", SIGUSR1);
        raise(SIGUSR1);
        exit(0);
}

void install_sigusr1_handler(void)
{
        struct sigaction newAct;

        if (sigemptyset(&newAct.sa_mask) != 0) {
                fprintf(stderr, "Warning, sigemptyset failed.\n");
        }

        newAct.sa_flags = 0;
        newAct.sa_flags |= SA_SIGINFO | SA_RESTART;

        newAct.sa_sigaction = (void
(*)(int,siginfo_t*,void*))sigusr_handler;

        if (sigaction(SIGUSR1, &newAct, NULL) != 0) {
                fprintf(stderr, "Couldn't install SIGUSR1 handler.\n");
                fprintf(stderr, "Exiting.\n");
                exit(1);
        }
}

void sigusr_handler(int signo, siginfo_t *siginfp, struct sigcontext * scp)
{
        printf("scp = %08x\n", scp);
        printf("scp->signal = %d\n", scp->signal);
}

Ultimately, I want to get at the regs, ie scp->pt_regs->nip for example.

Any ideas?

Thanks.
John Kacur/Toronto/IBM@IBMCA
jekacur@ca.ibm.com
(416) 448-2584 (phone)
778-2584 (tie line)

John Kacur <jkacur@home.com>@e1.ny.us.ibm.com on 01/24/2001 10:26:30 AM

Please respond to John Kacur <jkacur@home.com>

Sent by: jkacur@e1.ny.us.ibm.com

To: John Kacur/Toronto/IBM@IBMCA
cc:
Subject: [Fwd: sigcontext on Linux-ppc in user space]

----- Message from on -----
   
   
   

John Kacur <jkacur@home.com> writes:

> Does anyone know how to get at the struct sigcontext in a signal handler
> on Linux for powerpc? sigaction of course lets you create a signal
> handler as a function with the prototype void(*)(int, siginfo_t *, void
> *)
> where the last argument, a pointer to void, is the sigcontext. I believe
> that the last argument is NOT defined by POSIX and so is implementation
> dependent.
>
> On Intel it seems sufficient to use #include <asm/sigcontext.h>
> to get the definition of struct sigcontext, and then get the values
> you'd like out of the signal handler. But on Linux for powerpc, the same
> thing doesn't work. Does anyone know what the trick is here to
> accomplish this?

You should never include kernel headers in user space.

If you have a glibc 2.1 (or newer) based system, just include
<signal.h> which will include <bits/sigcontext.h> with the struct
(this works on all architectures).

Andreas 

--
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj
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