Date: Thu, 28 Jun 2001 14:46:28 -0400 From: "Louis-Philippe Gagnon" <louisphilippe@macadamian.com> To: "Daniel Eischen" <eischen@vigrid.com> Cc: <freebsd-hackers@FreeBSD.ORG> Subject: Re: pthread/longjmp/signal problem Message-ID: <067601c10002$a48811c0$2964a8c0@macadamian.com> References: <Pine.SUN.3.91.1010626165947.10822A-100000@pcnet1.pcnet.com>
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Thanks! I'll try it as soon as possible (I don't have a -stable machine ready, and I'd rather not try my first "make world"
attempts on my production machine...)
Louis-Philippe Gagnon
----- Original Message -----
From: "Daniel Eischen" <eischen@vigrid.com>
To: "Louis-Philippe Gagnon" <louisphilippe@macadamian.com>
Cc: <freebsd-hackers@FreeBSD.ORG>
Sent: Tuesday, June 26, 2001 5:08 PM
Subject: Re: pthread/longjmp/signal problem
> On Thu, 21 Jun 2001, Louis-Philippe Gagnon wrote:
> > No reactions the first time, let's try again.
> >
> > I've encountered a problem in the interaction betwen signals, longjmp and
> > pthreads; I'm hoping someone can help me make sense of it.
> >
> > I've been trying to implement a IsBadReadPtr-style function in FreeBSD by
> > using signal handlers and longjmp/setjmp. It seemed to work as expected,
> > until I started using the -pthread option to gcc (thus linking against
> > libc_r). Now the function only works on the first call; subsequent calls
> > hang on the segmentation fault.
> >
> > Here's an example of the kind of code that causes problems :
>
> Try this patch (to -stable). Only the patch to uthread_sig.c is
> needed for -current.
>
> --
> Dan Eischen
>
>
> Index: libc/i386/gen/setjmp.S
> ===================================================================
> RCS file: /opt/FreeBSD/cvs/src/lib/libc/i386/gen/setjmp.S,v
> retrieving revision 1.17.2.1
> diff -u -r1.17.2.1 setjmp.S
> --- libc/i386/gen/setjmp.S 2000/05/16 20:43:21 1.17.2.1
> +++ libc/i386/gen/setjmp.S 2001/06/26 21:07:23
> @@ -61,11 +61,7 @@
> pushl %eax /* (sigset_t*)oset */
> pushl $0 /* (sigset_t*)set */
> pushl $1 /* SIG_BLOCK */
> -#ifdef _THREAD_SAFE
> - call PIC_PLT(CNAME(_thread_sys_sigprocmask))
> -#else
> call PIC_PLT(CNAME(sigprocmask))
> -#endif
> addl $12,%esp
> PIC_EPILOGUE
> movl 4(%esp),%ecx
> @@ -91,11 +87,7 @@
> leal 28(%edx), %eax
> pushl %eax /* (sigset_t*)set */
> pushl $3 /* SIG_SETMASK */
> -#ifdef _THREAD_SAFE
> - call PIC_PLT(CNAME(_thread_sys_sigprocmask))
> -#else
> call PIC_PLT(CNAME(sigprocmask))
> -#endif
> addl $12,%esp
> PIC_EPILOGUE
> movl 4(%esp),%edx
> Index: libc/i386/gen/sigsetjmp.S
> ===================================================================
> RCS file: /opt/FreeBSD/cvs/src/lib/libc/i386/gen/sigsetjmp.S,v
> retrieving revision 1.19.2.1
> diff -u -r1.19.2.1 sigsetjmp.S
> --- libc/i386/gen/sigsetjmp.S 2000/05/16 20:43:21 1.19.2.1
> +++ libc/i386/gen/sigsetjmp.S 2001/06/26 21:04:34
> @@ -70,11 +70,7 @@
> pushl %eax /* (sigset_t*)oset */
> pushl $0 /* (sigset_t*)set */
> pushl $1 /* SIG_BLOCK */
> -#ifdef _THREAD_SAFE
> - call PIC_PLT(CNAME(_thread_sys_sigprocmask))
> -#else
> call PIC_PLT(CNAME(sigprocmask))
> -#endif
> addl $12,%esp
> PIC_EPILOGUE
> movl 4(%esp),%ecx
> @@ -102,11 +98,7 @@
> leal 28(%edx), %eax
> pushl %eax /* (sigset_t*)set */
> pushl $3 /* SIG_SETMASK */
> -#ifdef _THREAD_SAFE
> - call PIC_PLT(CNAME(_thread_sys_sigprocmask))
> -#else
> call PIC_PLT(CNAME(sigprocmask))
> -#endif
> addl $12,%esp
> PIC_EPILOGUE
> movl 4(%esp),%edx
> Index: libc_r/uthread/uthread_sig.c
> ===================================================================
> RCS file: /opt/FreeBSD/cvs/src/lib/libc_r/uthread/uthread_sig.c,v
> retrieving revision 1.25.2.7
> diff -u -r1.25.2.7 uthread_sig.c
> --- libc_r/uthread/uthread_sig.c 2001/06/23 00:47:05 1.25.2.7
> +++ libc_r/uthread/uthread_sig.c 2001/06/26 20:56:52
> @@ -931,6 +931,12 @@
> thread->curframe = NULL;
> PTHREAD_ASSERT(psf != NULL, "Invalid signal frame in signal handler");
>
> + /*
> + * We came here from the kernel scheduler; clear the in scheduler
> + * flag.
> + */
> + _thread_kern_in_sched = 0;
> +
> /* Check the threads previous state: */
> if (psf->saved_state.psd_state != PS_RUNNING) {
> /*
>
>
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