From owner-freebsd-emulation  Tue Sep  5 19:44:28 2000
Delivered-To: freebsd-emulation@freebsd.org
Received: from duke.cs.duke.edu (duke.cs.duke.edu [152.3.140.1])
	by hub.freebsd.org (Postfix) with ESMTP id 6389537B422
	for <freebsd-emulation@freebsd.org>; Tue,  5 Sep 2000 19:44:25 -0700 (PDT)
Received: from grasshopper.cs.duke.edu (grasshopper.cs.duke.edu [152.3.145.30])
	by duke.cs.duke.edu (8.9.3/8.9.3) with ESMTP id WAA01657;
	Tue, 5 Sep 2000 22:44:14 -0400 (EDT)
Received: (from gallatin@localhost)
	by grasshopper.cs.duke.edu (8.11.0/8.9.1) id e862iEM24144;
	Tue, 5 Sep 2000 22:44:14 -0400 (EDT)
	(envelope-from gallatin@cs.duke.edu)
From: Andrew Gallatin <gallatin@cs.duke.edu>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Date: Tue,  5 Sep 2000 22:44:14 -0400 (EDT)
To: marcel@cup.hp.com
Cc: freebsd-emulation@freebsd.org
Subject: IBM JDK fails due to lack of SA_SIGINFO support
X-Mailer: VM 6.43 under 20.4 "Emerald" XEmacs  Lucid
Message-ID: <14773.43466.744621.411519@grasshopper.cs.duke.edu>
Sender: owner-freebsd-emulation@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.org


Currently the IBM jdk & jvm don't run under our linux abi.  This had
previously been attributed to the "sigaltstack: Cannot allocate
memory" message one sees when running it.  Upon further investigation,
this appears to be a red herring.  The "real" problem is as simple
(or, rather, complex) as the fact that we don't support SA_SIGINFO
style signal handlers under the linux abi.

The program installs signal handlers for just about everything.  One
thread sends another a SIGUSR2, which is caught.  As soon as the
handler tries to dereference sip, it SEGV's.  It proceeds to catch
that, then gets caught in an infinate loop of catching SEGV's &
SEGV'ing in the handler.  

The appended program demonstrates the problem when its built on a
linux system & run on a FreeBSD one.  Run it in the background & send
it SIGUSR2.  Notice it faults as soon as it deref's sip. 

I've been trying to whip up a linux_rt_sendsig() that could handle
SA_SIGINFO style signal handlers. However, I've been failing
miserably.  Any help from x86 savy people would be appreciated -- I'm
mainly an alpha guy :-(

Cheers,

Drew
------------------------------------------------------------------------------
Andrew Gallatin, Sr Systems Programmer	http://www.cs.duke.edu/~gallatin
Duke University				Email: gallatin@cs.duke.edu
Department of Computer Science		Phone: (919) 660-6590



#include <signal.h>
#include <stdlib.h>
#include <ucontext.h>

static void
kill_handler(int sig, siginfo_t *sip, void  *context)
{
        printf("\n");
        printf("&sig = %p\n", &sig);
        printf("&sip = %p\n", &sip);
        printf("sip = %p\n", sip);
        printf("context = %p\n", context);
	printf("sip->si_signo = 0x%lx\n", sip->si_signo); /* KABOOM!*/                
        exit(0);
}

main(int argc, char *argv[])
{
        sigset_t sigset;
        struct sigaction sa;
        int i, ret;
        volatile int bar;
        int *array;

        bzero((char*)& (sa.sa_mask), sizeof(sigset_t));
        sa.sa_flags = SA_SIGINFO;
        sa.sa_sigaction = kill_handler;

        sigaction(SIGUSR2, &sa, NULL);

        while (1);
}








To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-emulation" in the body of the message