NetBSD Problem Report #38599

From mlelstv@henery.1st.de  Tue May  6 21:23:01 2008
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Date: Tue,  6 May 2008 23:21:13 +0200 (CEST)
From: mlelstv@serpens.de
Reply-To: mlelstv@serpens.de
To: gnats-bugs@gnats.NetBSD.org
Subject: panic crashes in early bootstrap
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>Number:         38599
>Category:       kern
>Synopsis:       panic crashes in early bootstrap
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue May 06 21:25:00 +0000 2008
>Closed-Date:    Mon Feb 15 09:54:49 +0000 2016
>Last-Modified:  Mon Feb 15 09:54:49 +0000 2016
>Originator:     Michael van Elst
>Release:        NetBSD 4.0_STABLE
>Organization:
-- 
                                Michael van Elst
Internet: mlelstv@serpens.de
                                "A potential Snark may lurk in every tree."
>Environment:


System: ELF 64-bit MSB executable, SPARC V9, version 1 (SYSV), statically linked, for NetBSD 4.99.62, not stripped
Architecture: sparc64
Machine: sparc64
>Description:
When panic is called early in bootstrap it crashes on a GENERIC kernel.
The reason is that it accesses curlwp and curcpu() to be safe on
multiprocessors. Those data structures haven't been initialized and
on sparc64 not even mapped before pmap_bootstrap() has run.

A panic in pmap_bootstrap() or earlier will therefore crash instead
of emitting a useful panic message.

>How-To-Repeat:
Try to boot a sparc64 kernel on a T2000.

>Fix:
Make the curlwp accesses conditional on wether the data
structures have been initialized. The first thing main()
does is initializing lwp0.l_cpu (unless LWP0_CPU_INFO
is #defined), therefore a possible check would be:

        if (lwp0.l_cpu && curlwp) {
                /*
                 * Disable preemption.  If already panicing on another CPU, sit
                 * here and spin until the system is rebooted.  Allow the CPU th
at
                 * first paniced to panic again.
                 */
                kpreempt_disable();
                ci = curcpu();
                oci = atomic_cas_ptr((void *)&paniccpu, NULL, ci);
                if (oci != NULL && oci != ci) {
                        /* Give interrupts a chance to try and prevent deadlock.
 */
                        spl0();
                        for (;;) {
                                DELAY(10);
                        }
                }

                /*
                 * Convert the current thread to a bound thread and prevent all
                 * CPUs from scheduling unbound jobs.  Do so without taking any
                 * locks.
                 */
                curlwp->l_pflag |= LP_BOUND;
                for (CPU_INFO_FOREACH(cii, ci)) {
                        ci->ci_schedstate.spc_flags |= SPCF_OFFLINE;
                }
        }

>Release-Note:

>Audit-Trail:
From: Michael van Elst <mlelstv@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/38599 CVS commit: src/sys/kern
Date: Tue, 10 Mar 2009 10:48:10 +0000

 Module Name:	src
 Committed By:	mlelstv
 Date:		Tue Mar 10 10:48:10 UTC 2009

 Modified Files:
 	src/sys/kern: subr_prf.c

 Log Message:
 Make curlwp accesses conditional on wether the data structures
 have been initialized. Fixes PR kern/38599.


 To generate a diff of this commit:
 cvs rdiff -u -r1.130 -r1.131 src/sys/kern/subr_prf.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: open->closed
State-Changed-By: pooka@NetBSD.org
State-Changed-When: Tue, 29 Jun 2010 12:35:42 +0300
State-Changed-Why:
submitter committed a fix over a year ago


State-Changed-From-To: closed->analyzed
State-Changed-By: dholland@NetBSD.org
State-Changed-When: Tue, 29 Jun 2010 20:23:21 +0000
State-Changed-Why:
but, should be pulled up to -5


State-Changed-From-To: analyzed->closed
State-Changed-By: dholland@NetBSD.org
State-Changed-When: Mon, 15 Feb 2016 09:54:49 +0000
State-Changed-Why:
pullups to -5 are not in the cards these days


>Unformatted:

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