sparc64/93226: DEBUG_LOCKS (really stack_save()) causes panics on sparc64

[Kris Kennaway]

>Number:         93226
>Category:       sparc64
>Synopsis:       DEBUG_LOCKS (really stack_save()) causes panics on sparc64
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-sparc64
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Feb 12 06:30:06 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Kris Kennaway
>Release:        FreeBSD 7.0-CURRENT sparc64
>Organization:
>Environment:

FreeBSD/sparc64 7.0

>Description:

With option DEBUG_LOCKS in the kernel, the stack(9) code that is
intended to save stack traces when lockmgr locks are acquired is
broken:

> panic: trap: fast data access mmu miss
> cpuid = 1
> KDB: enter: panic
> [thread pid 1 tid 100009 ]
> Stopped at      kdb_enter+0x3c: ta              %xcc, 1
> db> wh
> Tracing pid 1 tid 100009 td 0xfffff800fed24750
> panic() at panic+0x164
> trap() at trap+0x418
> -- fast data access mmu miss tar=0x7fdffffe000 %o7=0xc027c940 --
> stack_save() at stack_save+0x24
[...]

>How-To-Repeat:

Build and boot a kernel with options DEBUG_LOCKS

>Fix:

A similar bug existed on i386, and was fixed in

  http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/i386/i386/db_trace.c.diff?r1=1.69&r2=1.70
>Release-Note:
>Audit-Trail:
>Unformatted: