NetBSD Problem Report #60658

From martin@duskware.de  Fri Aug 28 07:23:09 2026
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Date: Fri, 28 Aug 2026 09:23:01 +0200 (CEST)
From: martin@NetBSD.org
Reply-To: martin@NetBSD.org
To: gnats-bugs@NetBSD.org
Subject: netbsd32_process_read_dbregs() needs the same fix as native amd64 process_read_dbregs()
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>Number:         60658
>Category:       kern
>Synopsis:       netbsd32_process_read_dbregs() needs the same fix as native amd64 process_read_dbregs()
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          needs-pullups
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Aug 28 07:25:00 +0000 2026
>Closed-Date:    
>Last-Modified:  Wed Sep 02 16:40:45 +0000 2026
>Originator:     Martin Husemann
>Release:        NetBSD 11.99.7
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD seven-days-to-the-wolves.aprisoft.de 11.99.7 NetBSD 11.99.7 (GENERIC) #885: Thu Aug 27 08:06:24 CEST 2026 martin@seven-days-to-the-wolves.aprisoft.de:/work/src/sys/arch/amd64/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:

Running i386 atf tests on an amd64 kernel crashes the machine:

kernel diagnostic assertion "lwp_locked(l, NULL)" failed: file "../../../arch/x86/x86/dbregs.c", line 185

in netbsd32_process_read_dbregs()

>How-To-Repeat:
s/a

>Fix:
n/a

>Release-Note:

>Audit-Trail:
From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60658 CVS commit: src/sys/compat/netbsd32
Date: Fri, 28 Aug 2026 16:02:32 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Fri Aug 28 16:02:32 UTC 2026

 Modified Files:
 	src/sys/compat/netbsd32: netbsd32_ptrace.c

 Log Message:
 netbsd32_ptrace: Fix locking around ptrace register access.

 PR kern/60658: netbsd32_process_read_dbregs() needs the same fix as
 native amd64 process_read_dbregs()


 To generate a diff of this commit:
 cvs rdiff -u -r1.9 -r1.10 src/sys/compat/netbsd32/netbsd32_ptrace.c

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

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60658 CVS commit: src/sys/kern
Date: Fri, 28 Aug 2026 16:15:15 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Fri Aug 28 16:15:15 UTC 2026

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

 Log Message:
 ptrace(2): Tidy register access: no sketchy function pointer casts.

 Followups for:

 PR port-amd64/60556: panic in process_read_fpregs_xmm

 PR kern/60595: System lockup using gdb(1) on kernel with
 DEBUG+LOCKDEBUG

 PR kern/60658: netbsd32_process_read_dbregs() needs the same fix as
 native amd64 process_read_dbregs()


 To generate a diff of this commit:
 cvs rdiff -u -r1.8 -r1.9 src/sys/kern/sys_process_lwpstatus.c

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

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60658 CVS commit: src/sys/kern
Date: Sat, 29 Aug 2026 12:46:56 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Sat Aug 29 12:46:56 UTC 2026

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

 Log Message:
 ptrace(2): Fix compat32 register set types in previous.

 Not always `struct reg32' or `struct fpreg32', notably on arm32 --
 make sure to say `process_reg32'/`process_fpreg32'/`process_dbreg32'.
 (Here `compat32' means oabi?)

 Followups for:

 PR port-amd64/60556: panic in process_read_fpregs_xmm

 PR kern/60595: System lockup using gdb(1) on kernel with
 DEBUG+LOCKDEBUG

 PR kern/60658: netbsd32_process_read_dbregs() needs the same fix as
 native amd64 process_read_dbregs()


 To generate a diff of this commit:
 cvs rdiff -u -r1.9 -r1.10 src/sys/kern/sys_process_lwpstatus.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->needs-pullups
State-Changed-By: riastradh@NetBSD.org
State-Changed-When: Sat, 29 Aug 2026 12:52:03 +0000
State-Changed-Why:
fixed in HEAD, needs pullup to whatever branches PR 60556 fixes go to


State-Changed-From-To: needs-pullups->open
State-Changed-By: martin@NetBSD.org
State-Changed-When: Wed, 02 Sep 2026 13:57:26 +0000
State-Changed-Why:
crashes a -current kernel again


From: Martin Husemann <martin@duskware.de>
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: kern/60658 (netbsd32_process_read_dbregs() needs the same fix as
 native amd64 process_read_dbregs())
Date: Wed, 2 Sep 2026 16:12:52 +0200

 I can reproduce the panic with todays kernel again:

 db{0}> bt
 breakpoint() at netbsd:breakpoint+0x5
 vpanic() at netbsd:vpanic+0x189
 kern_assert() at netbsd:kern_assert+0x4b
 x86_dbregs_read() at netbsd:x86_dbregs_read+0x17b
 netbsd32_process_read_dbregs() at netbsd:netbsd32_process_read_dbregs+0x1b
 netbsd32_proc_regio() at netbsd:netbsd32_proc_regio+0x92
 netbsd32_dodbregs() at netbsd:netbsd32_dodbregs+0x2a
 do_ptrace() at netbsd:do_ptrace+0x797
 netbsd32_ptrace() at netbsd:netbsd32_ptrace+0x42
 netbsd32_syscall() at netbsd:netbsd32_syscall+-0x23a741
 db{0}> dmesg
 [   1.0000000] Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
 [   1.0000000]     2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013,
 [   1.0000000]     2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023,
 [   1.0000000]     2024, 2025, 2026
 [   1.0000000]     The NetBSD Foundation, Inc.  All rights reserved.
 [   1.0000000] Copyright (c) 1982, 1986, 1989, 1991, 1993
 [   1.0000000]     The Regents of the University of California.  All rights rese
 rved.

 [   1.0000000] NetBSD 11.99.8 (GENERIC) #887: Wed Sep  2 10:40:14 CEST 2026
 [   1.0000000]  martin@seven-days-to-the-wolves.aprisoft.de:/work/src/sys/arch/a
 md64/compile/GENERIC
 db{0}> show panic
 Panic string: kernel diagnostic assertion "pcb->pcb_dbregs != NULL" failed: file
  "../../../../arch/x86/x86/dbregs.c", line 186


 Martin

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60658 CVS commit: src/sys/compat/netbsd32
Date: Wed, 2 Sep 2026 16:39:41 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Wed Sep  2 16:39:41 UTC 2026

 Modified Files:
 	src/sys/compat/netbsd32: netbsd32_ptrace.c

 Log Message:
 netbsd32_ptrace: Need to pre-allocate dbregs before read/write.

 Followup for:

 PR kern/60658: netbsd32_process_read_dbregs() needs the same fix as
 native amd64 process_read_dbregs()


 To generate a diff of this commit:
 cvs rdiff -u -r1.10 -r1.11 src/sys/compat/netbsd32/netbsd32_ptrace.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->needs-pullups
State-Changed-By: riastradh@NetBSD.org
State-Changed-When: Wed, 02 Sep 2026 16:40:45 +0000
State-Changed-Why:
fixed the fixed


>Unformatted:

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