The following reply was made to PR port-m68k/36848; it has been noted by GNATS.

From: "Michael L. Hitch" <mhitch@netbsd.org>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: PR/36848 CVS commit: src/sys/arch
Date: Sat,  1 Sep 2007 21:31:57 +0000 (UTC)

 Module Name:	src
 Committed By:	mhitch
 Date:		Sat Sep  1 21:31:57 UTC 2007
 
 Modified Files:
 	src/sys/arch/amiga/amiga: trap.c
 	src/sys/arch/atari/atari: trap.c
 	src/sys/arch/cesfic/cesfic: trap.c
 	src/sys/arch/hp300/hp300: trap.c
 	src/sys/arch/luna68k/luna68k: trap.c
 	src/sys/arch/mac68k/mac68k: trap.c
 	src/sys/arch/mvme68k/mvme68k: trap.c
 	src/sys/arch/news68k/news68k: trap.c
 	src/sys/arch/next68k/next68k: trap.c
 	src/sys/arch/sun3/sun3: trap.c
 	src/sys/arch/x68k/x68k: trap.c
 
 Log Message:
 68030 and 68040 processors consider the read portion of a read-modify-write
 transfer as a write to ensure the memory is writable before starting any
 transfer.  The fault status information does not reflect this in the 'read'
 status bit (i.e. it shows up as a read access), so faults with a RMW access
 to non-writable memory was not getting the correct protection.  The page would
 be read-only and the instruction would fault over and over.
 
 A specific example is when a process forks, and the child process attempts
 to execute a RMW access to a data page, which is read-only because it's CoP
 Copy-On-Write.
 
 When checking if the page needs to be writablek, also check the locked transfer
 and treat any locked transfer as a write.
 
 68060 already handled this correctly, since it has separate read and write
 fault bits, and both are set on a RMW access and the trap code was checking
 the write status bit.
 
 Fixes PR#36848.
 
 
 To generate a diff of this commit:
 cvs rdiff -r1.115 -r1.116 src/sys/arch/amiga/amiga/trap.c
 cvs rdiff -r1.91 -r1.92 src/sys/arch/atari/atari/trap.c
 cvs rdiff -r1.35 -r1.36 src/sys/arch/cesfic/cesfic/trap.c
 cvs rdiff -r1.131 -r1.132 src/sys/arch/hp300/hp300/trap.c
 cvs rdiff -r1.46 -r1.47 src/sys/arch/luna68k/luna68k/trap.c
 cvs rdiff -r1.128 -r1.129 src/sys/arch/mac68k/mac68k/trap.c
 cvs rdiff -r1.90 -r1.91 src/sys/arch/mvme68k/mvme68k/trap.c
 cvs rdiff -r1.53 -r1.54 src/sys/arch/news68k/news68k/trap.c
 cvs rdiff -r1.67 -r1.68 src/sys/arch/next68k/next68k/trap.c
 cvs rdiff -r1.130 -r1.131 src/sys/arch/sun3/sun3/trap.c
 cvs rdiff -r1.89 -r1.90 src/sys/arch/x68k/x68k/trap.c
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.