Kernel trap on linux compat load

[Eric Millbrandt]

John Baldwin wrote:

>On Friday 17 June 2005 05:56 pm, Eric Millbrandt wrote:
>  
>
>>John Baldwin wrote:
>>    
>>
>>>On Thursday 16 June 2005 08:21 pm, Eric Millbrandt wrote:
>>>      
>>>
>>>>John Baldwin wrote:
>>>>        
>>>>
>>>>>On Friday 10 June 2005 07:02 pm, Eric Millbrandt wrote:
>>>>>          
>>>>>
>>>>>>I've noticed that linux compatibility caused my system to crash since I
>>>>>>upgraded from RELENG_4_9 (RELENG_4_10, RELENG_4_11, RELENG_4).  I
>>>>>>upgraded using buildworld, I haven't had a change to test using a clean
>>>>>>binary install.  Has anyone else seen this behavior?  It's easy to
>>>>>>reproduce, the system traps right on linux compatibility load.  The
>>>>>>only similar behavior I've found on google is an unanswered post
>>>>>>http://lists.freebsd.org/pipermail/freebsd-alpha/2004-June/001555.html
>>>>>>
>>>>>>Jun  8 07:18:17 mongoloid /kernel: fatal kernel trap:
>>>>>>Jun  8 07:18:17 mongoloid /kernel:
>>>>>>Jun  8 07:18:17 mongoloid /kernel: trap entry = 0x4 (unaligned access
>>>>>>fault) Jun  8 07:18:17 mongoloid /kernel: a0         =
>>>>>>0xfffffe0015285e34 Jun  8 07:18:17 mongoloid /kernel: a1         =
>>>>>>0x2d
>>>>>>Jun  8 07:18:17 mongoloid /kernel: a2         = 0x1
>>>>>>Jun  8 07:18:17 mongoloid /kernel: pc         = 0xfffffc0000386e68
>>>>>>Jun  8 07:18:17 mongoloid /kernel: ra         = 0xfffffc0000386dd8
>>>>>>Jun  8 07:18:17 mongoloid /kernel: curproc    = 0xfffffe001177e780
>>>>>>Jun  8 07:18:17 mongoloid /kernel: pid = 173, comm = ldconfig
>>>>>>Jun  8 07:18:17 mongoloid /kernel:
>>>>>>Jun  8 07:18:17 mongoloid /kernel: panic: trap
>>>>>>
>>>>>>EEM
>>>>>>            
>>>>>>
>>>>>Did you rebuild your kernel with buildkernel / installkernel?  I believe
>>>>>that buildworld on 4.x still builds and installs new modules into
>>>>>/modules including the linux and osf1 compat modules.  New modules
>>>>>aren't guaranteed to work on older kernels, so if your kernel is still
>>>>>4.9, that is probably your problem.
>>>>>          
>>>>>
>>>>I used buildworld, buildkernel, installkernel, drop to single user,
>>>>installworld, and mergemaster.  This is with linux_compat loading from
>>>>rc.conf.  I misspoke earlier loading linux.ko works fine but running a
>>>>linux binary, /compat/linux/sbin/ldconfig or sophie, causes the trap.
>>>>On a side not osf1_compat works fine.
>>>>
>>>>Here are my stack traces after running /compat/linux/sbin/ldconfig...
>>>>Debugger() at Debugger=0x2c
>>>>panic() at panic+0x100
>>>>trap() at trap+0x600
>>>>XentUna() at XentUna+0x2c
>>>>--- unaligned access fault (from ipl0) ---
>>>>kernel_sysctl at kernel_sysctl+ox1a8
>>>>347() at -0x1fffe4a63d0
>>>>Here ddb traps on itself (memory management fault)
>>>>
>>>>This one is from running sophie
>>>>Debugger() at Debugger=0x2c
>>>>panic() at panic+0x100
>>>>trap() at trap+0x600
>>>>XentUna() at XentUna+0x2c
>>>>--- unaligned access fault (from ipl0) ---
>>>>kernel_sysctl at kernel_sysctl+ox1a8
>>>>linux_newuname() at linux_newuname+0xd0
>>>>syscall() at syscal+0x224
>>>>XentSys at XentSys+0x5c
>>>>--- syscall (339, Linux ELF, linux_newuname) ---
>>>>--- user mode ---
>>>>        
>>>>
>>>Ok, this is helpful.  Can you do 'gdb kernel.debug' and then type 'list
>>>*kernel_sysctl+0x1a8'?  This will give us the source file/line that it
>>>faulted at.  Thanks!
>>>      
>>>
>>Ok here is what I found.
>>
>>(gdb) list *kernel_sysctl+0x1a8
>>0xfffffc000038e9a8 is in kernel_sysctl
>>(/usr/src/sys/kern/kern_sysctl.c:938).
>>933                     if (req.oldptr && req.oldidx > req.oldlen)
>>934                             *retval = req.oldlen;
>>935                     else
>>936                             *retval = req.oldidx;
>>937             }
>>938             return (error);
>>939     }
>>940
>>941     int
>>942     kernel_sysctlbyname(struct proc *p, char *name, void *old,
>>size_t *oldlenp,
>>    
>>
>
>Ok, try this patch please:
>
>Index: compat/linux/linux_misc.c
>===================================================================
>RCS file: /usr/cvs/src/sys/compat/linux/linux_misc.c,v
>retrieving revision 1.85.2.11
>diff -u -r1.85.2.11 linux_misc.c
>--- compat/linux/linux_misc.c   23 Mar 2004 12:16:48 -0000      1.85.2.11
>+++ compat/linux/linux_misc.c   20 Jun 2005 18:33:07 -0000
>@@ -687,7 +687,8 @@
>        struct l_new_utsname utsname;
>        char *osrelease, *osname;
>        int name[2];
>-       int error, plen, olen;
>+       int error;
>+       size_t plen, olen;
>
> #ifdef DEBUG
>        if (ldebug(newuname))
>
>  
>
Ok, I rebuilt and installed linux.ko and linux binaries appear to be 
working!  At least sophie, compiled for linux, catches viruses again.  
Let me know if you need any further testing and where you will apply the 
patch in cvs.  Thanks for the help.
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