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In stack_save, stop when a trap-frame is encountered. This prevents

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trying to access user-space stack addresses when a user fault
is encountered, as occurs when GEOM KTR code is handling a page fault
and is using stack_save() to capture a trace for debug purposes.

It may be possible to walk beyond the trap-frame if it is a kernel fault,
as db_backtrace() does, but I don't think that complexity is needed in
this routine.

MFC after:	3 days
This commit is contained in:
grehan 2005-10-30 07:56:10 +00:00
parent 526f2e221d
commit 6350b203b9
1 changed files with 10 additions and 0 deletions
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10
sys/powerpc/powerpc/db_trace.c
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@ -305,6 +305,16 @@ stack_save(struct stack *st)
callpc = *(vm_offset_t *)(stackframe + 4) - 4;
if ((callpc & 3) || (callpc < 0x100))
break;
/*
* Don't bother traversing trap-frames - there should
* be enough info down to the frame to work out where
* things are going wrong. Plus, prevents this shortened
* version of code from accessing user-space frames
*/
if (callpc + 4 == (db_addr_t) &trapexit)
break;
if (stack_put(st, callpc) == -1)
break;
}