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From: Robert Watson <rwatson@FreeBSD.org>
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Subject: PERFORCE change 213103 for review
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http://p4web.freebsd.org/@@213103?ac=10

Change 213103 by rwatson@rwatson_svr_ctsrd_mipsbuild on 2012/06/18 22:40:01

	Annotate a bug in FreeBSD/mips in-kernel stack walking: pcb_regs is
	used instead of pcb_context.  However, if I drop in pcb_context, then
	I get a crash walking kernel stacks, so the existing stack walker
	appears inadequately robust.  Rather than fix these bugs now, make a
	note for later.

Affected files ...

.. //depot/projects/ctsrd/beribsd/src/sys/mips/mips/stack_machdep.c#2 edit

Differences ...

==== //depot/projects/ctsrd/beribsd/src/sys/mips/mips/stack_machdep.c#2 (text+ko) ====

@@ -57,6 +57,7 @@
 
 	stack_zero(st);
 
+	/* XXXRW: appears to be inadequately robust? */
 	for (;;) {
 		stacksize = 0;
 		if (pc <= (u_register_t)(intptr_t)btext)
@@ -137,6 +138,7 @@
 	if (TD_IS_RUNNING(td))
 		panic("stack_save_td: running");
 
+	/* XXXRW: Should be pcb_context? */
 	pc = td->td_pcb->pcb_regs.pc;
 	sp = td->td_pcb->pcb_regs.sp;
 	stack_capture(st, pc, sp);
@@ -150,6 +152,7 @@
 	if (curthread == NULL)
 		panic("stack_save: curthread == NULL)");
 
+	/* XXXRW: Should be pcb_context? */
 	pc = curthread->td_pcb->pcb_regs.pc;
 	sp = curthread->td_pcb->pcb_regs.sp;
 	stack_capture(st, pc, sp);