Implement makectx(). The makectx() function is used by KDB to create

a PCB from a trapframe for purposes of unwinding the stack. The PCB
is used as the thread context and all but the thread that entered the
debugger has a valid PCB.
This function can also be used to create a context for the threads
running on the CPUs that have been stopped when the debugger got
entered. This however is not done at the time of this commit.

2 files changed, 22 insertions, 1 deletions

diff --git a/sys/ia64/ia64/machdep.c b/sys/ia64/ia64/machdep.c
index ca75d2c7ce40..5c39d05c8a36 100644
--- a/sys/ia64/ia64/machdep.c
+++ b/sys/ia64/ia64/machdep.c
@@ -1017,6 +1017,23 @@ freebsd4_sigreturn(struct thread *td, struct freebsd4_sigreturn_args *uap)
 }
 #endif
 
+/*
+ * Construct a PCB from a trapframe. This is called from kdb_trap() where
+ * we want to start a backtrace from the function that caused us to enter
+ * the debugger. We have the context in the trapframe, but base the trace
+ * on the PCB. The PCB doesn't have to be perfect, as long as it contains
+ * enough for a backtrace.
+ */
+void
+makectx(struct trapframe *tf, struct pcb *pcb)
+{
+
+	pcb->pcb_special = tf->tf_special;
+	pcb->pcb_special.__spare = ~0UL;	/* XXX see unwind.c */
+	save_callee_saved(&pcb->pcb_preserved);
+	save_callee_saved_fp(&pcb->pcb_preserved_fp);
+}
+
 int
 get_mcontext(struct thread *td, mcontext_t *mc, int flags)
 {
diff --git a/sys/ia64/include/pcb.h b/sys/ia64/include/pcb.h
index 23d7e504c012..d018127561b7 100644
--- a/sys/ia64/include/pcb.h
+++ b/sys/ia64/include/pcb.h
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2003 Doug Rabson
+ * Copyright (c) 2003,2004 Marcel Moolenaar
  * Copyright (c) 2000 Doug Rabson
  * All rights reserved.
  *
@@ -59,6 +59,10 @@ struct pcb {
 #ifdef _KERNEL
 
 #define	savectx(p)	swapctx(p, NULL)
+
+struct trapframe;
+
+void makectx(struct trapframe *, struct pcb *);
 void restorectx(struct pcb *) __dead2;
 int swapctx(struct pcb *old, struct pcb *new);