Break out stack(9) from ddb(4):

- Introduce per-architecture stack_machdep.c to hold stack_save(9).
- Introduce per-architecture machine/stack.h to capture any common
  definitions required between db_trace.c and stack_machdep.c.
- Add new kernel option "options STACK"; we will build in stack(9) if it is
  defined, or also if "options DDB" is defined to provide compatibility
  with existing users of stack(9).

Add new stack_save_td(9) function, which allows the capture of a stacktrace
of another thread rather than the current thread, which the existing
stack_save(9) was limited to.  It requires that the thread be neither
swapped out nor running, which is the responsibility of the consumer to
enforce.

Update stack(9) man page.

Build tested:	amd64, arm, i386, ia64, powerpc, sparc64, sun4v
Runtime tested:	amd64 (rwatson), arm (cognet), i386 (rwatson)

3 files changed, 58 insertions, 12 deletions

diff --git a/sys/ia64/conf/GENERIC b/sys/ia64/conf/GENERIC
index 2fa5086..84a1fb7 100644
--- a/sys/ia64/conf/GENERIC
+++ b/sys/ia64/conf/GENERIC
@@ -50,6 +50,7 @@ options 	SCSI_DELAY=5000	# Delay (in ms) before probing SCSI
 options 	SMP		# Symmetric Multi-Processor support
 options 	SOFTUPDATES	# Enable FFS soft updates support
 options 	UFS_GJOURNAL	# Enable gjournal-based UFS journaling
+options 	STACK		# stack(9) support
 options 	SYSVMSG		# SYSV-style message queues
 options 	SYSVSEM		# SYSV-style semaphores
 options 	SYSVSHM		# SYSV-style shared memory
diff --git a/sys/ia64/ia64/db_machdep.c b/sys/ia64/ia64/db_machdep.c
index 6579f3b..cdd60ab 100644
--- a/sys/ia64/ia64/db_machdep.c
+++ b/sys/ia64/ia64/db_machdep.c
@@ -597,18 +597,6 @@ db_trace_thread(struct thread *td, int count)
 	return (db_backtrace(td, ctx, count));
 }
 
-void
-stack_save(struct stack *st)
-{
-
-	stack_zero(st);
-	/*
-	 * Nothing for now.
-	 * Is libuwx reentrant?
-	 * Can unw_create* sleep?
-	 */
-}
-
 #ifdef EXCEPTION_TRACING
 
 extern long xtrace[];
diff --git a/sys/ia64/ia64/stack_machdep.c b/sys/ia64/ia64/stack_machdep.c
new file mode 100644
index 0000000..5e513ea
--- /dev/null
+++ b/sys/ia64/ia64/stack_machdep.c
@@ -0,0 +1,57 @@
+/*-
+ * Copyright (c) 2005 Antoine Brodin
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/proc.h>
+#include <sys/stack.h>
+
+void
+stack_save_td(struct stack *st, struct thread *td)
+{
+
+	if (TD_IS_SWAPPED(td))
+		panic("stack_save_td: swapped");
+	if (TD_IS_RUNNING(td))
+		panic("stack_save_td: running");
+
+	stack_zero(st);
+}
+
+void
+stack_save(struct stack *st)
+{
+
+	stack_zero(st);
+	/*
+	 * Nothing for now.
+	 * Is libuwx reentrant?
+	 * Can unw_create* sleep?
+	 */
+}