1/*
2 * Copyright (c) 2015 Roger Pau Monn�� <roger.pau@citrix.com>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28#include "opt_stack.h"
29#include "opt_ddb.h"
30
31#include <sys/param.h>
32#include <sys/systm.h>
33#include <sys/bus.h>
34#include <sys/kernel.h>
35#include <sys/lock.h>
36#include <sys/module.h>
37#include <sys/mutex.h>
38#include <sys/pcpu.h>
39#include <sys/smp.h>
40#include <sys/stack.h>
41#include <sys/sbuf.h>
42
43#include <xen/xen-os.h>
44#include <xen/xen_intr.h>
45#include <xen/hypervisor.h>
46
47/*
48 * Xen debug device
49 *
50 * Handles the VIRQ_DEBUG interrupt and prints the backtrace of each
51 * vCPU on the Xen console.
52 */
53
54DPCPU_DEFINE(xen_intr_handle_t, xendebug_handler);
55static struct mtx lock;
56static struct sbuf *buf;
57
58static int
59xendebug_drain(void *arg, const char *str, int len)
60{
61	/*
62	 * Use xen_emergency_print() instead of xc_printf() to avoid the
63	 * overhead of parsing a format string when it's not needed.
64	 */
65	xen_emergency_print(str, len);
66	return (len);
67}
68
69extern void
70stack_capture(struct stack *st, register_t rbp);
71
72static int
73xendebug_filter(void *arg __unused)
74{
75#if defined(STACK) && defined(DDB)
76	struct stack st;
77
78	stack_save(&st);
79
80	mtx_lock_spin(&lock);
81	xc_printf("Printing stack trace vCPU%u\n", XEN_VCPUID());
82	stack_sbuf_print_ddb(buf, &st);
83	sbuf_drain(buf);
84	mtx_unlock_spin(&lock);
85#endif
86
87	return (FILTER_HANDLED);
88}
89
90static void
91xendebug_identify(driver_t *driver, device_t parent)
92{
93
94	KASSERT(xen_domain(),
95	    ("Trying to add Xen debug device to non-xen guest"));
96
97	if (!xen_has_percpu_evtchn())
98		return;
99
100	if (BUS_ADD_CHILD(parent, 0, "debug", 0) == NULL)
101		panic("Unable to add Xen debug device.");
102}
103
104static int
105xendebug_probe(device_t dev)
106{
107
108	device_set_desc(dev, "Xen debug handler");
109	return (BUS_PROBE_NOWILDCARD);
110}
111
112static int
113xendebug_attach(device_t dev)
114{
115	int i, error;
116
117	mtx_init(&lock, "xen-dbg", NULL, MTX_SPIN);
118	buf = sbuf_new(NULL, NULL, 1024, SBUF_FIXEDLEN);
119	if (buf == NULL)
120		panic("Unable to create sbuf for stack dump");
121	sbuf_set_drain(buf, xendebug_drain, NULL);
122
123	/* Bind an event channel to a VIRQ on each VCPU. */
124	CPU_FOREACH(i) {
125		error = xen_intr_bind_virq(dev, VIRQ_DEBUG, i, xendebug_filter,
126		    NULL, NULL, INTR_TYPE_TTY,
127		    DPCPU_ID_PTR(i, xendebug_handler));
128		if (error != 0) {
129			printf("Failed to bind VIRQ_DEBUG to vCPU %d: %d",
130			    i, error);
131			continue;
132		}
133		xen_intr_describe(DPCPU_ID_GET(i, xendebug_handler), "d%d", i);
134	}
135
136	return (0);
137}
138
139static device_method_t xendebug_methods[] = {
140	DEVMETHOD(device_identify, xendebug_identify),
141	DEVMETHOD(device_probe, xendebug_probe),
142	DEVMETHOD(device_attach, xendebug_attach),
143
144	DEVMETHOD_END
145};
146
147static driver_t xendebug_driver = {
148	"debug",
149	xendebug_methods,
150	0,
151};
152
153DRIVER_MODULE(xendebug, xenpv, xendebug_driver, 0, 0);
154MODULE_DEPEND(xendebug, xenpv, 1, 1, 1);
155