1 /*
2 * Copyright (c) 2015 Roger Pau Monné <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
54 DPCPU_DEFINE(xen_intr_handle_t, xendebug_handler);
55 static struct mtx lock;
56 static struct sbuf *buf;
57
58 static int
xendebug_drain(void * arg,const char * str,int len)59 xendebug_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
69 extern void
70 stack_capture(struct stack *st, register_t rbp);
71
72 static int
xendebug_filter(void * arg __unused)73 xendebug_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
90 static void
xendebug_identify(driver_t * driver,device_t parent)91 xendebug_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
104 static int
xendebug_probe(device_t dev)105 xendebug_probe(device_t dev)
106 {
107
108 device_set_desc(dev, "Xen debug handler");
109 return (BUS_PROBE_NOWILDCARD);
110 }
111
112 static int
xendebug_attach(device_t dev)113 xendebug_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
139 static 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
147 static driver_t xendebug_driver = {
148 "debug",
149 xendebug_methods,
150 0,
151 };
152
153 DRIVER_MODULE(xendebug, xenpv, xendebug_driver, 0, 0);
154 MODULE_DEPEND(xendebug, xenpv, 1, 1, 1);
155