1 /*
2 * Copyright (c) 2015 Roger Pau Monné <[email protected]>
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 HYPERVISOR_console_write(__DECONST(char *, str), len);
63 return (len);
64 }
65
66 extern void
67 stack_capture(struct stack *st, register_t rbp);
68
69 static int
xendebug_filter(void * arg __unused)70 xendebug_filter(void *arg __unused)
71 {
72 #if defined(STACK) && defined(DDB)
73 struct stack st;
74
75 stack_save(&st);
76
77 mtx_lock_spin(&lock);
78 sbuf_clear(buf);
79 xc_printf("Printing stack trace vCPU%u\n", XEN_VCPUID());
80 stack_sbuf_print_ddb(buf, &st);
81 sbuf_finish(buf);
82 mtx_unlock_spin(&lock);
83 #endif
84
85 return (FILTER_HANDLED);
86 }
87
88 static void
xendebug_identify(driver_t * driver,device_t parent)89 xendebug_identify(driver_t *driver, device_t parent)
90 {
91
92 KASSERT(xen_domain(),
93 ("Trying to add Xen debug device to non-xen guest"));
94
95 if (!xen_has_percpu_evtchn())
96 return;
97
98 if (BUS_ADD_CHILD(parent, 0, "debug", 0) == NULL)
99 panic("Unable to add Xen debug device.");
100 }
101
102 static int
xendebug_probe(device_t dev)103 xendebug_probe(device_t dev)
104 {
105
106 device_set_desc(dev, "Xen debug handler");
107 return (BUS_PROBE_NOWILDCARD);
108 }
109
110 static int
xendebug_attach(device_t dev)111 xendebug_attach(device_t dev)
112 {
113 int i, error;
114
115 mtx_init(&lock, "xen-dbg", NULL, MTX_SPIN);
116 buf = sbuf_new(NULL, NULL, 1024, SBUF_FIXEDLEN);
117 if (buf == NULL)
118 panic("Unable to create sbuf for stack dump");
119 sbuf_set_drain(buf, xendebug_drain, NULL);
120
121 /* Bind an event channel to a VIRQ on each VCPU. */
122 CPU_FOREACH(i) {
123 error = xen_intr_bind_virq(dev, VIRQ_DEBUG, i, xendebug_filter,
124 NULL, NULL, INTR_TYPE_TTY,
125 DPCPU_ID_PTR(i, xendebug_handler));
126 if (error != 0) {
127 printf("Failed to bind VIRQ_DEBUG to vCPU %d: %d",
128 i, error);
129 continue;
130 }
131 xen_intr_describe(DPCPU_ID_GET(i, xendebug_handler), "d%d", i);
132 }
133
134 return (0);
135 }
136
137 static device_method_t xendebug_methods[] = {
138 DEVMETHOD(device_identify, xendebug_identify),
139 DEVMETHOD(device_probe, xendebug_probe),
140 DEVMETHOD(device_attach, xendebug_attach),
141
142 DEVMETHOD_END
143 };
144
145 static driver_t xendebug_driver = {
146 "debug",
147 xendebug_methods,
148 0,
149 };
150
151 DRIVER_MODULE(xendebug, xenpv, xendebug_driver, 0, 0);
152 MODULE_DEPEND(xendebug, xenpv, 1, 1, 1);
153