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 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 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 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 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 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