1 /*-
2 * Copyright (c) 2017 Andrew Turner
3 * All rights reserved.
4 *
5 * This software was developed by SRI International and the University of
6 * Cambridge Computer Laboratory under DARPA/AFRL contract FA8750-10-C-0237
7 * ("CTSRD"), as part of the DARPA CRASH research programme.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
33
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
37 #include <sys/malloc.h>
38 #include <sys/proc.h>
39 #include <sys/queue.h>
40 #include <sys/signal.h>
41 #include <sys/signalvar.h>
42 #include <sys/sysent.h>
43
44 #include <machine/frame.h>
45 #include <machine/undefined.h>
46 #include <machine/vmparam.h>
47
48 MALLOC_DEFINE(M_UNDEF, "undefhandler", "Undefined instruction handler data");
49
50 struct undef_handler {
51 LIST_ENTRY(undef_handler) uh_link;
52 undef_handler_t uh_handler;
53 };
54
55 /*
56 * Create two undefined instruction handler lists, one for userspace, one for
57 * the kernel. This allows us to handle instructions that will trap
58 */
59 LIST_HEAD(, undef_handler) undef_handlers[2];
60
61 /*
62 * Work around a bug in QEMU prior to 2.5.1 where reading unknown ID
63 * registers would raise an exception when they should return 0.
64 */
65 static int
id_aa64mmfr2_handler(vm_offset_t va,uint32_t insn,struct trapframe * frame,uint32_t esr)66 id_aa64mmfr2_handler(vm_offset_t va, uint32_t insn, struct trapframe *frame,
67 uint32_t esr)
68 {
69 int reg;
70
71 #define MRS_ID_AA64MMFR2_EL0_MASK (MRS_MASK | 0x000fffe0)
72 #define MRS_ID_AA64MMFR2_EL0_VALUE (MRS_VALUE | 0x00080740)
73
74 /* mrs xn, id_aa64mfr2_el1 */
75 if ((insn & MRS_ID_AA64MMFR2_EL0_MASK) == MRS_ID_AA64MMFR2_EL0_VALUE) {
76 reg = MRS_REGISTER(insn);
77
78 frame->tf_elr += INSN_SIZE;
79 if (reg < nitems(frame->tf_x)) {
80 frame->tf_x[reg] = 0;
81 } else if (reg == 30) {
82 frame->tf_lr = 0;
83 }
84 /* If reg is 32 then write to xzr, i.e. do nothing */
85
86 return (1);
87 }
88 return (0);
89 }
90
91 #ifdef COMPAT_FREEBSD32
92 /* arm32 GDB breakpoints */
93 #define GDB_BREAKPOINT 0xe6000011
94 #define GDB5_BREAKPOINT 0xe7ffdefe
95 static int
gdb_trapper(vm_offset_t va,uint32_t insn,struct trapframe * frame,uint32_t esr)96 gdb_trapper(vm_offset_t va, uint32_t insn, struct trapframe *frame,
97 uint32_t esr)
98 {
99 struct thread *td = curthread;
100
101 if (insn == GDB_BREAKPOINT || insn == GDB5_BREAKPOINT) {
102 if (SV_PROC_FLAG(td->td_proc, SV_ILP32) &&
103 va < VM_MAXUSER_ADDRESS) {
104 ksiginfo_t ksi;
105
106 ksiginfo_init_trap(&ksi);
107 ksi.ksi_signo = SIGTRAP;
108 ksi.ksi_code = TRAP_TRACE;
109 ksi.ksi_addr = (void *)va;
110 trapsignal(td, &ksi);
111 return 1;
112 }
113 }
114 return 0;
115 }
116 #endif
117
118 void
undef_init(void)119 undef_init(void)
120 {
121
122 LIST_INIT(&undef_handlers[0]);
123 LIST_INIT(&undef_handlers[1]);
124
125 install_undef_handler(false, id_aa64mmfr2_handler);
126 #ifdef COMPAT_FREEBSD32
127 install_undef_handler(true, gdb_trapper);
128 #endif
129 }
130
131 void *
install_undef_handler(bool user,undef_handler_t func)132 install_undef_handler(bool user, undef_handler_t func)
133 {
134 struct undef_handler *uh;
135
136 uh = malloc(sizeof(*uh), M_UNDEF, M_WAITOK);
137 uh->uh_handler = func;
138 LIST_INSERT_HEAD(&undef_handlers[user ? 0 : 1], uh, uh_link);
139
140 return (uh);
141 }
142
143 void
remove_undef_handler(void * handle)144 remove_undef_handler(void *handle)
145 {
146 struct undef_handler *uh;
147
148 uh = handle;
149 LIST_REMOVE(uh, uh_link);
150 free(handle, M_UNDEF);
151 }
152
153 int
undef_insn(u_int el,struct trapframe * frame)154 undef_insn(u_int el, struct trapframe *frame)
155 {
156 struct undef_handler *uh;
157 uint32_t insn;
158 int ret;
159
160 KASSERT(el < 2, ("Invalid exception level %u", el));
161
162 if (el == 0) {
163 ret = fueword32((uint32_t *)frame->tf_elr, &insn);
164 if (ret != 0)
165 panic("Unable to read userspace faulting instruction");
166 } else {
167 insn = *(uint32_t *)frame->tf_elr;
168 }
169
170 LIST_FOREACH(uh, &undef_handlers[el], uh_link) {
171 ret = uh->uh_handler(frame->tf_elr, insn, frame, frame->tf_esr);
172 if (ret)
173 return (1);
174 }
175
176 return (0);
177 }
178