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 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 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 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 * 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 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 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