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/queue.h> 39 40 #include <machine/frame.h> 41 #include <machine/undefined.h> 42 43 MALLOC_DEFINE(M_UNDEF, "undefhandler", "Undefined instruction handler data"); 44 45 struct undef_handler { 46 LIST_ENTRY(undef_handler) uh_link; 47 undef_handler_t uh_handler; 48 }; 49 50 /* 51 * Create two undefined instruction handler lists, one for userspace, one for 52 * the kernel. This allows us to handle instructions that will trap 53 */ 54 LIST_HEAD(, undef_handler) undef_handlers[2]; 55 56 /* 57 * Work around a bug in QEMU prior to 2.5.1 where reading unknown ID 58 * registers would raise an exception when they should return 0. 59 */ 60 static int 61 id_aa64mmfr2_handler(vm_offset_t va, uint32_t insn, struct trapframe *frame, 62 uint32_t esr) 63 { 64 int reg; 65 66 #define MRS_ID_AA64MMFR2_EL0_MASK (MRS_MASK | 0x000fffe0) 67 #define MRS_ID_AA64MMFR2_EL0_VALUE (MRS_VALUE | 0x00080740) 68 69 /* mrs xn, id_aa64mfr2_el1 */ 70 if ((insn & MRS_ID_AA64MMFR2_EL0_MASK) == MRS_ID_AA64MMFR2_EL0_VALUE) { 71 reg = MRS_REGISTER(insn); 72 73 frame->tf_elr += INSN_SIZE; 74 if (reg < nitems(frame->tf_x)) { 75 frame->tf_x[reg] = 0; 76 } else if (reg == 30) { 77 frame->tf_lr = 0; 78 } 79 /* If reg is 32 then write to xzr, i.e. do nothing */ 80 81 return (1); 82 } 83 return (0); 84 } 85 86 void 87 undef_init(void) 88 { 89 90 LIST_INIT(&undef_handlers[0]); 91 LIST_INIT(&undef_handlers[1]); 92 93 install_undef_handler(false, id_aa64mmfr2_handler); 94 } 95 96 void * 97 install_undef_handler(bool user, undef_handler_t func) 98 { 99 struct undef_handler *uh; 100 101 uh = malloc(sizeof(*uh), M_UNDEF, M_WAITOK); 102 uh->uh_handler = func; 103 LIST_INSERT_HEAD(&undef_handlers[user ? 0 : 1], uh, uh_link); 104 105 return (uh); 106 } 107 108 void 109 remove_undef_handler(void *handle) 110 { 111 struct undef_handler *uh; 112 113 uh = handle; 114 LIST_REMOVE(uh, uh_link); 115 free(handle, M_UNDEF); 116 } 117 118 int 119 undef_insn(u_int el, struct trapframe *frame) 120 { 121 struct undef_handler *uh; 122 uint32_t insn; 123 int ret; 124 125 KASSERT(el < 2, ("Invalid exception level %u", el)); 126 127 if (el == 0) { 128 ret = fueword32((uint32_t *)frame->tf_elr, &insn); 129 if (ret != 0) 130 panic("Unable to read userspace faulting instruction"); 131 } else { 132 insn = *(uint32_t *)frame->tf_elr; 133 } 134 135 LIST_FOREACH(uh, &undef_handlers[el], uh_link) { 136 ret = uh->uh_handler(frame->tf_elr, insn, frame, frame->tf_esr); 137 if (ret) 138 return (1); 139 } 140 141 return (0); 142 } 143