1 /* 2 * Copyright (c) 2016-2020 Apple Inc. All rights reserved. 3 * 4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ 5 * 6 * This file contains Original Code and/or Modifications of Original Code 7 * as defined in and that are subject to the Apple Public Source License 8 * Version 2.0 (the 'License'). You may not use this file except in 9 * compliance with the License. The rights granted to you under the License 10 * may not be used to create, or enable the creation or redistribution of, 11 * unlawful or unlicensed copies of an Apple operating system, or to 12 * circumvent, violate, or enable the circumvention or violation of, any 13 * terms of an Apple operating system software license agreement. 14 * 15 * Please obtain a copy of the License at 16 * http://www.opensource.apple.com/apsl/ and read it before using this file. 17 * 18 * The Original Code and all software distributed under the License are 19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 23 * Please see the License for the specific language governing rights and 24 * limitations under the License. 25 * 26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ 27 */ 28 29 #include <kern/backtrace.h> 30 #include <kern/kalloc.h> 31 #include <sys/errno.h> 32 #include <sys/sysctl.h> 33 #include <sys/systm.h> 34 35 #if DEVELOPMENT || DEBUG 36 37 #define MAX_BACKTRACE (128) 38 39 #define BACKTRACE_USER (0) 40 #define BACKTRACE_USER_RESUME (1) 41 static int backtrace_user_sysctl SYSCTL_HANDLER_ARGS; 42 43 #define BACKTRACE_KERN_TEST_PACK_UNPACK (0) 44 #define BACKTRACE_KERN_TEST_PACKED (1) 45 static int backtrace_kernel_sysctl SYSCTL_HANDLER_ARGS; 46 47 SYSCTL_NODE(_kern, OID_AUTO, backtrace, CTLFLAG_RW | CTLFLAG_LOCKED, 0, 48 "backtrace"); 49 50 SYSCTL_PROC(_kern_backtrace, OID_AUTO, user, 51 CTLFLAG_RW | CTLFLAG_LOCKED, (void *)BACKTRACE_USER, 52 sizeof(uint64_t), backtrace_user_sysctl, "O", 53 "take user backtrace of current thread"); 54 55 SYSCTL_PROC(_kern_backtrace, OID_AUTO, kernel_tests, 56 CTLFLAG_RW | CTLFLAG_LOCKED, (void *)BACKTRACE_USER, 57 sizeof(uint64_t), backtrace_kernel_sysctl, "O", 58 "take user backtrace of current thread"); 59 60 static int 61 backtrace_kernel_sysctl SYSCTL_HANDLER_ARGS 62 { 63 unsigned int scenario = (unsigned int)req->newlen; 64 uintptr_t *bt = NULL; 65 uint8_t *packed_bt = NULL; 66 uintptr_t *unpacked_bt = NULL; 67 unsigned int bt_len = 0; 68 size_t bt_size = 0; 69 errno_t error = 0; 70 71 bt_len = 24; 72 bt_size = sizeof(bt[0]) * bt_len; 73 bt = kalloc_data(bt_size, Z_WAITOK | Z_ZERO); 74 packed_bt = kalloc_data(bt_size, Z_WAITOK | Z_ZERO); 75 unpacked_bt = kalloc_data(bt_size, Z_WAITOK | Z_ZERO); 76 if (!bt || !packed_bt || !unpacked_bt) { 77 error = ENOBUFS; 78 goto out; 79 } 80 backtrace_info_t info = BTI_NONE; 81 unsigned int len = backtrace(bt, bt_len, NULL, &info); 82 backtrace_info_t packed_info = BTI_NONE; 83 size_t packed_size = 0; 84 if (scenario == BACKTRACE_KERN_TEST_PACK_UNPACK) { 85 packed_size = backtrace_pack(BTP_KERN_OFFSET_32, packed_bt, bt_size, 86 bt, len); 87 } else { 88 packed_size = backtrace_packed(BTP_KERN_OFFSET_32, packed_bt, bt_size, 89 NULL, &packed_info); 90 } 91 unsigned int unpacked_len = backtrace_unpack(BTP_KERN_OFFSET_32, 92 unpacked_bt, bt_len, packed_bt, packed_size); 93 if (unpacked_len != len) { 94 printf("backtrace_tests: length %u != %u unpacked\n", len, 95 unpacked_len); 96 error = ERANGE; 97 goto out; 98 } 99 for (unsigned int i = 0; i < len; i++) { 100 if (unpacked_bt[i] != bt[i]) { 101 printf("backtrace_tests: bad address %u: 0x%lx != 0x%lx unpacked", 102 i, bt[i], unpacked_bt[i]); 103 error = EINVAL; 104 } 105 } 106 107 out: 108 if (bt) { 109 kfree_data(bt, bt_size); 110 } 111 if (packed_bt) { 112 kfree_data(packed_bt, bt_size); 113 } 114 if (unpacked_bt) { 115 kfree_data(unpacked_bt, bt_size); 116 } 117 return error; 118 } 119 120 static int 121 backtrace_user_sysctl SYSCTL_HANDLER_ARGS 122 { 123 #pragma unused(oidp, arg1, arg2) 124 unsigned int scenario = (unsigned int)req->newlen; 125 uintptr_t *bt = NULL; 126 unsigned int bt_len = 0, bt_filled = 0, bt_space = 0; 127 size_t bt_size = 0; 128 errno_t error = 0; 129 130 bool user_scenario = scenario == BACKTRACE_USER; 131 bool resume_scenario = scenario == BACKTRACE_USER_RESUME; 132 if (!user_scenario && !resume_scenario) { 133 return ENOTSUP; 134 } 135 136 if (req->oldptr == USER_ADDR_NULL || req->oldlen == 0) { 137 return EFAULT; 138 } 139 140 bt_len = req->oldlen > MAX_BACKTRACE ? MAX_BACKTRACE : 141 (unsigned int)req->oldlen; 142 bt_size = sizeof(bt[0]) * bt_len; 143 bt = kalloc_data(bt_size, Z_WAITOK | Z_ZERO); 144 if (!bt) { 145 return ENOBUFS; 146 } 147 bt_space = resume_scenario ? bt_len / 2 : bt_len; 148 struct backtrace_user_info btinfo = BTUINFO_INIT; 149 bt_filled = backtrace_user(bt, bt_space, NULL, &btinfo); 150 error = btinfo.btui_error; 151 if (error != 0) { 152 goto out; 153 } 154 if (resume_scenario) { 155 if (!(btinfo.btui_info & BTI_TRUNCATED)) { 156 error = ENOSPC; 157 goto out; 158 } 159 struct backtrace_control ctl = { 160 .btc_frame_addr = btinfo.btui_next_frame_addr, 161 }; 162 btinfo = BTUINFO_INIT; 163 unsigned int bt_more = backtrace_user(bt + bt_filled, bt_space, &ctl, 164 &btinfo); 165 error = btinfo.btui_error; 166 if (error != 0) { 167 goto out; 168 } 169 bt_filled += bt_more; 170 } 171 bt_filled = min(bt_filled, bt_len); 172 if (btinfo.btui_async_frame_addr != 0 && 173 btinfo.btui_async_start_index != 0) { 174 // Put the async call stack inline after the real call stack. 175 unsigned int start_index = btinfo.btui_async_start_index; 176 uintptr_t frame_addr = btinfo.btui_async_frame_addr; 177 unsigned int bt_left = bt_len - start_index; 178 struct backtrace_control ctl = { .btc_frame_addr = frame_addr, }; 179 btinfo = BTUINFO_INIT; 180 unsigned int async_filled = backtrace_user(bt + start_index, bt_left, 181 &ctl, &btinfo); 182 error = btinfo.btui_error; 183 if (error != 0) { 184 goto out; 185 } 186 bt_filled = min(start_index + async_filled, bt_len); 187 } 188 189 error = copyout(bt, req->oldptr, sizeof(bt[0]) * bt_filled); 190 if (error) { 191 goto out; 192 } 193 req->oldidx = bt_filled; 194 195 out: 196 kfree_data(bt, bt_size); 197 return error; 198 } 199 200 #endif /* DEVELOPMENT || DEBUG */ 201