1 /* 2 * Copyright (c) 2013 Luca Clementi <luca.clementi (at) gmail.com> 3 * Copyright (c) 2013-2018 The strace developers. 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 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "defs.h" 29 #include "unwind.h" 30 31 #include "mmap_cache.h" 32 #include <libunwind-ptrace.h> 33 34 static unw_addr_space_t libunwind_as; 35 36 static void 37 init(void) 38 { 39 mmap_cache_enable(); 40 41 libunwind_as = unw_create_addr_space(&_UPT_accessors, 0); 42 if (!libunwind_as) 43 error_msg_and_die("failed to create address space" 44 " for stack tracing"); 45 unw_set_caching_policy(libunwind_as, UNW_CACHE_GLOBAL); 46 } 47 48 static void * 49 tcb_init(struct tcb *tcp) 50 { 51 void *r = _UPT_create(tcp->pid); 52 53 if (!r) 54 perror_msg_and_die("_UPT_create"); 55 return r; 56 } 57 58 static void 59 tcb_fin(struct tcb *tcp) 60 { 61 _UPT_destroy(tcp->unwind_ctx); 62 } 63 64 static void 65 get_symbol_name(unw_cursor_t *cursor, char **name, 66 size_t *size, unw_word_t *offset) 67 { 68 for (;;) { 69 int rc = unw_get_proc_name(cursor, *name, *size, offset); 70 71 if (rc == 0) 72 break; 73 if (rc != -UNW_ENOMEM) { 74 **name = '\0'; 75 *offset = 0; 76 break; 77 } 78 *name = xgrowarray(*name, size, 1); 79 } 80 } 81 82 static int 83 print_stack_frame(struct tcb *tcp, 84 unwind_call_action_fn call_action, 85 unwind_error_action_fn error_action, 86 void *data, 87 unw_cursor_t *cursor, 88 char **symbol_name, 89 size_t *symbol_name_size) 90 { 91 unw_word_t ip; 92 93 if (unw_get_reg(cursor, UNW_REG_IP, &ip) < 0) { 94 perror_msg("cannot walk the stack of process %d", tcp->pid); 95 return -1; 96 } 97 98 struct mmap_cache_entry_t *entry = mmap_cache_search(tcp, ip); 99 100 if (entry 101 /* ignore mappings that have no PROT_EXEC bit set */ 102 && (entry->protections & MMAP_CACHE_PROT_EXECUTABLE)) { 103 unw_word_t function_offset; 104 105 get_symbol_name(cursor, symbol_name, symbol_name_size, 106 &function_offset); 107 unsigned long true_offset = 108 ip - entry->start_addr + entry->mmap_offset; 109 call_action(data, 110 entry->binary_filename, 111 *symbol_name, 112 function_offset, 113 true_offset); 114 115 return 0; 116 } 117 118 /* 119 * there is a bug in libunwind >= 1.0 120 * after a set_tid_address syscall 121 * unw_get_reg returns IP == 0 122 */ 123 if (ip) 124 error_action(data, "unexpected_backtracing_error", ip); 125 return -1; 126 } 127 128 static void 129 walk(struct tcb *tcp, 130 unwind_call_action_fn call_action, 131 unwind_error_action_fn error_action, 132 void *data) 133 { 134 char *symbol_name; 135 size_t symbol_name_size = 40; 136 unw_cursor_t cursor; 137 int stack_depth; 138 139 if (!tcp->mmap_cache) 140 error_func_msg_and_die("mmap_cache is NULL"); 141 142 symbol_name = xmalloc(symbol_name_size); 143 144 if (unw_init_remote(&cursor, libunwind_as, tcp->unwind_ctx) < 0) 145 perror_func_msg_and_die("cannot initialize libunwind"); 146 147 for (stack_depth = 0; stack_depth < 256; ++stack_depth) { 148 if (print_stack_frame(tcp, call_action, error_action, data, 149 &cursor, &symbol_name, &symbol_name_size) < 0) 150 break; 151 if (unw_step(&cursor) <= 0) 152 break; 153 } 154 if (stack_depth >= 256) 155 error_action(data, "too many stack frames", 0); 156 157 free(symbol_name); 158 } 159 160 static void 161 tcb_walk(struct tcb *tcp, 162 unwind_call_action_fn call_action, 163 unwind_error_action_fn error_action, 164 void *data) 165 { 166 switch (mmap_cache_rebuild_if_invalid(tcp, __func__)) { 167 case MMAP_CACHE_REBUILD_RENEWED: 168 /* 169 * Rebuild the unwinder internal cache. 170 * Called when mmap cache subsystem detects a 171 * change of tracee memory mapping. 172 */ 173 unw_flush_cache(libunwind_as, 0, 0); 174 ATTRIBUTE_FALLTHROUGH; 175 case MMAP_CACHE_REBUILD_READY: 176 walk(tcp, call_action, error_action, data); 177 break; 178 default: 179 /* Do nothing */ 180 ; 181 } 182 } 183 184 const struct unwind_unwinder_t unwinder = { 185 .name = "libunwind", 186 .init = init, 187 .tcb_init = tcb_init, 188 .tcb_fin = tcb_fin, 189 .tcb_walk = tcb_walk, 190 }; 191
