| 1 | /* |
| 2 | * Copyright (C) 2009 Pierre-Marc Fournier |
| 3 | * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 4 | * |
| 5 | * This library is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of the GNU Lesser General Public |
| 7 | * License as published by the Free Software Foundation; either |
| 8 | * version 2.1 of the License, or (at your option) any later version. |
| 9 | * |
| 10 | * This library is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | * Lesser General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU Lesser General Public |
| 16 | * License along with this library; if not, write to the Free Software |
| 17 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 18 | */ |
| 19 | |
| 20 | #define _GNU_SOURCE |
| 21 | #include <dlfcn.h> |
| 22 | #include <sys/types.h> |
| 23 | #include <stdio.h> |
| 24 | #include <assert.h> |
| 25 | #include <urcu/system.h> |
| 26 | #include <urcu/uatomic.h> |
| 27 | #include <urcu/compiler.h> |
| 28 | #include <lttng/align.h> |
| 29 | |
| 30 | #define TRACEPOINT_DEFINE |
| 31 | #define TRACEPOINT_CREATE_PROBES |
| 32 | #include "ust_libc.h" |
| 33 | |
| 34 | #define STATIC_CALLOC_LEN 4096 |
| 35 | static char static_calloc_buf[STATIC_CALLOC_LEN]; |
| 36 | static unsigned long static_calloc_buf_offset; |
| 37 | |
| 38 | struct alloc_functions { |
| 39 | void *(*calloc)(size_t nmemb, size_t size); |
| 40 | void *(*malloc)(size_t size); |
| 41 | void (*free)(void *ptr); |
| 42 | void *(*realloc)(void *ptr, size_t size); |
| 43 | void *(*memalign)(size_t alignment, size_t size); |
| 44 | int (*posix_memalign)(void **memptr, size_t alignment, size_t size); |
| 45 | }; |
| 46 | |
| 47 | static |
| 48 | struct alloc_functions cur_alloc; |
| 49 | |
| 50 | /* |
| 51 | * Static allocator to use when initially executing dlsym(). It keeps a |
| 52 | * size_t value of each object size prior to the object. |
| 53 | */ |
| 54 | static |
| 55 | void *static_calloc_aligned(size_t nmemb, size_t size, size_t alignment) |
| 56 | { |
| 57 | size_t prev_offset, new_offset, res_offset, aligned_offset; |
| 58 | |
| 59 | if (nmemb * size == 0) { |
| 60 | return NULL; |
| 61 | } |
| 62 | |
| 63 | /* |
| 64 | * Protect static_calloc_buf_offset from concurrent updates |
| 65 | * using a cmpxchg loop rather than a mutex to remove a |
| 66 | * dependency on pthread. This will minimize the risk of bad |
| 67 | * interaction between mutex and malloc instrumentation. |
| 68 | */ |
| 69 | res_offset = CMM_LOAD_SHARED(static_calloc_buf_offset); |
| 70 | do { |
| 71 | prev_offset = res_offset; |
| 72 | aligned_offset = ALIGN(prev_offset + sizeof(size_t), alignment); |
| 73 | new_offset = aligned_offset + nmemb * size; |
| 74 | if (new_offset > sizeof(static_calloc_buf)) { |
| 75 | abort(); |
| 76 | } |
| 77 | } while ((res_offset = uatomic_cmpxchg(&static_calloc_buf_offset, |
| 78 | prev_offset, new_offset)) != prev_offset); |
| 79 | *(size_t *) &static_calloc_buf[aligned_offset - sizeof(size_t)] = size; |
| 80 | return &static_calloc_buf[aligned_offset]; |
| 81 | } |
| 82 | |
| 83 | static |
| 84 | void *static_calloc(size_t nmemb, size_t size) |
| 85 | { |
| 86 | void *retval; |
| 87 | |
| 88 | retval = static_calloc_aligned(nmemb, size, 1); |
| 89 | tracepoint(ust_libc, calloc, nmemb, size, retval); |
| 90 | return retval; |
| 91 | } |
| 92 | |
| 93 | static |
| 94 | void *static_malloc(size_t size) |
| 95 | { |
| 96 | void *retval; |
| 97 | |
| 98 | retval = static_calloc_aligned(1, size, 1); |
| 99 | tracepoint(ust_libc, malloc, size, retval); |
| 100 | return retval; |
| 101 | } |
| 102 | |
| 103 | static |
| 104 | void static_free(void *ptr) |
| 105 | { |
| 106 | /* no-op. */ |
| 107 | tracepoint(ust_libc, free, ptr); |
| 108 | } |
| 109 | |
| 110 | static |
| 111 | void *static_realloc(void *ptr, size_t size) |
| 112 | { |
| 113 | size_t *old_size = NULL; |
| 114 | void *retval; |
| 115 | |
| 116 | if (size == 0) { |
| 117 | retval = NULL; |
| 118 | goto end; |
| 119 | } |
| 120 | |
| 121 | if (ptr) { |
| 122 | old_size = (size_t *) ptr - 1; |
| 123 | if (size <= *old_size) { |
| 124 | /* We can re-use the old entry. */ |
| 125 | *old_size = size; |
| 126 | retval = ptr; |
| 127 | goto end; |
| 128 | } |
| 129 | } |
| 130 | /* We need to expand. Don't free previous memory location. */ |
| 131 | retval = static_calloc_aligned(1, size, 1); |
| 132 | assert(retval); |
| 133 | if (ptr) |
| 134 | memcpy(retval, ptr, *old_size); |
| 135 | end: |
| 136 | tracepoint(ust_libc, realloc, ptr, size, retval); |
| 137 | return retval; |
| 138 | } |
| 139 | |
| 140 | static |
| 141 | void *static_memalign(size_t alignment, size_t size) |
| 142 | { |
| 143 | void *retval; |
| 144 | |
| 145 | retval = static_calloc_aligned(1, size, alignment); |
| 146 | tracepoint(ust_libc, memalign, alignment, size, retval); |
| 147 | return retval; |
| 148 | } |
| 149 | |
| 150 | static |
| 151 | int static_posix_memalign(void **memptr, size_t alignment, size_t size) |
| 152 | { |
| 153 | int retval = 0; |
| 154 | void *ptr; |
| 155 | |
| 156 | /* Check for power of 2, larger than void *. */ |
| 157 | if (alignment & (alignment - 1) |
| 158 | || alignment < sizeof(void *) |
| 159 | || alignment == 0) { |
| 160 | retval = EINVAL; |
| 161 | goto end; |
| 162 | } |
| 163 | ptr = static_calloc_aligned(1, size, alignment); |
| 164 | *memptr = ptr; |
| 165 | if (size && !ptr) |
| 166 | retval = ENOMEM; |
| 167 | end: |
| 168 | tracepoint(ust_libc, posix_memalign, *memptr, alignment, size, retval); |
| 169 | return 0; |
| 170 | } |
| 171 | |
| 172 | static |
| 173 | void setup_static_allocator(void) |
| 174 | { |
| 175 | assert(cur_alloc.calloc == NULL); |
| 176 | cur_alloc.calloc = static_calloc; |
| 177 | assert(cur_alloc.malloc == NULL); |
| 178 | cur_alloc.malloc = static_malloc; |
| 179 | assert(cur_alloc.free == NULL); |
| 180 | cur_alloc.free = static_free; |
| 181 | assert(cur_alloc.realloc == NULL); |
| 182 | cur_alloc.realloc = static_realloc; |
| 183 | assert(cur_alloc.memalign == NULL); |
| 184 | cur_alloc.memalign = static_memalign; |
| 185 | assert(cur_alloc.posix_memalign == NULL); |
| 186 | cur_alloc.posix_memalign = static_posix_memalign; |
| 187 | } |
| 188 | |
| 189 | static |
| 190 | void lookup_all_symbols(void) |
| 191 | { |
| 192 | struct alloc_functions af; |
| 193 | |
| 194 | /* |
| 195 | * Temporarily redirect allocation functions to |
| 196 | * static_calloc_aligned, and free function to static_free |
| 197 | * (no-op), until the dlsym lookup has completed. |
| 198 | */ |
| 199 | setup_static_allocator(); |
| 200 | |
| 201 | /* Perform the actual lookups */ |
| 202 | af.calloc = dlsym(RTLD_NEXT, "calloc"); |
| 203 | af.malloc = dlsym(RTLD_NEXT, "malloc"); |
| 204 | af.free = dlsym(RTLD_NEXT, "free"); |
| 205 | af.realloc = dlsym(RTLD_NEXT, "realloc"); |
| 206 | af.memalign = dlsym(RTLD_NEXT, "memalign"); |
| 207 | af.posix_memalign = dlsym(RTLD_NEXT, "posix_memalign"); |
| 208 | |
| 209 | /* Populate the new allocator functions */ |
| 210 | memcpy(&cur_alloc, &af, sizeof(cur_alloc)); |
| 211 | } |
| 212 | |
| 213 | void *malloc(size_t size) |
| 214 | { |
| 215 | void *retval; |
| 216 | |
| 217 | if (cur_alloc.malloc == NULL) { |
| 218 | lookup_all_symbols(); |
| 219 | if (cur_alloc.malloc == NULL) { |
| 220 | fprintf(stderr, "mallocwrap: unable to find malloc\n"); |
| 221 | abort(); |
| 222 | } |
| 223 | } |
| 224 | retval = cur_alloc.malloc(size); |
| 225 | tracepoint(ust_libc, malloc, size, retval); |
| 226 | return retval; |
| 227 | } |
| 228 | |
| 229 | void free(void *ptr) |
| 230 | { |
| 231 | tracepoint(ust_libc, free, ptr); |
| 232 | |
| 233 | /* |
| 234 | * Check whether the memory was allocated with |
| 235 | * static_calloc_align, in which case there is nothing to free. |
| 236 | */ |
| 237 | if (caa_unlikely((char *)ptr >= static_calloc_buf && |
| 238 | (char *)ptr < static_calloc_buf + STATIC_CALLOC_LEN)) { |
| 239 | return; |
| 240 | } |
| 241 | |
| 242 | if (cur_alloc.free == NULL) { |
| 243 | lookup_all_symbols(); |
| 244 | if (cur_alloc.free == NULL) { |
| 245 | fprintf(stderr, "mallocwrap: unable to find free\n"); |
| 246 | abort(); |
| 247 | } |
| 248 | } |
| 249 | cur_alloc.free(ptr); |
| 250 | } |
| 251 | |
| 252 | void *calloc(size_t nmemb, size_t size) |
| 253 | { |
| 254 | void *retval; |
| 255 | |
| 256 | if (cur_alloc.calloc == NULL) { |
| 257 | lookup_all_symbols(); |
| 258 | if (cur_alloc.calloc == NULL) { |
| 259 | fprintf(stderr, "callocwrap: unable to find calloc\n"); |
| 260 | abort(); |
| 261 | } |
| 262 | } |
| 263 | retval = cur_alloc.calloc(nmemb, size); |
| 264 | tracepoint(ust_libc, calloc, nmemb, size, retval); |
| 265 | return retval; |
| 266 | } |
| 267 | |
| 268 | void *realloc(void *ptr, size_t size) |
| 269 | { |
| 270 | void *retval; |
| 271 | |
| 272 | /* Check whether the memory was allocated with |
| 273 | * static_calloc_align, in which case there is nothing |
| 274 | * to free, and we need to copy the old data. |
| 275 | */ |
| 276 | if (caa_unlikely((char *)ptr >= static_calloc_buf && |
| 277 | (char *)ptr < static_calloc_buf + STATIC_CALLOC_LEN)) { |
| 278 | size_t *old_size; |
| 279 | |
| 280 | old_size = (size_t *) ptr - 1; |
| 281 | if (cur_alloc.calloc == NULL) { |
| 282 | lookup_all_symbols(); |
| 283 | if (cur_alloc.calloc == NULL) { |
| 284 | fprintf(stderr, "reallocwrap: unable to find calloc\n"); |
| 285 | abort(); |
| 286 | } |
| 287 | } |
| 288 | retval = cur_alloc.calloc(1, size); |
| 289 | if (retval) { |
| 290 | memcpy(retval, ptr, *old_size); |
| 291 | } |
| 292 | goto end; |
| 293 | } |
| 294 | |
| 295 | if (cur_alloc.realloc == NULL) { |
| 296 | lookup_all_symbols(); |
| 297 | if (cur_alloc.realloc == NULL) { |
| 298 | fprintf(stderr, "reallocwrap: unable to find realloc\n"); |
| 299 | abort(); |
| 300 | } |
| 301 | } |
| 302 | retval = cur_alloc.realloc(ptr, size); |
| 303 | end: |
| 304 | tracepoint(ust_libc, realloc, ptr, size, retval); |
| 305 | return retval; |
| 306 | } |
| 307 | |
| 308 | void *memalign(size_t alignment, size_t size) |
| 309 | { |
| 310 | void *retval; |
| 311 | |
| 312 | if (cur_alloc.memalign == NULL) { |
| 313 | lookup_all_symbols(); |
| 314 | if (cur_alloc.memalign == NULL) { |
| 315 | fprintf(stderr, "memalignwrap: unable to find memalign\n"); |
| 316 | abort(); |
| 317 | } |
| 318 | } |
| 319 | retval = cur_alloc.memalign(alignment, size); |
| 320 | tracepoint(ust_libc, memalign, alignment, size, retval); |
| 321 | return retval; |
| 322 | } |
| 323 | |
| 324 | int posix_memalign(void **memptr, size_t alignment, size_t size) |
| 325 | { |
| 326 | int retval; |
| 327 | |
| 328 | if (cur_alloc.posix_memalign == NULL) { |
| 329 | lookup_all_symbols(); |
| 330 | if (cur_alloc.posix_memalign == NULL) { |
| 331 | fprintf(stderr, "posix_memalignwrap: unable to find posix_memalign\n"); |
| 332 | abort(); |
| 333 | } |
| 334 | } |
| 335 | retval = cur_alloc.posix_memalign(memptr, alignment, size); |
| 336 | tracepoint(ust_libc, posix_memalign, *memptr, alignment, size, retval); |
| 337 | return retval; |
| 338 | } |
| 339 | |
| 340 | __attribute__((constructor)) |
| 341 | void lttng_ust_malloc_wrapper_init(void) |
| 342 | { |
| 343 | /* Initialization already done */ |
| 344 | if (cur_alloc.calloc) { |
| 345 | return; |
| 346 | } |
| 347 | /* |
| 348 | * Ensure the allocator is in place before the process becomes |
| 349 | * multithreaded. |
| 350 | */ |
| 351 | lookup_all_symbols(); |
| 352 | } |