microsoft/qdk
Publicmirrored fromhttps://github.com/microsoft/qdkAvailable
source/allocator/mimalloc-sys/mimalloc/src/free.c
572lines · modecode
| 1 | /* ---------------------------------------------------------------------------- |
| 2 | Copyright (c) 2018-2024, Microsoft Research, Daan Leijen |
| 3 | This is free software; you can redistribute it and/or modify it under the |
| 4 | terms of the MIT license. A copy of the license can be found in the file |
| 5 | "LICENSE" at the root of this distribution. |
| 6 | -----------------------------------------------------------------------------*/ |
| 7 | #if !defined(MI_IN_ALLOC_C) |
| 8 | #error "this file should be included from 'alloc.c' (so aliases can work from alloc-override)" |
| 9 | // add includes help an IDE |
| 10 | #include "mimalloc.h" |
| 11 | #include "mimalloc/internal.h" |
| 12 | #include "mimalloc/prim.h" // _mi_prim_thread_id() |
| 13 | #endif |
| 14 | |
| 15 | // forward declarations |
| 16 | static void mi_check_padding(const mi_page_t* page, const mi_block_t* block); |
| 17 | static bool mi_check_is_double_free(const mi_page_t* page, const mi_block_t* block); |
| 18 | static size_t mi_page_usable_size_of(const mi_page_t* page, const mi_block_t* block); |
| 19 | static void mi_stat_free(const mi_page_t* page, const mi_block_t* block); |
| 20 | |
| 21 | |
| 22 | // ------------------------------------------------------ |
| 23 | // Free |
| 24 | // ------------------------------------------------------ |
| 25 | |
| 26 | // forward declaration of multi-threaded free (`_mt`) (or free in huge block if compiled with MI_HUGE_PAGE_ABANDON) |
| 27 | static mi_decl_noinline void mi_free_block_mt(mi_page_t* page, mi_segment_t* segment, mi_block_t* block); |
| 28 | |
| 29 | // regular free of a (thread local) block pointer |
| 30 | // fast path written carefully to prevent spilling on the stack |
| 31 | static inline void mi_free_block_local(mi_page_t* page, mi_block_t* block, bool track_stats, bool check_full) |
| 32 | { |
| 33 | // checks |
| 34 | if mi_unlikely(mi_check_is_double_free(page, block)) return; |
| 35 | mi_check_padding(page, block); |
| 36 | if (track_stats) { mi_stat_free(page, block); } |
| 37 | #if (MI_DEBUG>0) && !MI_TRACK_ENABLED && !MI_TSAN && !MI_GUARDED |
| 38 | if (!mi_page_is_huge(page)) { // huge page content may be already decommitted |
| 39 | memset(block, MI_DEBUG_FREED, mi_page_block_size(page)); |
| 40 | } |
| 41 | #endif |
| 42 | if (track_stats) { mi_track_free_size(block, mi_page_usable_size_of(page, block)); } // faster then mi_usable_size as we already know the page and that p is unaligned |
| 43 | |
| 44 | // actual free: push on the local free list |
| 45 | mi_block_set_next(page, block, page->local_free); |
| 46 | page->local_free = block; |
| 47 | if mi_unlikely(--page->used == 0) { |
| 48 | _mi_page_retire(page); |
| 49 | } |
| 50 | else if mi_unlikely(check_full && mi_page_is_in_full(page)) { |
| 51 | _mi_page_unfull(page); |
| 52 | } |
| 53 | } |
| 54 | |
| 55 | // Adjust a block that was allocated aligned, to the actual start of the block in the page. |
| 56 | // note: this can be called from `mi_free_generic_mt` where a non-owning thread accesses the |
| 57 | // `page_start` and `block_size` fields; however these are constant and the page won't be |
| 58 | // deallocated (as the block we are freeing keeps it alive) and thus safe to read concurrently. |
| 59 | mi_block_t* _mi_page_ptr_unalign(const mi_page_t* page, const void* p) { |
| 60 | mi_assert_internal(page!=NULL && p!=NULL); |
| 61 | |
| 62 | size_t diff = (uint8_t*)p - page->page_start; |
| 63 | size_t adjust; |
| 64 | if mi_likely(page->block_size_shift != 0) { |
| 65 | adjust = diff & (((size_t)1 << page->block_size_shift) - 1); |
| 66 | } |
| 67 | else { |
| 68 | adjust = diff % mi_page_block_size(page); |
| 69 | } |
| 70 | |
| 71 | return (mi_block_t*)((uintptr_t)p - adjust); |
| 72 | } |
| 73 | |
| 74 | // forward declaration for a MI_GUARDED build |
| 75 | #if MI_GUARDED |
| 76 | static void mi_block_unguard(mi_page_t* page, mi_block_t* block, void* p); // forward declaration |
| 77 | static inline void mi_block_check_unguard(mi_page_t* page, mi_block_t* block, void* p) { |
| 78 | if (mi_block_ptr_is_guarded(block, p)) { mi_block_unguard(page, block, p); } |
| 79 | } |
| 80 | #else |
| 81 | static inline void mi_block_check_unguard(mi_page_t* page, mi_block_t* block, void* p) { |
| 82 | MI_UNUSED(page); MI_UNUSED(block); MI_UNUSED(p); |
| 83 | } |
| 84 | #endif |
| 85 | |
| 86 | // free a local pointer (page parameter comes first for better codegen) |
| 87 | static void mi_decl_noinline mi_free_generic_local(mi_page_t* page, mi_segment_t* segment, void* p) mi_attr_noexcept { |
| 88 | MI_UNUSED(segment); |
| 89 | mi_block_t* const block = (mi_page_has_aligned(page) ? _mi_page_ptr_unalign(page, p) : (mi_block_t*)p); |
| 90 | mi_block_check_unguard(page, block, p); |
| 91 | mi_free_block_local(page, block, true /* track stats */, true /* check for a full page */); |
| 92 | } |
| 93 | |
| 94 | // free a pointer owned by another thread (page parameter comes first for better codegen) |
| 95 | static void mi_decl_noinline mi_free_generic_mt(mi_page_t* page, mi_segment_t* segment, void* p) mi_attr_noexcept { |
| 96 | mi_block_t* const block = _mi_page_ptr_unalign(page, p); // don't check `has_aligned` flag to avoid a race (issue #865) |
| 97 | mi_block_check_unguard(page, block, p); |
| 98 | mi_free_block_mt(page, segment, block); |
| 99 | } |
| 100 | |
| 101 | // generic free (for runtime integration) |
| 102 | void mi_decl_noinline _mi_free_generic(mi_segment_t* segment, mi_page_t* page, bool is_local, void* p) mi_attr_noexcept { |
| 103 | if (is_local) mi_free_generic_local(page,segment,p); |
| 104 | else mi_free_generic_mt(page,segment,p); |
| 105 | } |
| 106 | |
| 107 | // Get the segment data belonging to a pointer |
| 108 | // This is just a single `and` in release mode but does further checks in debug mode |
| 109 | // (and secure mode) to see if this was a valid pointer. |
| 110 | static inline mi_segment_t* mi_checked_ptr_segment(const void* p, const char* msg) |
| 111 | { |
| 112 | MI_UNUSED(msg); |
| 113 | |
| 114 | #if (MI_DEBUG>0) |
| 115 | if mi_unlikely(((uintptr_t)p & (MI_INTPTR_SIZE - 1)) != 0 && !mi_option_is_enabled(mi_option_guarded_precise)) { |
| 116 | _mi_error_message(EINVAL, "%s: invalid (unaligned) pointer: %p\n", msg, p); |
| 117 | return NULL; |
| 118 | } |
| 119 | #endif |
| 120 | |
| 121 | mi_segment_t* const segment = _mi_ptr_segment(p); |
| 122 | if mi_unlikely(segment==NULL) return segment; |
| 123 | |
| 124 | #if (MI_DEBUG>0) |
| 125 | if mi_unlikely(!mi_is_in_heap_region(p)) { |
| 126 | #if (MI_INTPTR_SIZE == 8 && defined(__linux__)) |
| 127 | if (((uintptr_t)p >> 40) != 0x7F) { // linux tends to align large blocks above 0x7F000000000 (issue #640) |
| 128 | #else |
| 129 | { |
| 130 | #endif |
| 131 | _mi_warning_message("%s: pointer might not point to a valid heap region: %p\n" |
| 132 | "(this may still be a valid very large allocation (over 64MiB))\n", msg, p); |
| 133 | if mi_likely(_mi_ptr_cookie(segment) == segment->cookie) { |
| 134 | _mi_warning_message("(yes, the previous pointer %p was valid after all)\n", p); |
| 135 | } |
| 136 | } |
| 137 | } |
| 138 | #endif |
| 139 | #if (MI_DEBUG>0 || MI_SECURE>=4) |
| 140 | if mi_unlikely(_mi_ptr_cookie(segment) != segment->cookie) { |
| 141 | _mi_error_message(EINVAL, "%s: pointer does not point to a valid heap space: %p\n", msg, p); |
| 142 | return NULL; |
| 143 | } |
| 144 | #endif |
| 145 | |
| 146 | return segment; |
| 147 | } |
| 148 | |
| 149 | // Free a block |
| 150 | // Fast path written carefully to prevent register spilling on the stack |
| 151 | void mi_free(void* p) mi_attr_noexcept |
| 152 | { |
| 153 | mi_segment_t* const segment = mi_checked_ptr_segment(p,"mi_free"); |
| 154 | if mi_unlikely(segment==NULL) return; |
| 155 | |
| 156 | const bool is_local = (_mi_prim_thread_id() == mi_atomic_load_relaxed(&segment->thread_id)); |
| 157 | mi_page_t* const page = _mi_segment_page_of(segment, p); |
| 158 | |
| 159 | if mi_likely(is_local) { // thread-local free? |
| 160 | if mi_likely(page->flags.full_aligned == 0) { // and it is not a full page (full pages need to move from the full bin), nor has aligned blocks (aligned blocks need to be unaligned) |
| 161 | // thread-local, aligned, and not a full page |
| 162 | mi_block_t* const block = (mi_block_t*)p; |
| 163 | mi_free_block_local(page, block, true /* track stats */, false /* no need to check if the page is full */); |
| 164 | } |
| 165 | else { |
| 166 | // page is full or contains (inner) aligned blocks; use generic path |
| 167 | mi_free_generic_local(page, segment, p); |
| 168 | } |
| 169 | } |
| 170 | else { |
| 171 | // not thread-local; use generic path |
| 172 | mi_free_generic_mt(page, segment, p); |
| 173 | } |
| 174 | } |
| 175 | |
| 176 | // return true if successful |
| 177 | bool _mi_free_delayed_block(mi_block_t* block) { |
| 178 | // get segment and page |
| 179 | mi_assert_internal(block!=NULL); |
| 180 | const mi_segment_t* const segment = _mi_ptr_segment(block); |
| 181 | mi_assert_internal(_mi_ptr_cookie(segment) == segment->cookie); |
| 182 | mi_assert_internal(_mi_thread_id() == segment->thread_id); |
| 183 | mi_page_t* const page = _mi_segment_page_of(segment, block); |
| 184 | |
| 185 | // Clear the no-delayed flag so delayed freeing is used again for this page. |
| 186 | // This must be done before collecting the free lists on this page -- otherwise |
| 187 | // some blocks may end up in the page `thread_free` list with no blocks in the |
| 188 | // heap `thread_delayed_free` list which may cause the page to be never freed! |
| 189 | // (it would only be freed if we happen to scan it in `mi_page_queue_find_free_ex`) |
| 190 | if (!_mi_page_try_use_delayed_free(page, MI_USE_DELAYED_FREE, false /* dont overwrite never delayed */)) { |
| 191 | return false; |
| 192 | } |
| 193 | |
| 194 | // collect all other non-local frees (move from `thread_free` to `free`) to ensure up-to-date `used` count |
| 195 | _mi_page_free_collect(page, false); |
| 196 | |
| 197 | // and free the block (possibly freeing the page as well since `used` is updated) |
| 198 | mi_free_block_local(page, block, false /* stats have already been adjusted */, true /* check for a full page */); |
| 199 | return true; |
| 200 | } |
| 201 | |
| 202 | // ------------------------------------------------------ |
| 203 | // Multi-threaded Free (`_mt`) |
| 204 | // ------------------------------------------------------ |
| 205 | |
| 206 | // Push a block that is owned by another thread on its page-local thread free |
| 207 | // list or it's heap delayed free list. Such blocks are later collected by |
| 208 | // the owning thread in `_mi_free_delayed_block`. |
| 209 | static void mi_decl_noinline mi_free_block_delayed_mt( mi_page_t* page, mi_block_t* block ) |
| 210 | { |
| 211 | // Try to put the block on either the page-local thread free list, |
| 212 | // or the heap delayed free list (if this is the first non-local free in that page) |
| 213 | mi_thread_free_t tfreex; |
| 214 | bool use_delayed; |
| 215 | mi_thread_free_t tfree = mi_atomic_load_relaxed(&page->xthread_free); |
| 216 | do { |
| 217 | use_delayed = (mi_tf_delayed(tfree) == MI_USE_DELAYED_FREE); |
| 218 | if mi_unlikely(use_delayed) { |
| 219 | // unlikely: this only happens on the first concurrent free in a page that is in the full list |
| 220 | tfreex = mi_tf_set_delayed(tfree,MI_DELAYED_FREEING); |
| 221 | } |
| 222 | else { |
| 223 | // usual: directly add to page thread_free list |
| 224 | mi_block_set_next(page, block, mi_tf_block(tfree)); |
| 225 | tfreex = mi_tf_set_block(tfree,block); |
| 226 | } |
| 227 | } while (!mi_atomic_cas_weak_release(&page->xthread_free, &tfree, tfreex)); |
| 228 | |
| 229 | // If this was the first non-local free, we need to push it on the heap delayed free list instead |
| 230 | if mi_unlikely(use_delayed) { |
| 231 | // racy read on `heap`, but ok because MI_DELAYED_FREEING is set (see `mi_heap_delete` and `mi_heap_collect_abandon`) |
| 232 | mi_heap_t* const heap = (mi_heap_t*)(mi_atomic_load_acquire(&page->xheap)); //mi_page_heap(page); |
| 233 | mi_assert_internal(heap != NULL); |
| 234 | if (heap != NULL) { |
| 235 | // add to the delayed free list of this heap. (do this atomically as the lock only protects heap memory validity) |
| 236 | mi_block_t* dfree = mi_atomic_load_ptr_relaxed(mi_block_t, &heap->thread_delayed_free); |
| 237 | do { |
| 238 | mi_block_set_nextx(heap,block,dfree, heap->keys); |
| 239 | } while (!mi_atomic_cas_ptr_weak_release(mi_block_t,&heap->thread_delayed_free, &dfree, block)); |
| 240 | } |
| 241 | |
| 242 | // and reset the MI_DELAYED_FREEING flag |
| 243 | tfree = mi_atomic_load_relaxed(&page->xthread_free); |
| 244 | do { |
| 245 | tfreex = tfree; |
| 246 | mi_assert_internal(mi_tf_delayed(tfree) == MI_DELAYED_FREEING); |
| 247 | tfreex = mi_tf_set_delayed(tfree,MI_NO_DELAYED_FREE); |
| 248 | } while (!mi_atomic_cas_weak_release(&page->xthread_free, &tfree, tfreex)); |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | // Multi-threaded free (`_mt`) (or free in huge block if compiled with MI_HUGE_PAGE_ABANDON) |
| 253 | static void mi_decl_noinline mi_free_block_mt(mi_page_t* page, mi_segment_t* segment, mi_block_t* block) |
| 254 | { |
| 255 | // first see if the segment was abandoned and if we can reclaim it into our thread |
| 256 | if (_mi_option_get_fast(mi_option_abandoned_reclaim_on_free) != 0 && |
| 257 | #if MI_HUGE_PAGE_ABANDON |
| 258 | segment->page_kind != MI_PAGE_HUGE && |
| 259 | #endif |
| 260 | mi_atomic_load_relaxed(&segment->thread_id) == 0 && // segment is abandoned? |
| 261 | mi_prim_get_default_heap() != (mi_heap_t*)&_mi_heap_empty) // and we did not already exit this thread (without this check, a fresh heap will be initalized (issue #944)) |
| 262 | { |
| 263 | // the segment is abandoned, try to reclaim it into our heap |
| 264 | if (_mi_segment_attempt_reclaim(mi_heap_get_default(), segment)) { |
| 265 | mi_assert_internal(_mi_thread_id() == mi_atomic_load_relaxed(&segment->thread_id)); |
| 266 | mi_assert_internal(mi_heap_get_default()->tld->segments.subproc == segment->subproc); |
| 267 | mi_free(block); // recursively free as now it will be a local free in our heap |
| 268 | return; |
| 269 | } |
| 270 | } |
| 271 | |
| 272 | // The padding check may access the non-thread-owned page for the key values. |
| 273 | // that is safe as these are constant and the page won't be freed (as the block is not freed yet). |
| 274 | mi_check_padding(page, block); |
| 275 | |
| 276 | // adjust stats (after padding check and potentially recursive `mi_free` above) |
| 277 | mi_stat_free(page, block); // stat_free may access the padding |
| 278 | mi_track_free_size(block, mi_page_usable_size_of(page,block)); |
| 279 | |
| 280 | // for small size, ensure we can fit the delayed thread pointers without triggering overflow detection |
| 281 | _mi_padding_shrink(page, block, sizeof(mi_block_t)); |
| 282 | |
| 283 | if (segment->kind == MI_SEGMENT_HUGE) { |
| 284 | #if MI_HUGE_PAGE_ABANDON |
| 285 | // huge page segments are always abandoned and can be freed immediately |
| 286 | _mi_segment_huge_page_free(segment, page, block); |
| 287 | return; |
| 288 | #else |
| 289 | // huge pages are special as they occupy the entire segment |
| 290 | // as these are large we reset the memory occupied by the page so it is available to other threads |
| 291 | // (as the owning thread needs to actually free the memory later). |
| 292 | _mi_segment_huge_page_reset(segment, page, block); |
| 293 | #endif |
| 294 | } |
| 295 | else { |
| 296 | #if (MI_DEBUG>0) && !MI_TRACK_ENABLED && !MI_TSAN // note: when tracking, cannot use mi_usable_size with multi-threading |
| 297 | memset(block, MI_DEBUG_FREED, mi_usable_size(block)); |
| 298 | #endif |
| 299 | } |
| 300 | |
| 301 | // and finally free the actual block by pushing it on the owning heap |
| 302 | // thread_delayed free list (or heap delayed free list) |
| 303 | mi_free_block_delayed_mt(page,block); |
| 304 | } |
| 305 | |
| 306 | |
| 307 | // ------------------------------------------------------ |
| 308 | // Usable size |
| 309 | // ------------------------------------------------------ |
| 310 | |
| 311 | // Bytes available in a block |
| 312 | static size_t mi_decl_noinline mi_page_usable_aligned_size_of(const mi_page_t* page, const void* p) mi_attr_noexcept { |
| 313 | const mi_block_t* block = _mi_page_ptr_unalign(page, p); |
| 314 | const size_t size = mi_page_usable_size_of(page, block); |
| 315 | const ptrdiff_t adjust = (uint8_t*)p - (uint8_t*)block; |
| 316 | mi_assert_internal(adjust >= 0 && (size_t)adjust <= size); |
| 317 | const size_t aligned_size = (size - adjust); |
| 318 | #if MI_GUARDED |
| 319 | if (mi_block_ptr_is_guarded(block, p)) { |
| 320 | return aligned_size - _mi_os_page_size(); |
| 321 | } |
| 322 | #endif |
| 323 | return aligned_size; |
| 324 | } |
| 325 | |
| 326 | static inline size_t _mi_usable_size(const void* p, const char* msg) mi_attr_noexcept { |
| 327 | const mi_segment_t* const segment = mi_checked_ptr_segment(p, msg); |
| 328 | if mi_unlikely(segment==NULL) return 0; |
| 329 | const mi_page_t* const page = _mi_segment_page_of(segment, p); |
| 330 | if mi_likely(!mi_page_has_aligned(page)) { |
| 331 | const mi_block_t* block = (const mi_block_t*)p; |
| 332 | return mi_page_usable_size_of(page, block); |
| 333 | } |
| 334 | else { |
| 335 | // split out to separate routine for improved code generation |
| 336 | return mi_page_usable_aligned_size_of(page, p); |
| 337 | } |
| 338 | } |
| 339 | |
| 340 | mi_decl_nodiscard size_t mi_usable_size(const void* p) mi_attr_noexcept { |
| 341 | return _mi_usable_size(p, "mi_usable_size"); |
| 342 | } |
| 343 | |
| 344 | |
| 345 | // ------------------------------------------------------ |
| 346 | // Free variants |
| 347 | // ------------------------------------------------------ |
| 348 | |
| 349 | void mi_free_size(void* p, size_t size) mi_attr_noexcept { |
| 350 | MI_UNUSED_RELEASE(size); |
| 351 | #if MI_DEBUG |
| 352 | const size_t available = _mi_usable_size(p,"mi_free_size"); |
| 353 | mi_assert(p == NULL || size <= available || available == 0 /* invalid pointer */ ); |
| 354 | #endif |
| 355 | mi_free(p); |
| 356 | } |
| 357 | |
| 358 | void mi_free_size_aligned(void* p, size_t size, size_t alignment) mi_attr_noexcept { |
| 359 | MI_UNUSED_RELEASE(alignment); |
| 360 | mi_assert(((uintptr_t)p % alignment) == 0); |
| 361 | mi_free_size(p,size); |
| 362 | } |
| 363 | |
| 364 | void mi_free_aligned(void* p, size_t alignment) mi_attr_noexcept { |
| 365 | MI_UNUSED_RELEASE(alignment); |
| 366 | mi_assert(((uintptr_t)p % alignment) == 0); |
| 367 | mi_free(p); |
| 368 | } |
| 369 | |
| 370 | |
| 371 | // ------------------------------------------------------ |
| 372 | // Check for double free in secure and debug mode |
| 373 | // This is somewhat expensive so only enabled for secure mode 4 |
| 374 | // ------------------------------------------------------ |
| 375 | |
| 376 | #if (MI_ENCODE_FREELIST && (MI_SECURE>=4 || MI_DEBUG!=0)) |
| 377 | // linear check if the free list contains a specific element |
| 378 | static bool mi_list_contains(const mi_page_t* page, const mi_block_t* list, const mi_block_t* elem) { |
| 379 | while (list != NULL) { |
| 380 | if (elem==list) return true; |
| 381 | list = mi_block_next(page, list); |
| 382 | } |
| 383 | return false; |
| 384 | } |
| 385 | |
| 386 | static mi_decl_noinline bool mi_check_is_double_freex(const mi_page_t* page, const mi_block_t* block) { |
| 387 | // The decoded value is in the same page (or NULL). |
| 388 | // Walk the free lists to verify positively if it is already freed |
| 389 | if (mi_list_contains(page, page->free, block) || |
| 390 | mi_list_contains(page, page->local_free, block) || |
| 391 | mi_list_contains(page, mi_page_thread_free(page), block)) |
| 392 | { |
| 393 | _mi_error_message(EAGAIN, "double free detected of block %p with size %zu\n", block, mi_page_block_size(page)); |
| 394 | return true; |
| 395 | } |
| 396 | return false; |
| 397 | } |
| 398 | |
| 399 | #define mi_track_page(page,access) { size_t psize; void* pstart = _mi_page_start(_mi_page_segment(page),page,&psize); mi_track_mem_##access( pstart, psize); } |
| 400 | |
| 401 | static inline bool mi_check_is_double_free(const mi_page_t* page, const mi_block_t* block) { |
| 402 | bool is_double_free = false; |
| 403 | mi_block_t* n = mi_block_nextx(page, block, page->keys); // pretend it is freed, and get the decoded first field |
| 404 | if (((uintptr_t)n & (MI_INTPTR_SIZE-1))==0 && // quick check: aligned pointer? |
| 405 | (n==NULL || mi_is_in_same_page(block, n))) // quick check: in same page or NULL? |
| 406 | { |
| 407 | // Suspicious: decoded value a in block is in the same page (or NULL) -- maybe a double free? |
| 408 | // (continue in separate function to improve code generation) |
| 409 | is_double_free = mi_check_is_double_freex(page, block); |
| 410 | } |
| 411 | return is_double_free; |
| 412 | } |
| 413 | #else |
| 414 | static inline bool mi_check_is_double_free(const mi_page_t* page, const mi_block_t* block) { |
| 415 | MI_UNUSED(page); |
| 416 | MI_UNUSED(block); |
| 417 | return false; |
| 418 | } |
| 419 | #endif |
| 420 | |
| 421 | |
| 422 | // --------------------------------------------------------------------------- |
| 423 | // Check for heap block overflow by setting up padding at the end of the block |
| 424 | // --------------------------------------------------------------------------- |
| 425 | |
| 426 | #if MI_PADDING // && !MI_TRACK_ENABLED |
| 427 | static bool mi_page_decode_padding(const mi_page_t* page, const mi_block_t* block, size_t* delta, size_t* bsize) { |
| 428 | *bsize = mi_page_usable_block_size(page); |
| 429 | const mi_padding_t* const padding = (mi_padding_t*)((uint8_t*)block + *bsize); |
| 430 | mi_track_mem_defined(padding,sizeof(mi_padding_t)); |
| 431 | *delta = padding->delta; |
| 432 | uint32_t canary = padding->canary; |
| 433 | uintptr_t keys[2]; |
| 434 | keys[0] = page->keys[0]; |
| 435 | keys[1] = page->keys[1]; |
| 436 | bool ok = (mi_ptr_encode_canary(page,block,keys) == canary && *delta <= *bsize); |
| 437 | mi_track_mem_noaccess(padding,sizeof(mi_padding_t)); |
| 438 | return ok; |
| 439 | } |
| 440 | |
| 441 | // Return the exact usable size of a block. |
| 442 | static size_t mi_page_usable_size_of(const mi_page_t* page, const mi_block_t* block) { |
| 443 | size_t bsize; |
| 444 | size_t delta; |
| 445 | bool ok = mi_page_decode_padding(page, block, &delta, &bsize); |
| 446 | mi_assert_internal(ok); mi_assert_internal(delta <= bsize); |
| 447 | return (ok ? bsize - delta : 0); |
| 448 | } |
| 449 | |
| 450 | // When a non-thread-local block is freed, it becomes part of the thread delayed free |
| 451 | // list that is freed later by the owning heap. If the exact usable size is too small to |
| 452 | // contain the pointer for the delayed list, then shrink the padding (by decreasing delta) |
| 453 | // so it will later not trigger an overflow error in `mi_free_block`. |
| 454 | void _mi_padding_shrink(const mi_page_t* page, const mi_block_t* block, const size_t min_size) { |
| 455 | size_t bsize; |
| 456 | size_t delta; |
| 457 | bool ok = mi_page_decode_padding(page, block, &delta, &bsize); |
| 458 | mi_assert_internal(ok); |
| 459 | if (!ok || (bsize - delta) >= min_size) return; // usually already enough space |
| 460 | mi_assert_internal(bsize >= min_size); |
| 461 | if (bsize < min_size) return; // should never happen |
| 462 | size_t new_delta = (bsize - min_size); |
| 463 | mi_assert_internal(new_delta < bsize); |
| 464 | mi_padding_t* padding = (mi_padding_t*)((uint8_t*)block + bsize); |
| 465 | mi_track_mem_defined(padding,sizeof(mi_padding_t)); |
| 466 | padding->delta = (uint32_t)new_delta; |
| 467 | mi_track_mem_noaccess(padding,sizeof(mi_padding_t)); |
| 468 | } |
| 469 | #else |
| 470 | static size_t mi_page_usable_size_of(const mi_page_t* page, const mi_block_t* block) { |
| 471 | MI_UNUSED(block); |
| 472 | return mi_page_usable_block_size(page); |
| 473 | } |
| 474 | |
| 475 | void _mi_padding_shrink(const mi_page_t* page, const mi_block_t* block, const size_t min_size) { |
| 476 | MI_UNUSED(page); |
| 477 | MI_UNUSED(block); |
| 478 | MI_UNUSED(min_size); |
| 479 | } |
| 480 | #endif |
| 481 | |
| 482 | #if MI_PADDING && MI_PADDING_CHECK |
| 483 | |
| 484 | static bool mi_verify_padding(const mi_page_t* page, const mi_block_t* block, size_t* size, size_t* wrong) { |
| 485 | size_t bsize; |
| 486 | size_t delta; |
| 487 | bool ok = mi_page_decode_padding(page, block, &delta, &bsize); |
| 488 | *size = *wrong = bsize; |
| 489 | if (!ok) return false; |
| 490 | mi_assert_internal(bsize >= delta); |
| 491 | *size = bsize - delta; |
| 492 | if (!mi_page_is_huge(page)) { |
| 493 | uint8_t* fill = (uint8_t*)block + bsize - delta; |
| 494 | const size_t maxpad = (delta > MI_MAX_ALIGN_SIZE ? MI_MAX_ALIGN_SIZE : delta); // check at most the first N padding bytes |
| 495 | mi_track_mem_defined(fill, maxpad); |
| 496 | for (size_t i = 0; i < maxpad; i++) { |
| 497 | if (fill[i] != MI_DEBUG_PADDING) { |
| 498 | *wrong = bsize - delta + i; |
| 499 | ok = false; |
| 500 | break; |
| 501 | } |
| 502 | } |
| 503 | mi_track_mem_noaccess(fill, maxpad); |
| 504 | } |
| 505 | return ok; |
| 506 | } |
| 507 | |
| 508 | static void mi_check_padding(const mi_page_t* page, const mi_block_t* block) { |
| 509 | size_t size; |
| 510 | size_t wrong; |
| 511 | if (!mi_verify_padding(page,block,&size,&wrong)) { |
| 512 | _mi_error_message(EFAULT, "buffer overflow in heap block %p of size %zu: write after %zu bytes\n", block, size, wrong ); |
| 513 | } |
| 514 | } |
| 515 | |
| 516 | #else |
| 517 | |
| 518 | static void mi_check_padding(const mi_page_t* page, const mi_block_t* block) { |
| 519 | MI_UNUSED(page); |
| 520 | MI_UNUSED(block); |
| 521 | } |
| 522 | |
| 523 | #endif |
| 524 | |
| 525 | // only maintain stats for smaller objects if requested |
| 526 | #if (MI_STAT>0) |
| 527 | static void mi_stat_free(const mi_page_t* page, const mi_block_t* block) { |
| 528 | MI_UNUSED(block); |
| 529 | mi_heap_t* const heap = mi_heap_get_default(); |
| 530 | const size_t bsize = mi_page_usable_block_size(page); |
| 531 | // #if (MI_STAT>1) |
| 532 | // const size_t usize = mi_page_usable_size_of(page, block); |
| 533 | // mi_heap_stat_decrease(heap, malloc_requested, usize); |
| 534 | // #endif |
| 535 | if (bsize <= MI_MEDIUM_OBJ_SIZE_MAX) { |
| 536 | mi_heap_stat_decrease(heap, malloc_normal, bsize); |
| 537 | #if (MI_STAT > 1) |
| 538 | mi_heap_stat_decrease(heap, malloc_bins[_mi_bin(bsize)], 1); |
| 539 | #endif |
| 540 | } |
| 541 | //else if (bsize <= MI_LARGE_OBJ_SIZE_MAX) { |
| 542 | // mi_heap_stat_decrease(heap, malloc_large, bsize); |
| 543 | //} |
| 544 | else { |
| 545 | mi_heap_stat_decrease(heap, malloc_huge, bsize); |
| 546 | } |
| 547 | } |
| 548 | #else |
| 549 | static void mi_stat_free(const mi_page_t* page, const mi_block_t* block) { |
| 550 | MI_UNUSED(page); MI_UNUSED(block); |
| 551 | } |
| 552 | #endif |
| 553 | |
| 554 | |
| 555 | // Remove guard page when building with MI_GUARDED |
| 556 | #if MI_GUARDED |
| 557 | static void mi_block_unguard(mi_page_t* page, mi_block_t* block, void* p) { |
| 558 | MI_UNUSED(p); |
| 559 | mi_assert_internal(mi_block_ptr_is_guarded(block, p)); |
| 560 | mi_assert_internal(mi_page_has_aligned(page)); |
| 561 | mi_assert_internal((uint8_t*)p - (uint8_t*)block >= (ptrdiff_t)sizeof(mi_block_t)); |
| 562 | mi_assert_internal(block->next == MI_BLOCK_TAG_GUARDED); |
| 563 | |
| 564 | const size_t bsize = mi_page_block_size(page); |
| 565 | const size_t psize = _mi_os_page_size(); |
| 566 | mi_assert_internal(bsize > psize); |
| 567 | mi_assert_internal(_mi_page_segment(page)->allow_decommit); |
| 568 | void* gpage = (uint8_t*)block + bsize - psize; |
| 569 | mi_assert_internal(_mi_is_aligned(gpage, psize)); |
| 570 | _mi_os_unprotect(gpage, psize); |
| 571 | } |
| 572 | #endif |
| 573 | |