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initial working guarded pages

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daanx 2024-08-19 21:21:40 -07:00
parent 7b5df14bea
commit 0c19eb60cf
12 changed files with 196 additions and 37 deletions
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25
src/free.c
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@ -34,11 +34,21 @@ static inline void mi_free_block_local(mi_page_t* page, mi_block_t* block, bool
if mi_unlikely(mi_check_is_double_free(page, block)) return;
mi_check_padding(page, block);
if (track_stats) { mi_stat_free(page, block); }
#if (MI_DEBUG>0) && !MI_TRACK_ENABLED && !MI_TSAN
#if MI_DEBUG_GUARDED
if (mi_page_has_guarded(page)) {
const size_t bsize = mi_page_block_size(page);
const size_t psize = _mi_os_page_size();
mi_assert_internal(bsize > psize);
mi_assert_internal(_mi_page_segment(page)->allow_decommit);
void* gpage = (uint8_t*)block + (bsize - psize);
_mi_os_unprotect(gpage, psize);
}
#endif
#if (MI_DEBUG>0) && !MI_TRACK_ENABLED && !MI_TSAN && !MI_DEBUG_GUARDED
memset(block, MI_DEBUG_FREED, mi_page_block_size(page));
#endif
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
// actual free: push on the local free list
mi_block_set_next(page, block, page->local_free);
page->local_free = block;
@ -51,8 +61,8 @@ static inline void mi_free_block_local(mi_page_t* page, mi_block_t* block, bool
}
// Adjust a block that was allocated aligned, to the actual start of the block in the page.
// note: this can be called from `mi_free_generic_mt` where a non-owning thread accesses the
// `page_start` and `block_size` fields; however these are constant and the page won't be
// note: this can be called from `mi_free_generic_mt` where a non-owning thread accesses the
// `page_start` and `block_size` fields; however these are constant and the page won't be
// deallocated (as the block we are freeing keeps it alive) and thus safe to read concurrently.
mi_block_t* _mi_page_ptr_unalign(const mi_page_t* page, const void* p) {
mi_assert_internal(page!=NULL && p!=NULL);
@ -298,6 +308,13 @@ static inline size_t _mi_usable_size(const void* p, const char* msg) mi_attr_noe
const mi_segment_t* const segment = mi_checked_ptr_segment(p, msg);
if mi_unlikely(segment==NULL) return 0;
const mi_page_t* const page = _mi_segment_page_of(segment, p);
#if MI_DEBUG_GUARDED
if (mi_page_has_guarded(page)) {
const size_t bsize = mi_page_usable_aligned_size_of(page, p);
mi_assert_internal(bsize > _mi_os_page_size());
return (bsize > _mi_os_page_size() ? bsize - _mi_os_page_size() : bsize);
} else
#endif
if mi_likely(!mi_page_has_aligned(page)) {
const mi_block_t* block = (const mi_block_t*)p;
return mi_page_usable_size_of(page, block);