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support zero-initialized memory detection

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This commit is contained in:
daan 2019-09-02 13:16:52 -07:00
parent 216d75a222
commit d1bd1644d5
9 changed files with 123 additions and 48 deletions
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25
src/segment.c
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@ -330,6 +330,7 @@ static mi_segment_t* mi_segment_alloc(size_t required, mi_page_kind_t page_kind,
bool eager = !eager_delay && mi_option_is_enabled(mi_option_eager_commit);
bool commit = eager || (page_kind > MI_PAGE_MEDIUM);
bool protection_still_good = false;
bool is_zero = false;
mi_segment_t* segment = mi_segment_cache_pop(segment_size, tld);
if (segment != NULL) {
if (mi_option_is_enabled(mi_option_secure)) {
@ -343,23 +344,27 @@ static mi_segment_t* mi_segment_alloc(size_t required, mi_page_kind_t page_kind,
}
if (!segment->mem_is_committed && page_kind > MI_PAGE_MEDIUM) {
mi_assert_internal(!segment->mem_is_fixed);
_mi_mem_commit(segment, segment->segment_size, tld->stats);
_mi_mem_commit(segment, segment->segment_size, &is_zero, tld->stats);
segment->mem_is_committed = true;
}
if (!segment->mem_is_fixed &&
(mi_option_is_enabled(mi_option_cache_reset) || mi_option_is_enabled(mi_option_page_reset))) {
_mi_mem_unreset(segment, segment->segment_size, tld->stats);
bool reset_zero = false;
_mi_mem_unreset(segment, segment->segment_size, &reset_zero, tld->stats);
if (reset_zero) is_zero = true;
}
}
else {
// Allocate the segment from the OS
size_t memid;
bool mem_large = (!eager_delay && !mi_option_is_enabled(mi_option_secure)); // only allow large OS pages once we are no longer lazy
segment = (mi_segment_t*)_mi_mem_alloc_aligned(segment_size, MI_SEGMENT_SIZE, &commit, &mem_large, &memid, os_tld);
segment = (mi_segment_t*)_mi_mem_alloc_aligned(segment_size, MI_SEGMENT_SIZE, &commit, &mem_large, &is_zero, &memid, os_tld);
if (segment == NULL) return NULL; // failed to allocate
if (!commit) {
// ensure the initial info is committed
_mi_mem_commit(segment, info_size, tld->stats);
bool commit_zero = false;
_mi_mem_commit(segment, info_size, &commit_zero, tld->stats);
if (commit_zero) is_zero = true;
}
segment->memid = memid;
segment->mem_is_fixed = mem_large;
@ -403,6 +408,7 @@ static mi_segment_t* mi_segment_alloc(size_t required, mi_page_kind_t page_kind,
segment->pages[i].segment_idx = i;
segment->pages[i].is_reset = false;
segment->pages[i].is_committed = commit;
segment->pages[i].is_zero_init = is_zero;
}
_mi_stat_increase(&tld->stats->page_committed, segment->segment_info_size);
//fprintf(stderr,"mimalloc: alloc segment at %p\n", (void*)segment);
@ -463,12 +469,16 @@ static mi_page_t* mi_segment_find_free(mi_segment_t* segment, mi_stats_t* stats)
if (!page->is_committed) {
mi_assert_internal(!segment->mem_is_fixed);
page->is_committed = true;
_mi_mem_commit(start,psize,stats);
bool is_zero = false;
_mi_mem_commit(start,psize,&is_zero,stats);
if (is_zero) page->is_zero_init = true;
}
if (page->is_reset) {
mi_assert_internal(!segment->mem_is_fixed);
page->is_reset = false;
_mi_mem_unreset(start, psize, stats);
bool is_zero = false;
_mi_mem_unreset(start, psize, &is_zero, stats);
if (is_zero) page->is_zero_init = true;
}
}
return page;
@ -493,7 +503,7 @@ static void mi_segment_page_clear(mi_segment_t* segment, mi_page_t* page, mi_sta
size_t inuse = page->capacity * page->block_size;
_mi_stat_decrease(&stats->page_committed, inuse);
_mi_stat_decrease(&stats->pages, 1);
// reset the page memory to reduce memory pressure?
if (!segment->mem_is_fixed && !page->is_reset && mi_option_is_enabled(mi_option_page_reset)) {
size_t psize;
@ -503,6 +513,7 @@ static void mi_segment_page_clear(mi_segment_t* segment, mi_page_t* page, mi_sta
}
// zero the page data, but not the segment fields
page->is_zero_init = false;
ptrdiff_t ofs = offsetof(mi_page_t,capacity);
memset((uint8_t*)page + ofs, 0, sizeof(*page) - ofs);
page->segment_in_use = false;