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San: Bump alloc frequently reused guarded allocations

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To utilize a separate retained area for guarded extents, use bump alloc
to allocate those extents.
This commit is contained in:
Alex Lapenkou
2021-10-28 12:08:10 -07:00
committed by Alexander Lapenkov
parent f56f5b9930
commit 800ce49c19
10 changed files with 106 additions and 56 deletions
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22
test/unit/san.c
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@@ -13,6 +13,11 @@ verify_extent_guarded(tsdn_t *tsdn, void *ptr) {
#define MAX_SMALL_ALLOCATIONS 4096
void *small_alloc[MAX_SMALL_ALLOCATIONS];
/*
* This test allocates page sized slabs and checks that every two slabs have
* at least one page in between them. That page is supposed to be the guard
* page.
*/
TEST_BEGIN(test_guarded_small) {
test_skip_if(opt_prof);
@@ -21,7 +26,8 @@ TEST_BEGIN(test_guarded_small) {
VARIABLE_ARRAY(uintptr_t, pages, npages);
/* Allocate to get sanitized pointers. */
size_t sz = PAGE / 8;
size_t slab_sz = PAGE;
size_t sz = slab_sz / 8;
unsigned n_alloc = 0;
while (n_alloc < MAX_SMALL_ALLOCATIONS) {
void *ptr = malloc(sz);
@@ -50,8 +56,9 @@ TEST_BEGIN(test_guarded_small) {
for (unsigned j = i + 1; j < npages; j++) {
uintptr_t ptr_diff = pages[i] > pages[j] ?
pages[i] - pages[j] : pages[j] - pages[i];
expect_zu_gt((size_t)ptr_diff, 2 * PAGE,
"Pages should not be next to each other.");
expect_zu_ge((size_t)ptr_diff, slab_sz + PAGE,
"There should be at least one pages between "
"guarded slabs");
}
}
@@ -76,20 +83,15 @@ TEST_BEGIN(test_guarded_large) {
}
/* Verify the pages are not continuous, i.e. separated by guards. */
uintptr_t min_diff = (uintptr_t)-1;
for (unsigned i = 0; i < nlarge; i++) {
for (unsigned j = i + 1; j < nlarge; j++) {
uintptr_t ptr_diff = large[i] > large[j] ?
large[i] - large[j] : large[j] - large[i];
expect_zu_ge((size_t)ptr_diff, large_sz + 2 * PAGE,
"Pages should not be next to each other.");
if (ptr_diff < min_diff) {
min_diff = ptr_diff;
}
"There should be at least two pages between "
" guarded large allocations");
}
}
expect_zu_ge((size_t)min_diff, large_sz + 2 * PAGE,
"Pages should not be next to each other.");
for (unsigned i = 0; i < nlarge; i++) {
free((void *)large[i]);