6cb585b13a
When opt_retain is on, slab extents remain guarded in all states, even retained. This works well if arena is never destroyed, because we anticipate those slabs will be eventually reused. But if the arena is destroyed, the slabs must be unguarded to prevent leaking guard pages.
84 lines
2.3 KiB
C
84 lines
2.3 KiB
C
#ifndef JEMALLOC_INTERNAL_GUARD_H
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#define JEMALLOC_INTERNAL_GUARD_H
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#include "jemalloc/internal/ehooks.h"
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#include "jemalloc/internal/emap.h"
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#define PAGE_GUARDS_SIZE (2 * PAGE)
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#define SAN_GUARD_LARGE_EVERY_N_EXTENTS_DEFAULT 0
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#define SAN_GUARD_SMALL_EVERY_N_EXTENTS_DEFAULT 0
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/* 0 means disabled, i.e. never guarded. */
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extern size_t opt_san_guard_large;
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extern size_t opt_san_guard_small;
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void guard_pages(tsdn_t *tsdn, ehooks_t *ehooks, edata_t *edata, emap_t *emap);
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void unguard_pages(tsdn_t *tsdn, ehooks_t *ehooks, edata_t *edata,
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emap_t *emap);
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/*
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* Unguard the extent, but don't modify emap boundaries. Must be called on an
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* extent that has been erased from emap and shouldn't be placed back.
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*/
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void unguard_pages_pre_destroy(tsdn_t *tsdn, ehooks_t *ehooks, edata_t *edata,
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emap_t *emap);
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void tsd_san_init(tsd_t *tsd);
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static inline bool
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san_enabled(void) {
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return (opt_san_guard_large != 0 || opt_san_guard_small != 0);
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}
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static inline bool
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large_extent_decide_guard(tsdn_t *tsdn, ehooks_t *ehooks, size_t size,
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size_t alignment) {
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if (opt_san_guard_large == 0 || ehooks_guard_will_fail(ehooks) ||
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tsdn_null(tsdn)) {
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return false;
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}
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tsd_t *tsd = tsdn_tsd(tsdn);
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uint64_t n = tsd_san_extents_until_guard_large_get(tsd);
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assert(n >= 1);
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if (n > 1) {
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/*
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* Subtract conditionally because the guard may not happen due
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* to alignment or size restriction below.
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*/
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*tsd_san_extents_until_guard_largep_get(tsd) = n - 1;
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}
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if (n == 1 && (alignment <= PAGE) &&
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(size + PAGE_GUARDS_SIZE <= SC_LARGE_MAXCLASS)) {
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*tsd_san_extents_until_guard_largep_get(tsd) =
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opt_san_guard_large;
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return true;
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} else {
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assert(tsd_san_extents_until_guard_large_get(tsd) >= 1);
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return false;
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}
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}
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static inline bool
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slab_extent_decide_guard(tsdn_t *tsdn, ehooks_t *ehooks) {
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if (opt_san_guard_small == 0 || ehooks_guard_will_fail(ehooks) ||
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tsdn_null(tsdn)) {
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return false;
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}
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tsd_t *tsd = tsdn_tsd(tsdn);
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uint64_t n = tsd_san_extents_until_guard_small_get(tsd);
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assert(n >= 1);
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if (n == 1) {
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*tsd_san_extents_until_guard_smallp_get(tsd) =
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opt_san_guard_small;
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return true;
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} else {
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*tsd_san_extents_until_guard_smallp_get(tsd) = n - 1;
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assert(tsd_san_extents_until_guard_small_get(tsd) >= 1);
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return false;
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}
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}
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#endif /* JEMALLOC_INTERNAL_GUARD_H */
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