server-skynet-source-3rd-je.../include/jemalloc/internal/guard.h
Qi Wang deb8e62a83 Implement guard pages.
Adding guarded extents, which are regular extents surrounded by guard pages
(mprotected).  To reduce syscalls, small guarded extents are cached as a
separate eset in ecache, and decay through the dirty / muzzy / retained pipeline
as usual.
2021-09-26 16:30:15 -07:00

77 lines
2.0 KiB
C

#ifndef JEMALLOC_INTERNAL_GUARD_H
#define JEMALLOC_INTERNAL_GUARD_H
#include "jemalloc/internal/ehooks.h"
#include "jemalloc/internal/emap.h"
#define PAGE_GUARDS_SIZE (2 * PAGE)
#define SAN_GUARD_LARGE_EVERY_N_EXTENTS_DEFAULT 0
#define SAN_GUARD_SMALL_EVERY_N_EXTENTS_DEFAULT 0
/* 0 means disabled, i.e. never guarded. */
extern size_t opt_san_guard_large;
extern size_t opt_san_guard_small;
void guard_pages(tsdn_t *tsdn, ehooks_t *ehooks, edata_t *edata, emap_t *emap);
void unguard_pages(tsdn_t *tsdn, ehooks_t *ehooks, edata_t *edata, emap_t *emap);
void tsd_san_init(tsd_t *tsd);
static inline bool
san_enabled(void) {
return (opt_san_guard_large != 0 || opt_san_guard_small != 0);
}
static inline bool
large_extent_decide_guard(tsdn_t *tsdn, ehooks_t *ehooks, size_t size,
size_t alignment) {
if (opt_san_guard_large == 0 || ehooks_guard_will_fail(ehooks) ||
tsdn_null(tsdn)) {
return false;
}
tsd_t *tsd = tsdn_tsd(tsdn);
uint64_t n = tsd_san_extents_until_guard_large_get(tsd);
assert(n >= 1);
if (n > 1) {
/*
* Subtract conditionally because the guard may not happen due
* to alignment or size restriction below.
*/
*tsd_san_extents_until_guard_largep_get(tsd) = n - 1;
}
if (n == 1 && (alignment <= PAGE) &&
(size + PAGE_GUARDS_SIZE <= SC_LARGE_MAXCLASS)) {
*tsd_san_extents_until_guard_largep_get(tsd) =
opt_san_guard_large;
return true;
} else {
assert(tsd_san_extents_until_guard_large_get(tsd) >= 1);
return false;
}
}
static inline bool
slab_extent_decide_guard(tsdn_t *tsdn, ehooks_t *ehooks) {
if (opt_san_guard_small == 0 || ehooks_guard_will_fail(ehooks) ||
tsdn_null(tsdn)) {
return false;
}
tsd_t *tsd = tsdn_tsd(tsdn);
uint64_t n = tsd_san_extents_until_guard_small_get(tsd);
assert(n >= 1);
if (n == 1) {
*tsd_san_extents_until_guard_smallp_get(tsd) =
opt_san_guard_small;
return true;
} else {
*tsd_san_extents_until_guard_smallp_get(tsd) = n - 1;
assert(tsd_san_extents_until_guard_small_get(tsd) >= 1);
return false;
}
}
#endif /* JEMALLOC_INTERNAL_GUARD_H */