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hardened_malloc
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scale slab quarantine based on size

pull/69/head
Daniel Micay 2019-01-02 14:22:28 -05:00
parent ccc2a86501
commit 57f115b33c
2 changed files with 19 additions and 6 deletions
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9
README.md
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@ -142,9 +142,14 @@ for the chosen values are not written yet, so use them at your own peril:
* `CONFIG_SLAB_QUARANTINE_RANDOM_LENGTH`: `0` (default) to control the number
of slots in the random array used to randomize reuse for small memory
allocations
allocations. This sets the length for the largest size class (currently
16384) and the quarantine length for smaller size classes is scaled to match
the total memory of the quarantined allocations.
* `CONFIG_SLAB_QUARANTINE_QUEUE_LENGTH`: `0` (default) to control the number of
slots in the queue used to delay reuse for small memory allocations
slots in the queue used to delay reuse for small memory allocations. This
sets the length for the largest size class (currently 16384) and the
quarantine length for smaller size classes is scaled to match the total
memory of the quarantined allocations.
* `CONFIG_GUARD_SLABS_INTERVAL`: `1` (default) to control the number of slabs
before a slab is skipped and left as an unused memory protected guard slab
* `CONFIG_GUARD_SIZE_DIVISOR`: `2` (default) to control the maximum size of the

16
h_malloc.c
View File

@ -74,6 +74,8 @@ struct slab_metadata {
static const size_t min_align = 16;
static const size_t max_slab_size_class = 16384;
#define MIN_SLAB_SIZE_CLASS_SHIFT 4
#define MAX_SLAB_SIZE_CLASS_SHIFT 14
static const u16 size_classes[] = {
/* 0 */ 0,
@ -178,11 +180,11 @@ struct __attribute__((aligned(CACHELINE_SIZE))) size_class {
struct libdivide_u64_t slab_size_divisor;
#if SLAB_QUARANTINE_RANDOM_LENGTH > 0
void *quarantine_random[SLAB_QUARANTINE_RANDOM_LENGTH];
void *quarantine_random[SLAB_QUARANTINE_RANDOM_LENGTH << (MAX_SLAB_SIZE_CLASS_SHIFT - MIN_SLAB_SIZE_CLASS_SHIFT)];
#endif
#if SLAB_QUARANTINE_QUEUE_LENGTH > 0
void *quarantine_queue[SLAB_QUARANTINE_QUEUE_LENGTH];
void *quarantine_queue[SLAB_QUARANTINE_QUEUE_LENGTH << (MAX_SLAB_SIZE_CLASS_SHIFT - MIN_SLAB_SIZE_CLASS_SHIFT)];
size_t quarantine_queue_index;
#endif
@ -590,8 +592,12 @@ static inline void deallocate_small(void *p, const size_t *expected_size) {
set_quarantine(metadata, slot);
size_t quarantine_shift = __builtin_clzl(size) - (63 - MAX_SLAB_SIZE_CLASS_SHIFT);
#if SLAB_QUARANTINE_RANDOM_LENGTH > 0
size_t random_index = get_random_u16_uniform(&c->rng, SLAB_QUARANTINE_RANDOM_LENGTH);
size_t slab_quarantine_random_length = SLAB_QUARANTINE_RANDOM_LENGTH << quarantine_shift;
size_t random_index = get_random_u16_uniform(&c->rng, slab_quarantine_random_length);
void *random_substitute = c->quarantine_random[random_index];
c->quarantine_random[random_index] = p;
@ -604,9 +610,11 @@ static inline void deallocate_small(void *p, const size_t *expected_size) {
#endif
#if SLAB_QUARANTINE_QUEUE_LENGTH > 0
size_t slab_quarantine_queue_length = SLAB_QUARANTINE_QUEUE_LENGTH << quarantine_shift;
void *queue_substitute = c->quarantine_queue[c->quarantine_queue_index];
c->quarantine_queue[c->quarantine_queue_index] = p;
c->quarantine_queue_index = (c->quarantine_queue_index + 1) % SLAB_QUARANTINE_QUEUE_LENGTH;
c->quarantine_queue_index = (c->quarantine_queue_index + 1) % slab_quarantine_queue_length;
if (queue_substitute == NULL) {
mutex_unlock(&c->lock);