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use slab_region_start for init checks

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This commit is contained in:
Daniel Micay 2018-11-05 02:19:04 -05:00
parent a8112fc5c3
commit fea335282a
1 changed files with 21 additions and 17 deletions
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38
malloc.c
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@ -39,7 +39,7 @@ static const size_t canary_size = SLAB_CANARY ? sizeof(u64) : 0;
static union { static union {
struct { struct {
void *slab_region_start; void *_Atomic slab_region_start;
void *slab_region_end; void *slab_region_end;
struct size_class *size_class_metadata; struct size_class *size_class_metadata;
struct region_allocator *region_allocator; struct region_allocator *region_allocator;
@ -47,11 +47,14 @@ static union {
#ifdef USE_PKEY #ifdef USE_PKEY
int metadata_pkey; int metadata_pkey;
#endif #endif
atomic_bool initialized;
}; };
char padding[PAGE_SIZE]; char padding[PAGE_SIZE];
} ro __attribute__((aligned(PAGE_SIZE))); } ro __attribute__((aligned(PAGE_SIZE)));
static inline void *get_slab_region_start() {
return atomic_load_explicit(&ro.slab_region_start, memory_order_acquire);
}
#define SLAB_METADATA_COUNT #define SLAB_METADATA_COUNT
struct slab_metadata { struct slab_metadata {
@ -815,7 +818,7 @@ static void post_fork_child(void) {
} }
static inline bool is_init(void) { static inline bool is_init(void) {
return atomic_load_explicit(&ro.initialized, memory_order_acquire); return get_slab_region_start() != NULL;
} }
static inline void enforce_init(void) { static inline void enforce_init(void) {
@ -874,11 +877,11 @@ COLD static void init_slow_path(void) {
fatal_error("failed to unprotect memory for regions table"); fatal_error("failed to unprotect memory for regions table");
} }
ro.slab_region_start = memory_map(slab_region_size); void *slab_region_start = memory_map(slab_region_size);
if (ro.slab_region_start == NULL) { if (slab_region_start == NULL) {
fatal_error("failed to allocate slab region"); fatal_error("failed to allocate slab region");
} }
ro.slab_region_end = (char *)ro.slab_region_start + slab_region_size; ro.slab_region_end = (char *)slab_region_start + slab_region_size;
ro.size_class_metadata = allocator_state->size_class_metadata; ro.size_class_metadata = allocator_state->size_class_metadata;
for (unsigned class = 0; class < N_SIZE_CLASSES; class++) { for (unsigned class = 0; class < N_SIZE_CLASSES; class++) {
@ -889,7 +892,7 @@ COLD static void init_slow_path(void) {
size_t bound = (REAL_CLASS_REGION_SIZE - CLASS_REGION_SIZE) / PAGE_SIZE - 1; size_t bound = (REAL_CLASS_REGION_SIZE - CLASS_REGION_SIZE) / PAGE_SIZE - 1;
size_t gap = (get_random_u64_uniform(rng, bound) + 1) * PAGE_SIZE; size_t gap = (get_random_u64_uniform(rng, bound) + 1) * PAGE_SIZE;
c->class_region_start = (char *)ro.slab_region_start + REAL_CLASS_REGION_SIZE * class + gap; c->class_region_start = (char *)slab_region_start + REAL_CLASS_REGION_SIZE * class + gap;
size_t size = size_classes[class]; size_t size = size_classes[class];
if (size == 0) { if (size == 0) {
@ -903,7 +906,7 @@ COLD static void init_slow_path(void) {
deallocate_pages(rng, sizeof(struct random_state), PAGE_SIZE); deallocate_pages(rng, sizeof(struct random_state), PAGE_SIZE);
atomic_store_explicit(&ro.initialized, true, memory_order_release); atomic_store_explicit(&ro.slab_region_start, slab_region_start, memory_order_release);
if (memory_protect_ro(&ro, sizeof(ro))) { if (memory_protect_ro(&ro, sizeof(ro))) {
fatal_error("failed to protect allocator data"); fatal_error("failed to protect allocator data");
@ -1041,12 +1044,11 @@ EXPORT void *h_realloc(void *old, size_t size) {
size = adjust_size_for_canaries(size); size = adjust_size_for_canaries(size);
size_t old_size; size_t old_size;
if (old >= ro.slab_region_start && old < ro.slab_region_end) { if (old >= get_slab_region_start() && old < ro.slab_region_end) {
old_size = slab_usable_size(old); old_size = slab_usable_size(old);
if (size <= max_slab_size_class && get_size_info(size).size == old_size) { if (size <= max_slab_size_class && get_size_info(size).size == old_size) {
return old; return old;
} }
enforce_init();
thread_unseal_metadata(); thread_unseal_metadata();
} else { } else {
enforce_init(); enforce_init();
@ -1262,7 +1264,7 @@ EXPORT void h_free(void *p) {
return; return;
} }
if (p >= ro.slab_region_start && p < ro.slab_region_end) { if (p >= get_slab_region_start() && p < ro.slab_region_end) {
thread_unseal_metadata(); thread_unseal_metadata();
deallocate_small(p, NULL); deallocate_small(p, NULL);
thread_seal_metadata(); thread_seal_metadata();
@ -1281,7 +1283,7 @@ EXPORT void h_free_sized(void *p, size_t expected_size) {
return; return;
} }
if (p >= ro.slab_region_start && p < ro.slab_region_end) { if (p >= get_slab_region_start() && p < ro.slab_region_end) {
thread_unseal_metadata(); thread_unseal_metadata();
expected_size = get_size_info(adjust_size_for_canaries(expected_size)).size; expected_size = get_size_info(adjust_size_for_canaries(expected_size)).size;
deallocate_small(p, &expected_size); deallocate_small(p, &expected_size);
@ -1299,7 +1301,7 @@ EXPORT size_t h_malloc_usable_size(void *p) {
return 0; return 0;
} }
if (p >= ro.slab_region_start && p < ro.slab_region_end) { if (p >= get_slab_region_start() && p < ro.slab_region_end) {
size_t size = slab_usable_size(p); size_t size = slab_usable_size(p);
return size ? size - canary_size : 0; return size ? size - canary_size : 0;
} }
@ -1325,12 +1327,13 @@ EXPORT size_t h_malloc_object_size(void *p) {
return 0; return 0;
} }
if (p >= ro.slab_region_start && p < ro.slab_region_end) { void *slab_region_start = get_slab_region_start();
if (p >= slab_region_start && p < ro.slab_region_end) {
size_t size = slab_usable_size(p); size_t size = slab_usable_size(p);
return size ? size - canary_size : 0; return size ? size - canary_size : 0;
} }
if (unlikely(!is_init())) { if (unlikely(slab_region_start == NULL)) {
return 0; return 0;
} }
@ -1351,12 +1354,13 @@ EXPORT size_t h_malloc_object_size_fast(void *p) {
return 0; return 0;
} }
if (p >= ro.slab_region_start && p < ro.slab_region_end) { void *slab_region_start = get_slab_region_start();
if (p >= slab_region_start && p < ro.slab_region_end) {
size_t size = slab_usable_size(p); size_t size = slab_usable_size(p);
return size ? size - canary_size : 0; return size ? size - canary_size : 0;
} }
if (unlikely(!is_init())) { if (unlikely(slab_region_start == NULL)) {
return 0; return 0;
} }