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mte: refactor tag_and_clear_slab_slot()

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Explicitly call is_memtag_enabled() before calling tag_and_clear_slab_slot() to make it clearer that
memory is not zeroed when MTE is disabled.
This commit is contained in:
Dmitry Muhomor 2023-10-30 12:34:41 +02:00 • committed by Daniel Micay
parent b560431c01
commit c75cb4c3f3
1 changed files with 22 additions and 15 deletions
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37
h_malloc.c
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@ -562,12 +562,8 @@ static inline void stats_slab_deallocate(UNUSED struct size_class *c, UNUSED siz
#endif #endif
} }
static void *tag_and_clear_slab_slot(struct slab_metadata *metadata, void *slot_ptr, size_t slot_idx, size_t slot_size) {
#ifdef HAS_ARM_MTE #ifdef HAS_ARM_MTE
if (unlikely(!is_memtag_enabled())) { static void *tag_and_clear_slab_slot(struct slab_metadata *metadata, void *slot_ptr, size_t slot_idx, size_t slot_size) {
return slot_ptr;
}
// arm_mte_tags is an array of 4-bit unsigned integers stored as u8 array (MTE tags are 4-bit wide) // arm_mte_tags is an array of 4-bit unsigned integers stored as u8 array (MTE tags are 4-bit wide)
// //
// It stores the most recent tag for each slab slot, or 0 if the slot was never used. // It stores the most recent tag for each slab slot, or 0 if the slot was never used.
@ -596,13 +592,8 @@ static void *tag_and_clear_slab_slot(struct slab_metadata *metadata, void *slot_
u4_arr_set(slot_tags, slot_idx + 1, get_pointer_tag(tagged_ptr)); u4_arr_set(slot_tags, slot_idx + 1, get_pointer_tag(tagged_ptr));
return tagged_ptr; return tagged_ptr;
#else
(void) metadata;
(void) slot_idx;
(void) slot_size;
return slot_ptr;
#endif
} }
#endif
static inline void *allocate_small(unsigned arena, size_t requested_size) { static inline void *allocate_small(unsigned arena, size_t requested_size) {
struct size_info info = get_size_info(requested_size); struct size_info info = get_size_info(requested_size);
@ -632,7 +623,11 @@ static inline void *allocate_small(unsigned arena, size_t requested_size) {
if (requested_size) { if (requested_size) {
write_after_free_check(p, size - canary_size); write_after_free_check(p, size - canary_size);
set_canary(metadata, p, size); set_canary(metadata, p, size);
p = tag_and_clear_slab_slot(metadata, p, slot, size); #ifdef HAS_ARM_MTE
if (likely(is_memtag_enabled())) {
p = tag_and_clear_slab_slot(metadata, p, slot, size);
}
#endif
} }
stats_small_allocate(c, size); stats_small_allocate(c, size);
@ -665,7 +660,11 @@ static inline void *allocate_small(unsigned arena, size_t requested_size) {
void *p = slot_pointer(size, slab, slot); void *p = slot_pointer(size, slab, slot);
if (requested_size) { if (requested_size) {
set_canary(metadata, p, size); set_canary(metadata, p, size);
p = tag_and_clear_slab_slot(metadata, p, slot, size); #ifdef HAS_ARM_MTE
if (likely(is_memtag_enabled())) {
p = tag_and_clear_slab_slot(metadata, p, slot, size);
}
#endif
} }
stats_slab_allocate(c, slab_size); stats_slab_allocate(c, slab_size);
stats_small_allocate(c, size); stats_small_allocate(c, size);
@ -688,7 +687,11 @@ static inline void *allocate_small(unsigned arena, size_t requested_size) {
void *p = slot_pointer(size, slab, slot); void *p = slot_pointer(size, slab, slot);
if (requested_size) { if (requested_size) {
set_canary(metadata, p, size); set_canary(metadata, p, size);
p = tag_and_clear_slab_slot(metadata, p, slot, size); #ifdef HAS_ARM_MTE
if (likely(is_memtag_enabled())) {
p = tag_and_clear_slab_slot(metadata, p, slot, size);
}
#endif
} }
stats_slab_allocate(c, slab_size); stats_slab_allocate(c, slab_size);
stats_small_allocate(c, size); stats_small_allocate(c, size);
@ -713,7 +716,11 @@ static inline void *allocate_small(unsigned arena, size_t requested_size) {
if (requested_size) { if (requested_size) {
write_after_free_check(p, size - canary_size); write_after_free_check(p, size - canary_size);
set_canary(metadata, p, size); set_canary(metadata, p, size);
p = tag_and_clear_slab_slot(metadata, p, slot, size); #ifdef HAS_ARM_MTE
if (likely(is_memtag_enabled())) {
p = tag_and_clear_slab_slot(metadata, p, slot, size);
}
#endif
} }
stats_small_allocate(c, size); stats_small_allocate(c, size);