Git-Mirrors/hardened_malloc
1
0
Fork 0
mirror of https://github.com/GrapheneOS/hardened_malloc.git synced 2025-05-23 08:21:24 -04:00
Code Issues Projects Releases Packages Wiki Activity

calculate slab size class instead of array loop

Browse source
This commit is contained in:
Daniel Micay 2022-01-16 14:05:59 -05:00
parent d8cb2d9f7a
commit 81cf2f27a0
2 changed files with 17 additions and 13 deletions
Download patch file Download diff file Expand all files Collapse all files

22
h_malloc.c
View file

@ -196,13 +196,16 @@ static inline struct size_info get_size_info(size_t size) {
if (size <= 128) {
return (struct size_info){align(size, 16), ((size - 1) >> 4) + 1};
}
for (unsigned class = 9; class < N_SIZE_CLASSES; class++) {
size_t real_size = size_classes[class];
if (size <= real_size) {
return (struct size_info){real_size, class};
}
}
fatal_error("invalid size for slabs");
const size_t initial_spacing_multiplier = 5;
const size_t special_small_sizes = 5; // 0, 16, 32, 48, 64
size_t spacing_class_shift = log2u64(size - 1) - 2;
size_t spacing_class = 1ULL << spacing_class_shift;
size_t real_size = align(size, spacing_class);
size_t spacing_class_index = (real_size >> spacing_class_shift) - initial_spacing_multiplier;
size_t index = (spacing_class_shift - 4) * 4 + special_small_sizes + spacing_class_index;
return (struct size_info){real_size, index};
}
// alignment must be a power of 2 <= PAGE_SIZE since slabs are only page aligned
@ -1199,10 +1202,7 @@ static size_t get_large_size_class(size_t size) {
// 512 KiB [2560 KiB, 3 MiB, 3584 KiB, 4 MiB]
// 1 MiB [5 MiB, 6 MiB, 7 MiB, 8 MiB]
// etc.
size = max(size, (size_t)PAGE_SIZE);
size_t spacing_shift = U64_WIDTH - clz64(size - 1) - 3;
size_t spacing_class = 1ULL << spacing_shift;
return align(size, spacing_class);
return get_size_info(max(size, (size_t)PAGE_SIZE)).size;
}
return page_align(size);
}