Git-Mirrors/hardened_malloc
1
0
Fork 0
mirror of https://github.com/GrapheneOS/hardened_malloc.git synced 2024-12-11 17:04:32 -05:00
Code Issues Packages Projects Releases Wiki Activity

reduce overhead of slot randomization

Browse Source
This commit is contained in:
Daniel Micay 2018-10-30 18:09:07 -04:00
parent ceffb1a0ec
commit c29a183687
1 changed files with 15 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
malloc.c
View File

@ -261,30 +261,31 @@ static size_t get_free_slot(struct random_state *rng, size_t slots, struct slab_
unsigned first_bitmap = random_index / 64;
u64 random_split = ~(~0UL << (random_index - first_bitmap * 64));
for (unsigned i = first_bitmap; i <= (slots - 1) / 64; i++) {
u64 masked = metadata->bitmap[i];
unsigned i = first_bitmap;
u64 masked = metadata->bitmap[i];
masked |= random_split;
for (;;) {
if (i == slots / 64) {
masked |= get_mask(slots - i * 64);
}
if (i == first_bitmap) {
masked |= random_split;
}
if (masked != ~0UL) {
return ffzl(masked) - 1 + i * 64;
}
}
}
for (unsigned i = 0; i <= (slots - 1) / 64; i++) {
u64 masked = metadata->bitmap[i];
if (i == (slots - 1) / 64) {
masked |= get_mask(slots - i * 64);
i = i == (slots - 1) / 64 ? 0 : i + 1;
masked = metadata->bitmap[i];
}
} else {
for (unsigned i = 0; i <= (slots - 1) / 64; i++) {
u64 masked = metadata->bitmap[i];
if (i == (slots - 1) / 64) {
masked |= get_mask(slots - i * 64);
}
if (masked != ~0UL) {
return ffzl(masked) - 1 + i * 64;
if (masked != ~0UL) {
return ffzl(masked) - 1 + i * 64;
}
}
}