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ldso, malloc: implement reclaim_gaps via __malloc_donate

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Split 'free' into unmap_chunk and bin_chunk, use the latter to introduce
__malloc_donate and use it in reclaim_gaps instead of calling 'free'.
This commit is contained in:
Alexander Monakov
2018-04-17 19:23:00 -04:00
committed by Rich Felker
parent d889cc3463
commit ce7ae11acf
2 changed files with 47 additions and 30 deletions
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src/malloc/malloc.c
+43 -18
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@@ -299,6 +299,8 @@ static int pretrim(struct chunk *self, size_t n, int i, int j)
return 1;
}
static void bin_chunk(struct chunk *);
static void trim(struct chunk *self, size_t n)
{
size_t n1 = CHUNK_SIZE(self);
@@ -314,7 +316,7 @@ static void trim(struct chunk *self, size_t n)
next->psize = n1-n | C_INUSE;
self->csize = n | C_INUSE;
free(CHUNK_TO_MEM(split));
bin_chunk(split);
}
void *malloc(size_t n)
@@ -465,29 +467,14 @@ copy_free_ret:
return new;
}
void free(void *p)
static void bin_chunk(struct chunk *self)
{
struct chunk *self, *next;
struct chunk *next = NEXT_CHUNK(self);
size_t final_size, new_size, size;
int reclaim=0;
int i;
if (!p) return;
self = MEM_TO_CHUNK(p);
if (IS_MMAPPED(self)) {
size_t extra = self->psize;
char *base = (char *)self - extra;
size_t len = CHUNK_SIZE(self) + extra;
/* Crash on double free */
if (extra & 1) a_crash();
__munmap(base, len);
return;
}
final_size = new_size = CHUNK_SIZE(self);
next = NEXT_CHUNK(self);
/* Crash on corrupted footer (likely from buffer overflow) */
if (next->psize != self->csize) a_crash();
@@ -548,3 +535,41 @@ void free(void *p)
unlock_bin(i);
}
static void unmap_chunk(struct chunk *self)
{
size_t extra = self->psize;
char *base = (char *)self - extra;
size_t len = CHUNK_SIZE(self) + extra;
/* Crash on double free */
if (extra & 1) a_crash();
__munmap(base, len);
}
void free(void *p)
{
if (!p) return;
struct chunk *self = MEM_TO_CHUNK(p);
if (IS_MMAPPED(self))
unmap_chunk(self);
else
bin_chunk(self);
}
void __malloc_donate(char *start, char *end)
{
size_t align_start_up = (SIZE_ALIGN-1) & (-(uintptr_t)start - OVERHEAD);
size_t align_end_down = (SIZE_ALIGN-1) & (uintptr_t)end;
if (end - start <= OVERHEAD + align_start_up + align_end_down)
return;
start += align_start_up + OVERHEAD;
end -= align_end_down;
struct chunk *c = MEM_TO_CHUNK(start), *n = MEM_TO_CHUNK(end);
c->psize = n->csize = C_INUSE;
c->csize = n->psize = C_INUSE | (end-start);
bin_chunk(c);
}