From ce7ae11acfd9db8eb92cc6823c132e1825918d92 Mon Sep 17 00:00:00 2001 From: Alexander Monakov Date: Mon, 16 Apr 2018 20:54:36 +0300 Subject: ldso, malloc: implement reclaim_gaps via __malloc_donate 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'. --- src/malloc/malloc.c | 61 +++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 43 insertions(+), 18 deletions(-) (limited to 'src/malloc') diff --git a/src/malloc/malloc.c b/src/malloc/malloc.c index db19bc34..6605ec3a 100644 --- a/src/malloc/malloc.c +++ b/src/malloc/malloc.c @@ -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); +} -- cgit v1.2.1