mirror of
https://gitlab.nic.cz/labs/bird.git
synced 2024-12-23 02:01:55 +00:00
886dd92eee
From now, there are no auxiliary pointers stored in the free slab nodes. This led to strange debugging problems if use-after-free happened in slab-allocated structures, especially if the structure's first member is a next pointer. This also reduces the memory needed by 1 pointer per allocated object. OTOH, we now rely on pages being aligned to their size's multiple, which is quite common anyway.
81 lines
1.4 KiB
C
81 lines
1.4 KiB
C
/*
|
|
* BIRD Internet Routing Daemon -- Raw allocation
|
|
*
|
|
* (c) 2020 Maria Matejka <mq@ucw.cz>
|
|
*
|
|
* Can be freely distributed and used under the terms of the GNU GPL.
|
|
*/
|
|
|
|
#include "nest/bird.h"
|
|
#include "lib/resource.h"
|
|
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
|
|
#ifdef HAVE_MMAP
|
|
#include <sys/mman.h>
|
|
#endif
|
|
|
|
#ifdef HAVE_MMAP
|
|
static u64 page_size = 0;
|
|
static _Bool use_fake = 0;
|
|
#else
|
|
static const u64 page_size = 4096; /* Fake page size */
|
|
#endif
|
|
|
|
u64 get_page_size(void)
|
|
{
|
|
if (page_size)
|
|
return page_size;
|
|
|
|
#ifdef HAVE_MMAP
|
|
if (page_size = sysconf(_SC_PAGESIZE))
|
|
{
|
|
if ((u64_popcount(page_size) > 1) || (page_size > 16384))
|
|
{
|
|
/* Too big or strange page, use the aligned allocator instead */
|
|
page_size = 4096;
|
|
use_fake = 1;
|
|
}
|
|
return page_size;
|
|
}
|
|
|
|
bug("Page size must be non-zero");
|
|
#endif
|
|
}
|
|
|
|
void *
|
|
alloc_page(void)
|
|
{
|
|
#ifdef HAVE_MMAP
|
|
if (!use_fake)
|
|
{
|
|
void *ret = mmap(NULL, get_page_size(), PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
if (ret == MAP_FAILED)
|
|
bug("mmap(%lu) failed: %m", page_size);
|
|
return ret;
|
|
}
|
|
else
|
|
#endif
|
|
{
|
|
void *ret = aligned_alloc(page_size, page_size);
|
|
if (!ret)
|
|
bug("aligned_alloc(%lu) failed", page_size);
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
void
|
|
free_page(void *ptr)
|
|
{
|
|
#ifdef HAVE_MMAP
|
|
if (!use_fake)
|
|
{
|
|
if (munmap(ptr, get_page_size()) < 0)
|
|
bug("munmap(%p) failed: %m", ptr);
|
|
}
|
|
else
|
|
#endif
|
|
free(ptr);
|
|
}
|