syscalls/mremap.c

   1 /*
   2  * asmlinkage unsigned long sys_mremap(unsigned long addr,
   3  *   unsigned long old_len, unsigned long new_len,
   4  *   unsigned long flags, unsigned long new_addr)
   5  */
   6
   7 #include <stdlib.h>
   8 #include <sys/mman.h>
   9 #include "arch.h"
  10 #include "maps.h"
  11 #include "random.h"
  12 #include "sanitise.h"
  13 #include "shm.h"
  14 #include "utils.h"
  15
  16 static unsigned long rand_size(void)
  17 {
  18         const unsigned long sizes[] = { 1 * MB, 2 * MB, 4 * MB, 10 * MB, 1 * GB, 2 * GB };
  19
  20         return sizes[rand() % ARRAY_SIZE(sizes)];
  21 }
  22
  23 static void sanitise_mremap(int childno)
  24 {
  25         struct map *map;
  26
  27         map = common_set_mmap_ptr_len(childno);
  28
  29         shm->syscall[childno].a3 = map->size;           //TODO: Munge this.
  30
  31         if (shm->syscall[childno].a4 & MREMAP_FIXED) {
  32                 shm->syscall[childno].a5 = rand_size();
  33         } else {
  34                 shm->syscall[childno].a5 = 0;
  35         }
  36
  37         /* Sometimes dirty the mapping first. */
  38         if (!(map->prot & PROT_WRITE))
  39                 return;
  40
  41         if (rand_bool())
  42                 dirty_mapping(map);
  43 }
  44
  45 /*
  46  * If we successfully remapped a range, we need to update our record of it
  47  * so we don't re-use the old address.
  48  */
  49 static void post_mremap(int childno)
  50 {
  51         struct map *map = (struct map *) shm->scratch[childno];
  52         void *ptr = (void *) shm->syscall[childno].retval;
  53
  54         if (ptr != MAP_FAILED)
  55                 map->ptr = ptr;
  56
  57         shm->scratch[childno] = 0;
  58 }
  59
  60 struct syscallentry syscall_mremap = {
  61         .name = "mremap",
  62         .num_args = 5,
  63         .sanitise = sanitise_mremap,
  64         .arg1name = "addr",
  65         .arg1type = ARG_MMAP,
  66         .arg2name = "old_len",
  67         .arg3name = "new_len",
  68         .arg4name = "flags",
  69         .arg4type = ARG_LIST,
  70         .arg4list = {
  71                 .num = 2,
  72                 .values = { MREMAP_MAYMOVE, MREMAP_FIXED },
  73         },
  74         .arg5name = "new_addr",
  75         .arg5type = ARG_ADDRESS,
  76         .group = GROUP_VM,
  77         .post = post_mremap,
  78 };