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 "utils.h"      // page_size
  10 #include "arch.h"
  11 #include "maps.h"
  12 #include "random.h"
  13 #include "sanitise.h"
  14 #include "shm.h"
  15 #include "utils.h"
  16
  17 static unsigned long rand_size(void)
  18 {
  19         const unsigned long sizes[] = { 1 * MB, 2 * MB, 4 * MB, 10 * MB, 1 * GB, 2 * GB };
  20
  21         return sizes[rand() % ARRAY_SIZE(sizes)];
  22 }
  23
  24 static void sanitise_mremap(int childno)
  25 {
  26         struct map *map;
  27
  28         map = common_set_mmap_ptr_len(childno);
  29
  30         shm->a3[childno] = map->size;           //TODO: Munge this.
  31
  32         if (shm->a4[childno] & MREMAP_FIXED) {
  33                 shm->a5[childno] = rand_size();
  34         } else {
  35                 shm->a5[childno] = 0;
  36         }
  37
  38         /* Sometimes dirty the mapping first. */
  39         if (!(map->prot & PROT_WRITE))
  40                 return;
  41
  42         if (rand_bool())
  43                 dirty_mapping(map);
  44 }
  45
  46 /*
  47  * If we successfully remapped a range, we need to update our record of it
  48  * so we don't re-use the old address.
  49  */
  50 static void post_mremap(int childno)
  51 {
  52         struct map *map = (struct map *) shm->scratch[childno];
  53         void *ptr = (void *) shm->retval[childno];
  54
  55         if (ptr != MAP_FAILED)
  56                 map->ptr = ptr;
  57
  58         shm->scratch[childno] = 0;
  59 }
  60
  61 struct syscallentry syscall_mremap = {
  62         .name = "mremap",
  63         .num_args = 5,
  64         .sanitise = sanitise_mremap,
  65         .arg1name = "addr",
  66         .arg1type = ARG_MMAP,
  67         .arg2name = "old_len",
  68         .arg3name = "new_len",
  69         .arg4name = "flags",
  70         .arg4type = ARG_LIST,
  71         .arg4list = {
  72                 .num = 2,
  73                 .values = { MREMAP_MAYMOVE, MREMAP_FIXED },
  74         },
  75         .arg5name = "new_addr",
  76         .arg5type = ARG_ADDRESS,
  77         .group = GROUP_VM,
  78         .post = post_mremap,
  79 };