shm.c

   1 /*
   2  * Shared mapping creation.
   3  */
   4
   5 #include <stdlib.h>
   6 #include <string.h>
   7 #include <unistd.h>
   8 #include <sys/mman.h>
   9 #include "arch.h"
  10 #include "log.h"
  11 #include "params.h"
  12 #include "pids.h"
  13 #include "random.h"
  14 #include "shm.h"
  15
  16 void * alloc_shared(unsigned int size)
  17 {
  18         void *ret;
  19
  20         ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_SHARED, -1, 0);
  21         if (ret == MAP_FAILED)
  22                 return NULL;
  23
  24         return ret;
  25 }
  26
  27 struct shm_s *shm;
  28
  29 #define SHM_PROT_PAGES 30
  30
  31 int create_shm(void)
  32 {
  33         void *p;
  34         unsigned int shm_pages;
  35
  36         shm_pages = ((sizeof(struct shm_s) + page_size - 1) & ~(page_size - 1)) / page_size;
  37
  38         /* Waste some address space to set up some "protection" near the SHM location. */
  39         p = alloc_shared((SHM_PROT_PAGES + shm_pages + SHM_PROT_PAGES) * page_size);
  40         if (p == NULL) {
  41                 perror("mmap");
  42                 return -1;
  43         }
  44
  45         mprotect(p, SHM_PROT_PAGES * page_size, PROT_NONE);
  46         mprotect(p + (SHM_PROT_PAGES + shm_pages) * page_size,
  47                         SHM_PROT_PAGES * page_size, PROT_NONE);
  48
  49         shm = p + SHM_PROT_PAGES * page_size;
  50
  51         memset(shm, 0, sizeof(struct shm_s));
  52
  53         shm->total_syscalls_done = 1;
  54         shm->regenerate = 0;
  55
  56         memset(shm->pids, EMPTY_PIDSLOT, sizeof(shm->pids));
  57
  58         shm->nr_active_syscalls = 0;
  59         shm->nr_active_32bit_syscalls = 0;
  60         shm->nr_active_64bit_syscalls = 0;
  61         memset(shm->active_syscalls, 0, sizeof(shm->active_syscalls));
  62         memset(shm->active_syscalls32, 0, sizeof(shm->active_syscalls32));
  63         memset(shm->active_syscalls64, 0, sizeof(shm->active_syscalls64));
  64
  65         /* Overwritten later in setup_shm_postargs if user passed -s */
  66         shm->seed = new_seed();
  67
  68         /* Set seed in parent thread */
  69         set_seed(0);
  70
  71         return 0;
  72 }
  73
  74 void setup_shm_postargs(void)
  75 {
  76         if (user_set_seed == TRUE) {
  77                 shm->seed = init_seed(seed);
  78                 /* Set seed in parent thread */
  79                 set_seed(0);
  80         }
  81
  82         if (user_specified_children != 0)
  83                 shm->max_children = user_specified_children;
  84         else
  85                 shm->max_children = sysconf(_SC_NPROCESSORS_ONLN);
  86
  87         if (shm->max_children > MAX_NR_CHILDREN) {
  88                 outputerr("Increase MAX_NR_CHILDREN!\n");
  89                 exit(EXIT_FAILURE);
  90         }
  91 }