lunaix-os/kernel/mm/cow.c

   1 #include <lunaix/mm/vmm.h>
   2
   3 void*
   4 vmm_dup_page(pid_t pid, void* pa)
   5 {
   6     void* new_ppg = pmm_alloc_page(pid, 0);
   7     vmm_set_mapping(PD_REFERENCED, PG_MOUNT_3, new_ppg, PG_PREM_RW, VMAP_NULL);
   8     vmm_set_mapping(PD_REFERENCED, PG_MOUNT_4, pa, PG_PREM_RW, VMAP_NULL);
   9
  10     asm volatile("movl %1, %%edi\n"
  11                  "movl %2, %%esi\n"
  12                  "rep movsl\n" ::"c"(1024),
  13                  "r"(PG_MOUNT_3),
  14                  "r"(PG_MOUNT_4)
  15                  : "memory", "%edi", "%esi");
  16
  17     vmm_del_mapping(PD_REFERENCED, PG_MOUNT_3);
  18     vmm_del_mapping(PD_REFERENCED, PG_MOUNT_4);
  19
  20     return new_ppg;
  21 }