lunaix-os/kernel/mm/cow.c

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