kernel/vm.c
void
uvmclear(pagetable_t pagetable, uint64 va)
{
  pte_t *pte;
  
  pte = walk(pagetable, va, 0);
  if(pte == NULL)
    panic("uvmclear");
  *pte &= ~PTE_U;
}
// mark a PTE invalid for user access.
// used by exec for the user stack guard page.
mark a PTE invalid for user access.
used by exec for the user stack guard page.
mark a PTE invalid for user access . used by exec for the user stack guard page .
void
uvmclear(pagetable_t pagetable, uint64 va)
{
  pte_t *pte;
  pte = walk(pagetable, va, 0);
  if(pte == NULL)
    panic("uvmclear");
  *pte &= ~PTE_U;
}
void uvmclear ( pagetable_t pagetable , uint64 va ) { pte_t * pte ; pte = walk ( pagetable , va , 0 ) ; if ( pte == NULL ) panic ( " " ) ; * pte &= ~ PTE_U ; }
mark a PTE invalid for user access.
mark a PTE invalid for user access .