static int copy_one_pte(struct vm_area_struct *vma, pte_t * src, pte_t * dst,
unsigned long old_addr, unsigned long new_addr,
struct pte_chain ** pte_chainp)
{
int error = 0;
pte_t pte;
struct page * page = NULL;
if (pte_present(*src))
page = pte_page(*src);
if (!pte_none(*src)) {
if (page)
page_remove_rmap(page, src);
pte = vm_ptep_get_and_clear(vma, old_addr, src);
if (!dst) {
/* No dest? We must put it back. */
dst = src;
error++;
}
vm_set_pte(vma, new_addr, dst, pte);
if (page)
*pte_chainp = page_add_rmap(page, dst, *pte_chainp);
}
return error;
}
/* mmlist_lock and vma->vm_mm->page_table_lock are held */
static void
unuse_pte(struct vm_area_struct * vma, unsigned long address, pte_t * dir,
swp_entry_t entry, struct page * page, struct pte_chain ** pte_chainp)
{
pte_t pte = *dir;
if (likely(pte_to_swp_entry(pte).val != entry.val))
return;
if (unlikely(pte_none(pte) || pte_present(pte)))
return;
get_page(page);
vm_set_pte(vma, address, dir, pte_mkold(mk_pte(page, vma->vm_page_prot)));
*pte_chainp = page_add_rmap(page, dir, *pte_chainp);
swap_free(entry);
++vma->vm_mm->rss;
}
void vm_init_paging(struct multiboot_info *boot_info)
{
struct x86_cpuid_info cpuid_info;
struct frame *pgdir_frame;
struct frame *pgtab_frame;
pte_t *pgtab;
ulong_t paddr, mem_max;
/*
* Check CPUID instruction to see if large pages (PSE feature)
* is supported.
*/
PANIC_IF(!x86_cpuid(&cpuid_info), "GeekOS requires a Pentium-class CPU");
PANIC_IF(!cpuid_info.feature_info_edx.pse, "Processor does not support PSE");
cons_printf("CPU supports PSE\n");
/*
* Enable PSE by setting the PSE bit in CR4.
*/
x86_set_cr4(x86_get_cr4() | CR4_PSE);
/*
* Allocate kernel page directory.
*/
pgdir_frame = mem_alloc_frame(FRAME_KERN, 1);
s_kernel_pagedir = mem_frame_to_pa(pgdir_frame);
memset(s_kernel_pagedir, '\0', PAGE_SIZE);
/*
* We will support at most 2G of physical memory.
*/
mem_max = ((ulong_t) boot_info->mem_upper) * 1024;
if (mem_max > (1 << 31)) {
mem_max = (ulong_t) (1 << 31);
}
/*
* We need a page table for the low 4M of the kernel address space,
* since we want to leave the zero page unmapped (to catch null pointer derefs).
*/
pgtab_frame = mem_alloc_frame(FRAME_KERN, 1);
pgtab = mem_frame_to_pa(pgtab_frame);
memset(pgtab, '\0', PAGE_SIZE);
/*
* Initialize low page table, leaving page 0 unmapped
*/
for (paddr = PAGE_SIZE; paddr < VM_PT_SPAN; paddr += PAGE_SIZE) {
vm_set_pte(pgtab, VM_WRITE|VM_READ|VM_EXEC, paddr, paddr);
}
/*
* Add low page table to the kernel pagedir.
*/
vm_set_pde(s_kernel_pagedir, VM_WRITE|VM_READ|VM_EXEC, 0UL, (u32_t) pgtab);
/*
* Use 4M pages to map the rest of the low 2G of memory
*/
for (paddr = VM_PT_SPAN; paddr < mem_max; paddr += VM_PT_SPAN) {
vm_set_pde_4m(s_kernel_pagedir, VM_WRITE|VM_READ|VM_EXEC, paddr, paddr);
}
/*
* Turn on paging!
*/
x86_set_cr3((u32_t) s_kernel_pagedir); /* set the kernel page directory */
x86_set_cr0(x86_get_cr0() | CR0_PG); /* turn on the paging bit in cr0 */
cons_printf("Paging enabled\n");
}
