static int
__change_page_attr(struct page *page, pgprot_t prot)
{
pte_t *kpte;
unsigned long address;
struct page *kpte_page;
BUG_ON(PageHighMem(page));
address = (unsigned long)page_address(page);
kpte = lookup_address(address);
if (!kpte)
return -EINVAL;
kpte_page = virt_to_page(kpte);
if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) {
if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
set_pte_atomic(kpte, mk_pte(page, prot));
} else {
pgprot_t ref_prot;
struct page *split;
ref_prot =
((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
? PAGE_KERNEL_EXEC : PAGE_KERNEL;
split = split_large_page(address, prot, ref_prot);
if (!split)
return -ENOMEM;
set_pmd_pte(kpte,address,mk_pte(split, ref_prot));
kpte_page = split;
}
page_private(kpte_page)++;
} else if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
BUG_ON(page_private(kpte_page) == 0);
page_private(kpte_page)--;
} else
BUG();
/*
* If the pte was reserved, it means it was created at boot
* time (not via split_large_page) and in turn we must not
* replace it with a largepage.
*/
if (!PageReserved(kpte_page)) {
if (cpu_has_pse && (page_private(kpte_page) == 0)) {
ClearPagePrivate(kpte_page);
list_add(&kpte_page->lru, &df_list);
revert_page(kpte_page, address);
}
}
return 0;
}
static int
__change_page_attr(struct page *page, pgprot_t prot)
{
pte_t *kpte;
unsigned long address;
struct page *kpte_page;
BUG_ON(PageHighMem(page));
address = (unsigned long)page_address(page);
kpte = lookup_address(address);
if (!kpte)
return -EINVAL;
kpte_page = virt_to_page(kpte);
if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) {
if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
set_pte_atomic(kpte, mk_pte(page, prot));
} else {
struct page *split = split_large_page(address, prot);
if (!split)
return -ENOMEM;
set_pmd_pte(kpte,address,mk_pte(split, PAGE_KERNEL));
kpte_page = split;
}
get_page(kpte_page);
} else if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
__put_page(kpte_page);
} else
BUG();
/*
* If the pte was reserved, it means it was created at boot
* time (not via split_large_page) and in turn we must not
* replace it with a largepage.
*/
if (!PageReserved(kpte_page)) {
/* memleak and potential failed 2M page regeneration */
BUG_ON(!page_count(kpte_page));
if (cpu_has_pse && (page_count(kpte_page) == 1)) {
list_add(&kpte_page->lru, &df_list);
revert_page(kpte_page, address);
}
}
return 0;
}
static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
{
struct page *page;
unsigned long flags;
set_pte_atomic(kpte, pte); /* change init_mm */
if (PTRS_PER_PMD > 1)
return;
spin_lock_irqsave(&pgd_lock, flags);
for (page = pgd_list; page; page = (struct page *)page->index) {
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pgd = (pgd_t *)page_address(page) + pgd_index(address);
pud = pud_offset(pgd, address);
pmd = pmd_offset(pud, address);
set_pte_atomic((pte_t *)pmd, pte);
}
spin_unlock_irqrestore(&pgd_lock, flags);
}
static inline void
unprotect_memory(void)
{
/* Unprotected kernel memory page containing for writing */
set_pte_atomic(pte, pte_mkwrite(*pte));
}
static inline void
protect_memory(void)
{
/* Restore kernel memory page protection */
set_pte_atomic(pte, pte_clear_flags(*pte, _PAGE_RW));
}
