/*
* When built with CONFIG_DEBUG_PAGEALLOC and CONFIG_HIBERNATION, this function
* is used to determine if a linear map page has been marked as not-valid by
* CONFIG_DEBUG_PAGEALLOC. Walk the page table and check the PTE_VALID bit.
* This is based on kern_addr_valid(), which almost does what we need.
*
* Because this is only called on the kernel linear map, p?d_sect() implies
* p?d_present(). When debug_pagealloc is enabled, sections mappings are
* disabled.
*/
bool kernel_page_present(struct page *page)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
unsigned long addr = (unsigned long)page_address(page);
pgd = pgd_offset_k(addr);
if (pgd_none(*pgd))
return false;
pud = pud_offset(pgd, addr);
if (pud_none(*pud))
return false;
if (pud_sect(*pud))
return true;
pmd = pmd_offset(pud, addr);
if (pmd_none(*pmd))
return false;
if (pmd_sect(*pmd))
return true;
pte = pte_offset_kernel(pmd, addr);
return pte_valid(*pte);
}
/*
* Changing some bits of contiguous entries requires us to follow a
* Break-Before-Make approach, breaking the whole contiguous set
* before we can change any entries. See ARM DDI 0487A.k_iss10775,
* "Misprogramming of the Contiguous bit", page D4-1762.
*
* This helper performs the break step.
*/
static pte_t get_clear_flush(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep,
unsigned long pgsize,
unsigned long ncontig)
{
struct vm_area_struct vma = { .vm_mm = mm };
pte_t orig_pte = huge_ptep_get(ptep);
bool valid = pte_valid(orig_pte);
unsigned long i, saddr = addr;
for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
pte_t pte = ptep_get_and_clear(mm, addr, ptep);
/*
* If HW_AFDBM is enabled, then the HW could turn on
* the dirty bit for any page in the set, so check
* them all. All hugetlb entries are already young.
*/
if (pte_dirty(pte))
orig_pte = pte_mkdirty(orig_pte);
}
if (valid)
flush_tlb_range(&vma, saddr, addr);
return orig_pte;
}
/*
* When built with CONFIG_DEBUG_PAGEALLOC and CONFIG_HIBERNATION, this function
* is used to determine if a linear map page has been marked as not-valid by
* CONFIG_DEBUG_PAGEALLOC. Walk the page table and check the PTE_VALID bit.
* This is based on kern_addr_valid(), which almost does what we need.
*
* Because this is only called on the kernel linear map, p?d_sect() implies
* p?d_present(). When debug_pagealloc is enabled, sections mappings are
* disabled.
*/
bool kernel_page_present(struct page *page)
{
pgd_t *pgdp;
pud_t *pudp, pud;
pmd_t *pmdp, pmd;
pte_t *ptep;
unsigned long addr = (unsigned long)page_address(page);
pgdp = pgd_offset_k(addr);
if (pgd_none(READ_ONCE(*pgdp)))
return false;
pudp = pud_offset(pgdp, addr);
pud = READ_ONCE(*pudp);
if (pud_none(pud))
return false;
if (pud_sect(pud))
return true;
pmdp = pmd_offset(pudp, addr);
pmd = READ_ONCE(*pmdp);
if (pmd_none(pmd))
return false;
if (pmd_sect(pmd))
return true;
ptep = pte_offset_kernel(pmdp, addr);
return pte_valid(READ_ONCE(*ptep));
}
/*
* Changing some bits of contiguous entries requires us to follow a
* Break-Before-Make approach, breaking the whole contiguous set
* before we can change any entries. See ARM DDI 0487A.k_iss10775,
* "Misprogramming of the Contiguous bit", page D4-1762.
*
* This helper performs the break step.
*/
static pte_t get_clear_flush(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep,
unsigned long pgsize,
unsigned long ncontig)
{
pte_t orig_pte = huge_ptep_get(ptep);
bool valid = pte_valid(orig_pte);
unsigned long i, saddr = addr;
for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
pte_t pte = ptep_get_and_clear(mm, addr, ptep);
/*
* If HW_AFDBM is enabled, then the HW could turn on
* the dirty or accessed bit for any page in the set,
* so check them all.
*/
if (pte_dirty(pte))
orig_pte = pte_mkdirty(orig_pte);
if (pte_young(pte))
orig_pte = pte_mkyoung(orig_pte);
}
if (valid) {
struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
flush_tlb_range(&vma, saddr, addr);
}
return orig_pte;
}
static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, unsigned long addr)
{
pte_t pte = READ_ONCE(*src_ptep);
if (pte_valid(pte)) {
/*
* Resume will overwrite areas that may be marked
* read only (code, rodata). Clear the RDONLY bit from
* the temporary mappings we use during restore.
*/
set_pte(dst_ptep, pte_mkwrite(pte));
} else if (debug_pagealloc_enabled() && !pte_none(pte)) {
/*
* debug_pagealloc will removed the PTE_VALID bit if
* the page isn't in use by the resume kernel. It may have
* been in use by the original kernel, in which case we need
* to put it back in our copy to do the restore.
*
* Before marking this entry valid, check the pfn should
* be mapped.
*/
BUG_ON(!pfn_valid(pte_pfn(pte)));
set_pte(dst_ptep, pte_mkpresent(pte_mkwrite(pte)));
}
}
