linux/arch/x86/mm/pgtable.c

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#include <linux/mm.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
return (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
}
pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
struct page *pte;
#ifdef CONFIG_HIGHPTE
pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT|__GFP_ZERO, 0);
#else
pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
#endif
if (pte)
pgtable_page_ctor(pte);
return pte;
}
void __pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
{
pgtable_page_dtor(pte);
paravirt_release_pte(page_to_pfn(pte));
tlb_remove_page(tlb, pte);
}
#if PAGETABLE_LEVELS > 2
void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
{
paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT);
tlb_remove_page(tlb, virt_to_page(pmd));
}
#if PAGETABLE_LEVELS > 3
void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
{
paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
tlb_remove_page(tlb, virt_to_page(pud));
}
#endif /* PAGETABLE_LEVELS > 3 */
#endif /* PAGETABLE_LEVELS > 2 */
static inline void pgd_list_add(pgd_t *pgd)
{
struct page *page = virt_to_page(pgd);
list_add(&page->lru, &pgd_list);
}
static inline void pgd_list_del(pgd_t *pgd)
{
struct page *page = virt_to_page(pgd);
list_del(&page->lru);
}
#ifdef CONFIG_X86_64
pgd_t *pgd_alloc(struct mm_struct *mm)
{
unsigned boundary;
pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT);
unsigned long flags;
if (!pgd)
return NULL;
spin_lock_irqsave(&pgd_lock, flags);
pgd_list_add(pgd);
spin_unlock_irqrestore(&pgd_lock, flags);
/*
* Copy kernel pointers in from init.
* Could keep a freelist or slab cache of those because the kernel
* part never changes.
*/
boundary = pgd_index(__PAGE_OFFSET);
memset(pgd, 0, boundary * sizeof(pgd_t));
memcpy(pgd + boundary,
init_level4_pgt + boundary,
(PTRS_PER_PGD - boundary) * sizeof(pgd_t));
return pgd;
}
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
unsigned long flags;
BUG_ON((unsigned long)pgd & (PAGE_SIZE-1));
spin_lock_irqsave(&pgd_lock, flags);
pgd_list_del(pgd);
spin_unlock_irqrestore(&pgd_lock, flags);
free_page((unsigned long)pgd);
}
#else
/*
* List of all pgd's needed for non-PAE so it can invalidate entries
* in both cached and uncached pgd's; not needed for PAE since the
* kernel pmd is shared. If PAE were not to share the pmd a similar
* tactic would be needed. This is essentially codepath-based locking
* against pageattr.c; it is the unique case in which a valid change
* of kernel pagetables can't be lazily synchronized by vmalloc faults.
* vmalloc faults work because attached pagetables are never freed.
* -- wli
*/
#define UNSHARED_PTRS_PER_PGD \
(SHARED_KERNEL_PMD ? USER_PTRS_PER_PGD : PTRS_PER_PGD)
static void pgd_ctor(void *p)
{
pgd_t *pgd = p;
unsigned long flags;
/* Clear usermode parts of PGD */
memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
spin_lock_irqsave(&pgd_lock, flags);
/* If the pgd points to a shared pagetable level (either the
ptes in non-PAE, or shared PMD in PAE), then just copy the
references from swapper_pg_dir. */
if (PAGETABLE_LEVELS == 2 ||
(PAGETABLE_LEVELS == 3 && SHARED_KERNEL_PMD)) {
clone_pgd_range(pgd + USER_PTRS_PER_PGD,
swapper_pg_dir + USER_PTRS_PER_PGD,
KERNEL_PGD_PTRS);
paravirt_alloc_pmd_clone(__pa(pgd) >> PAGE_SHIFT,
__pa(swapper_pg_dir) >> PAGE_SHIFT,
USER_PTRS_PER_PGD,
KERNEL_PGD_PTRS);
}
/* list required to sync kernel mapping updates */
if (!SHARED_KERNEL_PMD)
pgd_list_add(pgd);
spin_unlock_irqrestore(&pgd_lock, flags);
}
static void pgd_dtor(void *pgd)
{
unsigned long flags; /* can be called from interrupt context */
if (SHARED_KERNEL_PMD)
return;
spin_lock_irqsave(&pgd_lock, flags);
pgd_list_del(pgd);
spin_unlock_irqrestore(&pgd_lock, flags);
}
#ifdef CONFIG_X86_PAE
/*
* Mop up any pmd pages which may still be attached to the pgd.
* Normally they will be freed by munmap/exit_mmap, but any pmd we
* preallocate which never got a corresponding vma will need to be
* freed manually.
*/
static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp)
{
int i;
for(i = 0; i < UNSHARED_PTRS_PER_PGD; i++) {
pgd_t pgd = pgdp[i];
if (pgd_val(pgd) != 0) {
pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd);
pgdp[i] = native_make_pgd(0);
paravirt_release_pmd(pgd_val(pgd) >> PAGE_SHIFT);
pmd_free(mm, pmd);
}
}
}
/*
* In PAE mode, we need to do a cr3 reload (=tlb flush) when
* updating the top-level pagetable entries to guarantee the
* processor notices the update. Since this is expensive, and
* all 4 top-level entries are used almost immediately in a
* new process's life, we just pre-populate them here.
*
* Also, if we're in a paravirt environment where the kernel pmd is
* not shared between pagetables (!SHARED_KERNEL_PMDS), we allocate
* and initialize the kernel pmds here.
*/
static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd)
{
pud_t *pud;
unsigned long addr;
int i;
pud = pud_offset(pgd, 0);
for (addr = i = 0; i < UNSHARED_PTRS_PER_PGD;
i++, pud++, addr += PUD_SIZE) {
pmd_t *pmd = pmd_alloc_one(mm, addr);
if (!pmd) {
pgd_mop_up_pmds(mm, pgd);
return 0;
}
if (i >= USER_PTRS_PER_PGD)
memcpy(pmd, (pmd_t *)pgd_page_vaddr(swapper_pg_dir[i]),
sizeof(pmd_t) * PTRS_PER_PMD);
pud_populate(mm, pud, pmd);
}
return 1;
}
void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)
{
paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT);
/* Note: almost everything apart from _PAGE_PRESENT is
reserved at the pmd (PDPT) level. */
set_pud(pudp, __pud(__pa(pmd) | _PAGE_PRESENT));
/*
* According to Intel App note "TLBs, Paging-Structure Caches,
* and Their Invalidation", April 2007, document 317080-001,
* section 8.1: in PAE mode we explicitly have to flush the
* TLB via cr3 if the top-level pgd is changed...
*/
if (mm == current->active_mm)
write_cr3(read_cr3());
}
#else /* !CONFIG_X86_PAE */
/* No need to prepopulate any pagetable entries in non-PAE modes. */
static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd)
{
return 1;
}
static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgd)
{
}
#endif /* CONFIG_X86_PAE */
pgd_t *pgd_alloc(struct mm_struct *mm)
{
pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
/* so that alloc_pmd can use it */
mm->pgd = pgd;
if (pgd)
pgd_ctor(pgd);
if (pgd && !pgd_prepopulate_pmd(mm, pgd)) {
pgd_dtor(pgd);
free_page((unsigned long)pgd);
pgd = NULL;
}
return pgd;
}
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
pgd_mop_up_pmds(mm, pgd);
pgd_dtor(pgd);
free_page((unsigned long)pgd);
}
#endif