484 строки
11 KiB
C
484 строки
11 KiB
C
#include <linux/mm.h>
|
|
#include <linux/gfp.h>
|
|
#include <asm/pgalloc.h>
|
|
#include <asm/pgtable.h>
|
|
#include <asm/tlb.h>
|
|
#include <asm/fixmap.h>
|
|
|
|
#define PGALLOC_GFP GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO
|
|
|
|
#ifdef CONFIG_HIGHPTE
|
|
#define PGALLOC_USER_GFP __GFP_HIGHMEM
|
|
#else
|
|
#define PGALLOC_USER_GFP 0
|
|
#endif
|
|
|
|
gfp_t __userpte_alloc_gfp = PGALLOC_GFP | PGALLOC_USER_GFP;
|
|
|
|
pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
|
|
{
|
|
return (pte_t *)__get_free_page(PGALLOC_GFP);
|
|
}
|
|
|
|
pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
|
|
{
|
|
struct page *pte;
|
|
|
|
pte = alloc_pages(__userpte_alloc_gfp, 0);
|
|
if (!pte)
|
|
return NULL;
|
|
if (!pgtable_page_ctor(pte)) {
|
|
__free_page(pte);
|
|
return NULL;
|
|
}
|
|
return pte;
|
|
}
|
|
|
|
static int __init setup_userpte(char *arg)
|
|
{
|
|
if (!arg)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* "userpte=nohigh" disables allocation of user pagetables in
|
|
* high memory.
|
|
*/
|
|
if (strcmp(arg, "nohigh") == 0)
|
|
__userpte_alloc_gfp &= ~__GFP_HIGHMEM;
|
|
else
|
|
return -EINVAL;
|
|
return 0;
|
|
}
|
|
early_param("userpte", setup_userpte);
|
|
|
|
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)
|
|
{
|
|
struct page *page = virt_to_page(pmd);
|
|
paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT);
|
|
/*
|
|
* NOTE! For PAE, any changes to the top page-directory-pointer-table
|
|
* entries need a full cr3 reload to flush.
|
|
*/
|
|
#ifdef CONFIG_X86_PAE
|
|
tlb->need_flush_all = 1;
|
|
#endif
|
|
pgtable_pmd_page_dtor(page);
|
|
tlb_remove_page(tlb, page);
|
|
}
|
|
|
|
#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);
|
|
}
|
|
|
|
#define UNSHARED_PTRS_PER_PGD \
|
|
(SHARED_KERNEL_PMD ? KERNEL_PGD_BOUNDARY : PTRS_PER_PGD)
|
|
|
|
|
|
static void pgd_set_mm(pgd_t *pgd, struct mm_struct *mm)
|
|
{
|
|
BUILD_BUG_ON(sizeof(virt_to_page(pgd)->index) < sizeof(mm));
|
|
virt_to_page(pgd)->index = (pgoff_t)mm;
|
|
}
|
|
|
|
struct mm_struct *pgd_page_get_mm(struct page *page)
|
|
{
|
|
return (struct mm_struct *)page->index;
|
|
}
|
|
|
|
static void pgd_ctor(struct mm_struct *mm, pgd_t *pgd)
|
|
{
|
|
/* 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) ||
|
|
PAGETABLE_LEVELS == 4) {
|
|
clone_pgd_range(pgd + KERNEL_PGD_BOUNDARY,
|
|
swapper_pg_dir + KERNEL_PGD_BOUNDARY,
|
|
KERNEL_PGD_PTRS);
|
|
}
|
|
|
|
/* list required to sync kernel mapping updates */
|
|
if (!SHARED_KERNEL_PMD) {
|
|
pgd_set_mm(pgd, mm);
|
|
pgd_list_add(pgd);
|
|
}
|
|
}
|
|
|
|
static void pgd_dtor(pgd_t *pgd)
|
|
{
|
|
if (SHARED_KERNEL_PMD)
|
|
return;
|
|
|
|
spin_lock(&pgd_lock);
|
|
pgd_list_del(pgd);
|
|
spin_unlock(&pgd_lock);
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
* -- nyc
|
|
*/
|
|
|
|
#ifdef CONFIG_X86_PAE
|
|
/*
|
|
* 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.
|
|
*/
|
|
#define PREALLOCATED_PMDS UNSHARED_PTRS_PER_PGD
|
|
|
|
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...
|
|
*/
|
|
flush_tlb_mm(mm);
|
|
}
|
|
#else /* !CONFIG_X86_PAE */
|
|
|
|
/* No need to prepopulate any pagetable entries in non-PAE modes. */
|
|
#define PREALLOCATED_PMDS 0
|
|
|
|
#endif /* CONFIG_X86_PAE */
|
|
|
|
static void free_pmds(pmd_t *pmds[])
|
|
{
|
|
int i;
|
|
|
|
for(i = 0; i < PREALLOCATED_PMDS; i++)
|
|
if (pmds[i]) {
|
|
pgtable_pmd_page_dtor(virt_to_page(pmds[i]));
|
|
free_page((unsigned long)pmds[i]);
|
|
}
|
|
}
|
|
|
|
static int preallocate_pmds(pmd_t *pmds[])
|
|
{
|
|
int i;
|
|
bool failed = false;
|
|
|
|
for(i = 0; i < PREALLOCATED_PMDS; i++) {
|
|
pmd_t *pmd = (pmd_t *)__get_free_page(PGALLOC_GFP);
|
|
if (!pmd)
|
|
failed = true;
|
|
if (pmd && !pgtable_pmd_page_ctor(virt_to_page(pmd))) {
|
|
free_page((unsigned long)pmd);
|
|
pmd = NULL;
|
|
failed = true;
|
|
}
|
|
pmds[i] = pmd;
|
|
}
|
|
|
|
if (failed) {
|
|
free_pmds(pmds);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* 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 < PREALLOCATED_PMDS; 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);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[])
|
|
{
|
|
pud_t *pud;
|
|
int i;
|
|
|
|
if (PREALLOCATED_PMDS == 0) /* Work around gcc-3.4.x bug */
|
|
return;
|
|
|
|
pud = pud_offset(pgd, 0);
|
|
|
|
for (i = 0; i < PREALLOCATED_PMDS; i++, pud++) {
|
|
pmd_t *pmd = pmds[i];
|
|
|
|
if (i >= KERNEL_PGD_BOUNDARY)
|
|
memcpy(pmd, (pmd_t *)pgd_page_vaddr(swapper_pg_dir[i]),
|
|
sizeof(pmd_t) * PTRS_PER_PMD);
|
|
|
|
pud_populate(mm, pud, pmd);
|
|
}
|
|
}
|
|
|
|
pgd_t *pgd_alloc(struct mm_struct *mm)
|
|
{
|
|
pgd_t *pgd;
|
|
pmd_t *pmds[PREALLOCATED_PMDS];
|
|
|
|
pgd = (pgd_t *)__get_free_page(PGALLOC_GFP);
|
|
|
|
if (pgd == NULL)
|
|
goto out;
|
|
|
|
mm->pgd = pgd;
|
|
|
|
if (preallocate_pmds(pmds) != 0)
|
|
goto out_free_pgd;
|
|
|
|
if (paravirt_pgd_alloc(mm) != 0)
|
|
goto out_free_pmds;
|
|
|
|
/*
|
|
* Make sure that pre-populating the pmds is atomic with
|
|
* respect to anything walking the pgd_list, so that they
|
|
* never see a partially populated pgd.
|
|
*/
|
|
spin_lock(&pgd_lock);
|
|
|
|
pgd_ctor(mm, pgd);
|
|
pgd_prepopulate_pmd(mm, pgd, pmds);
|
|
|
|
spin_unlock(&pgd_lock);
|
|
|
|
return pgd;
|
|
|
|
out_free_pmds:
|
|
free_pmds(pmds);
|
|
out_free_pgd:
|
|
free_page((unsigned long)pgd);
|
|
out:
|
|
return NULL;
|
|
}
|
|
|
|
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
|
|
{
|
|
pgd_mop_up_pmds(mm, pgd);
|
|
pgd_dtor(pgd);
|
|
paravirt_pgd_free(mm, pgd);
|
|
free_page((unsigned long)pgd);
|
|
}
|
|
|
|
/*
|
|
* Used to set accessed or dirty bits in the page table entries
|
|
* on other architectures. On x86, the accessed and dirty bits
|
|
* are tracked by hardware. However, do_wp_page calls this function
|
|
* to also make the pte writeable at the same time the dirty bit is
|
|
* set. In that case we do actually need to write the PTE.
|
|
*/
|
|
int ptep_set_access_flags(struct vm_area_struct *vma,
|
|
unsigned long address, pte_t *ptep,
|
|
pte_t entry, int dirty)
|
|
{
|
|
int changed = !pte_same(*ptep, entry);
|
|
|
|
if (changed && dirty) {
|
|
*ptep = entry;
|
|
pte_update_defer(vma->vm_mm, address, ptep);
|
|
}
|
|
|
|
return changed;
|
|
}
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
int pmdp_set_access_flags(struct vm_area_struct *vma,
|
|
unsigned long address, pmd_t *pmdp,
|
|
pmd_t entry, int dirty)
|
|
{
|
|
int changed = !pmd_same(*pmdp, entry);
|
|
|
|
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
|
|
|
|
if (changed && dirty) {
|
|
*pmdp = entry;
|
|
pmd_update_defer(vma->vm_mm, address, pmdp);
|
|
/*
|
|
* We had a write-protection fault here and changed the pmd
|
|
* to to more permissive. No need to flush the TLB for that,
|
|
* #PF is architecturally guaranteed to do that and in the
|
|
* worst-case we'll generate a spurious fault.
|
|
*/
|
|
}
|
|
|
|
return changed;
|
|
}
|
|
#endif
|
|
|
|
int ptep_test_and_clear_young(struct vm_area_struct *vma,
|
|
unsigned long addr, pte_t *ptep)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (pte_young(*ptep))
|
|
ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
|
|
(unsigned long *) &ptep->pte);
|
|
|
|
if (ret)
|
|
pte_update(vma->vm_mm, addr, ptep);
|
|
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
int pmdp_test_and_clear_young(struct vm_area_struct *vma,
|
|
unsigned long addr, pmd_t *pmdp)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (pmd_young(*pmdp))
|
|
ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
|
|
(unsigned long *)pmdp);
|
|
|
|
if (ret)
|
|
pmd_update(vma->vm_mm, addr, pmdp);
|
|
|
|
return ret;
|
|
}
|
|
#endif
|
|
|
|
int ptep_clear_flush_young(struct vm_area_struct *vma,
|
|
unsigned long address, pte_t *ptep)
|
|
{
|
|
/*
|
|
* On x86 CPUs, clearing the accessed bit without a TLB flush
|
|
* doesn't cause data corruption. [ It could cause incorrect
|
|
* page aging and the (mistaken) reclaim of hot pages, but the
|
|
* chance of that should be relatively low. ]
|
|
*
|
|
* So as a performance optimization don't flush the TLB when
|
|
* clearing the accessed bit, it will eventually be flushed by
|
|
* a context switch or a VM operation anyway. [ In the rare
|
|
* event of it not getting flushed for a long time the delay
|
|
* shouldn't really matter because there's no real memory
|
|
* pressure for swapout to react to. ]
|
|
*/
|
|
return ptep_test_and_clear_young(vma, address, ptep);
|
|
}
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
int pmdp_clear_flush_young(struct vm_area_struct *vma,
|
|
unsigned long address, pmd_t *pmdp)
|
|
{
|
|
int young;
|
|
|
|
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
|
|
|
|
young = pmdp_test_and_clear_young(vma, address, pmdp);
|
|
if (young)
|
|
flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
|
|
|
|
return young;
|
|
}
|
|
|
|
void pmdp_splitting_flush(struct vm_area_struct *vma,
|
|
unsigned long address, pmd_t *pmdp)
|
|
{
|
|
int set;
|
|
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
|
|
set = !test_and_set_bit(_PAGE_BIT_SPLITTING,
|
|
(unsigned long *)pmdp);
|
|
if (set) {
|
|
pmd_update(vma->vm_mm, address, pmdp);
|
|
/* need tlb flush only to serialize against gup-fast */
|
|
flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* reserve_top_address - reserves a hole in the top of kernel address space
|
|
* @reserve - size of hole to reserve
|
|
*
|
|
* Can be used to relocate the fixmap area and poke a hole in the top
|
|
* of kernel address space to make room for a hypervisor.
|
|
*/
|
|
void __init reserve_top_address(unsigned long reserve)
|
|
{
|
|
#ifdef CONFIG_X86_32
|
|
BUG_ON(fixmaps_set > 0);
|
|
__FIXADDR_TOP = round_down(-reserve, 1 << PMD_SHIFT) - PAGE_SIZE;
|
|
printk(KERN_INFO "Reserving virtual address space above 0x%08lx (rounded to 0x%08lx)\n",
|
|
-reserve, __FIXADDR_TOP + PAGE_SIZE);
|
|
#endif
|
|
}
|
|
|
|
int fixmaps_set;
|
|
|
|
void __native_set_fixmap(enum fixed_addresses idx, pte_t pte)
|
|
{
|
|
unsigned long address = __fix_to_virt(idx);
|
|
|
|
if (idx >= __end_of_fixed_addresses) {
|
|
BUG();
|
|
return;
|
|
}
|
|
set_pte_vaddr(address, pte);
|
|
fixmaps_set++;
|
|
}
|
|
|
|
void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys,
|
|
pgprot_t flags)
|
|
{
|
|
__native_set_fixmap(idx, pfn_pte(phys >> PAGE_SHIFT, flags));
|
|
}
|