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// SPDX-License-Identifier: GPL-2.0
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/hugetlb.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/tlb.h>
#include <asm/fixmap.h>
#include <asm/mtrr.h>
#define PGALLOC_GFP (GFP_KERNEL_ACCOUNT | __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 & ~__GFP_ACCOUNT);
}
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_table(tlb, pte);
}
#if CONFIG_PGTABLE_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_table(tlb, page);
}
#if CONFIG_PGTABLE_LEVELS > 3
void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
{
paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
tlb_remove_table(tlb, virt_to_page(pud));
}
#if CONFIG_PGTABLE_LEVELS > 4
void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d)
{
paravirt_release_p4d(__pa(p4d) >> PAGE_SHIFT);
tlb_remove_table(tlb, virt_to_page(p4d));
}
#endif /* CONFIG_PGTABLE_LEVELS > 4 */
#endif /* CONFIG_PGTABLE_LEVELS > 3 */
#endif /* CONFIG_PGTABLE_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 (CONFIG_PGTABLE_LEVELS == 2 ||
(CONFIG_PGTABLE_LEVELS == 3 && SHARED_KERNEL_PMD) ||
CONFIG_PGTABLE_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(struct mm_struct *mm, 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]);
mm_dec_nr_pmds(mm);
}
}
static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[])
{
int i;
bool failed = false;
gfp_t gfp = PGALLOC_GFP;
if (mm == &init_mm)
gfp &= ~__GFP_ACCOUNT;
for(i = 0; i < PREALLOCATED_PMDS; i++) {
pmd_t *pmd = (pmd_t *)__get_free_page(gfp);
if (!pmd)
failed = true;
if (pmd && !pgtable_pmd_page_ctor(virt_to_page(pmd))) {
free_page((unsigned long)pmd);
pmd = NULL;
failed = true;
}
if (pmd)
mm_inc_nr_pmds(mm);
pmds[i] = pmd;
}
if (failed) {
free_pmds(mm, 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);
mm_dec_nr_pmds(mm);
}
}
}
static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[])
{
p4d_t *p4d;
pud_t *pud;
int i;
if (PREALLOCATED_PMDS == 0) /* Work around gcc-3.4.x bug */
return;
p4d = p4d_offset(pgd, 0);
pud = pud_offset(p4d, 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);
}
}
/*
* Xen paravirt assumes pgd table should be in one page. 64 bit kernel also
* assumes that pgd should be in one page.
*
* But kernel with PAE paging that is not running as a Xen domain
* only needs to allocate 32 bytes for pgd instead of one page.
*/
#ifdef CONFIG_X86_PAE
#include <linux/slab.h>
#define PGD_SIZE (PTRS_PER_PGD * sizeof(pgd_t))
#define PGD_ALIGN 32
static struct kmem_cache *pgd_cache;
static int __init pgd_cache_init(void)
{
/*
* When PAE kernel is running as a Xen domain, it does not use
* shared kernel pmd. And this requires a whole page for pgd.
*/
if (!SHARED_KERNEL_PMD)
return 0;
/*
* when PAE kernel is not running as a Xen domain, it uses
* shared kernel pmd. Shared kernel pmd does not require a whole
* page for pgd. We are able to just allocate a 32-byte for pgd.
* During boot time, we create a 32-byte slab for pgd table allocation.
*/
pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_ALIGN,
SLAB_PANIC, NULL);
if (!pgd_cache)
return -ENOMEM;
return 0;
}
core_initcall(pgd_cache_init);
static inline pgd_t *_pgd_alloc(void)
{
/*
* If no SHARED_KERNEL_PMD, PAE kernel is running as a Xen domain.
* We allocate one page for pgd.
*/
if (!SHARED_KERNEL_PMD)
return (pgd_t *)__get_free_page(PGALLOC_GFP);
/*
* Now PAE kernel is not running as a Xen domain. We can allocate
* a 32-byte slab for pgd to save memory space.
*/
return kmem_cache_alloc(pgd_cache, PGALLOC_GFP);
}
static inline void _pgd_free(pgd_t *pgd)
{
if (!SHARED_KERNEL_PMD)
free_page((unsigned long)pgd);
else
kmem_cache_free(pgd_cache, pgd);
}
#else
static inline pgd_t *_pgd_alloc(void)
{
return (pgd_t *)__get_free_pages(PGALLOC_GFP, PGD_ALLOCATION_ORDER);
}
static inline void _pgd_free(pgd_t *pgd)
{
free_pages((unsigned long)pgd, PGD_ALLOCATION_ORDER);
}
#endif /* CONFIG_X86_PAE */
pgd_t *pgd_alloc(struct mm_struct *mm)
{
pgd_t *pgd;
pmd_t *pmds[PREALLOCATED_PMDS];
pgd = _pgd_alloc();
if (pgd == NULL)
goto out;
mm->pgd = pgd;
if (preallocate_pmds(mm, 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(mm, pmds);
out_free_pgd:
_pgd_free(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);
_pgd_free(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;
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;
/*
* 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;
}
int pudp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
pud_t *pudp, pud_t entry, int dirty)
{
int changed = !pud_same(*pudp, entry);
VM_BUG_ON(address & ~HPAGE_PUD_MASK);
if (changed && dirty) {
*pudp = entry;
/*
* We had a write-protection fault here and changed the pud
* 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);
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);
return ret;
}
int pudp_test_and_clear_young(struct vm_area_struct *vma,
unsigned long addr, pud_t *pudp)
{
int ret = 0;
if (pud_young(*pudp))
ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
(unsigned long *)pudp);
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;
}
#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);
#ifdef CONFIG_X86_64
/*
* Ensure that the static initial page tables are covering the
* fixmap completely.
*/
BUILD_BUG_ON(__end_of_permanent_fixed_addresses >
(FIXMAP_PMD_NUM * PTRS_PER_PTE));
#endif
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));
}
#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
#ifdef CONFIG_X86_5LEVEL
/**
* p4d_set_huge - setup kernel P4D mapping
*
* No 512GB pages yet -- always return 0
*/
int p4d_set_huge(p4d_t *p4d, phys_addr_t addr, pgprot_t prot)
{
return 0;
}
/**
* p4d_clear_huge - clear kernel P4D mapping when it is set
*
* No 512GB pages yet -- always return 0
*/
int p4d_clear_huge(p4d_t *p4d)
{
return 0;
}
#endif
/**
* pud_set_huge - setup kernel PUD mapping
*
* MTRRs can override PAT memory types with 4KiB granularity. Therefore, this
* function sets up a huge page only if any of the following conditions are met:
*
* - MTRRs are disabled, or
*
* - MTRRs are enabled and the range is completely covered by a single MTRR, or
*
* - MTRRs are enabled and the corresponding MTRR memory type is WB, which
* has no effect on the requested PAT memory type.
*
* Callers should try to decrease page size (1GB -> 2MB -> 4K) if the bigger
* page mapping attempt fails.
*
* Returns 1 on success and 0 on failure.
*/
int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
{
u8 mtrr, uniform;
mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE, &uniform);
if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
(mtrr != MTRR_TYPE_WRBACK))
return 0;
/* Bail out if we are we on a populated non-leaf entry: */
if (pud_present(*pud) && !pud_huge(*pud))
return 0;
prot = pgprot_4k_2_large(prot);
set_pte((pte_t *)pud, pfn_pte(
(u64)addr >> PAGE_SHIFT,
__pgprot(pgprot_val(prot) | _PAGE_PSE)));
return 1;
}
/**
* pmd_set_huge - setup kernel PMD mapping
*
* See text over pud_set_huge() above.
*
* Returns 1 on success and 0 on failure.
*/
int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
{
u8 mtrr, uniform;
mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE, &uniform);
if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
(mtrr != MTRR_TYPE_WRBACK)) {
pr_warn_once("%s: Cannot satisfy [mem %#010llx-%#010llx] with a huge-page mapping due to MTRR override.\n",
__func__, addr, addr + PMD_SIZE);
return 0;
}
/* Bail out if we are we on a populated non-leaf entry: */
if (pmd_present(*pmd) && !pmd_huge(*pmd))
return 0;
prot = pgprot_4k_2_large(prot);
set_pte((pte_t *)pmd, pfn_pte(
(u64)addr >> PAGE_SHIFT,
__pgprot(pgprot_val(prot) | _PAGE_PSE)));
return 1;
}
/**
* pud_clear_huge - clear kernel PUD mapping when it is set
*
* Returns 1 on success and 0 on failure (no PUD map is found).
*/
int pud_clear_huge(pud_t *pud)
{
if (pud_large(*pud)) {
pud_clear(pud);
return 1;
}
return 0;
}
/**
* pmd_clear_huge - clear kernel PMD mapping when it is set
*
* Returns 1 on success and 0 on failure (no PMD map is found).
*/
int pmd_clear_huge(pmd_t *pmd)
{
if (pmd_large(*pmd)) {
pmd_clear(pmd);
return 1;
}
return 0;
}
#ifdef CONFIG_X86_64
/**
* pud_free_pmd_page - Clear pud entry and free pmd page.
* @pud: Pointer to a PUD.
* @addr: Virtual address associated with pud.
*
* Context: The pud range has been unmapped and TLB purged.
* Return: 1 if clearing the entry succeeded. 0 otherwise.
*
* NOTE: Callers must allow a single page allocation.
*/
int pud_free_pmd_page(pud_t *pud, unsigned long addr)
{
pmd_t *pmd, *pmd_sv;
pte_t *pte;
int i;
if (pud_none(*pud))
return 1;
pmd = (pmd_t *)pud_page_vaddr(*pud);
pmd_sv = (pmd_t *)__get_free_page(GFP_KERNEL);
if (!pmd_sv)
return 0;
for (i = 0; i < PTRS_PER_PMD; i++) {
pmd_sv[i] = pmd[i];
if (!pmd_none(pmd[i]))
pmd_clear(&pmd[i]);
}
pud_clear(pud);
/* INVLPG to clear all paging-structure caches */
flush_tlb_kernel_range(addr, addr + PAGE_SIZE-1);
for (i = 0; i < PTRS_PER_PMD; i++) {
if (!pmd_none(pmd_sv[i])) {
pte = (pte_t *)pmd_page_vaddr(pmd_sv[i]);
free_page((unsigned long)pte);
}
}
free_page((unsigned long)pmd_sv);
free_page((unsigned long)pmd);
return 1;
}
/**
* pmd_free_pte_page - Clear pmd entry and free pte page.
* @pmd: Pointer to a PMD.
* @addr: Virtual address associated with pmd.
*
* Context: The pmd range has been unmapped and TLB purged.
* Return: 1 if clearing the entry succeeded. 0 otherwise.
*/
int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
{
pte_t *pte;
if (pmd_none(*pmd))
return 1;
pte = (pte_t *)pmd_page_vaddr(*pmd);
pmd_clear(pmd);
/* INVLPG to clear all paging-structure caches */
flush_tlb_kernel_range(addr, addr + PAGE_SIZE-1);
free_page((unsigned long)pte);
return 1;
}
#else /* !CONFIG_X86_64 */
int pud_free_pmd_page(pud_t *pud, unsigned long addr)
{
return pud_none(*pud);
}
/*
* Disable free page handling on x86-PAE. This assures that ioremap()
* does not update sync'd pmd entries. See vmalloc_sync_one().
*/
int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
{
return pmd_none(*pmd);
}
#endif /* CONFIG_X86_64 */
#endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */