#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) pgtable_page_ctor(pte); 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) { 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); } #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]) 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 == 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; unsigned long addr; int i; if (PREALLOCATED_PMDS == 0) /* Work around gcc-3.4.x bug */ return; pud = pud_offset(pgd, 0); for (addr = i = 0; i < PREALLOCATED_PMDS; i++, pud++, addr += PUD_SIZE) { 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); flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); } 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) { int young; young = ptep_test_and_clear_young(vma, address, ptep); if (young) flush_tlb_page(vma, address); return young; } #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); printk(KERN_INFO "Reserving virtual address space above 0x%08x\n", (int)-reserve); __FIXADDR_TOP = -reserve - 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)); }