C++ pmd_none函数代码示例

static void stage2_flush_pmds(struct kvm *kvm, pud_t *pud,
			      phys_addr_t addr, phys_addr_t end)
{
	pmd_t *pmd;
	phys_addr_t next;

	pmd = pmd_offset(pud, addr);
	do {
		next = kvm_pmd_addr_end(addr, end);
		if (!pmd_none(*pmd)) {
			if (kvm_pmd_huge(*pmd)) {
				hva_t hva = gfn_to_hva(kvm, addr >> PAGE_SHIFT);
				kvm_flush_dcache_to_poc((void*)hva, PMD_SIZE);
			} else {
				stage2_flush_ptes(kvm, pmd, addr, next);
			}
		}

static void shmedia_mapioaddr(unsigned long pa, unsigned long va,
			      unsigned long flags)
{
	pgd_t *pgdp;
	pud_t *pudp;
	pmd_t *pmdp;
	pte_t *ptep, pte;
	pgprot_t prot;

	pr_debug("shmedia_mapiopage pa %08lx va %08lx\n",  pa, va);

	if (!flags)
		flags = 1; /* 1 = CB0-1 device */

	pgdp = pgd_offset_k(va);
	if (pgd_none(*pgdp) || !pgd_present(*pgdp)) {
		pudp = (pud_t *)sh64_get_page();
		set_pgd(pgdp, __pgd((unsigned long)pudp | _KERNPG_TABLE));
	}

	pudp = pud_offset(pgdp, va);
	if (pud_none(*pudp) || !pud_present(*pudp)) {
		pmdp = (pmd_t *)sh64_get_page();
		set_pud(pudp, __pud((unsigned long)pmdp | _KERNPG_TABLE));
	}

	pmdp = pmd_offset(pudp, va);
	if (pmd_none(*pmdp) || !pmd_present(*pmdp)) {
		ptep = (pte_t *)sh64_get_page();
		set_pmd(pmdp, __pmd((unsigned long)ptep + _PAGE_TABLE));
	}

	prot = __pgprot(_PAGE_PRESENT | _PAGE_READ     | _PAGE_WRITE  |
			_PAGE_DIRTY   | _PAGE_ACCESSED | _PAGE_SHARED | flags);

	pte = pfn_pte(pa >> PAGE_SHIFT, prot);
	ptep = pte_offset_kernel(pmdp, va);

	if (!pte_none(*ptep) &&
	    pte_val(*ptep) != pte_val(pte))
		pte_ERROR(*ptep);

	set_pte(ptep, pte);

	flush_tlb_kernel_range(va, PAGE_SIZE);
}

static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
			  phys_addr_t addr, const pte_t *new_pte, bool iomap)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte, old_pte;

	/* Create 2nd stage page table mapping - Level 1 */
	pgd = kvm->arch.pgd + pgd_index(addr);
	pud = pud_offset(pgd, addr);
	if (pud_none(*pud)) {
		if (!cache)
			return 0; /* ignore calls from kvm_set_spte_hva */
		pmd = mmu_memory_cache_alloc(cache);
		pud_populate(NULL, pud, pmd);
		get_page(virt_to_page(pud));
	}

	pmd = pmd_offset(pud, addr);

	/* Create 2nd stage page table mapping - Level 2 */
	if (pmd_none(*pmd)) {
		if (!cache)
			return 0; /* ignore calls from kvm_set_spte_hva */
		pte = mmu_memory_cache_alloc(cache);
		kvm_clean_pte(pte);
		pmd_populate_kernel(NULL, pmd, pte);
		get_page(virt_to_page(pmd));
	}

	pte = pte_offset_kernel(pmd, addr);

	if (iomap && pte_present(*pte))
		return -EFAULT;

	/* Create 2nd stage page table mapping - Level 3 */
	old_pte = *pte;
	kvm_set_pte(pte, *new_pte);
	if (pte_present(old_pte))
		kvm_tlb_flush_vmid_ipa(kvm, addr);
	else
		get_page(virt_to_page(pte));

	return 0;
}

static void stage2_flush_pmds(struct kvm *kvm, pud_t *pud,
			      phys_addr_t addr, phys_addr_t end)
{
	pmd_t *pmd;
	phys_addr_t next;

	pmd = pmd_offset(pud, addr);
	do {
		next = kvm_pmd_addr_end(addr, end);
		if (!pmd_none(*pmd)) {
			if (kvm_pmd_huge(*pmd))
				kvm_flush_dcache_pmd(*pmd);
			else
				stage2_flush_ptes(kvm, pmd, addr, next);
		}
	} while (pmd++, addr = next, addr != end);
}

pte_t *lookup_address(unsigned long address) 
{ 
	pgd_t *pgd = pgd_offset_k(address);
	pud_t *pud;
	pmd_t *pmd;
	if (pgd_none(*pgd))
		return NULL;
	pud = pud_offset(pgd, address);
	if (pud_none(*pud))
		return NULL;
	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd))
		return NULL;
	if (pmd_large(*pmd))
		return (pte_t *)pmd;
        return pte_offset_kernel(pmd, address);
} 

/*
 * Section support is unsafe on SMP - If you iounmap and ioremap a region,
 * the other CPUs will not see this change until their next context switch.
 * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
 * which requires the new ioremap'd region to be referenced, the CPU will
 * reference the _old_ region.
 *
 * Note that get_vm_area_caller() allocates a guard 4K page, so we need to
 * mask the size back to 1MB aligned or we will overflow in the loop below.
 */
static void unmap_area_sections(unsigned long virt, unsigned long size)
{
	unsigned long addr = virt, end = virt + (size & ~(SZ_1M - 1));
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmdp;

	flush_cache_vunmap(addr, end);
	pgd = pgd_offset_k(addr);
	pud = pud_offset(pgd, addr);
	pmdp = pmd_offset(pud, addr);
	do {
		pmd_t pmd = *pmdp;

		if (!pmd_none(pmd)) {
			/*
			 * Clear the PMD from the page table, and
			 * increment the kvm sequence so others
			 * notice this change.
			 *
			 * Note: this is still racy on SMP machines.
			 */
			pmd_clear(pmdp);
			init_mm.context.kvm_seq++;

			/*
			 * Free the page table, if there was one.
			 */
			if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
				pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
		}

		addr += PMD_SIZE;
		pmdp += 2;
	} while (addr < end);

	/*
	 * Ensure that the active_mm is up to date - we want to
	 * catch any use-after-iounmap cases.
	 */
	if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
		__check_kvm_seq(current->active_mm);

	flush_tlb_kernel_range(virt, end);
}

/*
 * Initialise the consistent memory allocation.
 */
static int __init consistent_init(void)
{
	int ret = 0;
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	int i = 0;
	u32 base = CONSISTENT_BASE;

	return 0;

#if 0
	do {
		pgd = pgd_offset(&init_mm, base);

		pud = pud_alloc(&init_mm, pgd, base);
		if (!pud) {
			printk(KERN_ERR "%s: no pud tables\n", __func__);
			ret = -ENOMEM;
			break;
		}

		pmd = pmd_alloc(&init_mm, pud, base);
		if (!pmd) {
			printk(KERN_ERR "%s: no pmd tables\n", __func__);
			ret = -ENOMEM;
			break;
		}
		WARN_ON(!pmd_none(*pmd));

		pte = pte_alloc_kernel(pmd, base);
		if (!pte) {
			printk(KERN_ERR "%s: no pte tables\n", __func__);
			ret = -ENOMEM;
			break;
		}

		consistent_pte[i++] = pte;
		base += (1 << PGDIR_SHIFT);
	} while (base < CONSISTENT_END);

	return ret;
#endif
}

static hugepte_t *hugepte_offset(struct mm_struct *mm, unsigned long addr)
{
	pgd_t *pgd;
	pmd_t *pmd = NULL;

	BUG_ON(!in_hugepage_area(mm->context, addr));

	pgd = pgd_offset(mm, addr);
	if (pgd_none(*pgd))
		return NULL;

	pmd = pmd_offset(pgd, addr);

	/* We shouldn't find a (normal) PTE page pointer here */
	BUG_ON(!pmd_none(*pmd) && !pmd_hugepage(*pmd));

	return (hugepte_t *)pmd;
}

/*
 * NOTE: The pagetables are allocated contiguous on the physical space
 * so we can cache the place of the first one and move around without
 * checking the pgd every time.
 */
static void __init page_table_range_init(unsigned long start,
					 unsigned long end, pgd_t *pgd_base)
{
	pgd_t *pgd;
	int pgd_idx;
	unsigned long vaddr;

	vaddr = start;
	pgd_idx = pgd_index(vaddr);
	pgd = pgd_base + pgd_idx;

	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
		pmd_t *pmd = pmd_offset(pud_offset(pgd, vaddr), vaddr);
		if (pmd_none(*pmd))
			assign_pte(pmd, alloc_pte());
		vaddr += PMD_SIZE;
	}
}

/**
 * get_struct_page - Gets a struct page for a particular address
 * @address - the address of the page we need
 *
 * Two versions of this function have to be provided for working
 * between the 2.4 and 2.5 kernels. Rather than littering the
 * function with #defines, there is just two separate copies.
 * Look at the one that is relevant to the kernel you're using
 */
struct page *get_struct_page(unsigned long addr)
{
	struct mm_struct *mm;
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
	unsigned long pfn;
	struct page *page=NULL;

	mm = current->mm;
	/* Is this possible? */
	if (!mm) return NULL;

	spin_lock(&mm->page_table_lock);

	pgd = pgd_offset(mm, addr);
	if (!pgd_none(*pgd) && !pgd_bad(*pgd)) {
		pud = pud_offset(pgd, addr);
		if (!pud_none(*pud) && !pud_bad(*pud)) {
			pmd = pmd_offset(pud, addr);
			if (!pmd_none(*pmd) && !pmd_bad(*pmd)) {
				/*
			 	* disable preemption because of potential kmap().
			 	* page_table_lock should already have disabled
			 	* preemtion.  But, be paranoid.
			 	*/
				preempt_disable();
				ptep = pte_offset_map(pmd, addr);
				pte = *ptep;
				pte_unmap(ptep);
				preempt_enable();
				if (pte_present(pte)) {
					pfn = pte_pfn(pte);
					if (pfn_valid(pfn))
						page = pte_page(pte);
				}
			}
		}
	}

	spin_unlock(&mm->page_table_lock);
	return page;
}

static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
			  struct mm_walk *walk)
{
	pmd_t *pmd;
	unsigned long next;
	int err = 0;

	pmd = pmd_offset(pud, addr);
	do {
again:
		next = pmd_addr_end(addr, end);
		if (pmd_none(*pmd)) {
			if (walk->pte_hole)
				err = walk->pte_hole(addr, next, walk);
			if (err)
				break;
			continue;
		}
		/*
		 * This implies that each ->pmd_entry() handler
		 * needs to know about pmd_trans_huge() pmds
		 */
		if (walk->pmd_entry)
			err = walk->pmd_entry(pmd, addr, next, walk);
		if (err)
			break;

		/*
		 * Check this here so we only break down trans_huge
		 * pages when we _need_ to
		 */
		if (!walk->pte_entry)
			continue;

		split_huge_page_pmd(walk->mm, pmd);
		if (pmd_none_or_trans_huge_or_clear_bad(pmd))
			goto again;
		err = walk_pte_range(pmd, addr, next, walk);
		if (err)
			break;
	} while (pmd++, addr = next, addr != end);

	return err;
}

/*
 * First Level Translation Fault Handler
 *
 * We enter here because the first level page table doesn't contain
 * a valid entry for the address.
 *
 * If the address is in kernel space (>= TASK_SIZE), then we are
 * probably faulting in the vmalloc() area.
 *
 * If the init_task's first level page tables contains the relevant
 * entry, we copy the it to this task.  If not, we send the process
 * a signal, fixup the exception, or oops the kernel.
 *
 * NOTE! We MUST NOT take any locks for this case. We may be in an
 * interrupt or a critical region, and should only copy the information
 * from the master page table, nothing more.
 */
int do_translation_fault(unsigned long addr, unsigned int fsr,
			 struct pt_regs *regs)
{
	struct task_struct *tsk;
	int offset;
	pgd_t *pgd, *pgd_k;
	pmd_t *pmd, *pmd_k;

	if (addr < TASK_SIZE)
		return do_page_fault(addr, fsr, regs);

	offset = __pgd_offset(addr);

	/*
	 * FIXME: CP15 C1 is write only on ARMv3 architectures.
	 * You really need to read the value in the page table
	 * register, not a copy.
	 */
	pgd = cpu_get_pgd() + offset;
	pgd_k = init_mm.pgd + offset;

	if (pgd_none(*pgd_k))
		goto bad_area;

#if 0	/* note that we are two-level */
	if (!pgd_present(*pgd))
		set_pgd(pgd, *pgd_k);
#endif

	pmd_k = pmd_offset(pgd_k, addr);
	pmd   = pmd_offset(pgd, addr);

	if (pmd_none(*pmd_k))
		goto bad_area;

	set_pmd(pmd, *pmd_k);
	return 0;

bad_area:
	tsk = current;

	do_bad_area(tsk, tsk->active_mm, addr, fsr, regs);
	return 0;
}

struct page *kmem_vm_nopage(struct vm_area_struct *vma, unsigned long address, int write)
{
	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
	unsigned long kaddr;
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *ptep, pte;
	struct page *page = NULL;

	/* address is user VA; convert to kernel VA of desired page */
	kaddr = (address - vma->vm_start) + offset;
	kaddr = VMALLOC_VMADDR(kaddr);

	spin_lock(&init_mm.page_table_lock);

	/* Lookup page structure for kernel VA */
	pgd = pgd_offset(&init_mm, kaddr);
	if (pgd_none(*pgd) || pgd_bad(*pgd))
		goto out;
	pmd = pmd_offset(pgd, kaddr);
	if (pmd_none(*pmd) || pmd_bad(*pmd))
		goto out;
	ptep = pte_offset(pmd, kaddr);
	if (!ptep)
		goto out;
	pte = *ptep;
	if (!pte_present(pte))
		goto out;
	if (write && !pte_write(pte))
		goto out;
	page = pte_page(pte);
	if (!VALID_PAGE(page)) {
		page = NULL;
		goto out;
	}

	/* Increment reference count on page */
	get_page(page);

out:
	spin_unlock(&init_mm.page_table_lock);

	return page;
}

static int get_gate_page(struct mm_struct *mm, unsigned long address,
		unsigned int gup_flags, struct vm_area_struct **vma,
		struct page **page)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	int ret = -EFAULT;

	/* user gate pages are read-only */
	if (gup_flags & FOLL_WRITE)
		return -EFAULT;
	if (address > TASK_SIZE)
		pgd = pgd_offset_k(address);
	else
		pgd = pgd_offset_gate(mm, address);
	BUG_ON(pgd_none(*pgd));
	pud = pud_offset(pgd, address);
	BUG_ON(pud_none(*pud));
	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd))
		return -EFAULT;
	VM_BUG_ON(pmd_trans_huge(*pmd));
	pte = pte_offset_map(pmd, address);
	if (pte_none(*pte))
		goto unmap;
	*vma = get_gate_vma(mm);
	if (!page)
		goto out;
	*page = vm_normal_page(*vma, address, *pte);
	if (!*page) {
		if ((gup_flags & FOLL_DUMP) || !is_zero_pfn(pte_pfn(*pte)))
			goto unmap;
		*page = pte_page(*pte);
	}
	get_page(*page);
out:
	ret = 0;
unmap:
	pte_unmap(pte);
	return ret;
}

/*
 * First Level Translation Fault Handler
 *
 * We enter here because the first level page table doesn't contain
 * a valid entry for the address.
 *
 * If the address is in kernel space (>= TASK_SIZE), then we are
 * probably faulting in the vmalloc() area.
 *
 * If the init_task's first level page tables contains the relevant
 * entry, we copy the it to this task.  If not, we send the process
 * a signal, fixup the exception, or oops the kernel.
 *
 * NOTE! We MUST NOT take any locks for this case. We may be in an
 * interrupt or a critical region, and should only copy the information
 * from the master page table, nothing more.
 */
int do_translation_fault(unsigned long addr, int error_code, struct pt_regs *regs)
{
	struct task_struct *tsk;
	struct mm_struct *mm;
	int offset;
	pgd_t *pgd, *pgd_k;
	pmd_t *pmd, *pmd_k;

	if (addr < TASK_SIZE)
		return do_page_fault(addr, error_code, regs);

	offset = __pgd_offset(addr);

	/*
	 * FIXME: CP15 C1 is write only on ARMv3 architectures.
	 */
	pgd = cpu_get_pgd() + offset;
	pgd_k = init_mm.pgd + offset;

	if (pgd_none(*pgd_k))
		goto bad_area;

#if 0	/* note that we are two-level */
	if (!pgd_present(*pgd))
		set_pgd(pgd, *pgd_k);
#endif

	pmd_k = pmd_offset(pgd_k, addr);
	pmd   = pmd_offset(pgd, addr);

	if (pmd_none(*pmd_k))
		goto bad_area;

	set_pmd(pmd, *pmd_k);
	return 0;

bad_area:
	tsk = current;
	mm  = tsk->active_mm;

	do_bad_area(tsk, mm, addr, error_code, regs);
	return 0;
}