C++ pud_offset函数代码示例

/*
 * Creates a middle page table and puts a pointer to it in the
 * given global directory entry. This only returns the gd entry
 * in non-PAE compilation mode, since the middle layer is folded.
 */
static pmd_t * __init one_md_table_init(pgd_t *pgd)
{
	p4d_t *p4d;
	pud_t *pud;
	pmd_t *pmd_table;

#ifdef CONFIG_X86_PAE
	if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
		pmd_table = (pmd_t *)alloc_low_page();
		paravirt_alloc_pmd(&init_mm, __pa(pmd_table) >> PAGE_SHIFT);
		set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
		p4d = p4d_offset(pgd, 0);
		pud = pud_offset(p4d, 0);
		BUG_ON(pmd_table != pmd_offset(pud, 0));

		return pmd_table;
	}

static pud_t *stage2_get_pud(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
			     phys_addr_t addr)
{
	pgd_t *pgd;
	pud_t *pud;

	pgd = kvm->arch.pgd + kvm_pgd_index(addr);
	if (WARN_ON(pgd_none(*pgd))) {
		if (!cache)
			return NULL;
		pud = mmu_memory_cache_alloc(cache);
		pgd_populate(NULL, pgd, pud);
		get_page(virt_to_page(pgd));
	}

	return pud_offset(pgd, addr);
}

static void __init permanent_kmaps_init(pgd_t *pgd_base)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	unsigned long vaddr;

	vaddr = PKMAP_BASE;
	page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);

	pgd = swapper_pg_dir + pgd_index(vaddr);
	pud = pud_offset(pgd, vaddr);
	pmd = pmd_offset(pud, vaddr);
	pte = pte_offset_kernel(pmd, vaddr);
	pkmap_page_table = pte;
}

static void stage2_flush_puds(struct kvm *kvm, pgd_t *pgd,
			      phys_addr_t addr, phys_addr_t end)
{
	pud_t *pud;
	phys_addr_t next;

	pud = pud_offset(pgd, addr);
	do {
		next = kvm_pud_addr_end(addr, end);
		if (!pud_none(*pud)) {
			if (pud_huge(*pud))
				kvm_flush_dcache_pud(*pud);
			else
				stage2_flush_pmds(kvm, pud, addr, next);
		}
	} while (pud++, 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);
} 

static void mincore_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
			unsigned long addr, unsigned long end,
			unsigned char *vec)
{
	unsigned long next;
	pud_t *pud;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			mincore_unmapped_range(vma, addr, next, vec);
		else
			mincore_pmd_range(vma, pud, addr, next, vec);
		vec += (next - addr) >> PAGE_SHIFT;
	} while (pud++, addr = next, addr != end);
}

asmlinkage long long sys_my_syscall(int pid, unsigned long long va)
{
	unsigned long long pageFN;
	unsigned long long pa;

	pgd_t *pgd;
	pmd_t *pmd;
	pud_t *pud;
	pte_t *pte;
	
	struct mm_struct *mm;

	int found = 0;

	struct task_struct *task;
	for_each_process(task)
	{
		if(task->pid == pid)
			mm = task->mm;
	}
	pgd  = pgd_offset(mm,va);
	if(!pgd_none(*pgd) && !pgd_bad(*pgd))
	{
		pud = pud_offset(pgd,va);
		if(!pud_none(*pud) && !pud_bad(*pud))
		{
			pmd = pmd_offset(pud,va);
			if(!pmd_none(*pmd) && !pmd_bad(*pmd))
			{
				pte = pte_offset_kernel(pmd,va);
				if(!pte_none(*pte))
				{
					pageFN = pte_pfn(*pte);
					pa = ((pageFN<<12)|(va&0x00000FFF));
					found = 1;
					return pa;
				}
			}
		}
	}
	if(pgd_none(*pgd) || pud_none(*pud) || pmd_none(*pmd) || pte_none(*pte))
	{
		unsigned long long swapID = (pte_val(*pte) >> 32);
		found = 1;
		return swapID;
	}

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);
}

pte_t *huge_pte_alloc(struct mm_struct *mm,
			unsigned long addr, unsigned long sz)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	pgd = pgd_offset(mm, addr);
	pud = pud_offset(pgd, addr);
	pmd = pmd_offset(pud, addr);
	pte = pte_alloc_map(mm, NULL, pmd, addr);
	pgd->pgd &= ~_PAGE_SZ_MASK;
	pgd->pgd |= _PAGE_SZHUGE;

	return pte;
}

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 int early_map_kernel_page(unsigned long ea, unsigned long pa,
			  pgprot_t flags,
			  unsigned int map_page_size,
			  int nid,
			  unsigned long region_start, unsigned long region_end)
{
	unsigned long pfn = pa >> PAGE_SHIFT;
	pgd_t *pgdp;
	pud_t *pudp;
	pmd_t *pmdp;
	pte_t *ptep;

	pgdp = pgd_offset_k(ea);
	if (pgd_none(*pgdp)) {
		pudp = early_alloc_pgtable(PUD_TABLE_SIZE, nid,
						region_start, region_end);
		pgd_populate(&init_mm, pgdp, pudp);
	}
	pudp = pud_offset(pgdp, ea);
	if (map_page_size == PUD_SIZE) {
		ptep = (pte_t *)pudp;
		goto set_the_pte;
	}
	if (pud_none(*pudp)) {
		pmdp = early_alloc_pgtable(PMD_TABLE_SIZE, nid,
						region_start, region_end);
		pud_populate(&init_mm, pudp, pmdp);
	}
	pmdp = pmd_offset(pudp, ea);
	if (map_page_size == PMD_SIZE) {
		ptep = pmdp_ptep(pmdp);
		goto set_the_pte;
	}
	if (!pmd_present(*pmdp)) {
		ptep = early_alloc_pgtable(PAGE_SIZE, nid,
						region_start, region_end);
		pmd_populate_kernel(&init_mm, pmdp, ptep);
	}
	ptep = pte_offset_kernel(pmdp, ea);

set_the_pte:
	set_pte_at(&init_mm, ea, ptep, pfn_pte(pfn, flags));
	smp_wmb();
	return 0;
}

/*
 * 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);
}

/*
 * 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;
	}
}

static void machine_kexec_page_table_set_one(
	pgd_t *pgd, pmd_t *pmd, pte_t *pte,
	unsigned long vaddr, unsigned long paddr)
{
	pud_t *pud;

	pgd += pgd_index(vaddr);
#ifdef CONFIG_X86_PAE
	if (!(pgd_val(*pgd) & _PAGE_PRESENT))
		set_pgd(pgd, __pgd(__pa(pmd) | _PAGE_PRESENT));
#endif
	pud = pud_offset(pgd, vaddr);
	pmd = pmd_offset(pud, vaddr);
	if (!(pmd_val(*pmd) & _PAGE_PRESENT))
		set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
	pte = pte_offset_kernel(pmd, vaddr);
	set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
}

/*
 * The VSYSCALL page is the only user-accessible page in the kernel address
 * range.  Normally, the kernel page tables can have _PAGE_USER clear, but
 * the tables covering VSYSCALL_ADDR need _PAGE_USER set if vsyscalls
 * are enabled.
 *
 * Some day we may create a "minimal" vsyscall mode in which we emulate
 * vsyscalls but leave the page not present.  If so, we skip calling
 * this.
 */
void __init set_vsyscall_pgtable_user_bits(pgd_t *root)
{
	pgd_t *pgd;
	p4d_t *p4d;
	pud_t *pud;
	pmd_t *pmd;

	pgd = pgd_offset_pgd(root, VSYSCALL_ADDR);
	set_pgd(pgd, __pgd(pgd_val(*pgd) | _PAGE_USER));
	p4d = p4d_offset(pgd, VSYSCALL_ADDR);
#if CONFIG_PGTABLE_LEVELS >= 5
	set_p4d(p4d, __p4d(p4d_val(*p4d) | _PAGE_USER));
#endif
	pud = pud_offset(p4d, VSYSCALL_ADDR);
	set_pud(pud, __pud(pud_val(*pud) | _PAGE_USER));
	pmd = pmd_offset(pud, VSYSCALL_ADDR);
	set_pmd(pmd, __pmd(pmd_val(*pmd) | _PAGE_USER));
}