C++ pte_clear函数代码示例

void arch_exit_mmap(struct mm_struct *mm)
{
	pte_t *pte;

	pte = virt_to_pte(mm, STUB_CODE);
	if (pte != NULL)
		pte_clear(mm, STUB_CODE, pte);

	pte = virt_to_pte(mm, STUB_DATA);
	if (pte == NULL)
		return;

	pte_clear(mm, STUB_DATA, pte);
}

/*
 * copy_user_page
 * @to: P1 address
 * @from: P1 address
 * @address: U0 address to be mapped
 * @page: page (virt_to_page(to))
 */
void copy_user_page(void *to, void *from, unsigned long address, 
		    struct page *page)
{
	__set_bit(PG_mapped, &page->flags);
	if (((address ^ (unsigned long)to) & CACHE_ALIAS) == 0)
		copy_page(to, from);
	else {
		pgprot_t pgprot = __pgprot(_PAGE_PRESENT | 
					   _PAGE_RW | _PAGE_CACHABLE |
					   _PAGE_DIRTY | _PAGE_ACCESSED | 
					   _PAGE_HW_SHARED | _PAGE_FLAGS_HARD);
		unsigned long phys_addr = PHYSADDR(to);
		unsigned long p3_addr = P3SEG + (address & CACHE_ALIAS);
		pgd_t *dir = pgd_offset_k(p3_addr);
		pmd_t *pmd = pmd_offset(dir, p3_addr);
		pte_t *pte = pte_offset_kernel(pmd, p3_addr);
		pte_t entry;
		unsigned long flags;

		entry = pfn_pte(phys_addr >> PAGE_SHIFT, pgprot);
		down(&p3map_sem[(address & CACHE_ALIAS)>>12]);
		set_pte(pte, entry);
		local_irq_save(flags);
		__flush_tlb_page(get_asid(), p3_addr);
		local_irq_restore(flags);
		update_mmu_cache(NULL, p3_addr, entry);
		__copy_user_page((void *)p3_addr, from, to);
		pte_clear(&init_mm, p3_addr, pte);
		up(&p3map_sem[(address & CACHE_ALIAS)>>12]);
	}
}

static inline void zap_pte_range(pmd_t * pmd, unsigned long address, unsigned long size)
{
	pte_t * pte;

	if (pmd_none(*pmd))
		return;
	if (pmd_bad(*pmd)) {
		printk("zap_pte_range: bad pmd (%08lx)\n", pmd_val(*pmd));
		pmd_clear(pmd);
		return;
	}
	pte = pte_offset(pmd, address);
	address &= ~PMD_MASK;
	if (address + size > PMD_SIZE)
		size = PMD_SIZE - address;
	size >>= PAGE_SHIFT;
	for (;;) {
		pte_t page;
		if (!size)
			break;
		page = *pte;
		pte++;
		size--;
		if (pte_none(page))
			continue;
		pte_clear(pte-1);
		free_pte(page);
	}
}

void kunmap_atomic(void *kvaddr, enum km_type type)
{
#ifdef CONFIG_DEBUG_HIGHMEM
	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
	unsigned long idx = type + KM_TYPE_NR*smp_processor_id();

	if (vaddr < FIXADDR_START) { // FIXME
		pagefault_enable();
		return;
	}

	BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx));

/* XXX Fix - Anton */
#if 0
	__flush_cache_one(vaddr);
#else
	flush_cache_all();
#endif

	/*
	 * force other mappings to Oops if they'll try to access
	 * this pte without first remap it
	 */
	pte_clear(&init_mm, vaddr, kmap_pte-idx);
/* XXX Fix - Anton */
#if 0
	__flush_tlb_one(vaddr);
#else
	flush_tlb_all();
#endif
#endif

	pagefault_enable();
}

/*
 * copy_user_page
 * @to: kernel logical address
 * @from: kernel logical address
 * @address: U0 address to be mapped
 * @page: page (virt_to_page(to))
 */
void copy_user_page(void *to, void *from, unsigned long address,
		    struct page *page)
{
	extern void __copy_page_wb(void *to, void *from);

	if (((address ^ (unsigned long)to) & CACHE_ALIAS) == 0)
		__copy_page_wb(to, from);
	else {
		pgprot_t pgprot = __pgprot(_PAGE_PRESENT |
					   _PAGE_RW | _PAGE_CACHABLE |
					   _PAGE_DIRTY | _PAGE_ACCESSED |
					   _PAGE_HW_SHARED | _PAGE_FLAGS_HARD);
		unsigned long phys_addr = virt_to_phys(to);
		unsigned long p3_addr = P3SEG + (address & CACHE_ALIAS);
		pgd_t *pgd = pgd_offset_k(p3_addr);
		pud_t *pud = pud_offset(pgd, p3_addr);
		pmd_t *pmd = pmd_offset(pud, p3_addr);
		pte_t *pte = pte_offset_kernel(pmd, p3_addr);
		pte_t entry;
		unsigned long flags;

		entry = pfn_pte(phys_addr >> PAGE_SHIFT, pgprot);
		inc_preempt_count();
BUG_ON(atomic_inc_return(&concurreny_check[(address & CACHE_ALIAS)>>12]) != 1);
		set_pte(pte, entry);
		local_irq_save(flags);
		flush_tlb_one(get_asid(), p3_addr);
		local_irq_restore(flags);
		update_mmu_cache(NULL, p3_addr, entry);
		__copy_user_page((void *)p3_addr, from, to);
		pte_clear(&init_mm, p3_addr, pte);
atomic_dec(&concurreny_check[(address & CACHE_ALIAS)>>12]);
		dec_preempt_count();
	}
}

static void shmedia_unmapioaddr(unsigned long vaddr)
{
	pgd_t *pgdp;
	pud_t *pudp;
	pmd_t *pmdp;
	pte_t *ptep;

	pgdp = pgd_offset_k(vaddr);
	if (pgd_none(*pgdp) || pgd_bad(*pgdp))
		return;

	pudp = pud_offset(pgdp, vaddr);
	if (pud_none(*pudp) || pud_bad(*pudp))
		return;

	pmdp = pmd_offset(pudp, vaddr);
	if (pmd_none(*pmdp) || pmd_bad(*pmdp))
		return;

	ptep = pte_offset_kernel(pmdp, vaddr);

	if (pte_none(*ptep) || !pte_present(*ptep))
		return;

	clear_page((void *)ptep);
	pte_clear(&init_mm, vaddr, ptep);
}

/*
 * Associate a virtual page frame with a given physical page frame
 * and protection flags for that frame.
 */
static void set_pte_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
{
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd;
    pte_t *pte;

    pgd = swapper_pg_dir + pgd_index(vaddr);
    if (pgd_none(*pgd)) {
        BUG();
        return;
    }
    pud = pud_offset(pgd, vaddr);
    if (pud_none(*pud)) {
        BUG();
        return;
    }
    pmd = pmd_offset(pud, vaddr);
    if (pmd_none(*pmd)) {
        BUG();
        return;
    }
    pte = pte_offset_kernel(pmd, vaddr);
    if (pgprot_val(flags))
        /* <pfn,flags> stored as-is, to permit clearing entries */
        set_pte(pte, pfn_pte(pfn, flags));
    else
        pte_clear(&init_mm, vaddr, pte);

    /*
     * It's enough to flush this one mapping.
     * (PGE mappings get flushed as well)
     */
    __flush_tlb_one(vaddr);
}

void __kunmap_atomic(void *kv)
{
	unsigned long kvaddr = (unsigned long)kv;

	if (kvaddr >= FIXMAP_BASE && kvaddr < (FIXMAP_BASE + FIXMAP_SIZE)) {

		/*
		 * Because preemption is disabled, this vaddr can be associated
		 * with the current allocated index.
		 * But in case of multiple live kmap_atomic(), it still relies on
		 * callers to unmap in right order.
		 */
		int cpu_idx = kmap_atomic_idx();
		int idx = cpu_idx + KM_TYPE_NR * smp_processor_id();

		WARN_ON(kvaddr != FIXMAP_ADDR(idx));

		pte_clear(&init_mm, kvaddr, fixmap_page_table + idx);
		local_flush_tlb_kernel_range(kvaddr, kvaddr + PAGE_SIZE);

		kmap_atomic_idx_pop();
	}

	pagefault_enable();
	preempt_enable();
}

void kunmap_atomic(void *kvaddr, enum km_type type)
{
#ifdef CONFIG_DEBUG_HIGHMEM
	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
	enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();

	if (vaddr < FIXADDR_START) { // FIXME
		dec_preempt_count();
		preempt_check_resched();
		return;
	}

	if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
		BUG();

	/*
	 * force other mappings to Oops if they'll try to access
	 * this pte without first remap it
	 */
	pte_clear(&init_mm, vaddr, kmap_pte-idx);
	__flush_tlb_one(vaddr);
#endif

	dec_preempt_count();
	preempt_check_resched();
}

/*
 * maps a range of vmalloc()ed memory into the requested pages. the old
 * mappings are removed. 
 */
static inline void
vmap_pte_range (pte_t *pte, unsigned long address, unsigned long size, unsigned long vaddr)
{
	unsigned long end;
	pgd_t *vdir;
	pmd_t *vpmd;
	pte_t *vpte;
	
	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	do {
		pte_t oldpage = *pte;
		struct page * page;
		pte_clear(pte);

		vdir = pgd_offset_k (vaddr);
		vpmd = pmd_offset (vdir, vaddr);
		vpte = pte_offset (vpmd, vaddr);
		page = pte_page (*vpte);

		set_pte(pte, mk_pte(page, PAGE_USERIO));
		forget_pte(oldpage);
		address += PAGE_SIZE;
		vaddr += PAGE_SIZE;
		pte++;
	} while (address < end);
}

void __kunmap_atomic(void *kvaddr)
{
	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
	int type;

	if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
		pagefault_enable();
		return;
	}

	type = kmap_atomic_idx();
#ifdef CONFIG_DEBUG_HIGHMEM
	{
		unsigned int idx;

		idx = type + KM_TYPE_NR * smp_processor_id();
		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));

		/*
		 * force other mappings to Oops if they'll try to access
		 * this pte without first remap it
		 */
		pte_clear(&init_mm, vaddr, kmap_pte-idx);
		local_flush_tlb_page(NULL, vaddr);
	}
#endif
	kmap_atomic_idx_pop();
	pagefault_enable();
}

void __kunmap_atomic(void *kvaddr, enum km_type type)
{
	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
	enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();

	if (vaddr < FIXADDR_START) { // FIXME
		pagefault_enable();
		return;
	}

	BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));

	/*
	 * Protect against multiple unmaps
	 * Can't cache flush an unmapped page.
	 */
	if ( kmap_atomic_maps[smp_processor_id()].map[type].vaddr ) {
		kmap_atomic_maps[smp_processor_id()].map[type].page = (struct page *)0;
		kmap_atomic_maps[smp_processor_id()].map[type].vaddr = (void *) 0;

		flush_data_cache_page((unsigned long)vaddr);
	}

#ifdef CONFIG_DEBUG_HIGHMEM
	/*
	 * force other mappings to Oops if they'll try to access
	 * this pte without first remap it
	 */
	pte_clear(&init_mm, vaddr, kmap_pte-idx);
	local_flush_tlb_one(vaddr);
#endif

	pagefault_enable();
}

/*
 * copy_user_page
 * @to: P1 address
 * @from: P1 address
 * @address: U0 address to be mapped
 * @page: page (virt_to_page(to))
 */
void copy_user_page(void *to, void *from, unsigned long address,
		    struct page *page)
{
	__set_bit(PG_mapped, &page->flags);
	if (((address ^ (unsigned long)to) & CACHE_ALIAS) == 0)
		copy_page(to, from);
	else {
		unsigned long phys_addr = PHYSADDR(to);
		unsigned long p3_addr = P3SEG + (address & CACHE_ALIAS);
		pgd_t *pgd = pgd_offset_k(p3_addr);
		pud_t *pud = pud_offset(pgd, p3_addr);
		pmd_t *pmd = pmd_offset(pud, p3_addr);
		pte_t *pte = pte_offset_kernel(pmd, p3_addr);
		pte_t entry;
		unsigned long flags;

		entry = pfn_pte(phys_addr >> PAGE_SHIFT, PAGE_KERNEL);
		mutex_lock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
		set_pte(pte, entry);
		local_irq_save(flags);
		__flush_tlb_page(get_asid(), p3_addr);
		local_irq_restore(flags);
		update_mmu_cache(NULL, p3_addr, entry);
		__copy_user_page((void *)p3_addr, from, to);
		pte_clear(&init_mm, p3_addr, pte);
		mutex_unlock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
	}
}

static void * __init init_pmd(unsigned long vaddr, unsigned long n_pages)
{
	pgd_t *pgd = pgd_offset_k(vaddr);
	pmd_t *pmd = pmd_offset(pgd, vaddr);
	pte_t *pte;
	unsigned long i;

	n_pages = ALIGN(n_pages, PTRS_PER_PTE);

	pr_debug("%s: vaddr: 0x%08lx, n_pages: %ld\n",
		 __func__, vaddr, n_pages);

	pte = memblock_alloc_low(n_pages * sizeof(pte_t), PAGE_SIZE);

	for (i = 0; i < n_pages; ++i)
		pte_clear(NULL, 0, pte + i);

	for (i = 0; i < n_pages; i += PTRS_PER_PTE, ++pmd) {
		pte_t *cur_pte = pte + i;

		BUG_ON(!pmd_none(*pmd));
		set_pmd(pmd, __pmd(((unsigned long)cur_pte) & PAGE_MASK));
		BUG_ON(cur_pte != pte_offset_kernel(pmd, 0));
		pr_debug("%s: pmd: 0x%p, pte: 0x%p\n",
			 __func__, pmd, cur_pte);
	}
	return pte;
}

/*
 * Associate a virtual page frame with a given physical page frame 
 * and protection flags for that frame.
 */ 
void set_pte_vaddr(unsigned long vaddr, pte_t pteval)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	pgd = swapper_pg_dir + pgd_index(vaddr);
	if (pgd_none(*pgd)) {
		BUG();
		return;
	}
	pud = pud_offset(pgd, vaddr);
	if (pud_none(*pud)) {
		BUG();
		return;
	}
	pmd = pmd_offset(pud, vaddr);
	if (pmd_none(*pmd)) {
		BUG();
		return;
	}
	pte = pte_offset_kernel(pmd, vaddr);
	if (!pte_none(pteval))
		set_pte_at(&init_mm, vaddr, pte, pteval);
	else
		pte_clear(&init_mm, vaddr, pte);

	/*
	 * It's enough to flush this one mapping.
	 * (PGE mappings get flushed as well)
	 */
	__flush_tlb_one(vaddr);
}