arch/i386/mm/pageattr.c - arm/linux-arm-legacy - Git at Google

 /*
  * Copyright 2002 Andi Kleen, SuSE Labs.
  * Thanks to Ben LaHaise for precious feedback.
  */

 #include <linux/mm.h>
 #include <linux/sched.h>
 #include <linux/highmem.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <asm/uaccess.h>
 #include <asm/processor.h>
 #include <asm/tlbflush.h>
 #include <asm/pgalloc.h>
 #include <asm/sections.h>

 static DEFINE_SPINLOCK(cpa_lock);
 static struct list_head df_list = LIST_HEAD_INIT(df_list);


 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 struct page *split_large_page(unsigned long address, pgprot_t prot,
 					pgprot_t ref_prot)
 {
 	int i;
 	unsigned long addr;
 	struct page *base;
 	pte_t *pbase;

 	spin_unlock_irq(&cpa_lock);
 	base = alloc_pages(GFP_KERNEL, 0);
 	spin_lock_irq(&cpa_lock);
 	if (!base)
 		return NULL;

 	/*
 	 * page_private is used to track the number of entries in
 	 * the page table page that have non standard attributes.
 	 */
 	SetPagePrivate(base);
 	page_private(base) = 0;

 	address = __pa(address);
 	addr = address & LARGE_PAGE_MASK;
 	pbase = (pte_t *)page_address(base);
 	for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
                set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT,
                                           addr == address ? prot : ref_prot));
 	}
 	return base;
 }

 static void flush_kernel_map(void *dummy)
 {
 	/* Could use CLFLUSH here if the CPU supports it (Hammer,P4) */
 	if (boot_cpu_data.x86_model >= 4)
 		wbinvd();
 	/* Flush all to work around Errata in early athlons regarding
 	 * large page flushing.
 	 */
 	__flush_tlb_all();
 }

 static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
 {
 	struct page *page;
 	unsigned long flags;

 	set_pte_atomic(kpte, pte); 	/* change init_mm */
 	if (PTRS_PER_PMD > 1)
 		return;

 	spin_lock_irqsave(&pgd_lock, flags);
 	for (page = pgd_list; page; page = (struct page *)page->index) {
 		pgd_t *pgd;
 		pud_t *pud;
 		pmd_t *pmd;
 		pgd = (pgd_t *)page_address(page) + pgd_index(address);
 		pud = pud_offset(pgd, address);
 		pmd = pmd_offset(pud, address);
 		set_pte_atomic((pte_t *)pmd, pte);
 	}
 	spin_unlock_irqrestore(&pgd_lock, flags);
 }

 /*
  * No more special protections in this 2/4MB area - revert to a
  * large page again.
  */
 static inline void revert_page(struct page *kpte_page, unsigned long address)
 {
 	pgprot_t ref_prot;
 	pte_t *linear;

 	ref_prot =
 	((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
 		? PAGE_KERNEL_LARGE_EXEC : PAGE_KERNEL_LARGE;

 	linear = (pte_t *)
 		pmd_offset(pud_offset(pgd_offset_k(address), address), address);
 	set_pmd_pte(linear,  address,
 		    pfn_pte((__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT,
 			    ref_prot));
 }

 static int
 __change_page_attr(struct page *page, pgprot_t prot)
 {
 	pte_t *kpte;
 	unsigned long address;
 	struct page *kpte_page;

 	BUG_ON(PageHighMem(page));
 	address = (unsigned long)page_address(page);

 	kpte = lookup_address(address);
 	if (!kpte)
 		return -EINVAL;
 	kpte_page = virt_to_page(kpte);
 	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) {
 		if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
 			set_pte_atomic(kpte, mk_pte(page, prot));
 		} else {
 			pgprot_t ref_prot;
 			struct page *split;

 			ref_prot =
 			((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
 				? PAGE_KERNEL_EXEC : PAGE_KERNEL;
 			split = split_large_page(address, prot, ref_prot);
 			if (!split)
 				return -ENOMEM;
 			set_pmd_pte(kpte,address,mk_pte(split, ref_prot));
 			kpte_page = split;
 		}
 		page_private(kpte_page)++;
 	} else if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
 		set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
 		BUG_ON(page_private(kpte_page) == 0);
 		page_private(kpte_page)--;
 	} else
 		BUG();

 	/*
 	 * If the pte was reserved, it means it was created at boot
 	 * time (not via split_large_page) and in turn we must not
 	 * replace it with a largepage.
 	 */
 	if (!PageReserved(kpte_page)) {
 		if (cpu_has_pse && (page_private(kpte_page) == 0)) {
 			ClearPagePrivate(kpte_page);
 			list_add(&kpte_page->lru, &df_list);
 			revert_page(kpte_page, address);
 		}
 	}
 	return 0;
 }

 static inline void flush_map(void)
 {
 	on_each_cpu(flush_kernel_map, NULL, 1, 1);
 }

 /*
  * Change the page attributes of an page in the linear mapping.
  *
  * This should be used when a page is mapped with a different caching policy
  * than write-back somewhere - some CPUs do not like it when mappings with
  * different caching policies exist. This changes the page attributes of the
  * in kernel linear mapping too.
  *
  * The caller needs to ensure that there are no conflicting mappings elsewhere.
  * This function only deals with the kernel linear map.
  *
  * Caller must call global_flush_tlb() after this.
  */
 int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 {
 	int err = 0;
 	int i;
 	unsigned long flags;

 	spin_lock_irqsave(&cpa_lock, flags);
 	for (i = 0; i < numpages; i++, page++) {
 		err = __change_page_attr(page, prot);
 		if (err)
 			break;
 	}
 	spin_unlock_irqrestore(&cpa_lock, flags);
 	return err;
 }

 void global_flush_tlb(void)
 {
 	struct list_head l;
 	struct page *pg, *next;

 	BUG_ON(irqs_disabled());

 	spin_lock_irq(&cpa_lock);
 	list_replace_init(&df_list, &l);
 	spin_unlock_irq(&cpa_lock);
 	flush_map();
 	list_for_each_entry_safe(pg, next, &l, lru)
 		__free_page(pg);
 }

 #ifdef CONFIG_DEBUG_PAGEALLOC
 void kernel_map_pages(struct page *page, int numpages, int enable)
 {
 	if (PageHighMem(page))
 		return;
 	if (!enable)
 		debug_check_no_locks_freed(page_address(page),
 					   numpages * PAGE_SIZE);

 	/* the return value is ignored - the calls cannot fail,
 	 * large pages are disabled at boot time.
 	 */
 	change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
 	/* we should perform an IPI and flush all tlbs,
 	 * but that can deadlock->flush only current cpu.
 	 */
 	__flush_tlb_all();
 }
 #endif

 EXPORT_SYMBOL(change_page_attr);
 EXPORT_SYMBOL(global_flush_tlb);
	/*
	* Copyright 2002 Andi Kleen, SuSE Labs.
	* Thanks to Ben LaHaise for precious feedback.
	*/

	#include <linux/mm.h>
	#include <linux/sched.h>
	#include <linux/highmem.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <asm/uaccess.h>
	#include <asm/processor.h>
	#include <asm/tlbflush.h>
	#include <asm/pgalloc.h>
	#include <asm/sections.h>

	static DEFINE_SPINLOCK(cpa_lock);
	static struct list_head df_list = LIST_HEAD_INIT(df_list);


	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 struct page *split_large_page(unsigned long address, pgprot_t prot,
	pgprot_t ref_prot)
	{
	int i;
	unsigned long addr;
	struct page *base;
	pte_t *pbase;

	spin_unlock_irq(&cpa_lock);
	base = alloc_pages(GFP_KERNEL, 0);
	spin_lock_irq(&cpa_lock);
	if (!base)
	return NULL;

	/*
	* page_private is used to track the number of entries in
	* the page table page that have non standard attributes.
	*/
	SetPagePrivate(base);
	page_private(base) = 0;

	address = __pa(address);
	addr = address & LARGE_PAGE_MASK;
	pbase = (pte_t *)page_address(base);
	for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
	set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT,
	addr == address ? prot : ref_prot));
	}
	return base;
	}

	static void flush_kernel_map(void *dummy)
	{
	/* Could use CLFLUSH here if the CPU supports it (Hammer,P4) */
	if (boot_cpu_data.x86_model >= 4)
	wbinvd();
	/* Flush all to work around Errata in early athlons regarding
	* large page flushing.
	*/
	__flush_tlb_all();
	}

	static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
	{
	struct page *page;
	unsigned long flags;

	set_pte_atomic(kpte, pte); /* change init_mm */
	if (PTRS_PER_PMD > 1)
	return;

	spin_lock_irqsave(&pgd_lock, flags);
	for (page = pgd_list; page; page = (struct page *)page->index) {
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pgd = (pgd_t *)page_address(page) + pgd_index(address);
	pud = pud_offset(pgd, address);
	pmd = pmd_offset(pud, address);
	set_pte_atomic((pte_t *)pmd, pte);
	}
	spin_unlock_irqrestore(&pgd_lock, flags);
	}

	/*
	* No more special protections in this 2/4MB area - revert to a
	* large page again.
	*/
	static inline void revert_page(struct page *kpte_page, unsigned long address)
	{
	pgprot_t ref_prot;
	pte_t *linear;

	ref_prot =
	((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
	? PAGE_KERNEL_LARGE_EXEC : PAGE_KERNEL_LARGE;

	linear = (pte_t *)
	pmd_offset(pud_offset(pgd_offset_k(address), address), address);
	set_pmd_pte(linear, address,
	pfn_pte((__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT,
	ref_prot));
	}

	static int
	__change_page_attr(struct page *page, pgprot_t prot)
	{
	pte_t *kpte;
	unsigned long address;
	struct page *kpte_page;

	BUG_ON(PageHighMem(page));
	address = (unsigned long)page_address(page);

	kpte = lookup_address(address);
	if (!kpte)
	return -EINVAL;
	kpte_page = virt_to_page(kpte);
	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) {
	if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
	set_pte_atomic(kpte, mk_pte(page, prot));
	} else {
	pgprot_t ref_prot;
	struct page *split;

	ref_prot =
	((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
	? PAGE_KERNEL_EXEC : PAGE_KERNEL;
	split = split_large_page(address, prot, ref_prot);
	if (!split)
	return -ENOMEM;
	set_pmd_pte(kpte,address,mk_pte(split, ref_prot));
	kpte_page = split;
	}
	page_private(kpte_page)++;
	} else if ((pte_val(*kpte) & _PAGE_PSE) == 0) {
	set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
	BUG_ON(page_private(kpte_page) == 0);
	page_private(kpte_page)--;
	} else
	BUG();

	/*
	* If the pte was reserved, it means it was created at boot
	* time (not via split_large_page) and in turn we must not
	* replace it with a largepage.
	*/
	if (!PageReserved(kpte_page)) {
	if (cpu_has_pse && (page_private(kpte_page) == 0)) {
	ClearPagePrivate(kpte_page);
	list_add(&kpte_page->lru, &df_list);
	revert_page(kpte_page, address);
	}
	}
	return 0;
	}

	static inline void flush_map(void)
	{
	on_each_cpu(flush_kernel_map, NULL, 1, 1);
	}

	/*
	* Change the page attributes of an page in the linear mapping.
	*
	* This should be used when a page is mapped with a different caching policy
	* than write-back somewhere - some CPUs do not like it when mappings with
	* different caching policies exist. This changes the page attributes of the
	* in kernel linear mapping too.
	*
	* The caller needs to ensure that there are no conflicting mappings elsewhere.
	* This function only deals with the kernel linear map.
	*
	* Caller must call global_flush_tlb() after this.
	*/
	int change_page_attr(struct page *page, int numpages, pgprot_t prot)
	{
	int err = 0;
	int i;
	unsigned long flags;

	spin_lock_irqsave(&cpa_lock, flags);
	for (i = 0; i < numpages; i++, page++) {
	err = __change_page_attr(page, prot);
	if (err)
	break;
	}
	spin_unlock_irqrestore(&cpa_lock, flags);
	return err;
	}

	void global_flush_tlb(void)
	{
	struct list_head l;
	struct page pg, next;

	BUG_ON(irqs_disabled());

	spin_lock_irq(&cpa_lock);
	list_replace_init(&df_list, &l);
	spin_unlock_irq(&cpa_lock);
	flush_map();
	list_for_each_entry_safe(pg, next, &l, lru)
	__free_page(pg);
	}

	#ifdef CONFIG_DEBUG_PAGEALLOC
	void kernel_map_pages(struct page *page, int numpages, int enable)
	{
	if (PageHighMem(page))
	return;
	if (!enable)
	debug_check_no_locks_freed(page_address(page),
	numpages * PAGE_SIZE);

	/* the return value is ignored - the calls cannot fail,
	* large pages are disabled at boot time.
	*/
	change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
	/* we should perform an IPI and flush all tlbs,
	* but that can deadlock->flush only current cpu.
	*/
	__flush_tlb_all();
	}
	#endif

	EXPORT_SYMBOL(change_page_attr);
	EXPORT_SYMBOL(global_flush_tlb);