arch/x86/mm/pageattr_64.c - kernel/msm - Gitiles

 /*
  * 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/io.h>

 pte_t *lookup_address(unsigned long address)
 {
 	pgd_t *pgd = pgd_offset_k(address);
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
 	if (pgd_none(*pgd))
 		return NULL;
 	pud = pud_offset(pgd, address);
 	if (!pud_present(*pud))
 		return NULL;
 	pmd = pmd_offset(pud, address);
 	if (!pmd_present(*pmd))
 		return NULL;
 	if (pmd_large(*pmd))
 		return (pte_t *)pmd;
 	pte = pte_offset_kernel(pmd, address);
 	if (pte && !pte_present(*pte))
 		pte = NULL;
 	return pte;
 }

 static struct page *split_large_page(unsigned long address, pgprot_t prot,
 				     pgprot_t ref_prot)
 {
 	int i;
 	unsigned long addr;
 	struct page *base = alloc_pages(GFP_KERNEL, 0);
 	pte_t *pbase;
 	if (!base)
 		return NULL;
 	/*
 	 * page_private is used to track the number of entries in
 	 * the page table page 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) {
 		pbase[i] = pfn_pte(addr >> PAGE_SHIFT,
 				   addr == address ? prot : ref_prot);
 	}
 	return base;
 }

 void clflush_cache_range(void *adr, int size)
 {
 	int i;
 	for (i = 0; i < size; i += boot_cpu_data.x86_clflush_size)
 		clflush(adr+i);
 }

 static void flush_kernel_map(void *arg)
 {
 	struct list_head *l = (struct list_head *)arg;
 	struct page *pg;

 	/* When clflush is available always use it because it is
 	   much cheaper than WBINVD. */
 	/* clflush is still broken. Disable for now. */
 	if (1 || !cpu_has_clflush)
 		asm volatile("wbinvd" ::: "memory");
 	else list_for_each_entry(pg, l, lru) {
 		void *adr = page_address(pg);
 		clflush_cache_range(adr, PAGE_SIZE);
 	}
 	__flush_tlb_all();
 }

 static inline void flush_map(struct list_head *l)
 {
 	on_each_cpu(flush_kernel_map, l, 1, 1);
 }

 static LIST_HEAD(deferred_pages); /* protected by init_mm.mmap_sem */

 static inline void save_page(struct page *fpage)
 {
 	if (!test_and_set_bit(PG_arch_1, &fpage->flags))
 		list_add(&fpage->lru, &deferred_pages);
 }

 /*
  * No more special protections in this 2/4MB area - revert to a
  * large page again.
  */
 static void revert_page(unsigned long address, pgprot_t ref_prot)
 {
 	pgd_t *pgd;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t large_pte;
 	unsigned long pfn;

 	pgd = pgd_offset_k(address);
 	BUG_ON(pgd_none(*pgd));
 	pud = pud_offset(pgd,address);
 	BUG_ON(pud_none(*pud));
 	pmd = pmd_offset(pud, address);
 	BUG_ON(pmd_val(*pmd) & _PAGE_PSE);
 	pfn = (__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT;
 	large_pte = pfn_pte(pfn, ref_prot);
 	large_pte = pte_mkhuge(large_pte);
 	set_pte((pte_t *)pmd, large_pte);
 }

 static int
 __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
 				   pgprot_t ref_prot)
 {
 	pte_t *kpte;
 	struct page *kpte_page;
 	pgprot_t ref_prot2;

 	kpte = lookup_address(address);
 	if (!kpte) return 0;
 	kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
 	BUG_ON(PageLRU(kpte_page));
 	BUG_ON(PageCompound(kpte_page));
 	if (pgprot_val(prot) != pgprot_val(ref_prot)) {
 		if (!pte_huge(*kpte)) {
 			set_pte(kpte, pfn_pte(pfn, prot));
 		} else {
  			/*
 			 * split_large_page will take the reference for this
 			 * change_page_attr on the split page.
  			 */
 			struct page *split;
 			ref_prot2 = pte_pgprot(pte_clrhuge(*kpte));
 			split = split_large_page(address, prot, ref_prot2);
 			if (!split)
 				return -ENOMEM;
 			pgprot_val(ref_prot2) &= ~_PAGE_NX;
 			set_pte(kpte, mk_pte(split, ref_prot2));
 			kpte_page = split;
 		}
 		page_private(kpte_page)++;
 	} else if (!pte_huge(*kpte)) {
 		set_pte(kpte, pfn_pte(pfn, ref_prot));
 		BUG_ON(page_private(kpte_page) == 0);
 		page_private(kpte_page)--;
 	} else
 		BUG();

 	/* on x86-64 the direct mapping set at boot is not using 4k pages */
  	BUG_ON(PageReserved(kpte_page));

 	save_page(kpte_page);
 	if (page_private(kpte_page) == 0)
 		revert_page(address, ref_prot);
 	return 0;
 }

 /*
  * 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_addr(unsigned long address, int numpages, pgprot_t prot)
 {
 	int err = 0, kernel_map = 0;
 	int i;

 	if (address >= __START_KERNEL_map
 	    && address < __START_KERNEL_map + KERNEL_TEXT_SIZE) {
 		address = (unsigned long)__va(__pa(address));
 		kernel_map = 1;
 	}

 	down_write(&init_mm.mmap_sem);
 	for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
 		unsigned long pfn = __pa(address) >> PAGE_SHIFT;

 		if (!kernel_map || pte_present(pfn_pte(0, prot))) {
 			err = __change_page_attr(address, pfn, prot, PAGE_KERNEL);
 			if (err)
 				break;
 		}
 		/* Handle kernel mapping too which aliases part of the
 		 * lowmem */
 		if (__pa(address) < KERNEL_TEXT_SIZE) {
 			unsigned long addr2;
 			pgprot_t prot2;
 			addr2 = __START_KERNEL_map + __pa(address);
 			/* Make sure the kernel mappings stay executable */
 			prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
 			err = __change_page_attr(addr2, pfn, prot2,
 						 PAGE_KERNEL_EXEC);
 		}
 	}
 	up_write(&init_mm.mmap_sem);
 	return err;
 }

 /* Don't call this for MMIO areas that may not have a mem_map entry */
 int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 {
 	unsigned long addr = (unsigned long)page_address(page);
 	return change_page_attr_addr(addr, numpages, prot);
 }

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

 	/*
 	 * Write-protect the semaphore, to exclude two contexts
 	 * doing a list_replace_init() call in parallel and to
 	 * exclude new additions to the deferred_pages list:
 	 */
 	down_write(&init_mm.mmap_sem);
 	list_replace_init(&deferred_pages, &l);
 	up_write(&init_mm.mmap_sem);

 	flush_map(&l);

 	list_for_each_entry_safe(pg, next, &l, lru) {
 		list_del(&pg->lru);
 		clear_bit(PG_arch_1, &pg->flags);
 		if (page_private(pg) != 0)
 			continue;
 		ClearPagePrivate(pg);
 		__free_page(pg);
 	}
 }

 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/io.h>

	pte_t *lookup_address(unsigned long address)
	{
	pgd_t *pgd = pgd_offset_k(address);
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	if (pgd_none(*pgd))
	return NULL;
	pud = pud_offset(pgd, address);
	if (!pud_present(*pud))
	return NULL;
	pmd = pmd_offset(pud, address);
	if (!pmd_present(*pmd))
	return NULL;
	if (pmd_large(*pmd))
	return (pte_t *)pmd;
	pte = pte_offset_kernel(pmd, address);
	if (pte && !pte_present(*pte))
	pte = NULL;
	return pte;
	}

	static struct page *split_large_page(unsigned long address, pgprot_t prot,
	pgprot_t ref_prot)
	{
	int i;
	unsigned long addr;
	struct page *base = alloc_pages(GFP_KERNEL, 0);
	pte_t *pbase;
	if (!base)
	return NULL;
	/*
	* page_private is used to track the number of entries in
	* the page table page 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) {
	pbase[i] = pfn_pte(addr >> PAGE_SHIFT,
	addr == address ? prot : ref_prot);
	}
	return base;
	}

	void clflush_cache_range(void *adr, int size)
	{
	int i;
	for (i = 0; i < size; i += boot_cpu_data.x86_clflush_size)
	clflush(adr+i);
	}

	static void flush_kernel_map(void *arg)
	{
	struct list_head l = (struct list_head )arg;
	struct page *pg;

	/* When clflush is available always use it because it is
	much cheaper than WBINVD. */
	/* clflush is still broken. Disable for now. */
	if (1 \|\| !cpu_has_clflush)
	asm volatile("wbinvd" ::: "memory");
	else list_for_each_entry(pg, l, lru) {
	void *adr = page_address(pg);
	clflush_cache_range(adr, PAGE_SIZE);
	}
	__flush_tlb_all();
	}

	static inline void flush_map(struct list_head *l)
	{
	on_each_cpu(flush_kernel_map, l, 1, 1);
	}

	static LIST_HEAD(deferred_pages); /* protected by init_mm.mmap_sem */

	static inline void save_page(struct page *fpage)
	{
	if (!test_and_set_bit(PG_arch_1, &fpage->flags))
	list_add(&fpage->lru, &deferred_pages);
	}

	/*
	* No more special protections in this 2/4MB area - revert to a
	* large page again.
	*/
	static void revert_page(unsigned long address, pgprot_t ref_prot)
	{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t large_pte;
	unsigned long pfn;

	pgd = pgd_offset_k(address);
	BUG_ON(pgd_none(*pgd));
	pud = pud_offset(pgd,address);
	BUG_ON(pud_none(*pud));
	pmd = pmd_offset(pud, address);
	BUG_ON(pmd_val(*pmd) & _PAGE_PSE);
	pfn = (__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT;
	large_pte = pfn_pte(pfn, ref_prot);
	large_pte = pte_mkhuge(large_pte);
	set_pte((pte_t *)pmd, large_pte);
	}

	static int
	__change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
	pgprot_t ref_prot)
	{
	pte_t *kpte;
	struct page *kpte_page;
	pgprot_t ref_prot2;

	kpte = lookup_address(address);
	if (!kpte) return 0;
	kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
	BUG_ON(PageLRU(kpte_page));
	BUG_ON(PageCompound(kpte_page));
	if (pgprot_val(prot) != pgprot_val(ref_prot)) {
	if (!pte_huge(*kpte)) {
	set_pte(kpte, pfn_pte(pfn, prot));
	} else {
	/*
	* split_large_page will take the reference for this
	* change_page_attr on the split page.
	*/
	struct page *split;
	ref_prot2 = pte_pgprot(pte_clrhuge(*kpte));
	split = split_large_page(address, prot, ref_prot2);
	if (!split)
	return -ENOMEM;
	pgprot_val(ref_prot2) &= ~_PAGE_NX;
	set_pte(kpte, mk_pte(split, ref_prot2));
	kpte_page = split;
	}
	page_private(kpte_page)++;
	} else if (!pte_huge(*kpte)) {
	set_pte(kpte, pfn_pte(pfn, ref_prot));
	BUG_ON(page_private(kpte_page) == 0);
	page_private(kpte_page)--;
	} else
	BUG();

	/* on x86-64 the direct mapping set at boot is not using 4k pages */
	BUG_ON(PageReserved(kpte_page));

	save_page(kpte_page);
	if (page_private(kpte_page) == 0)
	revert_page(address, ref_prot);
	return 0;
	}

	/*
	* 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_addr(unsigned long address, int numpages, pgprot_t prot)
	{
	int err = 0, kernel_map = 0;
	int i;

	if (address >= __START_KERNEL_map
	&& address < __START_KERNEL_map + KERNEL_TEXT_SIZE) {
	address = (unsigned long)__va(__pa(address));
	kernel_map = 1;
	}

	down_write(&init_mm.mmap_sem);
	for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
	unsigned long pfn = __pa(address) >> PAGE_SHIFT;

	if (!kernel_map \|\| pte_present(pfn_pte(0, prot))) {
	err = __change_page_attr(address, pfn, prot, PAGE_KERNEL);
	if (err)
	break;
	}
	/* Handle kernel mapping too which aliases part of the
	* lowmem */
	if (__pa(address) < KERNEL_TEXT_SIZE) {
	unsigned long addr2;
	pgprot_t prot2;
	addr2 = __START_KERNEL_map + __pa(address);
	/* Make sure the kernel mappings stay executable */
	prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
	err = __change_page_attr(addr2, pfn, prot2,
	PAGE_KERNEL_EXEC);
	}
	}
	up_write(&init_mm.mmap_sem);
	return err;
	}

	/* Don't call this for MMIO areas that may not have a mem_map entry */
	int change_page_attr(struct page *page, int numpages, pgprot_t prot)
	{
	unsigned long addr = (unsigned long)page_address(page);
	return change_page_attr_addr(addr, numpages, prot);
	}

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

	/*
	* Write-protect the semaphore, to exclude two contexts
	* doing a list_replace_init() call in parallel and to
	* exclude new additions to the deferred_pages list:
	*/
	down_write(&init_mm.mmap_sem);
	list_replace_init(&deferred_pages, &l);
	up_write(&init_mm.mmap_sem);

	flush_map(&l);

	list_for_each_entry_safe(pg, next, &l, lru) {
	list_del(&pg->lru);
	clear_bit(PG_arch_1, &pg->flags);
	if (page_private(pg) != 0)
	continue;
	ClearPagePrivate(pg);
	__free_page(pg);
	}
	}

	EXPORT_SYMBOL(change_page_attr);
	EXPORT_SYMBOL(global_flush_tlb);