arch/arm/mm/fault-armv.c - kernel/skids - Git at Google

 /*
  *  linux/arch/arm/mm/fault-armv.c
  *
  *  Copyright (C) 1995  Linus Torvalds
  *  Modifications for ARM processor (c) 1995-2002 Russell King
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/bitops.h>
 #include <linux/vmalloc.h>
 #include <linux/init.h>
 #include <linux/pagemap.h>
 #include <linux/gfp.h>

 #include <asm/bugs.h>
 #include <asm/cacheflush.h>
 #include <asm/cachetype.h>
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>

 #include "mm.h"

 static unsigned long shared_pte_mask = L_PTE_MT_BUFFERABLE;

 /*
  * We take the easy way out of this problem - we make the
  * PTE uncacheable.  However, we leave the write buffer on.
  *
  * Note that the pte lock held when calling update_mmu_cache must also
  * guard the pte (somewhere else in the same mm) that we modify here.
  * Therefore those configurations which might call adjust_pte (those
  * without CONFIG_CPU_CACHE_VIPT) cannot support split page_table_lock.
  */
 static int do_adjust_pte(struct vm_area_struct *vma, unsigned long address,
 	unsigned long pfn, pte_t *ptep)
 {
 	pte_t entry = *ptep;
 	int ret;

 	/*
 	 * If this page is present, it's actually being shared.
 	 */
 	ret = pte_present(entry);

 	/*
 	 * If this page isn't present, or is already setup to
 	 * fault (ie, is old), we can safely ignore any issues.
 	 */
 	if (ret && (pte_val(entry) & L_PTE_MT_MASK) != shared_pte_mask) {
 		flush_cache_page(vma, address, pfn);
 		outer_flush_range((pfn << PAGE_SHIFT),
 				  (pfn << PAGE_SHIFT) + PAGE_SIZE);
 		pte_val(entry) &= ~L_PTE_MT_MASK;
 		pte_val(entry) |= shared_pte_mask;
 		set_pte_at(vma->vm_mm, address, ptep, entry);
 		flush_tlb_page(vma, address);
 	}

 	return ret;
 }

 #if USE_SPLIT_PTLOCKS
 /*
  * If we are using split PTE locks, then we need to take the page
  * lock here.  Otherwise we are using shared mm->page_table_lock
  * which is already locked, thus cannot take it.
  */
 static inline void do_pte_lock(spinlock_t *ptl)
 {
 	/*
 	 * Use nested version here to indicate that we are already
 	 * holding one similar spinlock.
 	 */
 	spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
 }

 static inline void do_pte_unlock(spinlock_t *ptl)
 {
 	spin_unlock(ptl);
 }
 #else /* !USE_SPLIT_PTLOCKS */
 static inline void do_pte_lock(spinlock_t *ptl) {}
 static inline void do_pte_unlock(spinlock_t *ptl) {}
 #endif /* USE_SPLIT_PTLOCKS */

 static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
 	unsigned long pfn)
 {
 	spinlock_t *ptl;
 	pgd_t *pgd;
 	pmd_t *pmd;
 	pte_t *pte;
 	int ret;

 	pgd = pgd_offset(vma->vm_mm, address);
 	if (pgd_none_or_clear_bad(pgd))
 		return 0;

 	pmd = pmd_offset(pgd, address);
 	if (pmd_none_or_clear_bad(pmd))
 		return 0;

 	/*
 	 * This is called while another page table is mapped, so we
 	 * must use the nested version.  This also means we need to
 	 * open-code the spin-locking.
 	 */
 	ptl = pte_lockptr(vma->vm_mm, pmd);
 	pte = pte_offset_map_nested(pmd, address);
 	do_pte_lock(ptl);

 	ret = do_adjust_pte(vma, address, pfn, pte);

 	do_pte_unlock(ptl);
 	pte_unmap_nested(pte);

 	return ret;
 }

 static void
 make_coherent(struct address_space *mapping, struct vm_area_struct *vma,
 	unsigned long addr, pte_t *ptep, unsigned long pfn)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	struct vm_area_struct *mpnt;
 	struct prio_tree_iter iter;
 	unsigned long offset;
 	pgoff_t pgoff;
 	int aliases = 0;

 	pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT);

 	/*
 	 * If we have any shared mappings that are in the same mm
 	 * space, then we need to handle them specially to maintain
 	 * cache coherency.
 	 */
 	flush_dcache_mmap_lock(mapping);
 	vma_prio_tree_foreach(mpnt, &iter, &mapping->i_mmap, pgoff, pgoff) {
 		/*
 		 * If this VMA is not in our MM, we can ignore it.
 		 * Note that we intentionally mask out the VMA
 		 * that we are fixing up.
 		 */
 		if (mpnt->vm_mm != mm || mpnt == vma)
 			continue;
 		if (!(mpnt->vm_flags & VM_MAYSHARE))
 			continue;
 		offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
 		aliases += adjust_pte(mpnt, mpnt->vm_start + offset, pfn);
 	}
 	flush_dcache_mmap_unlock(mapping);
 	if (aliases)
 		do_adjust_pte(vma, addr, pfn, ptep);
 }

 /*
  * Take care of architecture specific things when placing a new PTE into
  * a page table, or changing an existing PTE.  Basically, there are two
  * things that we need to take care of:
  *
  *  1. If PG_dcache_dirty is set for the page, we need to ensure
  *     that any cache entries for the kernels virtual memory
  *     range are written back to the page.
  *  2. If we have multiple shared mappings of the same space in
  *     an object, we need to deal with the cache aliasing issues.
  *
  * Note that the pte lock will be held.
  */
 void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
 	pte_t *ptep)
 {
 	unsigned long pfn = pte_pfn(*ptep);
 	struct address_space *mapping;
 	struct page *page;

 	if (!pfn_valid(pfn))
 		return;

 	/*
 	 * The zero page is never written to, so never has any dirty
 	 * cache lines, and therefore never needs to be flushed.
 	 */
 	page = pfn_to_page(pfn);
 	if (page == ZERO_PAGE(0))
 		return;

 	mapping = page_mapping(page);
 #ifndef CONFIG_SMP
 	if (test_and_clear_bit(PG_dcache_dirty, &page->flags))
 		__flush_dcache_page(mapping, page);
 #endif
 	if (mapping) {
 		if (cache_is_vivt())
 			make_coherent(mapping, vma, addr, ptep, pfn);
 		else if (vma->vm_flags & VM_EXEC)
 			__flush_icache_all();
 	}
 }

 /*
  * Check whether the write buffer has physical address aliasing
  * issues.  If it has, we need to avoid them for the case where
  * we have several shared mappings of the same object in user
  * space.
  */
 static int __init check_writebuffer(unsigned long *p1, unsigned long *p2)
 {
 	register unsigned long zero = 0, one = 1, val;

 	local_irq_disable();
 	mb();
 	*p1 = one;
 	mb();
 	*p2 = zero;
 	mb();
 	val = *p1;
 	mb();
 	local_irq_enable();
 	return val != zero;
 }

 void __init check_writebuffer_bugs(void)
 {
 	struct page *page;
 	const char *reason;
 	unsigned long v = 1;

 	printk(KERN_INFO "CPU: Testing write buffer coherency: ");

 	page = alloc_page(GFP_KERNEL);
 	if (page) {
 		unsigned long *p1, *p2;
 		pgprot_t prot = __pgprot_modify(PAGE_KERNEL,
 					L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE);

 		p1 = vmap(&page, 1, VM_IOREMAP, prot);
 		p2 = vmap(&page, 1, VM_IOREMAP, prot);

 		if (p1 && p2) {
 			v = check_writebuffer(p1, p2);
 			reason = "enabling work-around";
 		} else {
 			reason = "unable to map memory\n";
 		}

 		vunmap(p1);
 		vunmap(p2);
 		put_page(page);
 	} else {
 		reason = "unable to grab page\n";
 	}

 	if (v) {
 		printk("failed, %s\n", reason);
 		shared_pte_mask = L_PTE_MT_UNCACHED;
 	} else {
 		printk("ok\n");
 	}
 }
	/*
	* linux/arch/arm/mm/fault-armv.c
	*
	* Copyright (C) 1995 Linus Torvalds
	* Modifications for ARM processor (c) 1995-2002 Russell King
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/
	#include <linux/module.h>
	#include <linux/sched.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/bitops.h>
	#include <linux/vmalloc.h>
	#include <linux/init.h>
	#include <linux/pagemap.h>
	#include <linux/gfp.h>

	#include <asm/bugs.h>
	#include <asm/cacheflush.h>
	#include <asm/cachetype.h>
	#include <asm/pgtable.h>
	#include <asm/tlbflush.h>

	#include "mm.h"

	static unsigned long shared_pte_mask = L_PTE_MT_BUFFERABLE;

	/*
	* We take the easy way out of this problem - we make the
	* PTE uncacheable. However, we leave the write buffer on.
	*
	* Note that the pte lock held when calling update_mmu_cache must also
	* guard the pte (somewhere else in the same mm) that we modify here.
	* Therefore those configurations which might call adjust_pte (those
	* without CONFIG_CPU_CACHE_VIPT) cannot support split page_table_lock.
	*/
	static int do_adjust_pte(struct vm_area_struct *vma, unsigned long address,
	unsigned long pfn, pte_t *ptep)
	{
	pte_t entry = *ptep;
	int ret;

	/*
	* If this page is present, it's actually being shared.
	*/
	ret = pte_present(entry);

	/*
	* If this page isn't present, or is already setup to
	* fault (ie, is old), we can safely ignore any issues.
	*/
	if (ret && (pte_val(entry) & L_PTE_MT_MASK) != shared_pte_mask) {
	flush_cache_page(vma, address, pfn);
	outer_flush_range((pfn << PAGE_SHIFT),
	(pfn << PAGE_SHIFT) + PAGE_SIZE);
	pte_val(entry) &= ~L_PTE_MT_MASK;
	pte_val(entry) \|= shared_pte_mask;
	set_pte_at(vma->vm_mm, address, ptep, entry);
	flush_tlb_page(vma, address);
	}

	return ret;
	}

	#if USE_SPLIT_PTLOCKS
	/*
	* If we are using split PTE locks, then we need to take the page
	* lock here. Otherwise we are using shared mm->page_table_lock
	* which is already locked, thus cannot take it.
	*/
	static inline void do_pte_lock(spinlock_t *ptl)
	{
	/*
	* Use nested version here to indicate that we are already
	* holding one similar spinlock.
	*/
	spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
	}

	static inline void do_pte_unlock(spinlock_t *ptl)
	{
	spin_unlock(ptl);
	}
	#else /* !USE_SPLIT_PTLOCKS */
	static inline void do_pte_lock(spinlock_t *ptl) {}
	static inline void do_pte_unlock(spinlock_t *ptl) {}
	#endif /* USE_SPLIT_PTLOCKS */

	static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
	unsigned long pfn)
	{
	spinlock_t *ptl;
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;
	int ret;

	pgd = pgd_offset(vma->vm_mm, address);
	if (pgd_none_or_clear_bad(pgd))
	return 0;

	pmd = pmd_offset(pgd, address);
	if (pmd_none_or_clear_bad(pmd))
	return 0;

	/*
	* This is called while another page table is mapped, so we
	* must use the nested version. This also means we need to
	* open-code the spin-locking.
	*/
	ptl = pte_lockptr(vma->vm_mm, pmd);
	pte = pte_offset_map_nested(pmd, address);
	do_pte_lock(ptl);

	ret = do_adjust_pte(vma, address, pfn, pte);

	do_pte_unlock(ptl);
	pte_unmap_nested(pte);

	return ret;
	}

	static void
	make_coherent(struct address_space mapping, struct vm_area_struct vma,
	unsigned long addr, pte_t *ptep, unsigned long pfn)
	{
	struct mm_struct *mm = vma->vm_mm;
	struct vm_area_struct *mpnt;
	struct prio_tree_iter iter;
	unsigned long offset;
	pgoff_t pgoff;
	int aliases = 0;

	pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT);

	/*
	* If we have any shared mappings that are in the same mm
	* space, then we need to handle them specially to maintain
	* cache coherency.
	*/
	flush_dcache_mmap_lock(mapping);
	vma_prio_tree_foreach(mpnt, &iter, &mapping->i_mmap, pgoff, pgoff) {
	/*
	* If this VMA is not in our MM, we can ignore it.
	* Note that we intentionally mask out the VMA
	* that we are fixing up.
	*/
	if (mpnt->vm_mm != mm \|\| mpnt == vma)
	continue;
	if (!(mpnt->vm_flags & VM_MAYSHARE))
	continue;
	offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
	aliases += adjust_pte(mpnt, mpnt->vm_start + offset, pfn);
	}
	flush_dcache_mmap_unlock(mapping);
	if (aliases)
	do_adjust_pte(vma, addr, pfn, ptep);
	}

	/*
	* Take care of architecture specific things when placing a new PTE into
	* a page table, or changing an existing PTE. Basically, there are two
	* things that we need to take care of:
	*
	* 1. If PG_dcache_dirty is set for the page, we need to ensure
	* that any cache entries for the kernels virtual memory
	* range are written back to the page.
	* 2. If we have multiple shared mappings of the same space in
	* an object, we need to deal with the cache aliasing issues.
	*
	* Note that the pte lock will be held.
	*/
	void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
	pte_t *ptep)
	{
	unsigned long pfn = pte_pfn(*ptep);
	struct address_space *mapping;
	struct page *page;

	if (!pfn_valid(pfn))
	return;

	/*
	* The zero page is never written to, so never has any dirty
	* cache lines, and therefore never needs to be flushed.
	*/
	page = pfn_to_page(pfn);
	if (page == ZERO_PAGE(0))
	return;

	mapping = page_mapping(page);
	#ifndef CONFIG_SMP
	if (test_and_clear_bit(PG_dcache_dirty, &page->flags))
	__flush_dcache_page(mapping, page);
	#endif
	if (mapping) {
	if (cache_is_vivt())
	make_coherent(mapping, vma, addr, ptep, pfn);
	else if (vma->vm_flags & VM_EXEC)
	__flush_icache_all();
	}
	}

	/*
	* Check whether the write buffer has physical address aliasing
	* issues. If it has, we need to avoid them for the case where
	* we have several shared mappings of the same object in user
	* space.
	*/
	static int __init check_writebuffer(unsigned long p1, unsigned long p2)
	{
	register unsigned long zero = 0, one = 1, val;

	local_irq_disable();
	mb();
	*p1 = one;
	mb();
	*p2 = zero;
	mb();
	val = *p1;
	mb();
	local_irq_enable();
	return val != zero;
	}

	void __init check_writebuffer_bugs(void)
	{
	struct page *page;
	const char *reason;
	unsigned long v = 1;

	printk(KERN_INFO "CPU: Testing write buffer coherency: ");

	page = alloc_page(GFP_KERNEL);
	if (page) {
	unsigned long p1, p2;
	pgprot_t prot = __pgprot_modify(PAGE_KERNEL,
	L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE);

	p1 = vmap(&page, 1, VM_IOREMAP, prot);
	p2 = vmap(&page, 1, VM_IOREMAP, prot);

	if (p1 && p2) {
	v = check_writebuffer(p1, p2);
	reason = "enabling work-around";
	} else {
	reason = "unable to map memory\n";
	}

	vunmap(p1);
	vunmap(p2);
	put_page(page);
	} else {
	reason = "unable to grab page\n";
	}

	if (v) {
	printk("failed, %s\n", reason);
	shared_pte_mask = L_PTE_MT_UNCACHED;
	} else {
	printk("ok\n");
	}
	}