示例#1
0
文件: memory.c 项目: davidbau/davej
/*
 * These routines also need to handle stuff like marking pages dirty
 * and/or accessed for architectures that don't do it in hardware (most
 * RISC architectures).  The early dirtying is also good on the i386.
 *
 * There is also a hook called "update_mmu_cache()" that architectures
 * with external mmu caches can use to update those (ie the Sparc or
 * PowerPC hashed page tables that act as extended TLBs).
 *
 * Note the "page_table_lock". It is to protect against kswapd removing
 * pages from under us. Note that kswapd only ever _removes_ pages, never
 * adds them. As such, once we have noticed that the page is not present,
 * we can drop the lock early.
 *
 * The adding of pages is protected by the MM semaphore (which we hold),
 * so we don't need to worry about a page being suddenly been added into
 * our VM.
 */
static inline int handle_pte_fault(struct mm_struct *mm,
	struct vm_area_struct * vma, unsigned long address,
	int write_access, pte_t * pte)
{
	pte_t entry;

	/*
	 * We need the page table lock to synchronize with kswapd
	 * and the SMP-safe atomic PTE updates.
	 */
	spin_lock(&mm->page_table_lock);
	entry = *pte;
	if (!pte_present(entry)) {
		/*
		 * If it truly wasn't present, we know that kswapd
		 * and the PTE updates will not touch it later. So
		 * drop the lock.
		 */
		spin_unlock(&mm->page_table_lock);
		if (pte_none(entry))
			return do_no_page(mm, vma, address, write_access, pte);
		return do_swap_page(mm, vma, address, pte, pte_to_swp_entry(entry), write_access);
	}

	if (write_access) {
		if (!pte_write(entry))
			return do_wp_page(mm, vma, address, pte, entry);

		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
	establish_pte(vma, address, pte, entry);
	spin_unlock(&mm->page_table_lock);
	return 1;
}
示例#2
0
/*
 * Changing some bits of contiguous entries requires us to follow a
 * Break-Before-Make approach, breaking the whole contiguous set
 * before we can change any entries. See ARM DDI 0487A.k_iss10775,
 * "Misprogramming of the Contiguous bit", page D4-1762.
 *
 * This helper performs the break step.
 */
static pte_t get_clear_flush(struct mm_struct *mm,
			     unsigned long addr,
			     pte_t *ptep,
			     unsigned long pgsize,
			     unsigned long ncontig)
{
	pte_t orig_pte = huge_ptep_get(ptep);
	bool valid = pte_valid(orig_pte);
	unsigned long i, saddr = addr;

	for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
		pte_t pte = ptep_get_and_clear(mm, addr, ptep);

		/*
		 * If HW_AFDBM is enabled, then the HW could turn on
		 * the dirty or accessed bit for any page in the set,
		 * so check them all.
		 */
		if (pte_dirty(pte))
			orig_pte = pte_mkdirty(orig_pte);

		if (pte_young(pte))
			orig_pte = pte_mkyoung(orig_pte);
	}

	if (valid) {
		struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
		flush_tlb_range(&vma, saddr, addr);
	}
	return orig_pte;
}
示例#3
0
int huge_ptep_set_access_flags(struct vm_area_struct *vma,
			       unsigned long addr, pte_t *ptep,
			       pte_t pte, int dirty)
{
	int ncontig, i;
	size_t pgsize = 0;
	unsigned long pfn = pte_pfn(pte), dpfn;
	pgprot_t hugeprot;
	pte_t orig_pte;

	if (!pte_cont(pte))
		return ptep_set_access_flags(vma, addr, ptep, pte, dirty);

	ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
	dpfn = pgsize >> PAGE_SHIFT;

	if (!__cont_access_flags_changed(ptep, pte, ncontig))
		return 0;

	orig_pte = get_clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);

	/* Make sure we don't lose the dirty or young state */
	if (pte_dirty(orig_pte))
		pte = pte_mkdirty(pte);

	if (pte_young(orig_pte))
		pte = pte_mkyoung(pte);

	hugeprot = pte_pgprot(pte);
	for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
		set_pte_at(vma->vm_mm, addr, ptep, pfn_pte(pfn, hugeprot));

	return 1;
}
示例#4
0
/*
 * This routine handles present pages, when users try to write
 * to a shared page. It is done by copying the page to a new address
 * and decrementing the shared-page counter for the old page.
 *
 * Goto-purists beware: the only reason for goto's here is that it results
 * in better assembly code.. The "default" path will see no jumps at all.
 *
 * Note that this routine assumes that the protection checks have been
 * done by the caller (the low-level page fault routine in most cases).
 * Thus we can safely just mark it writable once we've done any necessary
 * COW.
 *
 * We also mark the page dirty at this point even though the page will
 * change only once the write actually happens. This avoids a few races,
 * and potentially makes it more efficient.
 *
 * We hold the mm semaphore and the page_table_lock on entry and exit
 * with the page_table_lock released.
 */
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma,
	unsigned long address, pte_t *page_table, pte_t pte)
{
	struct page *old_page, *new_page;

	old_page = pte_page(pte);
	if (!VALID_PAGE(old_page))
		goto bad_wp_page;

	if (!TryLockPage(old_page)) {
		int reuse = can_share_swap_page(old_page);
		unlock_page(old_page);
		if (reuse) {
#ifndef CONFIG_SUPERH
			/* Not needed for VIPT cache */
			flush_cache_page(vma, address);
#endif
			establish_pte(vma, address, page_table, pte_mkyoung(pte_mkdirty(pte_mkwrite(pte))));
			spin_unlock(&mm->page_table_lock);
			return 1;	/* Minor fault */
		}
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
	page_cache_get(old_page);
	spin_unlock(&mm->page_table_lock);

	new_page = alloc_page(GFP_HIGHUSER);
	if (!new_page)
		goto no_mem;
	copy_cow_page(old_page,new_page,address);

	/*
	 * Re-check the pte - we dropped the lock
	 */
	spin_lock(&mm->page_table_lock);
	if (pte_same(*page_table, pte)) {
		if (PageReserved(old_page))
			++mm->rss;
		break_cow(vma, new_page, address, page_table);
		lru_cache_add(new_page);

		/* Free the old page.. */
		new_page = old_page;
	}
	spin_unlock(&mm->page_table_lock);
	page_cache_release(new_page);
	page_cache_release(old_page);
	return 1;	/* Minor fault */

bad_wp_page:
	spin_unlock(&mm->page_table_lock);
	printk("do_wp_page: bogus page at address %08lx (page 0x%lx)\n",address,(unsigned long)old_page);
	return -1;
no_mem:
	page_cache_release(old_page);
	return -1;
}
示例#5
0
/*
 *  the function for the no-page and wp_page
 */
void handle_pte_fault(struct vm_area_struct *vma, unsigned long address, pte_t *pte,int write_access)
{
    // no page present
    if(!pte_present(*pte))
    {
        do_no_page(vma,address,write_access);
        return;
    }
    *pte = pte_mkyoung(*pte);
    if(!write_access)
    {
        *pte = pte_mkdirty(*pte);
        return;
    }
    // write the shared page 
    do_wp_page(vma, address, write_access);

}
示例#6
0
/*
 * The above separate functions for the no-page and wp-page
 * cases will go away (they mostly do the same thing anyway),
 * and we'll instead use only a general "handle_mm_fault()".
 *
 * These routines also need to handle stuff like marking pages dirty
 * and/or accessed for architectures that don't do it in hardware (most
 * RISC architectures).  The early dirtying is also good on the i386.
 *
 * There is also a hook called "update_mmu_cache()" that architectures
 * with external mmu caches can use to update those (ie the Sparc or
 * PowerPC hashed page tables that act as extended TLBs).
 */
static inline void handle_pte_fault(struct vm_area_struct * vma, unsigned long address,
	int write_access, pte_t * pte)
{
	if (!pte_present(*pte)) {
		do_no_page(current, vma, address, write_access);
		return;
	}
	set_pte(pte, pte_mkyoung(*pte));
	flush_tlb_page(vma, address);
	if (!write_access)
		return;
	if (pte_write(*pte)) {
		set_pte(pte, pte_mkdirty(*pte));
		flush_tlb_page(vma, address);
		return;
	}
	do_wp_page(current, vma, address, write_access);
}
示例#7
0
static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, unsigned int flags)
{
	/* No page to get reference */
	if (flags & FOLL_GET)
		return -EFAULT;

	if (flags & FOLL_TOUCH) {
		pte_t entry = *pte;

		if (flags & FOLL_WRITE)
			entry = pte_mkdirty(entry);
		entry = pte_mkyoung(entry);

		if (!pte_same(*pte, entry)) {
			set_pte_at(vma->vm_mm, address, pte, entry);
			update_mmu_cache(vma, address, pte);
		}
	}

	/* Proper page table entry exists, but no corresponding struct page */
	return -EEXIST;
}
示例#8
0
/*H:330
 * (i) Looking up a page table entry when the Guest faults.
 *
 * We saw this call in run_guest(): when we see a page fault in the Guest, we
 * come here.  That's because we only set up the shadow page tables lazily as
 * they're needed, so we get page faults all the time and quietly fix them up
 * and return to the Guest without it knowing.
 *
 * If we fixed up the fault (ie. we mapped the address), this routine returns
 * true.  Otherwise, it was a real fault and we need to tell the Guest.
 */
bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
{
	pgd_t gpgd;
	pgd_t *spgd;
	unsigned long gpte_ptr;
	pte_t gpte;
	pte_t *spte;

	/* Mid level for PAE. */
#ifdef CONFIG_X86_PAE
	pmd_t *spmd;
	pmd_t gpmd;
#endif

	/* First step: get the top-level Guest page table entry. */
	if (unlikely(cpu->linear_pages)) {
		/* Faking up a linear mapping. */
		gpgd = __pgd(CHECK_GPGD_MASK);
	} else {
		gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
		/* Toplevel not present?  We can't map it in. */
		if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
			return false;
	}

	/* Now look at the matching shadow entry. */
	spgd = spgd_addr(cpu, cpu->cpu_pgd, vaddr);
	if (!(pgd_flags(*spgd) & _PAGE_PRESENT)) {
		/* No shadow entry: allocate a new shadow PTE page. */
		unsigned long ptepage = get_zeroed_page(GFP_KERNEL);
		/*
		 * This is not really the Guest's fault, but killing it is
		 * simple for this corner case.
		 */
		if (!ptepage) {
			kill_guest(cpu, "out of memory allocating pte page");
			return false;
		}
		/* We check that the Guest pgd is OK. */
		check_gpgd(cpu, gpgd);
		/*
		 * And we copy the flags to the shadow PGD entry.  The page
		 * number in the shadow PGD is the page we just allocated.
		 */
		set_pgd(spgd, __pgd(__pa(ptepage) | pgd_flags(gpgd)));
	}

#ifdef CONFIG_X86_PAE
	if (unlikely(cpu->linear_pages)) {
		/* Faking up a linear mapping. */
		gpmd = __pmd(_PAGE_TABLE);
	} else {
		gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t);
		/* Middle level not present?  We can't map it in. */
		if (!(pmd_flags(gpmd) & _PAGE_PRESENT))
			return false;
	}

	/* Now look at the matching shadow entry. */
	spmd = spmd_addr(cpu, *spgd, vaddr);

	if (!(pmd_flags(*spmd) & _PAGE_PRESENT)) {
		/* No shadow entry: allocate a new shadow PTE page. */
		unsigned long ptepage = get_zeroed_page(GFP_KERNEL);

		/*
		 * This is not really the Guest's fault, but killing it is
		 * simple for this corner case.
		 */
		if (!ptepage) {
			kill_guest(cpu, "out of memory allocating pte page");
			return false;
		}

		/* We check that the Guest pmd is OK. */
		check_gpmd(cpu, gpmd);

		/*
		 * And we copy the flags to the shadow PMD entry.  The page
		 * number in the shadow PMD is the page we just allocated.
		 */
		set_pmd(spmd, __pmd(__pa(ptepage) | pmd_flags(gpmd)));
	}

	/*
	 * OK, now we look at the lower level in the Guest page table: keep its
	 * address, because we might update it later.
	 */
	gpte_ptr = gpte_addr(cpu, gpmd, vaddr);
#else
	/*
	 * OK, now we look at the lower level in the Guest page table: keep its
	 * address, because we might update it later.
	 */
	gpte_ptr = gpte_addr(cpu, gpgd, vaddr);
#endif

	if (unlikely(cpu->linear_pages)) {
		/* Linear?  Make up a PTE which points to same page. */
		gpte = __pte((vaddr & PAGE_MASK) | _PAGE_RW | _PAGE_PRESENT);
	} else {
		/* Read the actual PTE value. */
		gpte = lgread(cpu, gpte_ptr, pte_t);
	}

	/* If this page isn't in the Guest page tables, we can't page it in. */
	if (!(pte_flags(gpte) & _PAGE_PRESENT))
		return false;

	/*
	 * Check they're not trying to write to a page the Guest wants
	 * read-only (bit 2 of errcode == write).
	 */
	if ((errcode & 2) && !(pte_flags(gpte) & _PAGE_RW))
		return false;

	/* User access to a kernel-only page? (bit 3 == user access) */
	if ((errcode & 4) && !(pte_flags(gpte) & _PAGE_USER))
		return false;

	/*
	 * Check that the Guest PTE flags are OK, and the page number is below
	 * the pfn_limit (ie. not mapping the Launcher binary).
	 */
	check_gpte(cpu, gpte);

	/* Add the _PAGE_ACCESSED and (for a write) _PAGE_DIRTY flag */
	gpte = pte_mkyoung(gpte);
	if (errcode & 2)
		gpte = pte_mkdirty(gpte);

	/* Get the pointer to the shadow PTE entry we're going to set. */
	spte = spte_addr(cpu, *spgd, vaddr);

	/*
	 * If there was a valid shadow PTE entry here before, we release it.
	 * This can happen with a write to a previously read-only entry.
	 */
	release_pte(*spte);

	/*
	 * If this is a write, we insist that the Guest page is writable (the
	 * final arg to gpte_to_spte()).
	 */
	if (pte_dirty(gpte))
		*spte = gpte_to_spte(cpu, gpte, 1);
	else
		/*
		 * If this is a read, don't set the "writable" bit in the page
		 * table entry, even if the Guest says it's writable.  That way
		 * we will come back here when a write does actually occur, so
		 * we can update the Guest's _PAGE_DIRTY flag.
		 */
		set_pte(spte, gpte_to_spte(cpu, pte_wrprotect(gpte), 0));

	/*
	 * Finally, we write the Guest PTE entry back: we've set the
	 * _PAGE_ACCESSED and maybe the _PAGE_DIRTY flags.
	 */
	if (likely(!cpu->linear_pages))
		lgwrite(cpu, gpte_ptr, pte_t, gpte);

	/*
	 * The fault is fixed, the page table is populated, the mapping
	 * manipulated, the result returned and the code complete.  A small
	 * delay and a trace of alliteration are the only indications the Guest
	 * has that a page fault occurred at all.
	 */
	return true;
}
示例#9
0
文件: memory.c 项目: davidbau/davej
/*
 * This routine handles present pages, when users try to write
 * to a shared page. It is done by copying the page to a new address
 * and decrementing the shared-page counter for the old page.
 *
 * Goto-purists beware: the only reason for goto's here is that it results
 * in better assembly code.. The "default" path will see no jumps at all.
 *
 * Note that this routine assumes that the protection checks have been
 * done by the caller (the low-level page fault routine in most cases).
 * Thus we can safely just mark it writable once we've done any necessary
 * COW.
 *
 * We also mark the page dirty at this point even though the page will
 * change only once the write actually happens. This avoids a few races,
 * and potentially makes it more efficient.
 *
 * We enter with the page table read-lock held, and need to exit without
 * it.
 */
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma,
	unsigned long address, pte_t *page_table, pte_t pte)
{
	struct page *old_page, *new_page;

	old_page = pte_page(pte);
	if (!VALID_PAGE(old_page))
		goto bad_wp_page;
	
	/*
	 * We can avoid the copy if:
	 * - we're the only user (count == 1)
	 * - the only other user is the swap cache,
	 *   and the only swap cache user is itself,
	 *   in which case we can just continue to
	 *   use the same swap cache (it will be
	 *   marked dirty).
	 */
	switch (page_count(old_page)) {
	case 2:
		/*
		 * Lock the page so that no one can look it up from
		 * the swap cache, grab a reference and start using it.
		 * Can not do lock_page, holding page_table_lock.
		 */
		if (!PageSwapCache(old_page) || TryLockPage(old_page))
			break;
		if (is_page_shared(old_page)) {
			UnlockPage(old_page);
			break;
		}
		UnlockPage(old_page);
		/* FallThrough */
	case 1:
		flush_cache_page(vma, address);
		establish_pte(vma, address, page_table, pte_mkyoung(pte_mkdirty(pte_mkwrite(pte))));
		spin_unlock(&mm->page_table_lock);
		return 1;	/* Minor fault */
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
	spin_unlock(&mm->page_table_lock);
	new_page = page_cache_alloc();
	if (!new_page)
		return -1;
	spin_lock(&mm->page_table_lock);

	/*
	 * Re-check the pte - we dropped the lock
	 */
	if (pte_same(*page_table, pte)) {
		if (PageReserved(old_page))
			++mm->rss;
		break_cow(vma, old_page, new_page, address, page_table);

		/* Free the old page.. */
		new_page = old_page;
	}
	spin_unlock(&mm->page_table_lock);
	page_cache_release(new_page);
	return 1;	/* Minor fault */

bad_wp_page:
	spin_unlock(&mm->page_table_lock);
	printk("do_wp_page: bogus page at address %08lx (page 0x%lx)\n",address,(unsigned long)old_page);
	return -1;
}
示例#10
0
/*H:330
 * (i) Looking up a page table entry when the Guest faults.
 *
 * We saw this call in run_guest(): when we see a page fault in the Guest, we
 * come here.  That's because we only set up the shadow page tables lazily as
 * they're needed, so we get page faults all the time and quietly fix them up
 * and return to the Guest without it knowing.
 *
 * If we fixed up the fault (ie. we mapped the address), this routine returns
 * true.  Otherwise, it was a real fault and we need to tell the Guest.
 *
 * There's a corner case: they're trying to access memory between
 * pfn_limit and device_limit, which is I/O memory.  In this case, we
 * return false and set @iomem to the physical address, so the the
 * Launcher can handle the instruction manually.
 */
bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode,
		 unsigned long *iomem)
{
	unsigned long gpte_ptr;
	pte_t gpte;
	pte_t *spte;
	pmd_t gpmd;
	pgd_t gpgd;

	*iomem = 0;

	/* We never demand page the Switcher, so trying is a mistake. */
	if (vaddr >= switcher_addr)
		return false;

	/* First step: get the top-level Guest page table entry. */
	if (unlikely(cpu->linear_pages)) {
		/* Faking up a linear mapping. */
		gpgd = __pgd(CHECK_GPGD_MASK);
	} else {
		gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
		/* Toplevel not present?  We can't map it in. */
		if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
			return false;

		/* 
		 * This kills the Guest if it has weird flags or tries to
		 * refer to a "physical" address outside the bounds.
		 */
		if (!check_gpgd(cpu, gpgd))
			return false;
	}

	/* This "mid-level" entry is only used for non-linear, PAE mode. */
	gpmd = __pmd(_PAGE_TABLE);

#ifdef CONFIG_X86_PAE
	if (likely(!cpu->linear_pages)) {
		gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t);
		/* Middle level not present?  We can't map it in. */
		if (!(pmd_flags(gpmd) & _PAGE_PRESENT))
			return false;

		/* 
		 * This kills the Guest if it has weird flags or tries to
		 * refer to a "physical" address outside the bounds.
		 */
		if (!check_gpmd(cpu, gpmd))
			return false;
	}

	/*
	 * OK, now we look at the lower level in the Guest page table: keep its
	 * address, because we might update it later.
	 */
	gpte_ptr = gpte_addr(cpu, gpmd, vaddr);
#else
	/*
	 * OK, now we look at the lower level in the Guest page table: keep its
	 * address, because we might update it later.
	 */
	gpte_ptr = gpte_addr(cpu, gpgd, vaddr);
#endif

	if (unlikely(cpu->linear_pages)) {
		/* Linear?  Make up a PTE which points to same page. */
		gpte = __pte((vaddr & PAGE_MASK) | _PAGE_RW | _PAGE_PRESENT);
	} else {
		/* Read the actual PTE value. */
		gpte = lgread(cpu, gpte_ptr, pte_t);
	}

	/* If this page isn't in the Guest page tables, we can't page it in. */
	if (!(pte_flags(gpte) & _PAGE_PRESENT))
		return false;

	/*
	 * Check they're not trying to write to a page the Guest wants
	 * read-only (bit 2 of errcode == write).
	 */
	if ((errcode & 2) && !(pte_flags(gpte) & _PAGE_RW))
		return false;

	/* User access to a kernel-only page? (bit 3 == user access) */
	if ((errcode & 4) && !(pte_flags(gpte) & _PAGE_USER))
		return false;

	/* If they're accessing io memory, we expect a fault. */
	if (gpte_in_iomem(cpu, gpte)) {
		*iomem = (pte_pfn(gpte) << PAGE_SHIFT) | (vaddr & ~PAGE_MASK);
		return false;
	}

	/*
	 * Check that the Guest PTE flags are OK, and the page number is below
	 * the pfn_limit (ie. not mapping the Launcher binary).
	 */
	if (!check_gpte(cpu, gpte))
		return false;

	/* Add the _PAGE_ACCESSED and (for a write) _PAGE_DIRTY flag */
	gpte = pte_mkyoung(gpte);
	if (errcode & 2)
		gpte = pte_mkdirty(gpte);

	/* Get the pointer to the shadow PTE entry we're going to set. */
	spte = find_spte(cpu, vaddr, true, pgd_flags(gpgd), pmd_flags(gpmd));
	if (!spte)
		return false;

	/*
	 * If there was a valid shadow PTE entry here before, we release it.
	 * This can happen with a write to a previously read-only entry.
	 */
	release_pte(*spte);

	/*
	 * If this is a write, we insist that the Guest page is writable (the
	 * final arg to gpte_to_spte()).
	 */
	if (pte_dirty(gpte))
		*spte = gpte_to_spte(cpu, gpte, 1);
	else
		/*
		 * If this is a read, don't set the "writable" bit in the page
		 * table entry, even if the Guest says it's writable.  That way
		 * we will come back here when a write does actually occur, so
		 * we can update the Guest's _PAGE_DIRTY flag.
		 */
		set_pte(spte, gpte_to_spte(cpu, pte_wrprotect(gpte), 0));

	/*
	 * Finally, we write the Guest PTE entry back: we've set the
	 * _PAGE_ACCESSED and maybe the _PAGE_DIRTY flags.
	 */
	if (likely(!cpu->linear_pages))
		lgwrite(cpu, gpte_ptr, pte_t, gpte);

	/*
	 * The fault is fixed, the page table is populated, the mapping
	 * manipulated, the result returned and the code complete.  A small
	 * delay and a trace of alliteration are the only indications the Guest
	 * has that a page fault occurred at all.
	 */
	return true;
}
示例#11
0
文件: mcfmmu.c 项目: 0x7f454c46/linux
int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
{
	unsigned long flags, mmuar, mmutr;
	struct mm_struct *mm;
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;
	int asid;

	local_irq_save(flags);

	mmuar = (dtlb) ? mmu_read(MMUAR) :
		regs->pc + (extension_word * sizeof(long));

	mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
	if (!mm) {
		local_irq_restore(flags);
		return -1;
	}

	pgd = pgd_offset(mm, mmuar);
	if (pgd_none(*pgd))  {
		local_irq_restore(flags);
		return -1;
	}

	pmd = pmd_offset(pgd, mmuar);
	if (pmd_none(*pmd)) {
		local_irq_restore(flags);
		return -1;
	}

	pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
				: pte_offset_map(pmd, mmuar);
	if (pte_none(*pte) || !pte_present(*pte)) {
		local_irq_restore(flags);
		return -1;
	}

	if (write) {
		if (!pte_write(*pte)) {
			local_irq_restore(flags);
			return -1;
		}
		set_pte(pte, pte_mkdirty(*pte));
	}

	set_pte(pte, pte_mkyoung(*pte));
	asid = mm->context & 0xff;
	if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
		set_pte(pte, pte_wrprotect(*pte));

	mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
	if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
		mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
	mmu_write(MMUTR, mmutr);

	mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
		((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);

	if (dtlb)
		mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
	else
		mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);

	local_irq_restore(flags);
	return 0;
}
示例#12
0
static int fault_in_page(int taskid,
			 struct vm_area_struct *vma,
			 unsigned long address, int write)
{
	static unsigned last_address;
	static int last_task, loop_counter;
	struct task_struct *tsk = task[taskid];
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;

	if (!tsk || !tsk->mm)
		return 1;

	if (!vma || (write && !(vma->vm_flags & VM_WRITE)))
	  goto bad_area;
	if (vma->vm_start > address)
	  goto bad_area;

	if (address == last_address && taskid == last_task) {
		loop_counter++;
	} else {
		loop_counter = 0;
		last_address = address; 
		last_task = taskid;
	}

	if (loop_counter == WRITE_LIMIT && !write) {
		printk("MSC bug? setting write request\n");
		stats.errors++;
		write = 1;
	}

	if (loop_counter == LOOP_LIMIT) {
		printk("MSC bug? failing request\n");
		stats.errors++;
		return 1;
	}

	pgd = pgd_offset(vma->vm_mm, address);
	pmd = pmd_alloc(pgd,address);
	if(!pmd)
		goto no_memory;
	pte = pte_alloc(pmd, address);
	if(!pte)
		goto no_memory;
	if(!pte_present(*pte)) {
		handle_mm_fault(tsk, vma, address, write);
		goto finish_up;
	}
	set_pte(pte, pte_mkyoung(*pte));
	flush_tlb_page(vma, address);
	if(!write)
		goto finish_up;
	if(pte_write(*pte)) {
		set_pte(pte, pte_mkdirty(*pte));
		flush_tlb_page(vma, address);
		goto finish_up;
	}
	handle_mm_fault(tsk, vma, address, write);

	/* Fall through for do_wp_page */
finish_up:
	stats.success++;
	return 0;

no_memory:
	stats.failure++;
	oom(tsk);
	return 1;
	
bad_area:	  
	stats.failure++;
	tsk->tss.sig_address = address;
	tsk->tss.sig_desc = SUBSIG_NOMAPPING;
	send_sig(SIGSEGV, tsk, 1);
	return 1;
}