Commit 626c2c9d authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Ingo Molnar
Browse files

x86: use the pfn from the page when change its attributes 



When changing the attributes of a pte, we should use the PFN from the
existing PTE rather than going through hoops calculating what we think
it might have been; this is both fragile and totally unneeded. It also
makes it more hairy to call any of these functions on non-direct maps
for no good reason whatsover.

With this change, __change_page_attr() no longer takes a pfn as argument,
which simplifies all the callers.

Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@tglx.de>
parent cc0f21bb

arch/x86/mm/pageattr.c

+17 −14
Original line number Diff line number Diff line
@@ -277,17 +277,12 @@ out_unlock: 
}



static int

__change_page_attr(unsigned long address, unsigned long pfn,

		   pgprot_t mask_set, pgprot_t mask_clr)

__change_page_attr(unsigned long address, pgprot_t mask_set, pgprot_t mask_clr)

{

	struct page *kpte_page;

	int level, err = 0;

	pte_t *kpte;



#ifdef CONFIG_X86_32

	BUG_ON(pfn > max_low_pfn);

#endif



repeat:

	kpte = lookup_address(address, &level);

	if (!kpte)
@@ -298,17 +293,25 @@ repeat: 
	BUG_ON(PageCompound(kpte_page));



	if (level == PG_LEVEL_4K) {

		pgprot_t new_prot = pte_pgprot(*kpte);

		pte_t new_pte, old_pte = *kpte;

		pgprot_t new_prot = pte_pgprot(old_pte);



		if(!pte_val(old_pte)) {

			WARN_ON_ONCE(1);

			return -EINVAL;

		}



		pgprot_val(new_prot) &= ~pgprot_val(mask_clr);

		pgprot_val(new_prot) |= pgprot_val(mask_set);



		new_prot = static_protections(new_prot, address);



		new_pte = pfn_pte(pfn, canon_pgprot(new_prot));

		BUG_ON(pte_pfn(new_pte) != pte_pfn(old_pte));



		/*

		 * We need to keep the pfn from the existing PTE,

		 * after all we're only going to change it's attributes

		 * not the memory it points to

		 */

		new_pte = pfn_pte(pte_pfn(old_pte), canon_pgprot(new_prot));

		set_pte_atomic(kpte, new_pte);

	} else {

		err = split_large_page(kpte, address);
@@ -337,11 +340,11 @@ static int 
change_page_attr_addr(unsigned long address, pgprot_t mask_set,

		      pgprot_t mask_clr)

{

	unsigned long phys_addr = __pa(address);

	unsigned long pfn = phys_addr >> PAGE_SHIFT;

	int err;



#ifdef CONFIG_X86_64

	unsigned long phys_addr = __pa(address);



	/*

	 * If we are inside the high mapped kernel range, then we

	 * fixup the low mapping first. __va() returns the virtual
@@ -351,7 +354,7 @@ change_page_attr_addr(unsigned long address, pgprot_t mask_set, 
		address = (unsigned long) __va(phys_addr);

#endif



	err = __change_page_attr(address, pfn, mask_set, mask_clr);

	err = __change_page_attr(address, mask_set, mask_clr);

	if (err)

		return err;
@@ -375,7 +378,7 @@ change_page_attr_addr(unsigned long address, pgprot_t mask_set, 
		 * everything between 0 and KERNEL_TEXT_SIZE, so do

		 * not propagate lookup failures back to users:

		 */

		__change_page_attr(address, pfn, mask_set, mask_clr);

		__change_page_attr(address, mask_set, mask_clr);

	}

#endif

	return err;

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