Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f72a85e3 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Michael Ellerman
Browse files

powerpc/mm/book3s/64: Add proper pte access check helper 



pte_access_premitted get called in get_user_pages_fast path. If we
have marked the pte PROT_NONE, we should not allow a read access on
the address. With the current implementation we are not checking the
READ and only check for WRITE. This is needed on archs like ppc64 that
implement PROT_NONE using RWX access instead of _PAGE_PRESENT. Also
add pte_user check just to make sure we are not accessing kernel
mapping.

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 5fa5b16b

arch/powerpc/include/asm/book3s/64/pgtable.h

+41 −0
Original line number Diff line number Diff line
@@ -546,6 +546,30 @@ static inline int pte_present(pte_t pte) 
{

	return !!(pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT));

}



#define pte_access_permitted pte_access_permitted

static inline bool pte_access_permitted(pte_t pte, bool write)

{

	unsigned long pteval = pte_val(pte);

	/* Also check for pte_user */

	unsigned long clear_pte_bits = _PAGE_PRIVILEGED;

	/*

	 * _PAGE_READ is needed for any access and will be

	 * cleared for PROT_NONE

	 */

	unsigned long need_pte_bits = _PAGE_PRESENT | _PAGE_READ;



	if (write)

		need_pte_bits |= _PAGE_WRITE;



	if ((pteval & need_pte_bits) != need_pte_bits)

		return false;



	if ((pteval & clear_pte_bits) == clear_pte_bits)

		return false;

	return true;

}



/*

 * Conversion functions: convert a page and protection to a page entry,

 * and a page entry and page directory to the page they refer to.
@@ -850,6 +874,11 @@ static inline int pud_bad(pud_t pud) 
	return hash__pud_bad(pud);

}



#define pud_access_permitted pud_access_permitted

static inline bool pud_access_permitted(pud_t pud, bool write)

{

	return pte_access_permitted(pud_pte(pud), write);

}



#define pgd_write(pgd)		pte_write(pgd_pte(pgd))

static inline void pgd_set(pgd_t *pgdp, unsigned long val)
@@ -889,6 +918,12 @@ static inline int pgd_bad(pgd_t pgd) 
	return hash__pgd_bad(pgd);

}



#define pgd_access_permitted pgd_access_permitted

static inline bool pgd_access_permitted(pgd_t pgd, bool write)

{

	return pte_access_permitted(pgd_pte(pgd), write);

}



extern struct page *pgd_page(pgd_t pgd);



/* Pointers in the page table tree are physical addresses */
@@ -1009,6 +1044,12 @@ static inline int pmd_protnone(pmd_t pmd) 
#define __pmd_write(pmd)	__pte_write(pmd_pte(pmd))

#define pmd_savedwrite(pmd)	pte_savedwrite(pmd_pte(pmd))



#define pmd_access_permitted pmd_access_permitted

static inline bool pmd_access_permitted(pmd_t pmd, bool write)

{

	return pte_access_permitted(pmd_pte(pmd), write);

}



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);

extern pmd_t mk_pmd(struct page *page, pgprot_t pgprot);