Commit 773b93f1 authored by Aneesh Kumar K.V (IBM)'s avatar Aneesh Kumar K.V (IBM) Committed by Michael Ellerman
Browse files

powerpc/book3s/hash: Drop _PAGE_PRIVILEGED from PAGE_NONE 



There used to be a dependency on _PAGE_PRIVILEGED with pte_savedwrite.
But that got dropped by
commit 6a56ccbc ("mm/autonuma: use can_change_(pte|pmd)_writable() to replace savedwrite")

With the change in this patch numa fault pte (pte_protnone()) gets mapped as regular user pte
with RWX cleared (no-access) whereas earlier it used to be mapped _PAGE_PRIVILEGED.

Hash fault handling code gets some WARN_ON added in this patch because
those functions are not expected to get called with _PAGE_READ cleared.
commit 18061c17 ("powerpc/mm: Update PROTFAULT handling in the page
fault path") explains the details.

Signed-off-by: default avatar"Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Reviewed-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231204093638.71503-1-aneesh.kumar@kernel.org
parent 27951e1d

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

+2 −8
Original line number Diff line number Diff line
@@ -17,12 +17,6 @@ 
#define _PAGE_EXEC		0x00001 /* execute permission */

#define _PAGE_WRITE		0x00002 /* write access allowed */

#define _PAGE_READ		0x00004	/* read access allowed */

#define _PAGE_NA		_PAGE_PRIVILEGED

#define _PAGE_NAX		_PAGE_EXEC

#define _PAGE_RO		_PAGE_READ

#define _PAGE_ROX		(_PAGE_READ | _PAGE_EXEC)

#define _PAGE_RW		(_PAGE_READ | _PAGE_WRITE)

#define _PAGE_RWX		(_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC)

#define _PAGE_PRIVILEGED	0x00008 /* kernel access only */

#define _PAGE_SAO		0x00010 /* Strong access order */

#define _PAGE_NON_IDEMPOTENT	0x00020 /* non idempotent memory */
@@ -532,8 +526,8 @@ static inline bool pte_user(pte_t pte) 
static inline bool pte_access_permitted(pte_t pte, bool write)

{

	/*

	 * _PAGE_READ is needed for any access and will be

	 * cleared for PROT_NONE

	 * _PAGE_READ is needed for any access and will be cleared for

	 * PROT_NONE. Execute-only mapping via PROT_EXEC also returns false.

	 */

	if (!pte_present(pte) || !pte_user(pte) || !pte_read(pte))

		return false;

arch/powerpc/mm/book3s64/hash_utils.c

+7 −0
Original line number Diff line number Diff line
@@ -310,9 +310,16 @@ unsigned long htab_convert_pte_flags(unsigned long pteflags, unsigned long flags 
			else

				rflags |= 0x3;

		}

		VM_WARN_ONCE(!(pteflags & _PAGE_RWX), "no-access mapping request");

	} else {

		if (pteflags & _PAGE_RWX)

			rflags |= 0x2;

		/*

		 * We should never hit this in normal fault handling because

		 * a permission check (check_pte_access()) will bubble this

		 * to higher level linux handler even for PAGE_NONE.

		 */

		VM_WARN_ONCE(!(pteflags & _PAGE_RWX), "no-access mapping request");

		if (!((pteflags & _PAGE_WRITE) && (pteflags & _PAGE_DIRTY)))

			rflags |= 0x1;

	}