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powerpc/book3s/hash: Drop _PAGE_PRIVILEGED from PAGE_NONE

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There used to be a dependency on _PAGE_PRIVILEGED with pte_savedwrite.
But that got dropped by
commit 6a56ccbcf6 ("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 18061c17c8 ("powerpc/mm: Update PROTFAULT handling in the page
fault path") explains the details.

Signed-off-by: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231204093638.71503-1-aneesh.kumar@kernel.org
This commit is contained in:
Aneesh Kumar K.V (IBM) 2023-12-04 15:06:37 +05:30 committed by Michael Ellerman
parent 27951e1d82
commit 773b93f1d1
2 changed files with 9 additions and 8 deletions
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10
arch/powerpc/include/asm/book3s/64/pgtable.h
View File

@ -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;

7
arch/powerpc/mm/book3s64/hash_utils.c
View File

@ -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;
}