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powerpc/mm: Fixup kernel read only mapping

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With commit e58e87adc8 ("powerpc/mm: Update _PAGE_KERNEL_RO") we
started using the ppp value 0b110 to map kernel readonly. But that
facility was only added as part of ISA 2.04. For earlier ISA version
only supported ppp bit value for readonly mapping is 0b011. (This
implies both user and kernel get mapped using the same ppp bit value for
readonly mapping.).
Update the code such that for earlier architecture version we use ppp
value 0b011 for readonly mapping. We don't differentiate between power5+
and power5 here and apply the new ppp bits only from power6 (ISA 2.05).
This keep the changes minimal.

This fixes issue with PS3 spu usage reported at
https://lkml.kernel.org/r/rep.1421449714.geoff@infradead.org

Fixes: e58e87adc8 ("powerpc/mm: Update _PAGE_KERNEL_RO")
Cc: stable@vger.kernel.org # v4.7+
Tested-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Aneesh Kumar K.V 2016-11-24 15:09:54 +05:30 committed by Michael Ellerman
parent a1ff57416a
commit 984d7a1ec6
2 changed files with 16 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
arch/powerpc/include/asm/mmu.h
View File

@ -28,6 +28,12 @@
* Individual features below.
*/
/*
* Kernel read only support.
* We added the ppp value 0b110 in ISA 2.04.
*/
#define MMU_FTR_KERNEL_RO ASM_CONST(0x00004000)
/*
* We need to clear top 16bits of va (from the remaining 64 bits )in
* tlbie* instructions
@ -103,10 +109,10 @@
#define MMU_FTRS_POWER4 MMU_FTRS_DEFAULT_HPTE_ARCH_V2
#define MMU_FTRS_PPC970 MMU_FTRS_POWER4 | MMU_FTR_TLBIE_CROP_VA
#define MMU_FTRS_POWER5 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE
#define MMU_FTRS_POWER6 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE
#define MMU_FTRS_POWER7 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE
#define MMU_FTRS_POWER8 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE
#define MMU_FTRS_POWER9 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE
#define MMU_FTRS_POWER6 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_KERNEL_RO
#define MMU_FTRS_POWER7 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_KERNEL_RO
#define MMU_FTRS_POWER8 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_KERNEL_RO
#define MMU_FTRS_POWER9 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_KERNEL_RO
#define MMU_FTRS_CELL MMU_FTRS_DEFAULT_HPTE_ARCH_V2 | \
MMU_FTR_CI_LARGE_PAGE
#define MMU_FTRS_PA6T MMU_FTRS_DEFAULT_HPTE_ARCH_V2 | \

8
arch/powerpc/mm/hash_utils_64.c
View File

@ -193,8 +193,12 @@ unsigned long htab_convert_pte_flags(unsigned long pteflags)
/*
* Kernel read only mapped with ppp bits 0b110
*/
if (!(pteflags & _PAGE_WRITE))
rflags |= (HPTE_R_PP0 | 0x2);
if (!(pteflags & _PAGE_WRITE)) {
if (mmu_has_feature(MMU_FTR_KERNEL_RO))
rflags |= (HPTE_R_PP0 | 0x2);
else
rflags |= 0x3;
}
} else {
if (pteflags & _PAGE_RWX)
rflags |= 0x2;