This is a note to let you know that I've just added the patch titled

powerpc: Fix DABR match on hash based systems

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: powerpc-fix-dabr-match-on-hash-based-systems.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From f23ab3efb1b30cc5c5ef5ae4ef294ed467f30675 Mon Sep 17 00:00:00 2001

From: Benjamin Herrenschmidt benh@kernel.crashing.org Date: Fri, 10 Nov 2017 12:15:00 +1100 Subject: powerpc: Fix DABR match on hash based systems

From: Benjamin Herrenschmidt benh@kernel.crashing.org

commit f23ab3efb1b30cc5c5ef5ae4ef294ed467f30675 upstream.

Commit 398a719d34a1 ("powerpc/mm: Update bits used to skip hash_page") mistakenly dropped the DSISR_DABRMATCH bit from the mask of bit tested to skip trying to hash a page.

As a result, the DABR matches would no longer be detected.

This adds it back. We open code it in the 2 places where it matters rather than fold it into DSISR_BAD_FAULT_32S/64S because this isn't technically a bad fault and while we would never hit it with the current code, I prefer if page_fault_is_bad() didn't trigger on these.

Fixes: 398a719d34a1 ("powerpc/mm: Update bits used to skip hash_page") Cc: stable@vger.kernel.org # v4.14 Tested-by: Pedro Miraglia Franco de Carvalho pedromfc@br.ibm.com Signed-off-by: Benjamin Herrenschmidt benh@kernel.crashing.org Signed-off-by: Naveen N. Rao naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/powerpc/kernel/exceptions-64s.S | 2 +- arch/powerpc/kernel/head_32.S | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1617,7 +1617,7 @@ USE_TEXT_SECTION() .balign IFETCH_ALIGN_BYTES do_hash_page: #ifdef CONFIG_PPC_STD_MMU_64 - lis r0,DSISR_BAD_FAULT_64S@h + lis r0,(DSISR_BAD_FAULT_64S|DSISR_DABRMATCH)@h ori r0,r0,DSISR_BAD_FAULT_64S@l and. r0,r4,r0 /* weird error? */ bne- handle_page_fault /* if not, try to insert a HPTE */ --- a/arch/powerpc/kernel/head_32.S +++ b/arch/powerpc/kernel/head_32.S @@ -388,7 +388,7 @@ DataAccess: EXCEPTION_PROLOG mfspr r10,SPRN_DSISR stw r10,_DSISR(r11) - andis. r0,r10,DSISR_BAD_FAULT_32S@h + andis. r0,r10,(DSISR_BAD_FAULT_32S|DSISR_DABRMATCH)@h bne 1f /* if not, try to put a PTE */ mfspr r4,SPRN_DAR /* into the hash table */ rlwinm r3,r10,32-15,21,21 /* DSISR_STORE -> _PAGE_RW */

Patches currently in stable-queue which might be from benh@kernel.crashing.org are

queue-4.14/powerpc-fix-dabr-match-on-hash-based-systems.patch