Patch "powerpc: Fix DABR match on hash based systems" has been added to the 4.14-stable tree

Patch "powerpc: Fix DABR match on hash based systems" has been added to the 4.14-stable tree

[gregkh]

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;a=summary

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