Patch "ARC: [arcompact] handle unaligned access delay slot corner case" has been added to the 4.9-stable tree

Patch "ARC: [arcompact] handle unaligned access delay slot corner case" has been added to the 4.9-stable tree

[gregkh]

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

    ARC: [arcompact] handle unaligned access delay slot corner case

to the 4.9-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:
     arc-handle-unaligned-access-delay-slot-corner-case.patch
and it can be found in the queue-4.9 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 9aed02feae57bf7a40cb04ea0e3017cb7a998db4 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Fri, 27 Jan 2017 10:45:27 -0800
Subject: ARC: [arcompact] handle unaligned access delay slot corner case

From: Vineet Gupta <vgupta@synopsys.com>

commit 9aed02feae57bf7a40cb04ea0e3017cb7a998db4 upstream.

After emulating an unaligned access in delay slot of a branch, we
pretend as the delay slot never happened - so return back to actual
branch target (or next PC if branch was not taken).

Curently we did this by handling STATUS32.DE, we also need to clear the
BTA.T bit, which is disregarded when returning from original misaligned
exception, but could cause weirdness if it took the interrupt return
path (in case interrupt was acive too)

One ARC700 customer ran into this when enabling unaligned access fixup
for kernel mode accesses as well

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arc/kernel/unaligned.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/arc/kernel/unaligned.c
+++ b/arch/arc/kernel/unaligned.c
@@ -241,8 +241,9 @@ int misaligned_fixup(unsigned long addre
 	if (state.fault)
 		goto fault;
 
+	/* clear any remanants of delay slot */
 	if (delay_mode(regs)) {
-		regs->ret = regs->bta;
+		regs->ret = regs->bta ~1U;
 		regs->status32 &= ~STATUS_DE_MASK;
 	} else {
 		regs->ret += state.instr_len;


Patches currently in stable-queue which might be from vgupta@synopsys.com are

queue-4.9/arc-udelay-fix-inline-assembler-by-adding-lp_count-to-clobber-list.patch
queue-4.9/arc-handle-unaligned-access-delay-slot-corner-case.patch