arc770: backport upstream fix for unaligned access

This commit reverts 42f3c1fe ("arc770: fix broken upstream change")
and simultaneously adds back-ported fix from Linus' tree:
a524c218bc94 ("ARC: [arcompact] brown paper bag bug in unaligned
access delay slot fixup").

Note mentioned patch will appear in stable trees soon as well so
IMHO there's not much sense in adding this separate patch in lede/master branch.
As well as we will get rid of it here in 17.01 once we bump 4.4 kernel here
later down the line.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Felix Fietkau <nbd@nbd.name>
Cc: John Crispin <john@phrozen.org>
Cc: Jo-Philipp Wich <jo@mein.io>

target/linux/arc770/patches-4.4/001-ARC-arcompact-brown-paper-bag-bug-in-unaligned-access-delay-slot-fixup.patch

+From patchwork Tue Feb  7 17:44:58 2017
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: ARC: [arcompact] brown paper bag bug in unaligned access delay slot
+ fixup
+From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
+X-Patchwork-Id: 725238
+Message-Id: <1486489498-9221-1-git-send-email-vgupta@synopsys.com>
+To: Linus Torvalds <torvalds@linux-foundation.org>
+Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>,
+ linux-snps-arc@lists.infradead.org, Jo-Philipp Wich <jo@mein.io>,
+ linux-kernel@vger.kernel.org, stable@vger.kernel.org
+Date: Tue, 7 Feb 2017 09:44:58 -0800
+
+Reported-by: Jo-Philipp Wich <jo@mein.io>
+Fixes: 9aed02feae57bf7 ("ARC: [arcompact] handle unaligned access delay slot")
+Cc: linux-kernel@vger.kernel.org
+Cc: linux-snps-arc@lists.infradead.org
+Cc: stable@vger.kernel.org
+Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
+---
+ arch/arc/kernel/unaligned.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c
+index 91ebe382147f..5f69c3bd59bb 100644
+--- a/arch/arc/kernel/unaligned.c
++++ b/arch/arc/kernel/unaligned.c
+@@ -243,7 +243,7 @@ int misaligned_fixup(unsigned long address, struct pt_regs *regs,
+ 
+ 	/* clear any remanants of delay slot */
+ 	if (delay_mode(regs)) {
+-		regs->ret = regs->bta ~1U;
++		regs->ret = regs->bta & ~1U;
+ 		regs->status32 &= ~STATUS_DE_MASK;
+ 	} else {
+ 		regs->ret += state.instr_len;

target/linux/arc770/patches-4.4/900-revert-unaligned-access-delay-corner-case.patch

-From: Jo-Philipp Wich <jo@mein.io>
-Date: Tue, 7 Feb 2017 09:26:00 +0100
-Subject: [PATCH] arc: revert broken upstream change
-
-The upstream commit
-"9aed02f ARC: [arcompact] handle unaligned access delay slot corner case"
-introduced a syntax error in arch/arc/kernel/unaligned.c, leading to the
-following build failure:
-
-    arch/arc/kernel/unaligned.c: In function 'misaligned_fixup':
-    arch/arc/kernel/unaligned.c:246:25: error: expected ';' before '~' token
-       regs->ret = regs->bta ~1U;
-                         ^
-    make[6]: *** [arch/arc/kernel/unaligned.o] Error 1
-
-This patch reverts the offending change until an upstream fix is available.
-
-Signed-off-by: Jo-Philipp Wich <jo@mein.io>
---- a/arch/arc/kernel/unaligned.c
-+++ b/arch/arc/kernel/unaligned.c
-@@ -241,9 +241,8 @@ 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 ~1U;
-+		regs->ret = regs->bta;
- 		regs->status32 &= ~STATUS_DE_MASK;
- 	} else {
- 		regs->ret += state.instr_len;