linux-kernel - [PATCH 1/4] ARC: Handle zero-overhead-loop in unaligned access handler

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Date:	Fri, 27 Sep 2013 16:27:34 +0530
From:	Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:	<linux-kernel@...r.kernel.org>, <linux-arch@...r.kernel.org>
CC:	<arc-linux-dev@...opsys.com>, <u.kleine-koenig@...gutronix.de>,
	Noam Camus <noamc@...hip.com>,
	Gilad Ben-Yossef <gilad@...yossef.com>,
	Mischa Jonker <Mischa.Jonker@...opsys.com>,
	Vineet Gupta <Vineet.Gupta1@...opsys.com>
Subject: [PATCH 1/4] ARC: Handle zero-overhead-loop in unaligned access handler

From: Mischa Jonker <mjonker@...opsys.com>

If a load or store is the last instruction in a zero-overhead-loop, and
it's misaligned, the loop would execute only once.

This fixes that problem.

Signed-off-by: Mischa Jonker <mjonker@...opsys.com>
Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
---
 arch/arc/kernel/unaligned.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c
index 28d1700..7ff5b5c 100644
--- a/arch/arc/kernel/unaligned.c
+++ b/arch/arc/kernel/unaligned.c
@@ -245,6 +245,12 @@ int misaligned_fixup(unsigned long address, struct pt_regs *regs,
 		regs->status32 &= ~STATUS_DE_MASK;
 	} else {
 		regs->ret += state.instr_len;
+
+		/* handle zero-overhead-loop */
+		if ((regs->ret == regs->lp_end) && (regs->lp_count)) {
+			regs->ret = regs->lp_start;
+			regs->lp_count--;
+		}
 	}
 
 	return 0;
-- 
1.8.1.2

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