linux-kernel - [PATCH 1/2] ARC: Handle zero-overhead-loop in unaligned access handler

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Date:	Thu, 26 Sep 2013 15:44:56 +0200
From:	Mischa Jonker <Mischa.Jonker@...opsys.com>
To:	Vineet.Gupta1@...opsys.com, arnd@...db.de,
	linux-kernel@...r.kernel.org, arc-linux-dev@...opsys.com
Cc:	Mischa Jonker <Mischa.Jonker@...opsys.com>
Subject: [PATCH 1/2] ARC: Handle zero-overhead-loop in unaligned access handler

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>
---
 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 c0f832f..00ad070 100644
--- a/arch/arc/kernel/unaligned.c
+++ b/arch/arc/kernel/unaligned.c
@@ -233,6 +233,12 @@ 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;
-- 
1.7.9.5

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