linux-kernel - [PATCH v4 20/24] openrisc: entry: Fix delay slot detection

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Message-Id: <34caff307ead3a1b67a7226507082ace94e22875.1487910170.git.shorne@gmail.com>
Date:   Fri, 24 Feb 2017 13:32:40 +0900
From:   Stafford Horne <shorne@...il.com>
To:     Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
Cc:     linux@...ck-us.net, openrisc@...ts.librecores.org,
        linux-kernel@...r.kernel.org, Stafford Horne <shorne@...il.com>
Subject: [PATCH v4 20/24] openrisc: entry: Fix delay slot detection

Use execption SR stored in pt_regs for detection, the current SR is not
correct as the handler is running after return from exception.

Also, The code that checks for a delay slot uses a flag bitmask and then
wants to check if the result is not zero.  The test it implemented was
wrong.

Correct it by changing the test to check result against non zero.

Signed-off-by: Stafford Horne <shorne@...il.com>
---
 arch/openrisc/kernel/entry.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S
index daae2a4..bc65008 100644
--- a/arch/openrisc/kernel/entry.S
+++ b/arch/openrisc/kernel/entry.S
@@ -258,9 +258,9 @@ EXCEPTION_ENTRY(_data_page_fault_handler)
 
 #else
 
-	l.mfspr r6,r0,SPR_SR               // SR
+	l.lwz   r6,PT_SR(r3)               // SR
 	l.andi  r6,r6,SPR_SR_DSX           // check for delay slot exception
-	l.sfeqi r6,0x1                     // exception happened in delay slot
+	l.sfne  r6,r0                      // exception happened in delay slot
 	l.bnf   7f
 	 l.lwz  r6,PT_PC(r3)               // address of an offending insn
 
-- 
2.9.3