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

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Message-ID: <188dcb34-4e8e-7636-e31d-2ae451dac2ff@southpole.se>
Date:   Fri, 24 Feb 2017 10:32:32 +0100
From:   Jonas Bonn <jonas@...thpole.se>
To:     Stafford Horne <shorne@...il.com>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
Cc:     linux@...ck-us.net, openrisc@...ts.librecores.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 20/24] openrisc: entry: Fix delay slot detection

On 02/24/2017 05:32 AM, Stafford Horne wrote:
> 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.

This wants to be two patches as you are changing two different things.

/Joans

>
> 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
>