linux-kernel - Re: [PATCH v4 13/22] MIPS: traps: Give more explanations if ebase doesn't belong to KSEG0

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Date:   Fri, 8 Dec 2023 19:45:20 +0300
From:   Sergey Shtylyov <s.shtylyov@....ru>
To:     Gregory CLEMENT <gregory.clement@...tlin.com>,
        Paul Burton <paulburton@...nel.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        <linux-mips@...r.kernel.org>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>,
        Tawfik Bayouk <tawfik.bayouk@...ileye.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Théo Lebrun <theo.lebrun@...tlin.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v4 13/22] MIPS: traps: Give more explanations if ebase
 doesn't belong to KSEG0

On 12/8/23 7:12 PM, Gregory CLEMENT wrote:

> Now that we support having the kernel in XPHYS and not only in KSEG0,
> the case where ebase doesn't belong to KSEG0 is more likely to
> occur. However, in this scenariowe encounter a significant and

   Scenario we? :-)

> intimidating stack dump without any explanation. To address this, we
> should eliminate the uninformative stack dump and replace it with a
> warning that provides a clear explanation of the issue.
> 
> Signed-off-by: Gregory CLEMENT <gregory.clement@...tlin.com>
> ---
>  arch/mips/kernel/traps.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
> index 68f1dd54cde1c..ec0cebfd2ef7b 100644
> --- a/arch/mips/kernel/traps.c
> +++ b/arch/mips/kernel/traps.c
> @@ -2420,10 +2420,13 @@ void __init trap_init(void)
>  		 * EVA is special though as it allows segments to be rearranged
>  		 * and to become uncached during cache error handling.
>  		 */
> -		if (!IS_ENABLED(CONFIG_EVA) && !WARN_ON(ebase_pa >= 0x20000000))
> +		if (!IS_ENABLED(CONFIG_EVA) && ebase_pa < 0x20000000)
>  			ebase = CKSEG0ADDR(ebase_pa);
>  		else
>  			ebase = (unsigned long)phys_to_virt(ebase_pa);
> +		if (ebase_pa >= 0x20000000)
> +			pr_warn("ebase(%pa) should better be in KSeg0",

   I think it's called KSEG0...

[...]

MBR, Sergey