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Subject: Re: [PATCH v4 13/22] MIPS: traps: Give more explanations if ebase
 doesn't belong to KSEG0
To:     Gregory CLEMENT <gregory.clement@bootlin.com>,
        Paul Burton <paulburton@kernel.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        <linux-mips@vger.kernel.org>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>
CC:     Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>,
        Tawfik Bayouk <tawfik.bayouk@mobileye.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        =?UTF-8?Q?Th=c3=a9o_Lebrun?= <theo.lebrun@bootlin.com>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>
References: <20231208161249.1827174-1-gregory.clement@bootlin.com>
 <20231208161249.1827174-14-gregory.clement@bootlin.com>
From:   Sergey Shtylyov <s.shtylyov@omp.ru>
Organization: Open Mobile Platform
Message-ID: <dc3f201b-308c-a2b9-d64c-530fd32f6b9d@omp.ru>
Date:   Fri, 8 Dec 2023 19:45:20 +0300
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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@bootlin.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