linux-kernel - [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 17:12:29 +0100
From:   Gregory CLEMENT <gregory.clement@...tlin.com>
To:     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>,
        Gregory CLEMENT <gregory.clement@...tlin.com>
Subject: [PATCH v4 13/22] MIPS: traps: Give more explanations if ebase doesn't belong to KSEG0

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
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",
+				&ebase_pa);
 	}
 
 	if (cpu_has_mmips) {
-- 
2.42.0