linux-kernel - [PATCH v8 04/14] MIPS: traps: Give more explanations if ebase doesn't belong to KSEG0

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Date: Fri, 16 Feb 2024 18:42:13 +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 v8 04/14] MIPS: traps: Give more explanations if ebase doesn't belong to KSEG0

With the expanded support for placing the kernel in XPHYS rather than
just KSEG0, scenarios where ebase doesn't belong to KSEG0 are more
likely to occur. In such cases, we currently experience a substantial
and perplexing stack dump without any accompanying explanation. To
rectify this, we aim to replace the uninformative stack dump with a
warning that offers a clear explanation of the issue.

Reviewed-by: Jiaxun Yang <jiaxun.yang@...goat.com>
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 075bb08543eca..a9644c5e7ef4d 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -2345,10 +2345,13 @@ 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) {
-- 
2.43.0