linux-kernel - [PATCH AUTOSEL 4.4 28/30] ARM: 9136/1: ARMv7-M uses BE-8, not BE-32

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Message-Id: <20211109010918.1192063-28-sashal@kernel.org>
Date:   Mon,  8 Nov 2021 20:09:16 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Arnd Bergmann <arnd@...db.de>,
        Vladimir Murzin <vladimir.murzin@....com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Sasha Levin <sashal@...nel.org>, linux@...linux.org.uk,
        ndesaulniers@...gle.com, wangkefeng.wang@...wei.com,
        u.kleine-koenig@...gutronix.de,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH AUTOSEL 4.4 28/30] ARM: 9136/1: ARMv7-M uses BE-8, not BE-32

From: Arnd Bergmann <arnd@...db.de>

[ Upstream commit 345dac33f58894a56d17b92a41be10e16585ceff ]

When configuring the kernel for big-endian, we set either BE-8 or BE-32
based on the CPU architecture level. Until linux-4.4, we did not have
any ARMv7-M platform allowing big-endian builds, but now i.MX/Vybrid
is in that category, adn we get a build error because of this:

arch/arm/kernel/module-plts.c: In function 'get_module_plt':
arch/arm/kernel/module-plts.c:60:46: error: implicit declaration of function '__opcode_to_mem_thumb32' [-Werror=implicit-function-declaration]

This comes down to picking the wrong default, ARMv7-M uses BE8
like ARMv7-A does. Changing the default gets the kernel to compile
and presumably works.

https://lore.kernel.org/all/1455804123-2526139-2-git-send-email-arnd@arndb.de/

Tested-by: Vladimir Murzin <vladimir.murzin@....com>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm/mm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 71115afb71a05..f46089b24588f 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -724,7 +724,7 @@ config CPU_BIG_ENDIAN
 config CPU_ENDIAN_BE8
 	bool
 	depends on CPU_BIG_ENDIAN
-	default CPU_V6 || CPU_V6K || CPU_V7
+	default CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M
 	help
 	  Support for the BE-8 (big-endian) mode on ARMv6 and ARMv7 processors.
 
-- 
2.33.0