linux-kernel - [PATCH 5.10 047/236] m68k: Fix invalid RMW

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Message-Id: <20210913131101.948106276@linuxfoundation.org>
Date:   Mon, 13 Sep 2021 15:12:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, kernel test robot <lkp@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 047/236] m68k: Fix invalid RMW_INSNS on CPUs that lack CAS

From: Geert Uytterhoeven <geert@...ux-m68k.org>

[ Upstream commit 2189e928b62e91d8efbc9826ae7c0968f0d55790 ]

When enabling CONFIG_RMW_INSNS in e.g. a Coldfire build:

    {standard input}:3068: Error: invalid instruction for this architecture; needs 68020 or higher (68020 [68k, 68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060]) -- statement `casl %d4,%d0,(%a6)' ignored

Fix this by (a) adding a new config symbol to track if support for any
CPU that lacks the CAS instruction is enabled, and (b) making
CONFIG_RMW_INSNS depend on the new symbol not being set.

Fixes: 0e152d80507b75c0 ("m68k: reorganize Kconfig options to improve mmu/non-mmu selections")
Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Acked-by: Arnd Bergmann <arnd@...db.de>
Link: https://lore.kernel.org/r/20210725104413.318932-1-geert@linux-m68k.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/m68k/Kconfig.cpu | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/m68k/Kconfig.cpu b/arch/m68k/Kconfig.cpu
index 694c4fca9f5d..c17205da47fe 100644
--- a/arch/m68k/Kconfig.cpu
+++ b/arch/m68k/Kconfig.cpu
@@ -25,6 +25,7 @@ config COLDFIRE
 	bool "Coldfire CPU family support"
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select CPU_HAS_NO_BITFIELDS
+	select CPU_HAS_NO_CAS
 	select CPU_HAS_NO_MULDIV64
 	select GENERIC_CSUM
 	select GPIOLIB
@@ -38,6 +39,7 @@ config M68000
 	bool "MC68000"
 	depends on !MMU
 	select CPU_HAS_NO_BITFIELDS
+	select CPU_HAS_NO_CAS
 	select CPU_HAS_NO_MULDIV64
 	select CPU_HAS_NO_UNALIGNED
 	select GENERIC_CSUM
@@ -53,6 +55,7 @@ config M68000
 config MCPU32
 	bool
 	select CPU_HAS_NO_BITFIELDS
+	select CPU_HAS_NO_CAS
 	select CPU_HAS_NO_UNALIGNED
 	select CPU_NO_EFFICIENT_FFS
 	help
@@ -357,7 +360,7 @@ config ADVANCED
 
 config RMW_INSNS
 	bool "Use read-modify-write instructions"
-	depends on ADVANCED
+	depends on ADVANCED && !CPU_HAS_NO_CAS
 	help
 	  This allows to use certain instructions that work with indivisible
 	  read-modify-write bus cycles. While this is faster than the
@@ -411,6 +414,9 @@ config NODES_SHIFT
 config CPU_HAS_NO_BITFIELDS
 	bool
 
+config CPU_HAS_NO_CAS
+	bool
+
 config CPU_HAS_NO_MULDIV64
 	bool
 
-- 
2.30.2