[PATCH v2 4/7] MIPS: Detect toolchain support of o32 ABI with 64 bit CPU

From: Jiaxun Yang <jiaxun.yang@flygoat.com>
To: linux-mips@vger.kernel.org
Cc: llvm@lists.linux.dev, tsbogend@alpha.franken.de,
	ndesaulniers@google.com, nathan@kernel.org,
	Jiaxun Yang <jiaxun.yang@flygoat.com>
Subject: [PATCH v2 4/7] MIPS: Detect toolchain support of o32 ABI with 64 bit CPU
Date: Fri, 14 Apr 2023 09:06:58 +0100	[thread overview]
Message-ID: <20230414080701.15503-5-jiaxun.yang@flygoat.com> (raw)
In-Reply-To: <20230414080701.15503-1-jiaxun.yang@flygoat.com>

LLVM is not happy with using o32 ABI on 64 bit CPU, thus build 32 bit
kernel is unsupported.

Detect this in Kconfig to prevent user select 32 bit kernel with
unsupported toolchain.

Link: https://github.com/ClangBuiltLinux/linux/issues/884
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
---
 arch/mips/Kconfig | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 0cd9cd01b7ab..2374f859e001 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2016,6 +2016,7 @@ choice
 config 32BIT
 	bool "32-bit kernel"
 	depends on CPU_SUPPORTS_32BIT_KERNEL && SYS_SUPPORTS_32BIT_KERNEL
+	depends on CC_HAS_O32_ABI
 	select TRAD_SIGNALS
 	help
 	  Select this option if you want to build a 32-bit kernel.
@@ -3137,7 +3138,7 @@ config COMPAT
 
 config MIPS32_O32
 	bool "Kernel support for o32 binaries"
-	depends on 64BIT
+	depends on 64BIT && CC_HAS_O32_ABI
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select COMPAT
 	select MIPS32_COMPAT
@@ -3185,6 +3186,10 @@ config CC_HAS_DADDI_WORKAROUNDS
 config CC_HAS_BROKEN_INLINE_COMPAT_BRANCH
 	def_bool y if CC_IS_CLANG
 
+config CC_HAS_O32_ABI
+	def_bool y
+	depends on !CPU_SUPPORTS_64BIT_KERNEL || $(cc-option,-march=mips3 -mabi=32)
+
 config AS_HAS_MSA
 	def_bool $(cc-option,-Wa$(comma)-mmsa)
 
-- 
2.39.2 (Apple Git-143)

