linux-kernel - [PATCH] LoongArch: Disable module from accessing external data directly

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Message-ID: <20231108040447.288870-1-wangrui@loongson.cn>
Date:   Wed,  8 Nov 2023 12:04:47 +0800
From:   WANG Rui <wangrui@...ngson.cn>
To:     Huacai Chen <chenhuacai@...nel.org>
Cc:     WANG Xuerui <kernel@...0n.name>, Xi Ruoyao <xry111@...111.site>,
        linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev,
        linux-kbuild@...r.kernel.org, llvm@...ts.linux.dev,
        loongson-kernel@...ts.loongnix.cn, WANG Rui <wangrui@...ngson.cn>
Subject: [PATCH] LoongArch: Disable module from accessing external data directly

The distance between vmlinux and the module is too far so that PC-REL
cannot be accessed directly, only GOT.

When compiling module with GCC, the option `-mdirect-extern-access` is
disabled by default. The Clang option `-fdirect-access-external-data`
is enabled by default, so it needs to be explicitly disabled.

Signed-off-by: WANG Rui <wangrui@...ngson.cn>
---
 arch/loongarch/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index b86f2ff31659..9eeb0c05f3f4 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -68,6 +68,8 @@ LDFLAGS_vmlinux			+= -static -n -nostdlib
 ifdef CONFIG_AS_HAS_EXPLICIT_RELOCS
 cflags-y			+= $(call cc-option,-mexplicit-relocs)
 KBUILD_CFLAGS_KERNEL		+= $(call cc-option,-mdirect-extern-access)
+KBUILD_AFLAGS_MODULE		+= $(call cc-option,-fno-direct-access-external-data)
+KBUILD_CFLAGS_MODULE		+= $(call cc-option,-fno-direct-access-external-data)
 KBUILD_AFLAGS_MODULE		+= $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
 KBUILD_CFLAGS_MODULE		+= $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
 else
-- 
2.42.1