linux-kernel - [PATCH AUTOSEL 5.10 18/39] riscv: Use -mno-relax when using lld linker

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Date:   Mon,  7 Jun 2021 12:12:57 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Khem Raj <raj.khem@...il.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Sasha Levin <sashal@...nel.org>,
        linux-riscv@...ts.infradead.org
Subject: [PATCH AUTOSEL 5.10 18/39] riscv: Use -mno-relax when using lld linker

From: Khem Raj <raj.khem@...il.com>

[ Upstream commit ec3a5cb61146c91f0f7dcec8b7e7157a4879a9ee ]

lld does not implement the RISCV relaxation optimizations like GNU ld
therefore disable it when building with lld, Also pass it to
assembler when using external GNU assembler ( LLVM_IAS != 1 ), this
ensures that relevant assembler option is also enabled along. if these
options are not used then we see following relocations in objects

0000000000000000 R_RISCV_ALIGN     *ABS*+0x0000000000000002

These are then rejected by lld
ld.lld: error: capability.c:(.fixup+0x0): relocation R_RISCV_ALIGN requires unimplemented linker relaxation; recompile with -mno-relax but the .o is already compiled with -mno-relax

Signed-off-by: Khem Raj <raj.khem@...il.com>
Reviewed-by: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@...gle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/riscv/Makefile | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 0289a97325d1..e241e0e85ac8 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -36,6 +36,15 @@ else
 	KBUILD_LDFLAGS += -melf32lriscv
 endif
 
+ifeq ($(CONFIG_LD_IS_LLD),y)
+	KBUILD_CFLAGS += -mno-relax
+	KBUILD_AFLAGS += -mno-relax
+ifneq ($(LLVM_IAS),1)
+	KBUILD_CFLAGS += -Wa,-mno-relax
+	KBUILD_AFLAGS += -Wa,-mno-relax
+endif
+endif
+
 # ISA string setting
 riscv-march-$(CONFIG_ARCH_RV32I)	:= rv32ima
 riscv-march-$(CONFIG_ARCH_RV64I)	:= rv64ima
-- 
2.30.2