[PATCH 1/2] riscv: fix detection of toolchain Zicbom support

Conor Dooley
2022-10-06T17:36:28Z

From: Conor Dooley <conor.dooley@microchip.com>

It is not sufficient to check if a toolchain supports a particular
extension without checking if the linker supports that extension too.
For example, Clang 15 supports Zicbom but GNU bintutils 2.35.2 does
not, leading build errors like so:

riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zicbom1p0_zihintpause2p0: Invalid or unknown z ISA extension: 'zicbom'

Convert CC_HAS_ZICBOM to TOOLCHAIN_HAS_ZICBOM & check if the linker
also supports Zicbom.

Reported-by: Kevin Hilman <khilman@baylibre.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1714
Link: https://storage.kernelci.org/next/master/next-20220920/riscv/defconfig+CONFIG_EFI=n/clang-16/logs/kernel.log
Fixes: 1631ba1259d6 ("riscv: Add support for non-coherent devices using zicbom extension")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
arch/riscv/Kconfig | 10 ++++++----
arch/riscv/Makefile | 3 +--
2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d557cc50295d..6da36553158b 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -401,14 +401,16 @@ config RISCV_ISA_SVPBMT

If you don't know what to do here, say Y.

-config CC_HAS_ZICBOM
+config TOOLCHAIN_HAS_ZICBOM
bool
- default y if 64BIT && $(cc-option,-mabi=lp64 -march=rv64ima_zicbom)
- default y if 32BIT && $(cc-option,-mabi=ilp32 -march=rv32ima_zicbom)
+ default y
+ depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zicbom)
+ depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zicbom)
+ depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900

config RISCV_ISA_ZICBOM
bool "Zicbom extension support for non-coherent DMA operation"
- depends on CC_HAS_ZICBOM
+ depends on TOOLCHAIN_HAS_ZICBOM
depends on !XIP_KERNEL && MMU
select RISCV_DMA_NONCOHERENT
select RISCV_ALTERNATIVE
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 3fa8ef336822..3607d38edb4f 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -57,8 +57,7 @@ toolchain-need-zicsr-zifencei := $(call cc-option-yn, -march=$(riscv-march-y)_zi
riscv-march-$(toolchain-need-zicsr-zifencei) := $(riscv-march-y)_zicsr_zifencei

# Check if the toolchain supports Zicbom extension
-toolchain-supports-zicbom := $(call cc-option-yn, -march=$(riscv-march-y)_zicbom)
-riscv-march-$(toolchain-supports-zicbom) := $(riscv-march-y)_zicbom
+riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZICBOM) := $(riscv-march-y)_zicbom

# Check if the toolchain supports Zihintpause extension
toolchain-supports-zihintpause := $(call cc-option-yn, -march=$(riscv-march-y)_zihintpause)
--
2.37.3