riscv: fix detection of toolchain Zicbom support

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 <[email protected]>
Link: ClangBuiltLinux#1714
Link: https://storage.kernelci.org/next/master/next-20220920/riscv/defconfig+CONFIG_EFI=n/clang-16/logs/kernel.log
Fixes: 1631ba1 ("riscv: Add support for non-coherent devices using zicbom extension")
Signed-off-by: Conor Dooley <[email protected]>
Reviewed-by: Heiko Stuebner <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[Palmer: Check for ld-2.38, not 2.39, as 2.38 no longer errors.]
Signed-off-by: Palmer Dabbelt <[email protected]>

Author: ConchuOD

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 >= 23800
 
 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

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)