linux-kernel - Re: [PATCH] riscv: Make sure toolchain supports zba before using zba instructions

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Message-ID: <7352dfbf-51e0-47b0-81e2-264f30989bf1@rivosinc.com>
Date: Fri, 28 Mar 2025 13:51:44 +0100
From: Clément Léger <cleger@...osinc.com>
To: Alexandre Ghiti <alexghiti@...osinc.com>
Cc: kernel test robot <lkp@...el.com>,
 Paul Walmsley <paul.walmsley@...ive.com>, Alexandre Ghiti <alex@...ti.fr>,
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
 Palmer Dabbelt <palmer@...belt.com>
Subject: Re: [PATCH] riscv: Make sure toolchain supports zba before using zba
 instructions



On 28/03/2025 12:54, Alexandre Ghiti wrote:
> Old toolchain like gcc 8.5.0 does not support zba, so we must check that
> the toolchain supports this extension before using it in the kernel.
> 
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202503281836.8pntHm6I-lkp@intel.com/
> Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
> ---
>  arch/riscv/Kconfig                     | 8 ++++++++
>  arch/riscv/include/asm/runtime-const.h | 5 +++--
>  2 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 0d8def968a7e..ae6303f15b28 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -735,6 +735,14 @@ config TOOLCHAIN_HAS_VECTOR_CRYPTO
>  	def_bool $(as-instr, .option arch$(comma) +v$(comma) +zvkb)
>  	depends on AS_HAS_OPTION_ARCH
>  
> +config TOOLCHAIN_HAS_ZBA
> +	bool
> +	default y
> +	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zba)
> +	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zba)
> +	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
> +	depends on AS_HAS_OPTION_ARCH
> +
>  config RISCV_ISA_ZBA

Hi Alex,

Why not add a "depends on TOOLCHAIN_HAS_ZBA" here so you don't have to
check for that config option when using CONFIG_RISCV_ISA_ZBA ? This is
done like that for ZBB and ZBC.

Thanks,

Clément

>  	bool "Zba extension support for bit manipulation instructions"
>  	default y
> diff --git a/arch/riscv/include/asm/runtime-const.h b/arch/riscv/include/asm/runtime-const.h
> index ea2e49c7149c..c07d049fdd5d 100644
> --- a/arch/riscv/include/asm/runtime-const.h
> +++ b/arch/riscv/include/asm/runtime-const.h
> @@ -77,7 +77,8 @@
>  	".long 1b - .\n\t"					\
>  	".popsection"						\
>  
> -#if defined(CONFIG_RISCV_ISA_ZBA) && defined(CONFIG_RISCV_ISA_ZBKB)
> +#if defined(CONFIG_RISCV_ISA_ZBA) && defined(CONFIG_TOOLCHAIN_HAS_ZBA)	\
> +	&& defined(CONFIG_RISCV_ISA_ZBKB)


>  #define runtime_const_ptr(sym)						\
>  ({									\
>  	typeof(sym) __ret, __tmp;					\
> @@ -93,7 +94,7 @@
>  		: [__ret] "=r" (__ret), [__tmp] "=r" (__tmp));		\
>  	__ret;								\
>  })
> -#elif defined(CONFIG_RISCV_ISA_ZBA)
> +#elif defined(CONFIG_RISCV_ISA_ZBA) && defined(CONFIG_TOOLCHAIN_HAS_ZBA)
>  #define runtime_const_ptr(sym)						\
>  ({									\
>  	typeof(sym) __ret, __tmp;					\