linux-kernel - Re: [PATCH v2 1/2] riscv: allow case-insensitive ISA string parsing

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Date:   Fri, 28 Apr 2023 20:27:53 +0100
From:   Conor Dooley <conor@...nel.org>
To:     Yangyu Chen <cyy@...self.name>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Andrew Jones <ajones@...tanamicro.com>,
        Wende Tan <twd2.me@...il.com>, Soha Jin <soha@...u.info>,
        Hongren Zheng <i@...ithal.me>
Subject: Re: [PATCH v2 1/2] riscv: allow case-insensitive ISA string parsing

Hey Yangyu,

On Fri, Apr 28, 2023 at 10:16:00PM +0800, Yangyu Chen wrote:
> According to RISC-V Hart Capabilities Table (RHCT) description in UEFI
> Forum ECR, the format of the ISA string is defined in the RISC-V
> unprivileged specification which is case-insensitive. However, the
> current ISA string parser in the kernel does not support ISA strings
> with uppercase letters.
> 
> This patch modifies the ISA string parser in the kernel to support
> case-insensitive ISA string parsing.

@Palmer, @Sunil
Just to note, we probably should get this applied *before* we enable ACPI,
right?

> 
> Signed-off-by: Yangyu Chen <cyy@...self.name>
> ---
>  arch/riscv/kernel/cpu.c        |  3 ++-
>  arch/riscv/kernel/cpufeature.c | 25 ++++++++++++-------------
>  2 files changed, 14 insertions(+), 14 deletions(-)

> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 59d58ee0f68d..d1991c12e546 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -119,13 +119,10 @@ void __init riscv_fill_hwcap(void)
>  		}
>  
>  		temp = isa;
> -#if IS_ENABLED(CONFIG_32BIT)
> -		if (!strncmp(isa, "rv32", 4))
> +		if (IS_ENABLED(CONFIG_32BIT) && !strncasecmp(isa, "rv32", 4))
>  			isa += 4;
> -#elif IS_ENABLED(CONFIG_64BIT)
> -		if (!strncmp(isa, "rv64", 4))
> +		else if (IS_ENABLED(CONFIG_64BIT) && !strncasecmp(isa, "rv64", 4))
>  			isa += 4;
> -#endif
>  		/* The riscv,isa DT property must start with rv64 or rv32 */
>  		if (temp == isa)
>  			continue;
> @@ -136,6 +133,7 @@ void __init riscv_fill_hwcap(void)
>  			bool ext_long = false, ext_err = false;
>  
>  			switch (*ext) {
> +			case 'S':

Capital S should never be emitted by QEMU, so there's no need to have
this use the workaround, right? IOW, move it between s & X.

Otherwise, this looks good to me:
Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>

Thanks,
Conor.

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