linux-kernel - Re: [PATCH v4 5/6] RISC-V: Do no continue isa string parsing without correct XLEN

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Date:   Wed, 16 Feb 2022 12:46:05 +0100
From:   Heiko Stübner <heiko@...ech.de>
To:     linux-kernel@...r.kernel.org, Atish Patra <atishp@...osinc.com>
Cc:     Atish Patra <atishp@...osinc.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Atish Patra <atishp@...shpatra.org>,
        Anup Patel <anup@...infault.org>,
        Damien Le Moal <damien.lemoal@....com>,
        devicetree@...r.kernel.org, Jisheng Zhang <jszhang@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        linux-riscv@...ts.infradead.org,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v4 5/6] RISC-V: Do no continue isa string parsing without correct XLEN

Am Mittwoch, 16. Februar 2022, 01:29:10 CET schrieb Atish Patra:
> The isa string should begin with either rv64 or rv32. Otherwise, it is
> an incorrect isa string. Currently, the string parsing continues even if
> it doesnot begin with current XLEN.
> 
> Fix this by checking if it found "rv64" or "rv32" in the beginning.
> 
> Signed-off-by: Atish Patra <atishp@...osinc.com>
> ---
>  arch/riscv/kernel/cpufeature.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 59c70c104256..cb9c9e0aab31 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -84,6 +84,7 @@ void __init riscv_fill_hwcap(void)
>  	for_each_of_cpu_node(node) {
>  		unsigned long this_hwcap = 0;
>  		DECLARE_BITMAP(this_isa, RISCV_ISA_EXT_MAX);
> +		const char *temp;
>  
>  		if (riscv_of_processor_hartid(node) < 0)
>  			continue;
> @@ -93,6 +94,7 @@ void __init riscv_fill_hwcap(void)
>  			continue;
>  		}
>  
> +		temp = isa;
>  #if IS_ENABLED(CONFIG_32BIT)
>  		if (!strncmp(isa, "rv32", 4))
>  			isa += 4;
> @@ -100,6 +102,9 @@ void __init riscv_fill_hwcap(void)
>  		if (!strncmp(isa, "rv64", 4))
>  			isa += 4;
>  #endif
> +		/* The riscv,isa DT property must start with rv64 or rv32 */
> +		if (temp == isa)
> +			continue;

hmm, should (and can) this create some warning about the ignored
malformed ISA string?

Otherwise
Tested-by: Heiko Stuebner <heiko@...ech.de>

>  		bitmap_zero(this_isa, RISCV_ISA_EXT_MAX);
>  		for (; *isa; ++isa) {
>  			const char *ext = isa++;
>