linux-kernel - Re: [PATCH 2/4] RISC-V: don't parse dt isa string to get rv32/rv64

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Date:   Mon, 01 May 2023 07:51:34 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     heiko@...ech.de
CC:     linux-riscv@...ts.infradead.org,
        Paul Walmsley <paul.walmsley@...ive.com>, heiko@...ech.de,
        kito.cheng@...ive.com, jrtc27@...c27.com,
        Conor Dooley <conor.dooley@...rochip.com>,
        matthias.bgg@...il.com, heinrich.schuchardt@...onical.com,
        greentime.hu@...ive.com, nick.knight@...ive.com,
        christoph.muellner@...ll.eu, philipp.tomsich@...ll.eu,
        Richard Henderson <richard.henderson@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
        heiko.stuebner@...ll.eu
Subject:     Re: [PATCH 2/4] RISC-V: don't parse dt isa string to get rv32/rv64

On Mon, 24 Apr 2023 12:49:09 PDT (-0700), heiko@...ech.de wrote:
> From: Heiko Stuebner <heiko.stuebner@...ll.eu>
>
> When filling hwcap the kernel already expects the isa string to start with
> rv32 if CONFIG_32BIT and rv64 if CONFIG_64BIT.
>
> So when recreating the runtime isa-string we can also just go the other way
> to get the correct starting point for it.
>
> Signed-off-by: Heiko Stuebner <heiko.stuebner@...ll.eu>
> ---
>  arch/riscv/kernel/cpu.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> index ebc478f0a16c..06c2f587a176 100644
> --- a/arch/riscv/kernel/cpu.c
> +++ b/arch/riscv/kernel/cpu.c
> @@ -244,7 +244,7 @@ static void strcat_isa_ext(char *isa_str)
>   */
>  static const char base_riscv_exts[13] = "imafdqcbkjpvh";
>
> -static char *riscv_create_isa_string(const char *isa)
> +static char *riscv_create_isa_string(void)
>  {
>  	int maxlen = 4;
>  	char *isa_str;
> @@ -261,7 +261,11 @@ static char *riscv_create_isa_string(const char *isa)
>  		return ERR_PTR(-ENOMEM);
>
>  	/* Print the rv[64/32] part */
> -	strncat(isa_str, isa, 4);
> +#if IS_ENABLED(CONFIG_32BIT)
> +	strncat(isa_str, "rv32", 4);
> +#elif IS_ENABLED(CONFIG_64BIT)
> +	strncat(isa_str, "rv64", 4);
> +#endif
>
>  	for (i = 0; i < sizeof(base_riscv_exts); i++) {
>  		if (__riscv_isa_extension_available(NULL, base_riscv_exts[i] - 'a'))
> @@ -280,7 +284,7 @@ static void print_isa(struct seq_file *f, const char *isa)
>
>  	seq_puts(f, "isa\t\t: ");
>
> -	isa_str = riscv_create_isa_string(isa);
> +	isa_str = riscv_create_isa_string();
>  	if (!IS_ERR(isa_str)) {
>  		seq_write(f, isa_str, strlen(isa_str));
>  		kfree(isa_str);

Conor pointed out this one, I just looked at the cover letter and got 
distracted by uABI stuff.  It's not directly fixing anything so I'm 
going to leave it out of this merge window, particularly given that it's 
tied up with the rest.

Reviewed-by: Palmer Dabbelt <palmer@...osinc.com>