On Tue, Feb 15, 2022 at 2:32 PM Atish Patra <atishp@xxxxxxxxxxxx> wrote:
>
> From: Tsukasa OI <research_trasio@xxxxxxxxxxxx>
>
> Currently, there is no usage for version numbers in extensions as
> any ratified non base ISA extension will always at v1.0.
>
> Extract the extension names in place for future parsing.
>
> Signed-off-by: Tsukasa OI <research_trasio@xxxxxxxxxxxx>
> [Improved commit text and comments]
> Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx>
> Tested-by: Heiko Stuebner <heiko@xxxxxxxxx>
> ---
> arch/riscv/kernel/cpufeature.c | 38 ++++++++++++++++++++++++++--------
> 1 file changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 9d5448542226..cd9eb34f8d11 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -119,9 +119,28 @@ void __init riscv_fill_hwcap(void)
> ext_long = true;
> /* Multi-letter extension must be delimited */
> for (; *isa && *isa != '_'; ++isa)
> - if (!islower(*isa) && !isdigit(*isa))
> + if (unlikely(!islower(*isa)
> + && !isdigit(*isa)))
> ext_err = true;
> - /* ... but must be ignored. */
> + /* Parse backwards */
> + ext_end = isa;
> + if (unlikely(ext_err))
> + break;
> + if (!isdigit(ext_end[-1]))
> + break;
> + /* Skip the minor version */
> + while (isdigit(*--ext_end))
> + ;
> + if (ext_end[0] != 'p'
> + || !isdigit(ext_end[-1])) {
> + /* Advance it to offset the pre-decrement */
> + ++ext_end;
> + break;
> + }
> + /* Skip the major version */
> + while (isdigit(*--ext_end))
> + ;
> + ++ext_end;
> break;
> default:
> if (unlikely(!islower(*ext))) {
> @@ -131,6 +150,7 @@ void __init riscv_fill_hwcap(void)
> /* Find next extension */
> if (!isdigit(*isa))
> break;
> + /* Skip the minor version */
This comment should be moved to PATCH2
> while (isdigit(*++isa))
> ;
> if (*isa != 'p')
> @@ -139,20 +159,20 @@ void __init riscv_fill_hwcap(void)
> --isa;
> break;
> }
> + /* Skip the major version */
Same applies to this comment as well.
> while (isdigit(*++isa))
> ;
> break;
> }
> if (*isa != '_')
> --isa;
> - /*
> - * TODO: Full version-aware handling including
> - * multi-letter extensions will be added in-future.
> - */
> - if (ext_err || ext_long)
> +
> + if (unlikely(ext_err))
> continue;
> - this_hwcap |= isa2hwcap[(unsigned char)(*ext)];
> - this_isa |= (1UL << (*ext - 'a'));
> + if (!ext_long) {
> + this_hwcap |= isa2hwcap[(unsigned char)(*ext)];
> + this_isa |= (1UL << (*ext - 'a'));
> + }
> }
>
> /*
> --
> 2.30.2
>
Otherwise it looks good to me.
Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
Regards,
Anup
