[PATCH v2] riscv: Fix detecting FPU support in standard extension

[Padmarao.Begari at microchip.com]

> On Sat, 2022-11-05 at 14:02 +0800, Yu Chien Peter Lin wrote:
> 
> We should check the string until it hits underscore, in case it
> searches for the letters in the custom extension. For example,
> "rv64imac_xandes" will be treated as D extension support since
> there is a "d" in "andes", resulting illegal instruction caused
> by initializing FCSR.
> 
> Signed-off-by: Yu Chien Peter Lin <peterlin at andestech.com>
> ---
>  arch/riscv/cpu/cpu.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/riscv/cpu/cpu.c b/arch/riscv/cpu/cpu.c
> index 52ab02519f..d34c8efce0 100644
> --- a/arch/riscv/cpu/cpu.c
> +++ b/arch/riscv/cpu/cpu.c
> @@ -36,6 +36,7 @@ static inline bool supports_extension(char ext)
>  #ifdef CONFIG_CPU
>         struct udevice *dev;
>         char desc[32];
> +       int i;
> 
>         uclass_find_first_device(UCLASS_CPU, &dev);
>         if (!dev) {
> @@ -43,9 +44,16 @@ static inline bool supports_extension(char ext)
>                 return false;
>         }
>         if (!cpu_get_desc(dev, desc, sizeof(desc))) {
> -               /* skip the first 4 characters (rv32|rv64) */
> -               if (strchr(desc + 4, ext))
> -                       return true;
> +               /*
> +                * skip the first 4 characters (rv32|rv64) and
> +                * check until underscore
> +                */
> +               for (i = 4; i < sizeof(desc); i++) {
> +                       if (desc[i] == '_' || desc[i] == '\0')
> +                               break;
> +                       if (desc[i] == ext)
> +                               return true;
> +               }
> 

Reviewed-by: Padmarao Begari <padmarao.begari at microchip.com>

>         }
> 
>         return false;
> --
> 2.34.1
>