Re: [PATCH v2] linux-user/elfload: Implement ELF_HWCAP for RISC-V

[Richard Henderson]

On 7/4/21 11:43 PM, Kito Cheng wrote:
> +static uint32_t get_elf_hwcap(void)
> +{
> +    RISCVCPU *cpu = RISCV_CPU(thread_cpu);
> +    uint32_t hwcap = 0;
> +
> +#define MISA_BIT(EXT) (1 << (EXT - 'A'))
> +#define GET_EXT(EXT)                           \
> +    do {                                       \
> +        if (cpu->env.misa & MISA_BIT(EXT)) {    \
> +            hwcap |= MISA_BIT(EXT);            \
> +        }                                      \
> +    } while (0)
> +
> +    GET_EXT('I');
> +    GET_EXT('M');
> +    GET_EXT('A');
> +    GET_EXT('F');
> +    GET_EXT('D');
> +    GET_EXT('C');

You're not transforming the bits; there's no reason to be so around-the-bush about this. 
Just use

    uint32_t mask = MISA_BIT('I') | ...
    return cpu->env.misa & mask;


r~