Re: [PATCH V7 02/18] x86/fpu: Refactor arch_set_user_pkey_access()

[Thomas Gleixner]

On Tue, Aug 03 2021 at 21:32, ira weiny wrote:
> +/*
> + * Replace disable bits for @pkey with values from @flags
> + *
> + * Kernel users use the same flags as user space:
> + *     PKEY_DISABLE_ACCESS
> + *     PKEY_DISABLE_WRITE
> + */
> +u32 update_pkey_val(u32 pk_reg, int pkey, unsigned int flags)

pkey_.... please.

> +{
> +	int pkey_shift = pkey * PKR_BITS_PER_PKEY;
> +
> +	/*  Mask out old bit values */
> +	pk_reg &= ~(((1 << PKR_BITS_PER_PKEY) - 1) << pkey_shift);
> +
> +	/*  Or in new values */
> +	if (flags & PKEY_DISABLE_ACCESS)
> +		pk_reg |= PKR_AD_BIT << pkey_shift;
> +	if (flags & PKEY_DISABLE_WRITE)
> +		pk_reg |= PKR_WD_BIT << pkey_shift;
> +
> +	return pk_reg;

Also this code is silly.

#define PKEY_ACCESS_MASK	(PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE)

u32 pkey_update_pkval(u32 pkval, int pkey, u32 accessbits)
{
	int shift = pkey * PKR_BITS_PER_PKEY;

        if (WARN_ON_ONCE(accessbits & ~PKEY_ACCESS_MASK))
        	accessbits &= PKEY_ACCESS_MASK;

        pkval &= ~(PKEY_ACCESS_MASK << shift);
	return pkval | accessbit << pkey_shift;
}

See? It does not even need comments because it's self explaining and
uses sensible argument names matching the function name.