Re: [PATCH RFC V3 2/9] x86/fpu: Refactor arch_set_user_pkey_access() for PKS support

[Dave Hansen]

On 10/9/20 12:42 PM, ira.weiny@xxxxxxxxx wrote:
> +/*
> + * Update the pk_reg value and return it.

How about:

	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)
> +{
> +	int pkey_shift = pkey * PKR_BITS_PER_PKEY;
> +
> +	pk_reg &= ~(((1 << PKR_BITS_PER_PKEY) - 1) << pkey_shift);
> +
> +	if (flags & PKEY_DISABLE_ACCESS)
> +		pk_reg |= PKR_AD_BIT << pkey_shift;
> +	if (flags & PKEY_DISABLE_WRITE)
> +		pk_reg |= PKR_WD_BIT << pkey_shift;

I still think this deserves two lines of comments:

	/* Mask out old bit values */

	/* Or in new values */