Re: [RFC 1/2] x86/mm/cpa: always fail when user address is passed

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

On Tue, Jun 14, 2022 at 03:39:32PM +0900, Hyeonggon Yoo wrote:
> +
> +	if (WARN((IS_ENABLED(CONFIG_EFI) ? cpa->pgd != efi_mm.pgd : true)
> +		  && address <= TASK_SIZE_MAX,
> +		 KERN_WARNING "CPA: Got a user address"))
> +		return -EINVAL;

This looks rather unreadable.

Why not something like:

static bool cpa_addr_valid(struct cpa_data *cpa, unsigned long address)
{
	if (address > TASK_SIZE_MAX)
		return true;
	if (IS_ENABLED(CONFIG_EFI) && cpa->pgd == efi_mm.pgd)
		return true;
	return false;
}

....

	if (WARN_ON_ONCE(!cpa_addr_valid(cpa, address)))
		return -EINVAL;