linux-kernel - Re: [RFCv3][PATCH 1/3] create slow_virt_to

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <50F5B214.5060604@zytor.com>
Date:	Tue, 15 Jan 2013 11:46:28 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Dave Hansen <dave@...ux.vnet.ibm.com>
CC:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Gleb Natapov <gleb@...hat.com>, Avi Kivity <avi@...hat.com>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	Marcelo Tosatti <mtosatti@...hat.com>
Subject: Re: [RFCv3][PATCH 1/3] create slow_virt_to_phys()

On 01/09/2013 10:59 AM, Dave Hansen wrote:
> +	switch (level) {
> +	case PG_LEVEL_4K:
> +		psize = PAGE_SIZE;
> +		pmask = PAGE_MASK;
> +		break;
> +	case PG_LEVEL_2M:
> +		psize = PMD_PAGE_SIZE;
> +		pmask = PMD_PAGE_MASK;
> +		break;
> +#ifdef CONFIG_X86_64
> +	case PG_LEVEL_1G:
> +		psize = PUD_PAGE_SIZE;
> +		pmask = PUD_PAGE_MASK;
> +		break;
> +#endif
> +	default:
> +		BUG();
> +	}

I object to this switch statement.  If we are going to create new 
primitives, let's create a primitive that embody this and put it in 
pgtypes_types.h, especially since it is simply an algorithmic operation:

static inline unsigned long page_level_size(int level)
{
	return (PAGE_SIZE/PGDIR_SIZE) << (PGDIR_SHIFT*level);
}
static inline unsigned long page_level_shift(int level)
{
	return (PAGE_SHIFT-PGDIR_SHIFT) + (PGDIR_SHIFT*level);
}

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/