linux-kernel - Re: [PATCH v3 3/4] arm64: mm: support ARCH_MMAP_RND

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: <20151125120601.GC3109@e104818-lin.cambridge.arm.com>
Date:	Wed, 25 Nov 2015 12:06:01 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	Daniel Cashman <dcashman@...roid.com>
Cc:	Will Deacon <will.deacon@....com>, dcashman@...gle.com,
	linux-doc@...r.kernel.org, linux-mm@...ck.org, hpa@...or.com,
	mingo@...nel.org, aarcange@...hat.com, linux@....linux.org.uk,
	corbet@....net, xypron.glpk@....de, x86@...nel.org,
	hecmargi@....es, mgorman@...e.de, rientjes@...gle.com, bp@...e.de,
	nnk@...gle.com, dzickus@...hat.com, keescook@...omium.org,
	jpoimboe@...hat.com, tglx@...utronix.de, n-horiguchi@...jp.nec.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	salyzyn@...roid.com, ebiederm@...ssion.com, jeffv@...gle.com,
	akpm@...ux-foundation.org, kirill.shutemov@...ux.intel.com
Subject: Re: [PATCH v3 3/4] arm64: mm: support ARCH_MMAP_RND_BITS.

On Mon, Nov 23, 2015 at 10:55:16AM -0800, Daniel Cashman wrote:
> On 11/23/2015 07:04 AM, Will Deacon wrote:
> > On Wed, Nov 18, 2015 at 03:20:07PM -0800, Daniel Cashman wrote:
> >> +config ARCH_MMAP_RND_BITS_MAX
> >> +       default 20 if ARM64_64K_PAGES && ARCH_VA_BITS=39

Where is ARCH_VA_BITS defined? We only have options like
ARM64_VA_BITS_39.

BTW, we no longer allow the 64K pages and 39-bit VA combination.

> >> +       default 24 if ARCH_VA_BITS=39
> >> +       default 23 if ARM64_64K_PAGES && ARCH_VA_BITS=42
> >> +       default 27 if ARCH_VA_BITS=42
> >> +       default 29 if ARM64_64K_PAGES && ARCH_VA_BITS=48
> >> +       default 33 if ARCH_VA_BITS=48
> >> +       default 15 if ARM64_64K_PAGES
> >> +       default 19
> >> +
> >> +config ARCH_MMAP_RND_COMPAT_BITS_MIN
> >> +       default 7 if ARM64_64K_PAGES
> >> +       default 11
> > 
> > FYI: we now support 16k pages too, so this might need updating. It would
> > be much nicer if this was somehow computed rather than have the results
> > all open-coded like this.
> 
> Yes, I ideally wanted this to be calculated based on the different page
> options and VA_BITS (which itself has a similar stanza), but I don't
> know how to do that/if it is currently supported in Kconfig. This would
> be even more desirable with the addition of 16K_PAGES, as with this
> setup we have a combinatorial problem.

For KASan, we ended up calculating KASAN_SHADOW_OFFSET in
arch/arm64/Makefile. What would the formula be for the above
ARCH_MMAP_RND_BITS_MAX?

-- 
Catalin
--
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/