From: linux@armlinux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/7] 2 1-byte checks more safer for memory_is_poisoned_16
Date: Sun, 18 Mar 2018 13:21:27 +0000 [thread overview]
Message-ID: <20180318132126.GA565@n2100.armlinux.org.uk> (raw)
In-Reply-To: <20180318125342.4278-2-liuwenliang@huawei.com>
On Sun, Mar 18, 2018 at 08:53:36PM +0800, Abbott Liu wrote:
> Because in some architecture(eg. arm) instruction set, non-aligned
> access support is not very well, so 2 1-byte checks is more
> safer than 1 2-byte check. The impact on performance is small
> because 16-byte accesses are not too common.
This is unnecessary:
1. a load of a 16-bit quantity will work as desired on modern ARMs.
2. Networking already relies on unaligned loads to work as per x86
(iow, an unaligned 32-bit load loads the 32-bits at the address
even if it's not naturally aligned, and that also goes for 16-bit
accesses.)
If these are rare (which you say above - "not too common") then it's
much better to leave the code as-is, because it will most likely be
faster on modern CPUs, and the impact for older generation CPUs is
likely to be low.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2018-03-18 13:21 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-18 12:53 [PATCH v2 0/7] KASan for arm Abbott Liu
2018-03-18 12:53 ` [PATCH 1/7] 2 1-byte checks more safer for memory_is_poisoned_16 Abbott Liu
2018-03-18 13:21 ` Russell King - ARM Linux [this message]
2018-03-18 12:53 ` [PATCH 2/7] Add TTBR operator for kasan_init Abbott Liu
2018-03-18 12:53 ` [PATCH 3/7] Disable instrumentation for some code Abbott Liu
2018-03-19 8:38 ` Marc Zyngier
2018-03-18 12:53 ` [PATCH 4/7] Replace memory function for kasan Abbott Liu
2018-03-18 12:53 ` [PATCH 5/7] Define the virtual space of KASan's shadow region Abbott Liu
2018-03-18 12:53 ` [PATCH 6/7] Initialize the mapping of KASan shadow memory Abbott Liu
2018-03-18 12:53 ` [PATCH 7/7] Enable KASan for arm Abbott Liu
2018-03-19 20:43 ` kbuild test robot
2018-03-18 19:13 ` [PATCH v2 0/7] " Florian Fainelli
2018-03-19 18:29 ` Florian Fainelli
2018-03-25 23:58 ` Joel Stanley
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