Date: Wed, 7 Dec 2016 16:59:13 +0000
From: Catalin Marinas <catalin.marinas@arm.com>
To: Yury Norov <ynorov@caviumnetworks.com>
Cc: linux-doc@vger.kernel.org, szabolcs.nagy@arm.com,
        heiko.carstens@de.ibm.com, cmetcalf@ezchip.com,
        philipp.tomsich@theobroma-systems.com, joseph@codesourcery.com,
        linux-arch@vger.kernel.org, zhouchengming1@huawei.com,
        Prasun.Kapoor@caviumnetworks.com, agraf@suse.de, geert@linux-m68k.org,
        kilobyte@angband.pl, manuel.montezelo@gmail.com, arnd@arndb.de,
        pinskia@gmail.com, linyongting@huawei.com, klimov.linux@gmail.com,
        broonie@kernel.org, bamvor.zhangjian@huawei.com,
        Bamvor Zhang Jian <bamvor.zhangjian@linaro.org>,
        linux-arm-kernel@lists.infradead.org, maxim.kuvyrkov@linaro.org,
        Nathan_Lynch@mentor.com, linux-kernel@vger.kernel.org,
        schwidefsky@de.ibm.com, davem@davemloft.net,
        christoph.muellner@theobroma-systems.com
Subject: Re: [PATCH 16/18] arm64: ptrace: handle ptrace_request differently
 for aarch32 and ilp32
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On Tue, Dec 06, 2016 at 11:55:08AM +0530, Yury Norov wrote:
> On Mon, Dec 05, 2016 at 04:34:23PM +0000, Catalin Marinas wrote:
> > On Fri, Oct 21, 2016 at 11:33:15PM +0300, Yury Norov wrote:
> > > New aarch32 ptrace syscall handler is introduced to avoid run-time
> > > detection of the task type.
> > 
> > What's wrong with the run-time detection? If it's just to avoid a
> > negligible overhead, I would rather keep the code simpler by avoiding
> > duplicating the generic compat_sys_ptrace().
> 
> Nothing wrong. This is how Arnd asked me to do. You already asked this
> question: http://lkml.iu.edu/hypermail/linux/kernel/1604.3/00930.html

Hmm, I completely forgot about this ;). There is still an advantage to
doing run-time checking if we avoid touching core code (less acks to
gather and less code duplication).

Let's see what Arnd says but the initial patch looked simpler.

-- 
Catalin