From: Arnd Bergmann <arnd@arndb.de>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: "open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>,
kbuild test robot <fengguang.wu@intel.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Herbert Xu <herbert@gondor.apana.org.au>,
kbuild-all@01.org
Subject: Re: [cryptodev:master 130/134] aes_generic.c:undefined reference to `_restgpr_31_x'
Date: Fri, 12 Jan 2018 22:29:01 +0100 [thread overview]
Message-ID: <CAK8P3a2YVVseBFNoDbwOtqR3-JHFuZ-WZD6-PzztNTO_X_soaw@mail.gmail.com> (raw)
In-Reply-To: <20180112204154.GM21977@gate.crashing.org>
On Fri, Jan 12, 2018 at 9:41 PM, Segher Boessenkool
<segher@kernel.crashing.org> wrote:
> On Fri, Jan 12, 2018 at 08:43:21PM +0100, Arnd Bergmann wrote:
>> On Fri, Jan 12, 2018 at 5:39 PM, Segher Boessenkool
>> We could theoretically work around it by turning that into
>> "#if defined(CONFIG_CC_OPTIMIZE_FOR_SIZE) ||
>> defined(CONFIG_CRYPTO_AES)", but that seems rather ugly.
>>
>> My earlier patch already tried to be more specific, turning very
>> specific optimizations off rather than moving from -O2 to -Os,
>> but that turned out to lead to significantly worse performance,
>> where -Os improved performance slightly. Is there a way
>> to ask powerpc compilers to use mostly -Os but not the
>> specific thing that makes it link to _restgpr_31_x?
>
> There is no such thing, sorry. Would be very hard to implement, and
> older compilers will never get it, so it won't help you anyway :-(
We use -Os only for gcc-7.1 and higher, where it produces faster
code for AES and avoids running into
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83356
> Maybe for now just enable it in crtsavres.S always, with a comment?
> That -Os workaround is hopefully not going to live long either...
It depends on whether or how soon someone comes up with a
better fix for PR83356.
gcc-8.0.0 is currently not affected by it, so we could limit the
workaround (and the hack in crtsavres.S) to gcc-7-only.
Arnd
next prev parent reply other threads:[~2018-01-12 21:29 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-12 14:11 [cryptodev:master 130/134] aes_generic.c:undefined reference to `_restgpr_31_x' kbuild test robot
2018-01-12 14:55 ` Arnd Bergmann
2018-01-12 16:39 ` Segher Boessenkool
2018-01-12 19:43 ` Arnd Bergmann
2018-01-12 20:41 ` Segher Boessenkool
2018-01-12 21:29 ` Arnd Bergmann [this message]
2018-01-12 21:41 ` Segher Boessenkool
2018-01-12 21:45 ` Arnd Bergmann
2018-01-12 22:10 ` Segher Boessenkool
2018-01-14 21:40 ` Arnd Bergmann
2018-01-15 0:21 ` Segher Boessenkool
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