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Date: Mon, 20 Nov 2017 21:29:41 +0000
From: Alex Matveev <alxmtvv@gmail.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Sami Tolvanen <samitolvanen@google.com>,
        Andi Kleen <ak@linux.intel.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
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        Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
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Subject: Re: [PATCH v2 16/18] arm64: crypto: disable LTO for aes-ce-cipher.c
Message-ID: <20171120212941.051d11c4@delmar.localdomain>
In-Reply-To: <20171120152014.hftuded4zxwn2r7m@lakrids.cambridge.arm.com>
References: <20171115213428.22559-1-samitolvanen@google.com>
 <20171115213428.22559-17-samitolvanen@google.com>
 <20171120152014.hftuded4zxwn2r7m@lakrids.cambridge.arm.com>
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On Mon, 20 Nov 2017 15:20:14 +0000
Mark Rutland <mark.rutland@arm.com> wrote:

> On Wed, Nov 15, 2017 at 01:34:26PM -0800, Sami Tolvanen wrote:
> > CONFIG_LTO_CLANG requires the use of clang's integrated assembler,
> > which doesn't understand the inline assembly in aes-ce-cipher.c.
> > Disable LTO for the file to work around the issue.  
> 
> Could you elaborate on what the integrated asembler doesn't like?
> 
> It's not entirely clear at a glance, as the asm in that file doesn't
> seem to do anything that obscure.
> 
> Is it a bug?

Turns out, integrated assembler doesn't like this instruction in
aes_sub():
	umov	%w[out], v0.4s[0]

Specifically, it barks at "v0.4s[0]" part. And the way I read the spec,
it's quite correct in not accepting this argument. From UMOV
description:

UMOV <Wd>, <Vn>.<Ts>[<index>]

...

<Ts> For the 32-bit variant: is an element size specifier, encoded in
the "imm5" field. It can have the following values:
	B	when imm5 = xxxx1
	H	when imm5 = xxx10
	S	when imm5 = xx100


With "v0.s[0]" it builds fine.

Ard, since this is your code, can you comment? Feels like a typo.

Regards,
Alex

From mboxrd@z Thu Jan  1 00:00:00 1970
From: alxmtvv@gmail.com (Alex Matveev)
Date: Mon, 20 Nov 2017 21:29:41 +0000
Subject: [PATCH v2 16/18] arm64: crypto: disable LTO for aes-ce-cipher.c
In-Reply-To: <20171120152014.hftuded4zxwn2r7m@lakrids.cambridge.arm.com>
References: <20171115213428.22559-1-samitolvanen@google.com>
 <20171115213428.22559-17-samitolvanen@google.com>
 <20171120152014.hftuded4zxwn2r7m@lakrids.cambridge.arm.com>
Message-ID: <20171120212941.051d11c4@delmar.localdomain>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, 20 Nov 2017 15:20:14 +0000
Mark Rutland <mark.rutland@arm.com> wrote:

> On Wed, Nov 15, 2017 at 01:34:26PM -0800, Sami Tolvanen wrote:
> > CONFIG_LTO_CLANG requires the use of clang's integrated assembler,
> > which doesn't understand the inline assembly in aes-ce-cipher.c.
> > Disable LTO for the file to work around the issue.  
> 
> Could you elaborate on what the integrated asembler doesn't like?
> 
> It's not entirely clear at a glance, as the asm in that file doesn't
> seem to do anything that obscure.
> 
> Is it a bug?

Turns out, integrated assembler doesn't like this instruction in
aes_sub():
	umov	%w[out], v0.4s[0]

Specifically, it barks at "v0.4s[0]" part. And the way I read the spec,
it's quite correct in not accepting this argument. From UMOV
description:

UMOV <Wd>, <Vn>.<Ts>[<index>]

...

<Ts> For the 32-bit variant: is an element size specifier, encoded in
the "imm5" field. It can have the following values:
	B	when imm5 = xxxx1
	H	when imm5 = xxx10
	S	when imm5 = xx100


With "v0.s[0]" it builds fine.

Ard, since this is your code, can you comment? Feels like a typo.

Regards,
Alex