Re: [PATCH v2 16/18] arm64: crypto: disable LTO for aes-ce-cipher.c

Alex Matveev
2017-11-20T21:29:45Z

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