linux-kernel - Re: [PATCH 00/15] Add support for clang LTO

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Date:   Thu, 9 Nov 2017 11:03:45 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     AKASHI Takahiro <takahiro.akashi@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Greg Hackmann <ghackmann@...gle.com>,
        Matthias Kaehlcke <mka@...omium.org>,
        linux-arm-kernel@...ts.infradead.org, cdall@...aro.org,
        ard.biesheuvel@...aro.org
Subject: Re: [PATCH 00/15] Add support for clang LTO

On 09/11/17 10:54, AKASHI Takahiro wrote:
> On Sat, Nov 04, 2017 at 02:13:04AM +0000, Mark Rutland wrote:
>> On Fri, Nov 03, 2017 at 12:56:47PM -0700, Sami Tolvanen wrote:
>>> On Fri, Nov 03, 2017 at 07:26:35PM +0000, Mark Rutland wrote:
>>>> I guess that in Google you haven't tested on a platform with EL2
>>>> available?
>>>
>>> Correct. I'll look into this and include a fix in v2. Does this work on a
>>> clang build without LTO?
>>
>> I saw this on v4.14-rc7, with patch 7 (-mno-implicit-float), but no other
>> patches from this series (i.e. no LTO).
> 
> 
> Add -fno-jump-tables to ccflags-y of arch/arm64/kvm/hyp/Makefile.
> Without this option, clang generates a branch instruction (br x11)
> to an absolute (EL1) virtual address.

Instead of adding more compiler flags to the Makefile, is there any way
to have that as a function attribute?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...