linux-kernel - Re: [PATCH 07/15] arm64: use -mno-implicit-float instead of -mgeneral-regs-only

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Message-ID: <20171103201823.GB137924@samitolvanen.mtv.corp.google.com>
Date:   Fri, 3 Nov 2017 13:18:23 -0700
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Mark Rutland <mark.rutland@....com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Greg Hackmann <ghackmann@...gle.com>,
        Matthias Kaehlcke <mka@...omium.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 07/15] arm64: use -mno-implicit-float instead of
 -mgeneral-regs-only

On Fri, Nov 03, 2017 at 12:06:15PM -0700, Kees Cook wrote:
> Should a clang version test be included, since we know at least 5.0 is
> need (with this fix)? There are distros with much earlier versions of
> clang, for example...

Greg knows better, but I remember him mentioning that upstream clang
doesn't generate any worse code with -mno-implicit-float, so there should
be no harm in using this workaround with all versions.

This might change in future, of course, so I don't have objections to
adding a check for clang version < 6.0 here.

Sami