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From:   Sami Tolvanen <samitolvanen@google.com>
Date:   Thu, 30 Jul 2020 08:13:05 -0700
Message-ID: <CABCJKucS-DXPkHMCPKpbFduZApRdw=1DL4+YhULAsUNn=o-dTA@mail.gmail.com>
Subject: Re: [PATCH] arm64/alternatives: move length validation inside the subsection
To:     Catalin Marinas <catalin.marinas@arm.com>
Cc:     Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Kees Cook <keescook@chromium.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        stable@vger.kernel.org
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On Thu, Jul 30, 2020 at 5:22 AM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Wed, Jul 29, 2020 at 02:51:52PM -0700, Sami Tolvanen wrote:
> > Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement
> > sequences") breaks LLVM's integrated assembler, because due to its
> > one-pass design, it cannot compute instruction sequence lengths before the
> > layout for the subsection has been finalized. This change fixes the build
> > by moving the .org directives inside the subsection, so they are processed
> > after the subsection layout is known.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1078
> > Cc: <stable@vger.kernel.org> # 4.14+
>
> Commit f7b93d42945c went in 5.8-rc4. Why is this cc stable from 4.14? If
> Will picks it up for 5.8, it doesn't even need a cc stable.

Greg or Sasha can probably answer why, but this patch is in 4.14.189,
4.19.134, 5.4.53, and 5.7.10, which ended up breaking some downstream
Android kernel builds.

> Please add a Fixes: tag as well.

Sure, I'll send v2 shortly with the tag. Thanks.

Sami