From: Kees Cook <keescook@chromium.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, Sami Tolvanen <samitolvanen@google.com>,
"H. Peter Anvin" <hpa@zytor.com>,
LKML <linux-kernel@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [PATCH] x86: Enable clang LTO for 32-bit as well
Date: Fri, 30 Apr 2021 16:04:49 -0700 [thread overview]
Message-ID: <202104301604.9FB001A9@keescook> (raw)
In-Reply-To: <CAKwvOdngd5inT_sQP-PgqaMpVzfSdwoyhCcUSdS+09u=PKUEyA@mail.gmail.com>
On Fri, Apr 30, 2021 at 01:58:57PM -0700, Nick Desaulniers wrote:
> On Thu, Apr 29, 2021 at 4:26 PM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > Commit b33fff07e3e3 ("x86, build: allow LTO to be selected") enabled
> > support for LTO for x86_64 but 32-bit works fine as well.
> >
> > I tested the following config combinations:
> >
> > * i386_defconfig + CONFIG_LTO_CLANG_FULL=y
> >
> > * i386_defconfig + CONFIG_LTO_CLANG_THIN=y
> >
> > * ARCH=i386 allmodconfig + CONFIG_LTO_CLANG_THIN=y
>
> For allmodconfig
> HAS_LTO_CLANG cannot be selected unless
> FTRACE
> GCOV_KERNEL
> are disabled.
>
> I was able to run through similar tests, though I only did so for ToT LLVM.
>
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> Tested-by: Nick Desaulniers <ndesaulniers@google.com>
>
> I additionally tried full LTO allmodconfig. Full LTO allmodconfig can
> be tested by disabling CONFIG_COMPILE_TEST (in addition to the above),
> though I hit https://github.com/ClangBuiltLinux/linux/issues/1215 (the
> xfs tests aren't building under LTO). I think this change though is
> fine, and enables another avenue to help us debug that failure.
Awesome; thank you both! I'll collect this for -next once -rc2 is
released.
--
Kees Cook
next prev parent reply other threads:[~2021-04-30 23:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 23:26 [PATCH] x86: Enable clang LTO for 32-bit as well Nathan Chancellor
2021-04-30 20:58 ` Nick Desaulniers
2021-04-30 23:04 ` Kees Cook [this message]
2021-06-10 17:11 ` Kees Cook
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