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From: Kees Cook <keescook@chromium.org>
To: Will Deacon <will@kernel.org>
Cc: Sami Tolvanen <samitolvanen@google.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	clang-built-linux@googlegroups.com,
	kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-pci@vger.kernel.org
Subject: Re: [PATCH v7 00/17] Add support for Clang LTO
Date: Tue, 1 Dec 2020 09:31:00 -0800	[thread overview]
Message-ID: <202012010929.3788AF5@keescook> (raw)
In-Reply-To: <20201130120130.GF24563@willie-the-truck>

On Mon, Nov 30, 2020 at 12:01:31PM +0000, Will Deacon wrote:
> Hi Sami,
> 
> On Wed, Nov 18, 2020 at 02:07:14PM -0800, Sami Tolvanen wrote:
> > This patch series adds support for building the kernel with Clang's
> > Link Time Optimization (LTO). In addition to performance, the primary
> > motivation for LTO is to allow Clang's Control-Flow Integrity (CFI) to
> > be used in the kernel. Google has shipped millions of Pixel devices
> > running three major kernel versions with LTO+CFI since 2018.
> > 
> > Most of the patches are build system changes for handling LLVM bitcode,
> > which Clang produces with LTO instead of ELF object files, postponing
> > ELF processing until a later stage, and ensuring initcall ordering.
> > 
> > Note that v7 brings back arm64 support as Will has now staged the
> > prerequisite memory ordering patches [1], and drops x86_64 while we work
> > on fixing the remaining objtool warnings [2].
> 
> Sounds like you're going to post a v8, but that's the plan for merging
> that? The arm64 parts look pretty good to me now.

I haven't seen Masahiro comment on this in a while, so given the review
history and its use (for years now) in Android, I will carry v8 (assuming
all is fine with it) it in -next unless there are objections.

-- 
Kees Cook

  reply	other threads:[~2020-12-01 17:32 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-18 22:07 [PATCH v7 00/17] Add support for Clang LTO Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 01/17] tracing: move function tracer options to Kconfig Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 02/17] kbuild: add support for Clang LTO Sami Tolvanen
2020-11-18 23:48   ` Nick Desaulniers
2020-11-20 16:23     ` Sami Tolvanen
2020-11-20 19:47       ` Kees Cook
2020-11-20 20:29         ` Nathan Chancellor
2020-11-20 20:43           ` Kees Cook
2020-11-20 20:58             ` Sami Tolvanen
2020-11-20 23:59               ` Kees Cook
2020-11-21  1:46                 ` Sami Tolvanen
2020-11-21 20:11                   ` Kees Cook
2020-11-18 22:07 ` [PATCH v7 03/17] kbuild: lto: fix module versioning Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 04/17] kbuild: lto: limit inlining Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 05/17] kbuild: lto: merge module sections Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 06/17] kbuild: lto: remove duplicate dependencies from .mod files Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 07/17] init: lto: ensure initcall ordering Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 08/17] init: lto: fix PREL32 relocations Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 09/17] PCI: Fix PREL32 relocations for LTO Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 10/17] modpost: lto: strip .lto from module names Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 11/17] scripts/mod: disable LTO for empty.c Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 12/17] efi/libstub: disable LTO Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 13/17] drivers/misc/lkdtm: disable LTO for rodata.o Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 14/17] arm64: vdso: disable LTO Sami Tolvanen
2020-11-30 11:52   ` Will Deacon
2020-11-30 23:44     ` Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 15/17] KVM: arm64: disable LTO for the nVHE directory Sami Tolvanen
2020-11-23 10:21   ` David Brazdil
2020-11-23 18:34     ` Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 16/17] arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS Sami Tolvanen
2020-11-30 11:59   ` Will Deacon
2020-11-18 22:07 ` [PATCH v7 17/17] arm64: allow LTO_CLANG and THINLTO to be selected Sami Tolvanen
2020-11-30 12:00   ` Will Deacon
2020-11-18 23:42 ` [PATCH v7 00/17] Add support for Clang LTO Nick Desaulniers
2020-11-20 10:29   ` Ard Biesheuvel
2020-11-20 20:19     ` Nick Desaulniers
2020-11-20 23:30       ` Ard Biesheuvel
2020-11-20 23:53         ` Nick Desaulniers
2020-11-21  7:35           ` Ard Biesheuvel
2020-11-21 11:40           ` Marc Zyngier
2020-11-21  3:14     ` Nathan Chancellor
2020-11-20  4:04 ` Josh Poimboeuf
2020-11-20 20:25   ` Sami Tolvanen
2020-11-30 12:01 ` Will Deacon
2020-12-01 17:31   ` Kees Cook [this message]
2020-12-01 19:51     ` Nick Desaulniers
2020-12-01 21:38       ` Sami Tolvanen
2020-12-02  2:42     ` Masahiro Yamada
2020-12-02  5:46       ` Sami Tolvanen
2020-12-02 18:54       ` Kees Cook

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