From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>,
Sami Tolvanen <samitolvanen@google.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Alex Matveev <alxmtvv@gmail.com>, Andi Kleen <ak@linux.intel.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Greg Hackmann <ghackmann@google.com>,
Kees Cook <keescook@chromium.org>,
linux-arm-kernel@lists.infradead.org,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org>,
Michal Marek <michal.lkml@markovi.net>,
Yury Norov <ynorov@caviumnetworks.com>,
Matthias Kaehlcke <mka@chromium.org>,
Alexander Potapenko <glider@google.com>,
Stephen Hines <srhines@google.com>,
Pirama Arumuga Nainar <pirama@google.com>,
Manoj Gupta <manojgupta@google.com>
Subject: Re: [PATCH v2 18/18] arm64: select ARCH_SUPPORTS_LTO_CLANG
Date: Mon, 20 Nov 2017 12:53:50 -0800 [thread overview]
Message-ID: <20171120205350.GZ3624@linux.vnet.ibm.com> (raw)
In-Reply-To: <20171120193256.e6fnn2arwqc5wqkp@hirez.programming.kicks-ass.net>
On Mon, Nov 20, 2017 at 08:32:56PM +0100, Peter Zijlstra wrote:
> On Mon, Nov 20, 2017 at 06:05:55PM +0000, Will Deacon wrote:
> > Although the current direction of the C++ committee is to prefer
> > that dependencies are explicitly "marked", this is not deemed to be
> > acceptable for the kernel (in other words, everything is always considered
> > "marked").
>
> Yeah, that is an attitude not compatible with existing code. Much like
> the proposal to allow temporary/wide stores on everything not explicitly
> declared atomic. Such stuff instantly breaks all extant code that does
> multi-threading with no recourse.
If someone suggests temporary/wide stores, even on non-atomics, tell
them that the standard does not permit them to introduce data races.
Thanx, Paul
WARNING: multiple messages have this Message-ID (diff)
From: paulmck@linux.vnet.ibm.com (Paul E. McKenney)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 18/18] arm64: select ARCH_SUPPORTS_LTO_CLANG
Date: Mon, 20 Nov 2017 12:53:50 -0800 [thread overview]
Message-ID: <20171120205350.GZ3624@linux.vnet.ibm.com> (raw)
In-Reply-To: <20171120193256.e6fnn2arwqc5wqkp@hirez.programming.kicks-ass.net>
On Mon, Nov 20, 2017 at 08:32:56PM +0100, Peter Zijlstra wrote:
> On Mon, Nov 20, 2017 at 06:05:55PM +0000, Will Deacon wrote:
> > Although the current direction of the C++ committee is to prefer
> > that dependencies are explicitly "marked", this is not deemed to be
> > acceptable for the kernel (in other words, everything is always considered
> > "marked").
>
> Yeah, that is an attitude not compatible with existing code. Much like
> the proposal to allow temporary/wide stores on everything not explicitly
> declared atomic. Such stuff instantly breaks all extant code that does
> multi-threading with no recourse.
If someone suggests temporary/wide stores, even on non-atomics, tell
them that the standard does not permit them to introduce data races.
Thanx, Paul
next prev parent reply other threads:[~2017-11-20 20:53 UTC|newest]
Thread overview: 226+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-15 21:34 [PATCH v2 00/18] Add support for clang LTO Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 01/18] kbuild: add ld-name macro and support for GNU gold Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 21:53 ` Kees Cook
2017-11-15 21:53 ` Kees Cook
2017-11-15 21:34 ` [PATCH v2 02/18] kbuild: fix LD_DEAD_CODE_DATA_ELIMINATION with " Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 03/18] kbuild: move gcc-version.sh to cc-version.sh and add clang support Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 21:48 ` Kees Cook
2017-11-15 21:48 ` Kees Cook
2017-11-15 22:06 ` Sami Tolvanen
2017-11-15 22:06 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 04/18] arm64: use -mno-implicit-float instead of -mgeneral-regs-only Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 05/18] arm64: fix -m for GNU gold Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-16 10:55 ` Yury Norov
2017-11-16 10:55 ` Yury Norov
2017-11-16 16:55 ` Nick Desaulniers
2017-11-16 16:55 ` Nick Desaulniers
2017-11-15 21:34 ` [PATCH v2 06/18] arm64: kvm: use -fno-jump-tables with clang Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-16 11:46 ` Will Deacon
2017-11-16 11:46 ` Will Deacon
2017-11-16 16:25 ` Sami Tolvanen
2017-11-16 16:25 ` Sami Tolvanen
2017-11-20 14:41 ` Mark Rutland
2017-11-20 14:41 ` Mark Rutland
2017-11-20 14:43 ` Mark Rutland
2017-11-20 14:43 ` Mark Rutland
2017-11-20 14:47 ` Ard Biesheuvel
2017-11-20 14:47 ` Ard Biesheuvel
2017-11-20 14:47 ` Ard Biesheuvel
2017-11-15 21:34 ` [PATCH v2 07/18] arm64: keep .altinstructions and .altinstr_replacement Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 08/18] arm64: don't disable ADR_PREL_PG_HI21* with ARM64_ERRATUM_843419 Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 22:29 ` Ard Biesheuvel
2017-11-15 22:29 ` Ard Biesheuvel
2017-11-15 22:29 ` Ard Biesheuvel
2017-11-16 11:44 ` Will Deacon
2017-11-16 11:44 ` Will Deacon
2017-11-16 11:44 ` Will Deacon
2017-11-16 16:32 ` Sami Tolvanen
2017-11-16 16:32 ` Sami Tolvanen
2017-11-16 16:32 ` Sami Tolvanen
2017-11-16 16:34 ` Ard Biesheuvel
2017-11-16 16:34 ` Ard Biesheuvel
2017-11-16 16:34 ` Ard Biesheuvel
2017-11-16 21:37 ` Sami Tolvanen
2017-11-16 21:37 ` Sami Tolvanen
2017-11-16 21:37 ` Sami Tolvanen
2017-11-16 22:14 ` Ard Biesheuvel
2017-11-16 22:14 ` Ard Biesheuvel
2017-11-16 22:14 ` Ard Biesheuvel
2017-11-16 22:25 ` Ard Biesheuvel
2017-11-16 22:25 ` Ard Biesheuvel
2017-11-16 22:25 ` Ard Biesheuvel
2017-11-16 23:09 ` Sami Tolvanen
2017-11-16 23:09 ` Sami Tolvanen
2017-11-16 23:09 ` Sami Tolvanen
2017-11-16 23:20 ` Ard Biesheuvel
2017-11-16 23:20 ` Ard Biesheuvel
2017-11-16 23:20 ` Ard Biesheuvel
2017-11-16 23:50 ` Sami Tolvanen
2017-11-16 23:50 ` Sami Tolvanen
2017-11-16 23:50 ` Sami Tolvanen
2017-11-17 9:54 ` Ard Biesheuvel
2017-11-17 9:54 ` Ard Biesheuvel
2017-11-17 9:54 ` Ard Biesheuvel
2017-11-17 18:49 ` Sami Tolvanen
2017-11-17 18:49 ` Sami Tolvanen
2017-11-17 18:49 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 09/18] arm64: explicitly pass --no-fix-cortex-a53-843419 to GNU gold Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-16 11:47 ` Will Deacon
2017-11-16 11:47 ` Will Deacon
2017-11-16 16:35 ` Sami Tolvanen
2017-11-16 16:35 ` Sami Tolvanen
2017-11-20 14:47 ` Mark Rutland
2017-11-20 14:47 ` Mark Rutland
2017-11-20 20:35 ` Sami Tolvanen
2017-11-20 20:35 ` Sami Tolvanen
2017-11-21 11:15 ` Mark Rutland
2017-11-21 11:15 ` Mark Rutland
2017-11-15 21:34 ` [PATCH v2 10/18] arm64: add a workaround for GNU gold with ARM64_MODULE_PLTS Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-16 11:50 ` Will Deacon
2017-11-16 11:50 ` Will Deacon
2017-11-16 16:41 ` Sami Tolvanen
2017-11-16 16:41 ` Sami Tolvanen
2017-11-16 18:47 ` Will Deacon
2017-11-16 18:47 ` Will Deacon
2017-11-15 21:34 ` [PATCH v2 11/18] arm64: make mrs_s and msr_s macros work with LTO Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-16 11:54 ` Will Deacon
2017-11-16 11:54 ` Will Deacon
2017-11-16 13:07 ` Yury Norov
2017-11-16 13:07 ` Yury Norov
2017-11-16 13:55 ` Robin Murphy
2017-11-16 13:55 ` Robin Murphy
2017-11-16 21:29 ` Yury Norov
2017-11-16 21:29 ` Yury Norov
2017-11-16 22:54 ` Alex Matveev
2017-11-16 22:54 ` Alex Matveev
2017-12-04 17:34 ` Nick Desaulniers
2017-12-04 17:34 ` Nick Desaulniers
2017-11-16 13:56 ` Segher Boessenkool
2017-11-16 13:56 ` Segher Boessenkool
2017-11-16 16:46 ` Sami Tolvanen
2017-11-16 16:46 ` Sami Tolvanen
2017-11-16 17:01 ` Segher Boessenkool
2017-11-16 17:01 ` Segher Boessenkool
2017-11-16 17:11 ` Sami Tolvanen
2017-11-16 17:11 ` Sami Tolvanen
2017-11-16 16:43 ` Sami Tolvanen
2017-11-16 16:43 ` Sami Tolvanen
2017-11-16 16:44 ` Nick Desaulniers
2017-11-16 16:44 ` Nick Desaulniers
2017-11-16 18:14 ` Alex Matveev
2017-11-16 18:14 ` Alex Matveev
2017-11-15 21:34 ` [PATCH v2 12/18] kbuild: add support for clang LTO Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 22:06 ` Kees Cook
2017-11-15 22:06 ` Kees Cook
2017-11-18 3:21 ` [v2,12/18] " Nicholas Piggin
2017-11-18 3:21 ` Nicholas Piggin
2017-11-20 20:21 ` Sami Tolvanen
2017-11-20 20:21 ` Sami Tolvanen
2017-11-21 1:01 ` Nicholas Piggin
2017-11-21 1:01 ` Nicholas Piggin
2017-11-29 23:30 ` Sami Tolvanen
2017-11-29 23:30 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 13/18] kbuild: fix dynamic ftrace with " Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 14/18] scripts/mod: disable LTO for empty.c Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 15/18] efi/libstub: disable LTO Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 16/18] arm64: crypto: disable LTO for aes-ce-cipher.c Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-20 15:20 ` Mark Rutland
2017-11-20 15:20 ` Mark Rutland
2017-11-20 15:25 ` Ard Biesheuvel
2017-11-20 15:25 ` Ard Biesheuvel
2017-11-20 15:25 ` Ard Biesheuvel
2017-11-20 21:01 ` Sami Tolvanen
2017-11-20 21:01 ` Sami Tolvanen
2017-11-20 21:01 ` Sami Tolvanen
2017-11-21 11:47 ` Mark Rutland
2017-11-21 11:47 ` Mark Rutland
2017-11-21 11:47 ` Mark Rutland
2017-11-20 20:51 ` Sami Tolvanen
2017-11-20 20:51 ` Sami Tolvanen
2017-11-20 21:29 ` Alex Matveev
2017-11-20 21:29 ` Alex Matveev
2017-11-20 21:31 ` Ard Biesheuvel
2017-11-20 21:31 ` Ard Biesheuvel
2017-11-20 21:31 ` Ard Biesheuvel
2017-11-20 22:03 ` Alex Matveev
2017-11-20 22:03 ` Alex Matveev
2017-11-20 22:03 ` Alex Matveev
2017-11-15 21:34 ` [PATCH v2 17/18] arm64: disable RANDOMIZE_MODULE_REGION_FULL with LTO_CLANG Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-15 21:34 ` [PATCH v2 18/18] arm64: select ARCH_SUPPORTS_LTO_CLANG Sami Tolvanen
2017-11-15 21:34 ` Sami Tolvanen
2017-11-16 11:58 ` Will Deacon
2017-11-16 11:58 ` Will Deacon
2017-11-16 16:17 ` Sami Tolvanen
2017-11-16 16:17 ` Sami Tolvanen
2017-11-16 16:30 ` Peter Zijlstra
2017-11-16 16:30 ` Peter Zijlstra
2017-11-16 16:50 ` Nick Desaulniers
2017-11-16 16:50 ` Nick Desaulniers
2017-11-16 16:59 ` Peter Zijlstra
2017-11-16 16:59 ` Peter Zijlstra
2017-11-16 17:16 ` Nick Desaulniers
2017-11-16 17:16 ` Nick Desaulniers
2017-11-16 17:34 ` Peter Zijlstra
2017-11-16 17:34 ` Peter Zijlstra
2017-11-16 17:48 ` Paul E. McKenney
2017-11-16 17:48 ` Paul E. McKenney
2017-11-16 18:16 ` Nick Desaulniers
2017-11-16 18:16 ` Nick Desaulniers
2017-11-16 18:39 ` Paul E. McKenney
2017-11-16 18:39 ` Paul E. McKenney
2017-11-16 18:45 ` Will Deacon
2017-11-16 18:45 ` Will Deacon
2017-11-16 19:13 ` Paul E. McKenney
2017-11-16 19:13 ` Paul E. McKenney
2017-11-16 20:17 ` Sami Tolvanen
2017-11-16 20:17 ` Sami Tolvanen
2017-11-20 18:05 ` Will Deacon
2017-11-20 18:05 ` Will Deacon
2017-11-20 19:25 ` Peter Zijlstra
2017-11-20 19:25 ` Peter Zijlstra
2017-11-20 19:28 ` Peter Zijlstra
2017-11-20 19:28 ` Peter Zijlstra
2017-11-20 20:52 ` Paul E. McKenney
2017-11-20 20:52 ` Paul E. McKenney
2017-11-20 19:32 ` Peter Zijlstra
2017-11-20 19:32 ` Peter Zijlstra
2017-11-20 20:53 ` Paul E. McKenney [this message]
2017-11-20 20:53 ` Paul E. McKenney
2017-11-21 17:23 ` David Laight
2017-11-21 17:23 ` David Laight
2017-11-21 17:23 ` David Laight
2017-11-21 18:51 ` Paul E. McKenney
2017-11-21 18:51 ` Paul E. McKenney
2017-11-21 18:51 ` Paul E. McKenney
2017-11-23 13:42 ` Alexander Potapenko
2017-11-23 13:42 ` Alexander Potapenko
2017-11-24 7:52 ` Dmitry Vyukov
2017-11-24 7:52 ` Dmitry Vyukov
2017-11-16 20:53 ` [PATCH v2 00/18] Add support for clang LTO Yury Norov
2017-11-16 20:53 ` Yury Norov
2017-11-16 21:38 ` Sami Tolvanen
2017-11-16 21:38 ` Sami Tolvanen
2017-11-20 15:21 ` Mark Rutland
2017-11-20 15:21 ` Mark Rutland
2017-11-20 21:04 ` Sami Tolvanen
2017-11-20 21:04 ` Sami Tolvanen
2017-11-21 11:53 ` Mark Rutland
2017-11-21 11:53 ` Mark Rutland
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