From: Marco Elver <elver@google.com>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Jason Wang <jasowang@redhat.com>,
virtualization@lists.linux-foundation.org,
Will Deacon <will@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Alan Stern <stern@rowland.harvard.edu>,
Sami Tolvanen <samitolvanen@google.com>,
Matt Turner <mattst88@gmail.com>,
kernel-team <kernel-team@android.com>,
Dave Martin <Dave.Martin@arm.com>,
Kees Cook <keescook@chromium.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
Josh Triplett <josh@joshtriplett.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Richard Henderson <rth@twiddle.net>,
LKML <linux-kernel@vger.kernel.org>,
linux-alpha@vger.kernel.org
Subject: Re: [PATCH 18/18] arm64: lto: Strengthen READ_ONCE() to acquire when CLANG_LTO=y
Date: Wed, 8 Jul 2020 09:15:44 +0200 [thread overview]
Message-ID: <CANpmjNP8xwyjiDRgzWO13K3rPbxM0gRwTvMvX3Amm-QOWD0_tQ@mail.gmail.com> (raw)
In-Reply-To: <CAKwvOdkW__H21m8vqqk1-n6-KK67HBk=YbA+MkUS7igxfjV1iw@mail.gmail.com>
On Wed, 8 Jul 2020 at 01:01, Nick Desaulniers <ndesaulniers@google.com> wrote:
>
> I'm trying to put together a Micro Conference for Linux Plumbers
> conference focused on "make LLVM slightly less shitty." Do you all
> plan on attending the conference? Would it be worthwhile to hold a
> session focused on discussing this (LTO and memory models) be
> worthwhile?
I would welcome sessions on LLVM, and would try to attend. Apart from
general improvements to the LLVM ecosystem, we should also emphasize
the benefits LLVM provides and how we can enable them (one reason we
want LTO is to get CFI).
Regarding LTO and memory models, I'm not sure. Given the current state
of things, such a discussion needs to be carefully framed to not go in
circles, because we're trying to figure out things at the intersection
of architecture, what the compiler does, the C standard, and the
kernel wants. And because some of these boxes are difficult to change
(standard, arch, compiler) or difficult to precisely define behaviour
(compiler), we might end up going in circles. From what I see there
are efforts to fix the situation at the root (standard), and we might
have means to get the compiler to tell us what it's doing. But these
happen extremely slowly.
So, if we do this, we need to be careful to not end up re-discussing
what we discussed here, but rather try and make it a continuation that
hopefully leads to some constructive output.
Thanks,
-- Marco
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next prev parent reply other threads:[~2020-07-08 7:17 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-30 17:37 [PATCH 00/18] Allow architectures to override __READ_ONCE() Will Deacon
2020-06-30 17:37 ` [PATCH 01/18] tools: bpf: Use local copy of headers including uapi/linux/filter.h Will Deacon
2020-07-01 16:38 ` Alexei Starovoitov
2020-06-30 17:37 ` [PATCH 02/18] compiler.h: Split {READ, WRITE}_ONCE definitions out into rwonce.h Will Deacon
2020-06-30 19:11 ` Arnd Bergmann
2020-07-01 10:16 ` [PATCH 02/18] compiler.h: Split {READ,WRITE}_ONCE " Will Deacon
2020-07-01 11:33 ` [PATCH 02/18] compiler.h: Split {READ, WRITE}_ONCE " Arnd Bergmann
2020-06-30 17:37 ` [PATCH 03/18] asm/rwonce: Allow __READ_ONCE to be overridden by the architecture Will Deacon
2020-06-30 17:37 ` [PATCH 04/18] alpha: Override READ_ONCE() with barriered implementation Will Deacon
2020-07-02 9:32 ` Mark Rutland
2020-07-02 9:48 ` Will Deacon
2020-07-02 10:08 ` Arnd Bergmann
2020-07-02 11:18 ` Will Deacon
2020-07-02 11:39 ` Arnd Bergmann
2020-07-02 14:43 ` Joel Fernandes
2020-07-02 14:55 ` Will Deacon
2020-07-02 15:07 ` Joel Fernandes
2020-06-30 17:37 ` [PATCH 05/18] asm/rwonce: Remove smp_read_barrier_depends() invocation Will Deacon
2020-06-30 17:37 ` [PATCH 06/18] vhost: Remove redundant use of read_barrier_depends() barrier Will Deacon
2020-06-30 17:37 ` [PATCH 07/18] alpha: Replace smp_read_barrier_depends() usage with smp_[r]mb() Will Deacon
2020-06-30 17:37 ` [PATCH 08/18] locking/barriers: Remove definitions for [smp_]read_barrier_depends() Will Deacon
2020-06-30 17:37 ` [PATCH 09/18] Documentation/barriers: Remove references to [smp_]read_barrier_depends() Will Deacon
2020-06-30 17:37 ` [PATCH 10/18] Documentation/barriers/kokr: " Will Deacon
2020-06-30 17:37 ` [PATCH 11/18] tools/memory-model: Remove smp_read_barrier_depends() from informal doc Will Deacon
2020-06-30 17:37 ` [PATCH 12/18] include/linux: Remove smp_read_barrier_depends() from comments Will Deacon
2020-06-30 17:37 ` [PATCH 13/18] checkpatch: Remove checks relating to [smp_]read_barrier_depends() Will Deacon
2020-06-30 17:37 ` [PATCH 14/18] arm64: Reduce the number of header files pulled into vmlinux.lds.S Will Deacon
2020-06-30 17:37 ` [PATCH 15/18] arm64: alternatives: Split up alternative.h Will Deacon
2020-06-30 17:37 ` [PATCH 16/18] arm64: cpufeatures: Add capability for LDAPR instruction Will Deacon
2020-06-30 17:37 ` [PATCH 17/18] arm64: alternatives: Remove READ_ONCE() usage during patch operation Will Deacon
2020-06-30 17:37 ` [PATCH 18/18] arm64: lto: Strengthen READ_ONCE() to acquire when CLANG_LTO=y Will Deacon
2020-06-30 19:25 ` Arnd Bergmann
2020-07-01 10:19 ` Will Deacon
2020-07-01 10:59 ` Arnd Bergmann
2020-06-30 19:47 ` Marco Elver
2020-06-30 20:20 ` Peter Zijlstra
2020-06-30 22:57 ` Sami Tolvanen
2020-07-01 10:25 ` Will Deacon
2020-07-01 10:24 ` Will Deacon
2020-07-01 17:07 ` Dave P Martin
2020-07-02 7:23 ` Will Deacon
2020-07-06 16:00 ` Dave Martin
2020-07-06 16:34 ` Paul E. McKenney
2020-07-06 17:05 ` Dave Martin
2020-07-06 17:36 ` Paul E. McKenney
2020-07-07 10:29 ` Dave Martin
2020-07-07 22:51 ` Paul E. McKenney
2020-07-07 23:01 ` Nick Desaulniers
2020-07-08 7:15 ` Marco Elver [this message]
2020-07-08 9:16 ` Peter Zijlstra
2020-07-08 18:20 ` Paul E. McKenney
2020-07-06 18:35 ` Will Deacon
2020-07-06 19:23 ` Marco Elver
2020-07-06 19:42 ` Paul E. McKenney
2020-07-06 16:08 ` Dave Martin
2020-07-06 18:35 ` Will Deacon
2020-07-07 10:10 ` Dave Martin
2020-07-01 7:38 ` [PATCH 00/18] Allow architectures to override __READ_ONCE() Josh Triplett
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