Re: [PATCH 00/18] Allow architectures to override __READ_ONCE()
On Fri, Jul 10, 2020 at 05:51:44PM +0100, Will Deacon wrote:
> SeongJae Park (1):
> Documentation/barriers/kokr: Remove references to
> [smp_]read_barrier_depends()
>
> Will Deacon (18):
> tools: bpf: Use local copy of headers including uapi/linux/filter.h
> compiler.h: Split {READ,WRITE}_ONCE definitions out into rwonce.h
> asm/rwonce: Allow __READ_ONCE to be overridden by the architecture
> alpha: Override READ_ONCE() with barriered implementation
> asm/rwonce: Remove smp_read_barrier_depends() invocation
> asm/rwonce: Don't pull into 'asm-generic/rwonce.h'
> vhost: Remove redundant use of read_barrier_depends() barrier
> alpha: Replace smp_read_barrier_depends() usage with smp_[r]mb()
> locking/barriers: Remove definitions for [smp_]read_barrier_depends()
> Documentation/barriers: Remove references to
> [smp_]read_barrier_depends()
> tools/memory-model: Remove smp_read_barrier_depends() from informal
> doc
> include/linux: Remove smp_read_barrier_depends() from comments
> checkpatch: Remove checks relating to [smp_]read_barrier_depends()
> arm64: Reduce the number of header files pulled into vmlinux.lds.S
> arm64: alternatives: Split up alternative.h
> arm64: cpufeatures: Add capability for LDAPR instruction
> arm64: alternatives: Remove READ_ONCE() usage during patch operation
> arm64: lto: Strengthen READ_ONCE() to acquire when CONFIG_LTO=y
Acked-by: Peter Zijlstra (Intel)
___
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[PATCH 00/18] Allow architectures to override __READ_ONCE()
Hi all,
This is version three of the patches I previously posted here:
v1: https://lore.kernel.org/lkml/20191108170120.22331-1-w...@kernel.org/
v2: https://lore.kernel.org/r/20200630173734.14057-1-w...@kernel.org
Changes since v2 include:
* Actually add the barrier in READ_ONCE() for Alpha!
* Implement Alpha's smp_load_acquire() using __READ_ONCE(), rather than
the other way around.
* Further untangling of header files
* Use CONFIG_LTO instead of CONFIG_CLANG_LTO
I have booted this on arm64, and build-tested as follows:
- arm64 allnoconfig, defconfig (also bisected) and allmodconfig
- arm32 allnoconfig, defconfig and allmodconfig
- x86_64 allnoconfig, defconfig and allmodcofig
- alpha defconfig, defconfig+CONFIG_SMP=y
- riscv64 defconfig
- powerpc64 defconfig
- s390defconfig
- sparc32 defconfig, defconfig+CONFIG_SMP=y
- sparc64 defconfig
Cheers,
Will
Cc: Joel Fernandes
Cc: Sami Tolvanen
Cc: Nick Desaulniers
Cc: Kees Cook
Cc: Marco Elver
Cc: "Paul E. McKenney"
Cc: Matt Turner
Cc: Ivan Kokshaysky
Cc: Richard Henderson
Cc: Peter Zijlstra
Cc: Alan Stern
Cc: "Michael S. Tsirkin"
Cc: Jason Wang
Cc: Arnd Bergmann
Cc: Boqun Feng
Cc: Catalin Marinas
Cc: Mark Rutland
Cc: linux-arm-ker...@lists.infradead.org>
Cc: linux-al...@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Cc: kernel-t...@android.com
--->8
SeongJae Park (1):
Documentation/barriers/kokr: Remove references to
[smp_]read_barrier_depends()
Will Deacon (18):
tools: bpf: Use local copy of headers including uapi/linux/filter.h
compiler.h: Split {READ,WRITE}_ONCE definitions out into rwonce.h
asm/rwonce: Allow __READ_ONCE to be overridden by the architecture
alpha: Override READ_ONCE() with barriered implementation
asm/rwonce: Remove smp_read_barrier_depends() invocation
asm/rwonce: Don't pull into 'asm-generic/rwonce.h'
vhost: Remove redundant use of read_barrier_depends() barrier
alpha: Replace smp_read_barrier_depends() usage with smp_[r]mb()
locking/barriers: Remove definitions for [smp_]read_barrier_depends()
Documentation/barriers: Remove references to
[smp_]read_barrier_depends()
tools/memory-model: Remove smp_read_barrier_depends() from informal
doc
include/linux: Remove smp_read_barrier_depends() from comments
checkpatch: Remove checks relating to [smp_]read_barrier_depends()
arm64: Reduce the number of header files pulled into vmlinux.lds.S
arm64: alternatives: Split up alternative.h
arm64: cpufeatures: Add capability for LDAPR instruction
arm64: alternatives: Remove READ_ONCE() usage during patch operation
arm64: lto: Strengthen READ_ONCE() to acquire when CONFIG_LTO=y
.../RCU/Design/Requirements/Requirements.rst | 2 +-
Documentation/memory-barriers.txt | 156 +-
.../translations/ko_KR/memory-barriers.txt| 146 +
arch/alpha/include/asm/atomic.h | 16 +-
arch/alpha/include/asm/barrier.h | 59 +---
arch/alpha/include/asm/pgtable.h | 10 +-
arch/alpha/include/asm/rwonce.h | 35 +++
arch/arm/include/asm/vdso/gettimeofday.h | 1 +
arch/arm64/Kconfig| 3 +
arch/arm64/include/asm/alternative-macros.h | 276 ++
arch/arm64/include/asm/alternative.h | 267 +
arch/arm64/include/asm/cpucaps.h | 3 +-
arch/arm64/include/asm/insn.h | 3 +-
arch/arm64/include/asm/kernel-pgtable.h | 2 +-
arch/arm64/include/asm/memory.h | 11 +-
arch/arm64/include/asm/rwonce.h | 63
arch/arm64/include/asm/uaccess.h | 1 +
.../include/asm/vdso/compat_gettimeofday.h| 1 +
arch/arm64/include/asm/vdso/gettimeofday.h| 1 +
arch/arm64/kernel/alternative.c | 7 +-
arch/arm64/kernel/cpufeature.c| 10 +
arch/arm64/kernel/entry.S | 1 +
arch/arm64/kernel/vdso/Makefile | 2 +-
arch/arm64/kernel/vdso32/Makefile | 2 +-
arch/arm64/kernel/vmlinux.lds.S | 1 -
arch/arm64/kvm/hyp-init.S | 1 +
arch/riscv/include/asm/vdso/gettimeofday.h| 1 +
drivers/vhost/vhost.c | 5 -
include/asm-generic/Kbuild| 1 +
include/asm-generic/barrier.h | 19 +-
include/asm-generic/rwonce.h | 80 +
include/linux/compiler.h | 83 +-
include/linux/nospec.h| 2 +
include/linux/percpu-refcount.h | 2 +-
include/linux/ptr_ring.h | 2 +-
mm/memory.c | 2 +-
scripts/checkpatch.pl | 9 +-
tools/bpf/Makefile| 3 +-
tools/include/uapi/linux/filter.h | 90 ++
.../Documentation/
Re: [PATCH 00/18] Allow architectures to override __READ_ONCE()
On Tue, Jun 30, 2020 at 06:37:16PM +0100, Will Deacon wrote: > The patches allow architectures to provide their own implementation of > __READ_ONCE(). This serves two main purposes: > > 1. It finally allows us to remove [smp_]read_barrier_depends() from the > Linux memory model and make it an implementation detail of the Alpha > back-end. And there was much rejoicing. Thank you. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
[PATCH 00/18] Allow architectures to override __READ_ONCE()
Hi everyone,
This is the long-awaited version two of the patches I previously
posted in November last year:
https://lore.kernel.org/lkml/20191108170120.22331-1-w...@kernel.org/
I ended up parking the series while the READ_ONCE() implementation was
being overhauled, but with that merged during the recent merge window
and LTO patches being posted again [1], it was time for a refresh.
The patches allow architectures to provide their own implementation of
__READ_ONCE(). This serves two main purposes:
1. It finally allows us to remove [smp_]read_barrier_depends() from the
Linux memory model and make it an implementation detail of the Alpha
back-end.
2. It allows arm64 to upgrade __READ_ONCE() to have RCpc acquire
semantics when compiling with LTO, since this may enable compiler
optimisations that break dependency ordering and therefore we
require fencing to ensure ordering within the CPU.
Both of these are implemented by this series.
I've kept Paul's acks from v1 since, although the series has changed
somewhat, the patches with his Ack have not changed materially in my
opinion. I will drop them if anybody objects.
In terms of merging this, my preference would be a stable branch in the
arm64 tree, which others can pull in as they need it.
Cheers,
Will
[1] https://lore.kernel.org/r/20200624203200.78870-1-samitolva...@google.com
Cc: Sami Tolvanen
Cc: Nick Desaulniers
Cc: Kees Cook
Cc: Marco Elver
Cc: "Paul E. McKenney"
Cc: Josh Triplett
Cc: Matt Turner
Cc: Ivan Kokshaysky
Cc: Richard Henderson
Cc: Peter Zijlstra
Cc: Alan Stern
Cc: "Michael S. Tsirkin"
Cc: Jason Wang
Cc: Arnd Bergmann
Cc: Boqun Feng
Cc: Catalin Marinas
Cc: Mark Rutland
Cc: linux-arm-ker...@lists.infradead.org>
Cc: linux-al...@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Cc: kernel-t...@android.com
--->8
SeongJae Park (1):
Documentation/barriers/kokr: Remove references to
[smp_]read_barrier_depends()
Will Deacon (17):
tools: bpf: Use local copy of headers including uapi/linux/filter.h
compiler.h: Split {READ,WRITE}_ONCE definitions out into rwonce.h
asm/rwonce: Allow __READ_ONCE to be overridden by the architecture
alpha: Override READ_ONCE() with barriered implementation
asm/rwonce: Remove smp_read_barrier_depends() invocation
vhost: Remove redundant use of read_barrier_depends() barrier
alpha: Replace smp_read_barrier_depends() usage with smp_[r]mb()
locking/barriers: Remove definitions for [smp_]read_barrier_depends()
Documentation/barriers: Remove references to
[smp_]read_barrier_depends()
tools/memory-model: Remove smp_read_barrier_depends() from informal
doc
include/linux: Remove smp_read_barrier_depends() from comments
checkpatch: Remove checks relating to [smp_]read_barrier_depends()
arm64: Reduce the number of header files pulled into vmlinux.lds.S
arm64: alternatives: Split up alternative.h
arm64: cpufeatures: Add capability for LDAPR instruction
arm64: alternatives: Remove READ_ONCE() usage during patch operation
arm64: lto: Strengthen READ_ONCE() to acquire when CLANG_LTO=y
.../RCU/Design/Requirements/Requirements.rst | 2 +-
Documentation/memory-barriers.txt | 156 +-
.../translations/ko_KR/memory-barriers.txt| 146 +
arch/alpha/include/asm/atomic.h | 16 +-
arch/alpha/include/asm/barrier.h | 61 +---
arch/alpha/include/asm/pgtable.h | 10 +-
arch/alpha/include/asm/rwonce.h | 19 ++
arch/arm64/Kconfig| 3 +
arch/arm64/include/asm/alternative-macros.h | 276 ++
arch/arm64/include/asm/alternative.h | 267 +
arch/arm64/include/asm/cpucaps.h | 3 +-
arch/arm64/include/asm/insn.h | 3 +-
arch/arm64/include/asm/kernel-pgtable.h | 2 +-
arch/arm64/include/asm/memory.h | 11 +-
arch/arm64/include/asm/rwonce.h | 63
arch/arm64/include/asm/uaccess.h | 1 +
arch/arm64/kernel/alternative.c | 7 +-
arch/arm64/kernel/cpufeature.c| 10 +
arch/arm64/kernel/entry.S | 1 +
arch/arm64/kernel/vdso/Makefile | 2 +-
arch/arm64/kernel/vdso32/Makefile | 2 +-
arch/arm64/kernel/vmlinux.lds.S | 1 -
arch/arm64/kvm/hyp-init.S | 1 +
drivers/vhost/vhost.c | 5 -
include/asm-generic/Kbuild| 1 +
include/asm-generic/barrier.h | 17 --
include/asm-generic/rwonce.h | 82 ++
include/linux/compiler.h | 83 +-
include/linux/percpu-refcount.h | 2 +-
include/linux/ptr_ring.h | 2 +-
mm/memory.c | 2 +-
scripts/checkpatch.pl | 9 +-
tools/bpf/Makefile
