From: Andy Lutomirski <luto@kernel.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: x86 <x86@kernel.org>, Dave Hansen <dave.hansen@intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Nicholas Piggin <npiggin@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Peter Zijlstra <peterz@infradead.org>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH 8/8] membarrier: Rewrite sync_core_before_usermode() and improve documentation
Date: Thu, 17 Jun 2021 17:13:24 -0700 [thread overview]
Message-ID: <678def50-eecd-fb0f-eac0-c0ba1a442574@kernel.org> (raw)
In-Reply-To: <1939350496.10696.1623943014767.JavaMail.zimbra@efficios.com>
On 6/17/21 8:16 AM, Mathieu Desnoyers wrote:
> ----- On Jun 15, 2021, at 11:21 PM, Andy Lutomirski luto@kernel.org wrote:
>
> [...]
>
>> +# An architecture that wants to support
>> +# MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE needs to define precisely what it
>> +# is supposed to do and implement membarrier_sync_core_before_usermode() to
>> +# make it do that. Then it can select ARCH_HAS_MEMBARRIER_SYNC_CORE via
>> +# Kconfig.Unfortunately, MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE is not a
>> +# fantastic API and may not make sense on all architectures. Once an
>> +# architecture meets these requirements,
>
> Can we please remove the editorial comment about the quality of the membarrier
> sync-core's API ?
Done
>> +#
>> +# On x86, a program can safely modify code, issue
>> +# MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE, and then execute that code, via
>> +# the modified address or an alias, from any thread in the calling process.
>> +#
>> +# On arm64, a program can modify code, flush the icache as needed, and issue
>> +# MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE to force a "context synchronizing
>> +# event", aka pipeline flush on all CPUs that might run the calling process.
>> +# Then the program can execute the modified code as long as it is executed
>> +# from an address consistent with the icache flush and the CPU's cache type.
>> +#
>> +# On powerpc, a program can use MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE
>> +# similarly to arm64. It would be nice if the powerpc maintainers could
>> +# add a more clear explanantion.
>
> We should document the requirements on ARMv7 as well.
Done.
>
> Thanks,
>
> Mathieu
>
WARNING: multiple messages have this Message-ID (diff)
From: Andy Lutomirski <luto@kernel.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, linux-mm <linux-mm@kvack.org>,
Peter Zijlstra <peterz@infradead.org>, x86 <x86@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Nicholas Piggin <npiggin@gmail.com>,
Dave Hansen <dave.hansen@intel.com>,
Paul Mackerras <paulus@samba.org>,
stable <stable@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 8/8] membarrier: Rewrite sync_core_before_usermode() and improve documentation
Date: Thu, 17 Jun 2021 17:13:24 -0700 [thread overview]
Message-ID: <678def50-eecd-fb0f-eac0-c0ba1a442574@kernel.org> (raw)
In-Reply-To: <1939350496.10696.1623943014767.JavaMail.zimbra@efficios.com>
On 6/17/21 8:16 AM, Mathieu Desnoyers wrote:
> ----- On Jun 15, 2021, at 11:21 PM, Andy Lutomirski luto@kernel.org wrote:
>
> [...]
>
>> +# An architecture that wants to support
>> +# MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE needs to define precisely what it
>> +# is supposed to do and implement membarrier_sync_core_before_usermode() to
>> +# make it do that. Then it can select ARCH_HAS_MEMBARRIER_SYNC_CORE via
>> +# Kconfig.Unfortunately, MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE is not a
>> +# fantastic API and may not make sense on all architectures. Once an
>> +# architecture meets these requirements,
>
> Can we please remove the editorial comment about the quality of the membarrier
> sync-core's API ?
Done
>> +#
>> +# On x86, a program can safely modify code, issue
>> +# MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE, and then execute that code, via
>> +# the modified address or an alias, from any thread in the calling process.
>> +#
>> +# On arm64, a program can modify code, flush the icache as needed, and issue
>> +# MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE to force a "context synchronizing
>> +# event", aka pipeline flush on all CPUs that might run the calling process.
>> +# Then the program can execute the modified code as long as it is executed
>> +# from an address consistent with the icache flush and the CPU's cache type.
>> +#
>> +# On powerpc, a program can use MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE
>> +# similarly to arm64. It would be nice if the powerpc maintainers could
>> +# add a more clear explanantion.
>
> We should document the requirements on ARMv7 as well.
Done.
>
> Thanks,
>
> Mathieu
>
WARNING: multiple messages have this Message-ID (diff)
From: Andy Lutomirski <luto@kernel.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: x86 <x86@kernel.org>, Dave Hansen <dave.hansen@intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Nicholas Piggin <npiggin@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Peter Zijlstra <peterz@infradead.org>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH 8/8] membarrier: Rewrite sync_core_before_usermode() and improve documentation
Date: Thu, 17 Jun 2021 17:13:24 -0700 [thread overview]
Message-ID: <678def50-eecd-fb0f-eac0-c0ba1a442574@kernel.org> (raw)
In-Reply-To: <1939350496.10696.1623943014767.JavaMail.zimbra@efficios.com>
On 6/17/21 8:16 AM, Mathieu Desnoyers wrote:
> ----- On Jun 15, 2021, at 11:21 PM, Andy Lutomirski luto@kernel.org wrote:
>
> [...]
>
>> +# An architecture that wants to support
>> +# MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE needs to define precisely what it
>> +# is supposed to do and implement membarrier_sync_core_before_usermode() to
>> +# make it do that. Then it can select ARCH_HAS_MEMBARRIER_SYNC_CORE via
>> +# Kconfig.Unfortunately, MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE is not a
>> +# fantastic API and may not make sense on all architectures. Once an
>> +# architecture meets these requirements,
>
> Can we please remove the editorial comment about the quality of the membarrier
> sync-core's API ?
Done
>> +#
>> +# On x86, a program can safely modify code, issue
>> +# MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE, and then execute that code, via
>> +# the modified address or an alias, from any thread in the calling process.
>> +#
>> +# On arm64, a program can modify code, flush the icache as needed, and issue
>> +# MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE to force a "context synchronizing
>> +# event", aka pipeline flush on all CPUs that might run the calling process.
>> +# Then the program can execute the modified code as long as it is executed
>> +# from an address consistent with the icache flush and the CPU's cache type.
>> +#
>> +# On powerpc, a program can use MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE
>> +# similarly to arm64. It would be nice if the powerpc maintainers could
>> +# add a more clear explanantion.
>
> We should document the requirements on ARMv7 as well.
Done.
>
> Thanks,
>
> Mathieu
>
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next prev parent reply other threads:[~2021-06-18 0:13 UTC|newest]
Thread overview: 165+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 3:21 [PATCH 0/8] membarrier cleanups Andy Lutomirski
2021-06-16 3:21 ` [PATCH 1/8] membarrier: Document why membarrier() works Andy Lutomirski
2021-06-16 4:00 ` Nicholas Piggin
2021-06-16 7:30 ` Peter Zijlstra
2021-06-17 23:45 ` Andy Lutomirski
2021-06-16 3:21 ` [PATCH 2/8] x86/mm: Handle unlazying membarrier core sync in the arch code Andy Lutomirski
2021-06-16 4:25 ` Nicholas Piggin
2021-06-16 18:31 ` Andy Lutomirski
2021-06-16 17:49 ` Mathieu Desnoyers
2021-06-16 17:49 ` Mathieu Desnoyers
2021-06-16 18:31 ` Andy Lutomirski
2021-06-16 3:21 ` [PATCH 3/8] membarrier: Remove membarrier_arch_switch_mm() prototype in core code Andy Lutomirski
2021-06-16 4:26 ` Nicholas Piggin
2021-06-16 17:52 ` Mathieu Desnoyers
2021-06-16 17:52 ` Mathieu Desnoyers
2021-06-16 3:21 ` [PATCH 4/8] membarrier: Make the post-switch-mm barrier explicit Andy Lutomirski
2021-06-16 4:19 ` Nicholas Piggin
2021-06-16 7:35 ` Peter Zijlstra
2021-06-16 18:41 ` Andy Lutomirski
2021-06-17 1:37 ` Nicholas Piggin
2021-06-17 2:57 ` Andy Lutomirski
2021-06-17 5:32 ` Andy Lutomirski
2021-06-17 6:51 ` Nicholas Piggin
2021-06-17 23:49 ` Andy Lutomirski
2021-06-19 2:53 ` Nicholas Piggin
2021-06-19 3:20 ` Andy Lutomirski
2021-06-19 4:27 ` Nicholas Piggin
2021-06-17 9:08 ` [RFC][PATCH] sched: Use lightweight hazard pointers to grab lazy mms Peter Zijlstra
2021-06-17 9:10 ` Peter Zijlstra
2021-06-17 10:00 ` Nicholas Piggin
2021-06-17 9:13 ` Peter Zijlstra
2021-06-17 14:06 ` Andy Lutomirski
2021-06-17 9:28 ` Peter Zijlstra
2021-06-17 14:03 ` Andy Lutomirski
2021-06-17 14:10 ` Andy Lutomirski
2021-06-17 15:45 ` Peter Zijlstra
2021-06-18 3:29 ` Paul E. McKenney
2021-06-18 5:04 ` Andy Lutomirski
2021-06-17 15:02 ` [PATCH 4/8] membarrier: Make the post-switch-mm barrier explicit Paul E. McKenney
2021-06-18 0:06 ` Andy Lutomirski
2021-06-18 3:35 ` Paul E. McKenney
2021-06-17 8:45 ` Peter Zijlstra
2021-06-16 3:21 ` [PATCH 5/8] membarrier, kthread: Use _ONCE accessors for task->mm Andy Lutomirski
2021-06-16 4:28 ` Nicholas Piggin
2021-06-16 18:08 ` Mathieu Desnoyers
2021-06-16 18:08 ` Mathieu Desnoyers
2021-06-16 18:45 ` Andy Lutomirski
2021-06-16 3:21 ` [PATCH 6/8] powerpc/membarrier: Remove special barrier on mm switch Andy Lutomirski
2021-06-16 3:21 ` Andy Lutomirski
2021-06-16 4:36 ` Nicholas Piggin
2021-06-16 4:36 ` Nicholas Piggin
2021-06-16 3:21 ` [PATCH 7/8] membarrier: Remove arm (32) support for SYNC_CORE Andy Lutomirski
2021-06-16 3:21 ` Andy Lutomirski
2021-06-16 9:28 ` Russell King (Oracle)
2021-06-16 9:28 ` Russell King (Oracle)
2021-06-16 10:16 ` Peter Zijlstra
2021-06-16 10:16 ` Peter Zijlstra
2021-06-16 10:20 ` Peter Zijlstra
2021-06-16 10:20 ` Peter Zijlstra
2021-06-16 10:34 ` Russell King (Oracle)
2021-06-16 10:34 ` Russell King (Oracle)
2021-06-16 11:10 ` Peter Zijlstra
2021-06-16 11:10 ` Peter Zijlstra
2021-06-16 13:22 ` Russell King (Oracle)
2021-06-16 13:22 ` Russell King (Oracle)
2021-06-16 15:04 ` Catalin Marinas
2021-06-16 15:04 ` Catalin Marinas
2021-06-16 15:23 ` Russell King (Oracle)
2021-06-16 15:23 ` Russell King (Oracle)
2021-06-16 15:45 ` Catalin Marinas
2021-06-16 15:45 ` Catalin Marinas
2021-06-16 16:00 ` Catalin Marinas
2021-06-16 16:00 ` Catalin Marinas
2021-06-16 16:27 ` Russell King (Oracle)
2021-06-16 16:27 ` Russell King (Oracle)
2021-06-17 8:55 ` Krzysztof Hałasa
2021-06-17 8:55 ` Krzysztof Hałasa
2021-06-17 8:55 ` Krzysztof Hałasa
2021-06-18 12:54 ` Linus Walleij
2021-06-18 12:54 ` Linus Walleij
2021-06-18 12:54 ` Linus Walleij
2021-06-18 13:19 ` Russell King (Oracle)
2021-06-18 13:19 ` Russell King (Oracle)
2021-06-18 13:36 ` Arnd Bergmann
2021-06-18 13:36 ` Arnd Bergmann
2021-06-18 13:36 ` Arnd Bergmann
2021-06-17 10:40 ` Mark Rutland
2021-06-17 10:40 ` Mark Rutland
2021-06-17 11:23 ` Russell King (Oracle)
2021-06-17 11:23 ` Russell King (Oracle)
2021-06-17 11:33 ` Mark Rutland
2021-06-17 11:33 ` Mark Rutland
2021-06-17 13:41 ` Andy Lutomirski
2021-06-17 13:41 ` Andy Lutomirski
2021-06-17 13:51 ` Mark Rutland
2021-06-17 13:51 ` Mark Rutland
2021-06-17 14:00 ` Andy Lutomirski
2021-06-17 14:00 ` Andy Lutomirski
2021-06-17 14:20 ` Mark Rutland
2021-06-17 14:20 ` Mark Rutland
2021-06-17 15:01 ` Peter Zijlstra
2021-06-17 15:01 ` Peter Zijlstra
2021-06-17 15:13 ` Peter Zijlstra
2021-06-17 15:13 ` Peter Zijlstra
2021-06-17 14:16 ` Mathieu Desnoyers
2021-06-17 14:16 ` Mathieu Desnoyers
2021-06-17 14:05 ` Peter Zijlstra
2021-06-17 14:05 ` Peter Zijlstra
2021-06-18 0:07 ` Andy Lutomirski
2021-06-18 0:07 ` Andy Lutomirski
2021-06-16 3:21 ` [PATCH 8/8] membarrier: Rewrite sync_core_before_usermode() and improve documentation Andy Lutomirski
2021-06-16 3:21 ` Andy Lutomirski
2021-06-16 3:21 ` Andy Lutomirski
2021-06-16 4:45 ` Nicholas Piggin
2021-06-16 4:45 ` Nicholas Piggin
2021-06-16 4:45 ` Nicholas Piggin
2021-06-16 18:52 ` Andy Lutomirski
2021-06-16 18:52 ` Andy Lutomirski
2021-06-16 18:52 ` Andy Lutomirski
2021-06-16 23:48 ` Andy Lutomirski
2021-06-16 23:48 ` Andy Lutomirski
2021-06-16 23:48 ` Andy Lutomirski
2021-06-18 15:27 ` Christophe Leroy
2021-06-18 15:27 ` Christophe Leroy
2021-06-18 15:27 ` Christophe Leroy
2021-06-16 10:20 ` Will Deacon
2021-06-16 10:20 ` Will Deacon
2021-06-16 10:20 ` Will Deacon
2021-06-16 23:58 ` Andy Lutomirski
2021-06-16 23:58 ` Andy Lutomirski
2021-06-16 23:58 ` Andy Lutomirski
2021-06-17 14:47 ` Mathieu Desnoyers
2021-06-17 14:47 ` Mathieu Desnoyers
2021-06-17 14:47 ` Mathieu Desnoyers
2021-06-17 14:47 ` Mathieu Desnoyers
2021-06-18 0:12 ` Andy Lutomirski
2021-06-18 0:12 ` Andy Lutomirski
2021-06-18 0:12 ` Andy Lutomirski
2021-06-18 16:31 ` Mathieu Desnoyers
2021-06-18 16:31 ` Mathieu Desnoyers
2021-06-18 16:31 ` Mathieu Desnoyers
2021-06-18 16:31 ` Mathieu Desnoyers
2021-06-18 19:58 ` Andy Lutomirski
2021-06-18 19:58 ` Andy Lutomirski
2021-06-18 19:58 ` Andy Lutomirski
2021-06-18 20:09 ` Mathieu Desnoyers
2021-06-18 20:09 ` Mathieu Desnoyers
2021-06-18 20:09 ` Mathieu Desnoyers
2021-06-18 20:09 ` Mathieu Desnoyers
2021-06-19 6:02 ` Nicholas Piggin
2021-06-19 6:02 ` Nicholas Piggin
2021-06-19 6:02 ` Nicholas Piggin
2021-06-19 15:50 ` Andy Lutomirski
2021-06-19 15:50 ` Andy Lutomirski
2021-06-19 15:50 ` Andy Lutomirski
2021-06-20 2:10 ` Nicholas Piggin
2021-06-20 2:10 ` Nicholas Piggin
2021-06-20 2:10 ` Nicholas Piggin
2021-06-17 15:16 ` Mathieu Desnoyers
2021-06-17 15:16 ` Mathieu Desnoyers
2021-06-17 15:16 ` Mathieu Desnoyers
2021-06-17 15:16 ` Mathieu Desnoyers
2021-06-18 0:13 ` Andy Lutomirski [this message]
2021-06-18 0:13 ` Andy Lutomirski
2021-06-18 0:13 ` Andy Lutomirski
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