From: Mark Brown <broonie@kernel.org>
To: Alan Hayward <Alan.Hayward@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>,
Will Deacon <will@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>,
Shuah Khan <shuah@kernel.org>,
Luis Machado <Luis.Machado@arm.com>,
Salil Akerkar <Salil.Akerkar@arm.com>,
Basant KumarDwivedi <Basant.KumarDwivedi@arm.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>, nd <nd@arm.com>
Subject: Re: [PATCH v1 12/38] arm64/sme: Provide ABI documentation for SME
Date: Fri, 8 Oct 2021 16:28:39 +0100 [thread overview]
Message-ID: <YWBjp8UnkMaHsZRA@sirena.org.uk> (raw)
In-Reply-To: <59675B79-E426-4177-8A4E-43026E42B9E3@arm.com>
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On Fri, Oct 08, 2021 at 02:11:46PM +0000, Alan Hayward wrote:
> read looks fine, given this builds on the existing SVE implementation. Although
> I think effectively managing the different modes in the debugger may be tricky.
Sadly I don't see any way of handling the hardware in a way that
doesn't present some kind of hassle.
> The .rst files are a huge help too.
Glad to hear it.
> What is returned if SME is in streaming mode and I call GETREGSET with NT_ARM_SVE ?
> What is returned if SME is not in streaming mode and I call GETREGSET with NT_ARM_SSVE ?
In both cases you'll get the user_sve_header with no register
payload and neither of the register types flagged. I'll make
this a bit more explicit in the documentation, in the SVE
documentation it currently just talks about no register data
being available but doesn't ever actually explicitly say why that
would happen like we do for ZA, it's currently not super helpful.
> Can NT_ARM_SSVE return a fpsimd?
It's documented that way for simplicity but in the current
implementation it won't ever actually do so in practice. The
only case where I could see that it might happen would be if we
change the syscalls to stay in streaming mode over syscall, in
that case we could do as we do for SVE and preserve FPSIMD
registers only. At present we drop out of streaming mode if we
get a syscall with it enabled so it's a non-issue, if people
agree that that's the right thing for the syscalls then we should
update the documentation to specify this since otherwise we'll
doubtless catch someone by surprise if we ever manage to start
doing it in the future.
> > +* The presence of SVE is reported to userspace via HWCAP2_SME in the aux vector
>
> SME not SVE?
Ack, yes. Well, I guess given that SME should never appear in a
system without SVE the statement is true but...
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WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org>
To: Alan Hayward <Alan.Hayward@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>,
Will Deacon <will@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>,
Shuah Khan <shuah@kernel.org>,
Luis Machado <Luis.Machado@arm.com>,
Salil Akerkar <Salil.Akerkar@arm.com>,
Basant KumarDwivedi <Basant.KumarDwivedi@arm.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>, nd <nd@arm.com>
Subject: Re: [PATCH v1 12/38] arm64/sme: Provide ABI documentation for SME
Date: Fri, 8 Oct 2021 16:28:39 +0100 [thread overview]
Message-ID: <YWBjp8UnkMaHsZRA@sirena.org.uk> (raw)
In-Reply-To: <59675B79-E426-4177-8A4E-43026E42B9E3@arm.com>
[-- Attachment #1.1: Type: text/plain, Size: 1886 bytes --]
On Fri, Oct 08, 2021 at 02:11:46PM +0000, Alan Hayward wrote:
> read looks fine, given this builds on the existing SVE implementation. Although
> I think effectively managing the different modes in the debugger may be tricky.
Sadly I don't see any way of handling the hardware in a way that
doesn't present some kind of hassle.
> The .rst files are a huge help too.
Glad to hear it.
> What is returned if SME is in streaming mode and I call GETREGSET with NT_ARM_SVE ?
> What is returned if SME is not in streaming mode and I call GETREGSET with NT_ARM_SSVE ?
In both cases you'll get the user_sve_header with no register
payload and neither of the register types flagged. I'll make
this a bit more explicit in the documentation, in the SVE
documentation it currently just talks about no register data
being available but doesn't ever actually explicitly say why that
would happen like we do for ZA, it's currently not super helpful.
> Can NT_ARM_SSVE return a fpsimd?
It's documented that way for simplicity but in the current
implementation it won't ever actually do so in practice. The
only case where I could see that it might happen would be if we
change the syscalls to stay in streaming mode over syscall, in
that case we could do as we do for SVE and preserve FPSIMD
registers only. At present we drop out of streaming mode if we
get a syscall with it enabled so it's a non-issue, if people
agree that that's the right thing for the syscalls then we should
update the documentation to specify this since otherwise we'll
doubtless catch someone by surprise if we ever manage to start
doing it in the future.
> > +* The presence of SVE is reported to userspace via HWCAP2_SME in the aux vector
>
> SME not SVE?
Ack, yes. Well, I guess given that SME should never appear in a
system without SVE the statement is true but...
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next prev parent reply other threads:[~2021-10-08 15:28 UTC|newest]
Thread overview: 143+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 18:11 [PATCH v1 00/38] arm64/sme: Initial support for the Scalable Matrix Extension Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 01/38] arm64/fp: Reindent fpsimd_save() Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 9:39 ` Jonathan Cameron
2021-10-11 9:39 ` Jonathan Cameron
2021-10-11 13:02 ` Mark Brown
2021-10-11 13:02 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 02/38] arm64/sve: Remove sve_load_from_fpsimd_state() Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 03/38] arm64/sve: Make access to FFR optional Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 04/38] arm64/sve: Rename find_supported_vector_length() Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 05/38] arm64/sve: Use accessor functions for vector lengths in thread_struct Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 06/38] arm64/sve: Put system wide vector length information into structs Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-01 3:13 ` kernel test robot
2021-10-01 3:13 ` kernel test robot
2021-10-01 3:13 ` kernel test robot
2021-09-30 18:11 ` [PATCH v1 07/38] arm64/sve: Explicitly load vector length when restoring SVE state Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 08/38] arm64/sve: Track vector lengths for tasks in an array Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 10:20 ` Jonathan Cameron
2021-10-11 10:20 ` Jonathan Cameron
2021-10-11 13:14 ` Mark Brown
2021-10-11 13:14 ` Mark Brown
2021-10-11 13:18 ` Jonathan Cameron
2021-10-11 13:18 ` Jonathan Cameron
2021-09-30 18:11 ` [PATCH v1 09/38] arm64/sve: Make sysctl interface for SVE reusable by SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 10/38] arm64/sve: Generalise vector length configuration prctl() for SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 10:27 ` Jonathan Cameron
2021-10-11 10:27 ` Jonathan Cameron
2021-10-11 13:18 ` Mark Brown
2021-10-11 13:18 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 11/38] selftests: arm64: Parameterise ptrace vector length information Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 12/38] arm64/sme: Provide ABI documentation for SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-08 14:11 ` Alan Hayward
2021-10-08 14:11 ` Alan Hayward
2021-10-08 15:28 ` Mark Brown [this message]
2021-10-08 15:28 ` Mark Brown
2021-10-08 16:45 ` Alan Hayward
2021-10-08 16:45 ` Alan Hayward
2021-10-08 17:04 ` Mark Brown
2021-10-08 17:04 ` Mark Brown
2021-10-11 11:15 ` Alan Hayward
2021-10-11 11:15 ` Alan Hayward
2021-10-11 11:48 ` Mark Brown
2021-10-11 11:48 ` Mark Brown
2021-10-11 11:05 ` Jonathan Cameron
2021-10-11 11:05 ` Jonathan Cameron
2021-10-11 13:20 ` Mark Brown
2021-10-11 13:20 ` Mark Brown
2021-10-11 13:17 ` Szabolcs Nagy
2021-10-11 13:17 ` Szabolcs Nagy
2021-10-11 13:23 ` Mark Brown
2021-10-11 13:23 ` Mark Brown
2021-10-11 14:19 ` Szabolcs Nagy
2021-10-11 14:19 ` Szabolcs Nagy
2021-10-11 20:10 ` Mark Brown
2021-10-11 20:10 ` Mark Brown
2021-10-12 8:23 ` Szabolcs Nagy
2021-10-12 8:23 ` Szabolcs Nagy
2021-10-13 18:37 ` Mark Brown
2021-10-13 18:37 ` Mark Brown
2021-10-14 9:57 ` Szabolcs Nagy
2021-10-14 9:57 ` Szabolcs Nagy
2021-09-30 18:11 ` [PATCH v1 13/38] arm64/sme: System register and exception syndrome definitions Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 14/38] arm64/sme: Define macros for manually encoding SME instructions Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 15/38] arm64/sme: Early CPU setup for SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 16/38] arm64/sme: Basic enumeration support Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 17/38] arm64/sme: Identify supported SME vector lengths at boot Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 18/38] arm64/sme: Implement sysctl to set the default vector length Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 19/38] arm64/sme: Implement vector length configuration prctl()s Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-01 5:20 ` kernel test robot
2021-10-01 5:20 ` kernel test robot
2021-10-01 5:20 ` kernel test robot
2021-10-01 12:40 ` Mark Brown
2021-10-01 12:40 ` Mark Brown
2021-10-01 12:40 ` Mark Brown
2021-10-08 1:32 ` [kbuild-all] " Chen, Rong A
2021-10-08 1:32 ` Chen, Rong A
2021-10-08 1:32 ` [kbuild-all] " Chen, Rong A
2021-10-01 16:38 ` kernel test robot
2021-10-01 16:38 ` kernel test robot
2021-10-01 16:38 ` kernel test robot
2021-09-30 18:11 ` [PATCH v1 20/38] arm64/sme: Implement support for TPIDR2 Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 21/38] arm64/sme: Implement SVCR context switching Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 12:15 ` Jonathan Cameron
2021-10-11 12:15 ` Jonathan Cameron
2021-09-30 18:11 ` [PATCH v1 22/38] arm64/sme: Implement streaming SVE " Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 23/38] arm64/sme: Implement ZA " Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 12:27 ` Jonathan Cameron
2021-10-11 12:27 ` Jonathan Cameron
2021-09-30 18:11 ` [PATCH v1 24/38] arm64/sme: Implement traps and syscall handling for SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 12:37 ` Jonathan Cameron
2021-10-11 12:37 ` Jonathan Cameron
2021-09-30 18:11 ` [PATCH v1 25/38] arm64/sme: Implement streaming SVE signal handling Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 26/38] arm64/sme: Implement ZA " Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 27/38] arm64/sme: Implement ptrace support for streaming mode SVE registers Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 28/38] arm64/sme: Add ptrace support for ZA Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 29/38] arm64/sme: Disable streaming mode and ZA when flushing CPU state Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 30/38] arm64/sme: Save and restore streaming mode over EFI runtime calls Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 31/38] arm64/sme: Provide Kconfig for SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 32/38] kselftest/arm64: Add tests for TPIDR2 Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 33/38] kselftest/arm64: Extend vector configuration API tests to cover SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 34/38] kselftest/arm64: sme: Provide streaming mode SVE stress test Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 35/38] kselftest/arm64: Add stress test for SME ZA context switching Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 36/38] kselftest/arm64: signal: Add SME signal handling tests Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 37/38] selftests: arm64: Add streaming SVE to SVE ptrace tests Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 38/38] selftests: arm64: Add coverage for the ZA ptrace interface Mark Brown
2021-09-30 18:11 ` Mark Brown
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