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Date: Wed, 22 Nov 2017 16:31:51 +0000 (UTC)
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: shuah <shuah@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Boqun Feng <boqun.feng@...il.com>,
Andy Lutomirski <luto@...capital.net>,
Dave Watson <davejwatson@...com>,
linux-kernel <linux-kernel@...r.kernel.org>,
linux-api <linux-api@...r.kernel.org>,
Paul Turner <pjt@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Russell King <linux@....linux.org.uk>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Andrew Hunter <ahh@...gle.com>,
Andi Kleen <andi@...stfloor.org>, Chris Lameter <cl@...ux.com>,
Ben Maurer <bmaurer@...com>, rostedt <rostedt@...dmis.org>,
Josh Triplett <josh@...htriplett.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Michael Kerrisk <mtk.manpages@...il.com>,
linux-kselftest <linux-kselftest@...r.kernel.org>,
Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH update for 4.15 3/3] rseq: selftests: Provide self-tests
(v4)
----- On Nov 22, 2017, at 10:23 AM, shuah shuah@...nel.org wrote:
> On 11/21/2017 03:19 PM, Mathieu Desnoyers wrote:
>> Implements two basic tests of RSEQ functionality, and one more
>> exhaustive parameterizable test.
>>
>> The first, "basic_test" only asserts that RSEQ works moderately
>> correctly. E.g. that the CPUID pointer works.
>>
>> "basic_percpu_ops_test" is a slightly more "realistic" variant,
>> implementing a few simple per-cpu operations and testing their
>> correctness.
>>
>> "param_test" is a parametrizable restartable sequences test. See
>> the "--help" output for usage.
>>
>> A run_param_test.sh script runs many variants of the parametrizable
>> tests.
>>
>> As part of those tests, a helper library "rseq" implements a user-space
>> API around restartable sequences. It uses the cpu_opv system call as
>> fallback when single-stepped by a debugger. It exposes the instruction
>> pointer addresses where the rseq assembly blocks begin and end, as well
>> as the associated abort instruction pointer, in the __rseq_table
>> section. This section allows debuggers may know where to place
>> breakpoints when single-stepping through assembly blocks which may be
>> aborted at any point by the kernel.
>>
>> The rseq library expose APIs that present the fast-path operations.
>> The new from userspace is, e.g. for a counter increment:
>>
>> cpu = rseq_cpu_start();
>> ret = rseq_addv(&data->c[cpu].count, 1, cpu);
>> if (likely(!ret))
>> return 0; /* Success. */
>> do {
>> cpu = rseq_current_cpu();
>> ret = cpu_op_addv(&data->c[cpu].count, 1, cpu);
>> if (likely(!ret))
>> return 0; /* Success. */
>> } while (ret > 0 || errno == EAGAIN);
>> perror("cpu_op_addv");
>> return -1; /* Unexpected error. */
>>
>> PowerPC tests have been implemented by Boqun Feng.
>>
>> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
>> CC: Russell King <linux@....linux.org.uk>
>> CC: Catalin Marinas <catalin.marinas@....com>
>> CC: Will Deacon <will.deacon@....com>
>> CC: Thomas Gleixner <tglx@...utronix.de>
>> CC: Paul Turner <pjt@...gle.com>
>> CC: Andrew Hunter <ahh@...gle.com>
>> CC: Peter Zijlstra <peterz@...radead.org>
>> CC: Andy Lutomirski <luto@...capital.net>
>> CC: Andi Kleen <andi@...stfloor.org>
>> CC: Dave Watson <davejwatson@...com>
>> CC: Chris Lameter <cl@...ux.com>
>> CC: Ingo Molnar <mingo@...hat.com>
>> CC: "H. Peter Anvin" <hpa@...or.com>
>> CC: Ben Maurer <bmaurer@...com>
>> CC: Steven Rostedt <rostedt@...dmis.org>
>> CC: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
>> CC: Josh Triplett <josh@...htriplett.org>
>> CC: Linus Torvalds <torvalds@...ux-foundation.org>
>> CC: Andrew Morton <akpm@...ux-foundation.org>
>> CC: Boqun Feng <boqun.feng@...il.com>
>> CC: Shuah Khan <shuah@...nel.org>
>> CC: linux-kselftest@...r.kernel.org
>> CC: linux-api@...r.kernel.org
>> ---
>> Changes since v1:
>> - Provide abort-ip signature: The abort-ip signature is located just
>> before the abort-ip target. It is currently hardcoded, but a
>> user-space application could use the __rseq_table to iterate on all
>> abort-ip targets and use a random value as signature if needed in the
>> future.
>> - Add rseq_prepare_unload(): Libraries and JIT code using rseq critical
>> sections need to issue rseq_prepare_unload() on each thread at least
>> once before reclaim of struct rseq_cs.
>> - Use initial-exec TLS model, non-weak symbol: The initial-exec model is
>> signal-safe, whereas the global-dynamic model is not. Remove the
>> "weak" symbol attribute from the __rseq_abi in rseq.c. The rseq.so
>> library will have ownership of that symbol, and there is not reason for
>> an application or user library to try to define that symbol.
>> The expected use is to link against libreq.so, which owns and provide
>> that symbol.
>> - Set cpu_id to -2 on register error
>> - Add rseq_len syscall parameter, rseq_cs version
>> - Ensure disassember-friendly signature: x86 32/64 disassembler have a
>> hard time decoding the instruction stream after a bad instruction. Use
>> a nopl instruction to encode the signature. Suggested by Andy Lutomirski.
>> - Exercise parametrized tests variants in a shell scripts.
>> - Restartable sequences selftests: Remove use of event counter.
>> - Use cpu_id_start field: With the cpu_id_start field, the C
>> preparation phase of the fast-path does not need to compare cpu_id < 0
>> anymore.
>> - Signal-safe registration and refcounting: Allow libraries using
>> librseq.so to register it from signal handlers.
>> - Use OVERRIDE_TARGETS in makefile.
>> - Use "m" constraints for rseq_cs field.
>>
>> Changes since v2:
>> - Update based on Thomas Gleixner's comments.
>>
>> Changes since v3:
>> - Generate param_test_skip_fastpath and param_test_benchmark with
>> -DSKIP_FASTPATH and -DBENCHMARK (respectively). Add param_test_fastpath
>> to run_param_test.sh.
>> ---
>> MAINTAINERS | 1 +
>> tools/testing/selftests/Makefile | 1 +
>> tools/testing/selftests/rseq/.gitignore | 4 +
>> tools/testing/selftests/rseq/Makefile | 33 +
>> .../testing/selftests/rseq/basic_percpu_ops_test.c | 333 +++++
>> tools/testing/selftests/rseq/basic_test.c | 55 +
>> tools/testing/selftests/rseq/param_test.c | 1285 ++++++++++++++++++++
>> tools/testing/selftests/rseq/rseq-arm.h | 535 ++++++++
>> tools/testing/selftests/rseq/rseq-ppc.h | 567 +++++++++
>> tools/testing/selftests/rseq/rseq-x86.h | 898 ++++++++++++++
>> tools/testing/selftests/rseq/rseq.c | 116 ++
>> tools/testing/selftests/rseq/rseq.h | 154 +++
>> tools/testing/selftests/rseq/run_param_test.sh | 126 ++
>> 13 files changed, 4108 insertions(+)
>> create mode 100644 tools/testing/selftests/rseq/.gitignore
>> create mode 100644 tools/testing/selftests/rseq/Makefile
>> create mode 100644 tools/testing/selftests/rseq/basic_percpu_ops_test.c
>> create mode 100644 tools/testing/selftests/rseq/basic_test.c
>> create mode 100644 tools/testing/selftests/rseq/param_test.c
>> create mode 100644 tools/testing/selftests/rseq/rseq-arm.h
>> create mode 100644 tools/testing/selftests/rseq/rseq-ppc.h
>> create mode 100644 tools/testing/selftests/rseq/rseq-x86.h
>> create mode 100644 tools/testing/selftests/rseq/rseq.c
>> create mode 100644 tools/testing/selftests/rseq/rseq.h
>> create mode 100755 tools/testing/selftests/rseq/run_param_test.sh
>>
>
> Looks good.
>
> Acked-by: Shuah Khan <shuahkh@....samsung.com>
Thanks the the reviews!
Mathieu
>
> thanks,
> -- Shuah
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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