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Date:   Thu, 23 Nov 2017 21:16:52 +0000 (UTC)
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "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>,
        shuah <shuah@...nel.org>,
        linux-kselftest <linux-kselftest@...r.kernel.org>
Subject: Re: [RFC PATCH for 4.15 v3 15/22] rseq: selftests: Provide
 self-tests

----- On Nov 22, 2017, at 2:38 PM, Peter Zijlstra peterz@...radead.org wrote:

> On Tue, Nov 21, 2017 at 09:18:53AM -0500, 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.
> 
> Could I ask you to split this in smaller bits?
> 
> I'd start with just the rseq library, using only the rseq interface.
> Then add the whole cpu_opv fallback stuff.
> Then add the selftests using librseq.
> 
> As is this is a tad much to read in a single go.

Sure, will do! And I plan to change the selftests to use the new
"percpu_*()" API that removes the need to duplicate code in the
caller code.

Thanks,

Mathieu


-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

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