linux-kernel - Re: [RFC PATCH for 4.15 v3 15/22] rseq: selftests: Provide self-tests

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Message-ID: <20171122193821.GJ3165@worktop.lehotels.local>
Date:   Wed, 22 Nov 2017 20:38:21 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
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@...r.kernel.org,
        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>,
        Steven 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 Khan <shuah@...nel.org>, linux-kselftest@...r.kernel.org
Subject: Re: [RFC PATCH for 4.15 v3 15/22] rseq: selftests: Provide self-tests

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.