linux-kernel - Re: [PATCH v4 06/45] kmsan: add ReST documentation

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Date:   Fri, 15 Jul 2022 10:52:49 +0200
From:   Marco Elver <elver@...gle.com>
To:     Alexander Potapenko <glider@...gle.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Christoph Hellwig <hch@....de>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Ingo Molnar <mingo@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kees Cook <keescook@...omium.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthew Wilcox <willy@...radead.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Pekka Enberg <penberg@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Linux-Arch <linux-arch@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 06/45] kmsan: add ReST documentation

On Fri, Jul 15, 2022 at 09:42AM +0200, Alexander Potapenko wrote:
[...]
> > This sentence might still be confusing. I think it should highlight
> > that runtime and compiler go together, but depending on the scope of
> > the value, the compiler invokes the runtime to persist the shadow.
> 
> Changed to:
> """
> Compiler instrumentation also tracks the shadow values as they are used along
> the code. When needed, instrumentation code invokes the runtime library in
> ``mm/kmsan/`` to persist shadow values.
> """

Ack.

[...]
> > > +Passing uninitialized values to functions
> > > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > +
> > > +KMSAN instrumentation pass has an option, ``-fsanitize-memory-param-retval``,
> >
> > "KMSAN instrumentation pass" -> "Clang's instrumentation support" ?
> > Because it seems wrong to say that KMSAN has the instrumentation pass.
> How about "Clang's MSan instrumentation pass"?

Maybe just "Clang's MemorySanitizer instrumentation" - no abbreviation,
and "pass" is very compiler-implementation specific and not everyone
might know what "pass" even means in this context, so I'd leave it out.

[...]
> > It would be useful to move this section somewhere to the beginning,
> > closer to usage and the example, as this is information that a user of
> > KMSAN might want to know (but they might not want to know much about
> > how KMSAN works).
> 
> I restructured the TOC as follows:
> 
> == The Kernel Memory Sanitizer (KMSAN)
> == Usage
> --- Building the kernel
> --- Example report
> --- Disabling the instrumentation
> == Support
> == How KMSAN works
> --- KMSAN shadow memory
> --- Origin tracking
> ~~~~ Origin chaining
> --- Clang instrumentation API
> ~~~~ Shadow manipulation
> ~~~~ Handling locals
> ~~~~ Access to per-task data
> ~~~~ Passing uninitialized values to functions
> ~~~~ String functions
> ~~~~ Error reporting
> ~~~~ Inline assembly instrumentation
> --- Runtime library
> ~~~~ Per-task KMSAN state
> ~~~~ KMSAN contexts
> ~~~~ Metadata allocation
> == References

LGTM.

Thanks,
-- Marco