linux-kernel - Re: [PATCH v2 0/9] x86/entry/head: standardize the end of the stack

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Message-ID: <20161019132058.GA17681@gmail.com>
Date:   Wed, 19 Oct 2016 15:20:58 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Brian Gerst <brgerst@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Nilay Vaish <nilayvaish@...il.com>
Subject: Re: [PATCH v2 0/9] x86/entry/head: standardize the end of the stack


* Josh Poimboeuf <jpoimboe@...hat.com> wrote:

> On Wed, Sep 21, 2016 at 04:03:58PM -0500, Josh Poimboeuf wrote:
> > v2:
> > - keep 'restore_all' label in "x86/entry/head/32: use local labels"
> > 
> > ---
> > 
> > Thanks to all the recent x86 entry code refactoring, most tasks' kernel
> > stacks start at the same offset right below their saved pt_regs,
> > regardless of which syscall was used to enter the kernel.  That creates
> > a nice convention which makes it straightforward to identify the end of
> > the stack, which can be useful [*] for the unwinder.
> > 
> > But there a few places where tasks don't yet follow the convention.
> > This patch set finishes the job.
> > 
> > [*] This will be useful for three upcoming proposed features:
> > 
> > - Detecting corrupt stacks in the unwinder (which will also be a force
> >   for ensuring this end of stack convention continues to be followed in
> >   the future).
> > 
> > - Printing all saved pt_regs on the stack during an oops/warning.
> > 
> > - Validating stacks in the livepatch consistency model.
> 
> Ping?

Missed this one: I expected more discussion but nobody replied so it went missing.

Will have a look later this week!

Thanks,

	Ingo