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

From: Ingo Molnar
Date: Wed Oct 19 2016 - 10:19:25 EST



* Josh Poimboeuf <jpoimboe@xxxxxxxxxx> 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