linux-kernel - Re: [patch 00/14] x86/exceptions: Add guard patches to IST stacks

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Date:   Sun, 31 Mar 2019 21:03:42 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [patch 00/14] x86/exceptions: Add guard patches to IST stacks

On Sun, Mar 31, 2019 at 3:10 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> Hi!
>
> While looking for something different I stumbled over the comment in struct
> cpu_entry_area:
>
>          * Exception stacks used for IST entries.
>          *
>          * In the future, this should have a separate slot for each stack
>          * with guard pages between them.
>
> As usual with such comments they are added in good faith and then
> forgotten. Looking what it takes to fix that let me stumble over some other
> leftovers like orig_ist[], now unused macros, useless defines and a bunch
> of assumptions about the exception stacks being a big lump. Aside of that I
> found a too broad check of the exception stack in the x86/64 stack overflow
> detector.
>
> The following series cleans that up and gradually prepares for guard pages
> between the IST stacks.

Thanks!  I'll review this over the next couple days.

Meanwhile, if you're inspired, I have a WIP series to do the same
thing to the IRQ stacks here:

https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/log/?h=x86/guard_pages

Want to take a look or pick it up if you want to keep working on this?