linux-kernel - Re: [PATCH v2 1/3] x86/entry/64: Refactor IRQ stacks and make them NMI-safe

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAHp75Ve-mAO6LABaVp6+Prw6YE90V-4n+psAP8CkNyK87A4Dpg@mail.gmail.com>
Date:	Mon, 17 Aug 2015 14:18:27 +0300
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Andy Lutomirski <luto@...nel.org>
Cc:	X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Brian Gerst <brgerst@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>, Willy Tarreau <w@....eu>,
	Borislav Petkov <bp@...en8.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v2 1/3] x86/entry/64: Refactor IRQ stacks and make them NMI-safe

On Sat, Jul 25, 2015 at 8:57 AM, Andy Lutomirski <luto@...nel.org> wrote:
> This will allow IRQ stacks to nest inside NMIs or similar entries
> that can happen during IRQ stack setup or teardown.
>
> The Xen code here has a confusing comment.
>
> The new macros won't work correctly if they're invoked with IRQs on.
> Add a check under CONFIG_DEBUG_ENTRY to detect that.
>

> +/*
> + * Enters the IRQ stack if we're not already using it.  NMI-safe.  Clobbers
> + * flags and puts old RSP into old_rsp, and leaves all other GPRs alone.
> + * Requires kernel GSBASE.
> + *
> + * The invariant is that, if irq_count != 1, then the IRQ stack is in use.
> + */

I might be wrong, but shouldn't be this read as 'if irq_count != -1' ?

-- 
With Best Regards,
Andy Shevchenko
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/