linux-kernel - Re: [tip:x86/irq] x86: Always use irq stacks

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: <1279895042.3319.48.camel@gandalf.stny.rr.com>
Date:	Fri, 23 Jul 2010 10:24:02 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Christoph Hellwig <hch@....de>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/irq] x86: Always use irq stacks

On Fri, 2010-07-23 at 10:15 -0400, Steven Rostedt wrote:
> On Wed, 2010-07-14 at 17:47 +0200, Christoph Hellwig wrote:

> In arch/x86/kernel/dumpstack_32.c:
> 
>                 context = (struct thread_info *)
>                         ((unsigned long)stack & (~(THREAD_SIZE - 1)));
>                 bp = ops->walk_stack(context, stack, bp, ops, data, NULL, &graph);
> 
> Note: here, context (which ends up being tinfo) is just a bitmasking of
> the current stack. If the stack is the irqstack, then what is passed to
> walk_stack() is not the actual thread info structure.
> 
> Note, if THREAD_SIZE is 8k and irqstacks are 4K then context is totally
> wrong here.

irqstacks are indeed 8k as well, but:

union irq_ctx {
        struct thread_info      tinfo;
        u32                     stack[THREAD_SIZE/sizeof(u32)];
} __attribute__((aligned(PAGE_SIZE)));


The stack is 8k, but it is aligned 4k. Which will have

   context = (struct thread_info *)
                  ((unsigned long)stack & (~(THREAD_SIZE - 1)));

not give the expected result.

So we should do:

} __attribute__((aligned(THREAD_SIZE)));

-- Steve


--
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/