linux-kernel - Re: [RFC] swap image signature check upon resume

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Message-ID: <20071208113306.GA7573@gollum.tnic>
Date:	Sat, 8 Dec 2007 12:33:06 +0100
From:	Borislav Petkov <bbpetkov@...oo.de>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Pavel Machek <pavel@...e.cz>, linux-kernel@...r.kernel.org
Subject: Re: [RFC] swap image signature check upon resume

On Fri, Dec 07, 2007 at 09:19:09PM +0100, Rafael J. Wysocki wrote:

...

> > > Well, there's a patchset in the current mainline that allows you to use
> > > arbitrary (sufficiently new) kernel to load the image and then restore the
> > > image kernel.  So, you can hibernate 2.6.24-rc3 and use 2.6.24-rc2 to restore
> > > it, for example.
> > > 
> > > I'm going to do that for i386 too.
> > right, this is d307c4a8e826c44f9633bd3f7e60d0491e7d885a (Hibernation: Arbitrary
> > boot kernel support - generic code), i should've seen that. What's the status of
> > those bits, from a quick scan it seems they need some rewiring (Kconfig, e.g.
> > CONFIG_ARCH_HIBERNATION_HEADER etc..) and arch-specific save and restore
> > functions?
> 
> No, this code is fully functional. :-)
> 
> The arch save and restore functions are in arch/x86/kernel/suspend_64.c .
> 
> As I said, i386 is not yet supported.

nice, holler if you need a tester when you have some prototypes ready. By the way,
what do you do when the suspend image header mismatches and it is unsafe to continue booting?
Also, there's a freakishly long comment in suspend_64.c, might wanna shorten it:

Signed-off-by: Borislav Petkov <bbpetkov@...oo.de>

diff --git a/arch/x86/kernel/suspend_64.c b/arch/x86/kernel/suspend_64.c
index db284ef..0a23e5f 100644
--- a/arch/x86/kernel/suspend_64.c
+++ b/arch/x86/kernel/suspend_64.c
@@ -118,7 +118,12 @@ void fix_processor_context(void)
 	int cpu = smp_processor_id();
 	struct tss_struct *t = &per_cpu(init_tss, cpu);
 
-	set_tss_desc(cpu,t);	/* This just modifies memory; should not be necessary. But... This is necessary, because 386 hardware has concept of busy TSS or some similar stupidity. */
+	/*
+	 * This just modifies memory; should not be necessary. But... This
+	 * is necessary, because 386 hardware has concept of busy TSS or some
+	 * similar stupidity.
+	 */
+	set_tss_desc(cpu,t);
 
 	cpu_gdt(cpu)[GDT_ENTRY_TSS].type = 9;
 
@@ -138,7 +143,6 @@ void fix_processor_context(void)
                 loaddebug(&current->thread, 6);
                 loaddebug(&current->thread, 7);
 	}
-
 }
 
 #ifdef CONFIG_HIBERNATION

-- 
Regards/Gruß,
    Boris.
--
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