linux-kernel - Re: PROBLEM: Resume form hibernate broken by setting NX on gap

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Message-ID: <575B03F1.3060206@deltatee.com>
Date:	Fri, 10 Jun 2016 12:16:17 -0600
From:	Logan Gunthorpe <logang@...tatee.com>
To:	Kees Cook <keescook@...omium.org>
Cc:	"Rafael J. Wysocki" <rafael@...nel.org>,
	Stephen Smalley <sds@...ho.nsa.gov>,
	Ingo Molnar <mingo@...nel.org>, Ingo Molnar <mingo@...hat.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Brian Gerst <brgerst@...il.com>
Subject: Re: PROBLEM: Resume form hibernate broken by setting NX on gap

Hey,

On 10/06/16 12:09 PM, Kees Cook wrote:
>> restore_code: ffff880157c3b000
>> jump_addr: ffffffff81446be0
>>
>>
>> diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
>> index 009947d..6efedb7 100644
>> --- a/arch/x86/power/hibernate_64.c
>> +++ b/arch/x86/power/hibernate_64.c
>> @@ -92,6 +92,9 @@ int swsusp_arch_resume(void)
>>         memcpy(relocated_restore_code, &core_restore_code,
>>                &restore_registers - &core_restore_code);
>>
>> +       pr_info("restore_code: %p\n", relocated_restore_code);
>> +       pr_info("jump_addr: %lx\n", restore_jump_address);
>> +
> 
> Also interesting would be the "relocated_restore_code" address, as
> well as a dump of /sys/kernel/debug/kernel_page_tables (from
> CONFIG_X86_PTDUMP).

Is that not what I printed? If not, can you give me a better hint as to
what you're looking for so I can spin another kernel? I'll also provide
the kernel_page_tables once I do that.

> I'm baffled by the problem, but the best I can understand is the the
> relocated_restore_code range isn't executable (which should be visible
> from finding it in /sys/kernel/debug/kernel_page_tables), but I don't
> see how to solve that since my original patch didn't work.

Yeah this is definitely a baffling problem.

Thanks,

Logan