linux-kernel - Re: [Resend][PATCH] x86/power/64: Always create temporary identity mapping correctly

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Message-ID: <CAJZ5v0iEEb2ZqsLjvvm0XoGaBiZ5MBD+PRGNqD-_MtkOqdGKeg@mail.gmail.com>
Date:	Wed, 10 Aug 2016 23:58:29 +0200
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Jiri Kosina <jikos@...nel.org>
Cc:	Thomas Garnier <thgarnie@...gle.com>, Borislav Petkov <bp@...e.de>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	"the arch/x86 maintainers" <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Kees Cook <keescook@...omium.org>, Pavel Machek <pavel@....cz>,
	Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [Resend][PATCH] x86/power/64: Always create temporary identity
 mapping correctly

On Wed, Aug 10, 2016 at 11:52 PM, Jiri Kosina <jikos@...nel.org> wrote:
> On Wed, 10 Aug 2016, Thomas Garnier wrote:
>
>> Ok, I want to know if the problem is the PUD alignment or the change
>> of PAGE_OFFSET based all together. Can you test the following change?
>> (on top of everything else with KASLR enabled). It will randomize the
>> memory sections only on PGD level.
>>
>> diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
>> index ec8654f..a8477b0 100644
>> --- a/arch/x86/mm/kaslr.c
>> +++ b/arch/x86/mm/kaslr.c
>> @@ -120,7 +120,7 @@ void __init kernel_randomize_memory(void)
>>                  */
>>                 entropy = remain_entropy / (ARRAY_SIZE(kaslr_regions) - i);
>>                 prandom_bytes_state(&rand_state, &rand, sizeof(rand));
>> -               entropy = (rand % (entropy + 1)) & PUD_MASK;
>> +               entropy = (rand % (entropy + 1)) & PGDIR_MASK;
>>                 vaddr += entropy;
>>                 *kaslr_regions[i].base = vaddr;
>>
>> @@ -129,7 +129,7 @@ void __init kernel_randomize_memory(void)
>>                  * randomization alignment.
>>                  */
>>                 vaddr += get_padding(&kaslr_regions[i]);
>> -               vaddr = round_up(vaddr + 1, PUD_SIZE);
>> +               vaddr = round_up(vaddr + 1, PGDIR_SIZE);
>>                 remain_entropy -= entropy;
>>         }
>>  }
>
> I applied this on top of both fixes from Rafael from this thread; still no
> change in behavior, i.e. reboot immediately after reading the hibernation
> image.

Same for me on the box where I can reproduce the problem now.