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

From: Jiri Kosina
Date: Wed Aug 10 2016 - 17:52:45 EST


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.

--
Jiri Kosina
SUSE Labs