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

On Tue, 9 Aug 2016, Thomas Garnier wrote:

quoted

quoted

Okay, I did one-by-one reverts, and the one above, i.e.

      commit 021182e52fe01c1f7b126f97fd6ba048dc4234fd
      Author: Thomas Garnier [off-list ref]
      Date:   Tue Jun 21 17:47:03 2016 -0700

          x86/mm: Enable KASLR for physical mapping memory regions

is the one that is the culprit on my machine. With this one reverted,
resume hibernation doesn't reboot (tripple fault?), but proceeds
succesfully.

My .config is attached. It is basically defconfig (x86_64) + kvmconfig
plus the following:

CONFIG_PHYSICAL_START=0x1000000
CONFIG_RELOCATABLE=y
CONFIG_RANDOMIZE_BASE=y
CONFIG_X86_NEED_RELOCS=y
CONFIG_PHYSICAL_ALIGN=0x1000000
CONFIG_RANDOMIZE_MEMORY=y
CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING=0xa
CONFIG_X86_PTDUMP_CORE=y
CONFIG_X86_PTDUMP=y
CONFIG_KALLSYMS=y
CONFIG_KALLSYMS_ALL=y
CONFIG_KALLSYMS_ABSOLUTE_PERCPU=y
CONFIG_KALLSYMS_BASE_RELATIVE=y
CONFIG_PANIC_ON_OOPS=y
CONFIG_KGDB=y
CONFIG_EARLY_PRINTK=y
CONFIG_EARLY_PRINTK_DBGP=y
CONFIG_DEBUG_INFO=y
CONFIG_DEBUG_INFO_DWARF4=y

The config I am reproducing the bug with (on thinkpad x200s) can be found 
at

	http://www.jikos.cz/jikos/junk/.config

Either later today or tomorrow I could test with the same physical start 
and align values you're using to see whether that'd make any difference.

quoted

As discussed with Rafael privately, I also tried this very patch
(x86/power/64: Always create temporary identity mapping correctly) on top
of the reverted revert of 021182e52fe01c1f7b1 (see the full log below),
but such kernel triple faults on resume as well.

87c38d2 x86/power/64: Always create temporary identity mapping correctly
3cb504a Revert "Revert "x86/mm: Enable KASLR for physical mapping memory regions""
758850d Revert "x86/mm: Enable KASLR for physical mapping memory regions"
4a02dfb Revert "x86/mm: Enable KASLR for vmalloc memory regions"
037863f Revert "x86/mm: Add memory hotplug support for KASLR memory randomization"
3416a21 Revert "x86/mm: Do not reference phys addr beyond kernel"
69227be Revert "mm: reorganize SLAB freelist randomization"
a1d8d71 Revert "mm: SLUB freelist randomization"

IOW, 021182e52f introduces a bug for which there is no existing fix yet.

You mean it is something different from the previous KASLR bugs we saw?

No, I just wanted to explicitly point out that "x86/power/64: Always 
create temporary identity mapping correctly" is not a fix for this issue.

-- 
Jiri Kosina
SUSE Labs