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  1. Aug 03, 2016
    • Rafael J. Wysocki's avatar
      x86/power/64: Do not refer to __PAGE_OFFSET from assembly code · c226fab4
      Rafael J. Wysocki authored 
      

When CONFIG_RANDOMIZE_MEMORY is set on x86-64, __PAGE_OFFSET becomes
a variable and using it as a symbol in the image memory restoration
assembly code under core_restore_code is not correct any more.

To avoid that problem, modify set_up_temporary_mappings() to compute
the physical address of the temporary page tables and store it in
temp_level4_pgt, so that the value of that variable is ready to be
written into CR3.  Then, the assembly code doesn't have to worry
about converting that value into a physical address and things work
regardless of whether or not CONFIG_RANDOMIZE_MEMORY is set.

Reported-and-tested-by: default avatarThomas Garnier <thgarnie@google.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      c226fab4
  3. Jul 29, 2016
    • Josh Poimboeuf's avatar
      x86/power/64: Fix hibernation return address corruption · 4ce827b4
      Josh Poimboeuf authored 
      In kernel bug 150021, a kernel panic was reported when restoring a
hibernate image.  Only a picture of the oops was reported, so I can't
paste the whole thing here.  But here are the most interesting parts:

  kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
  BUG: unable to handle kernel paging request at ffff8804615cfd78
  ...
  RIP: ffff8804615cfd78
  RSP: ffff8804615f0000
  RBP: ffff8804615cfdc0
  ...
  Call Trace:
   do_signal+0x23
   exit_to_usermode_loop+0x64
   ...

The RIP is on the same page as RBP, so it apparently started executing
on the stack.

The bug was bisected to commit ef0f3ed5 (x86/asm/power: Create
stack frames in hibernate_asm_64.S), which in retrospect seems quite
dangerous, since that code saves and restores the stack pointer from a
global variable ('saved_context').

There are a lot of moving parts in the hibernate save and restore paths,
so I don't know exactly what caused the panic.  Presumably, a FRAME_END
was executed without the corresponding FRAME_BEGIN, or vice versa.  That
would corrupt the return address on the stack and would be consistent
with the details of the above panic.

[ rjw: One major problem is that by the time the FRAME_BEGIN in
  restore_registers() is executed, the stack pointer value may not
  be valid any more.  Namely, the stack area pointed to by it
  previously may have been overwritten by some image memory contents
  and that page frame may now be used for whatever different purpose
  it had been allocated for before hibernation.  In that case, the
  FRAME_BEGIN will corrupt that memory. ]

Instead of doing the frame pointer save/restore around the bounds of the
affected functions, just do it around the call to swsusp_save().

That has the same effect of ensuring that if swsusp_save() sleeps, the
frame pointers will be correct.  It's also a much more obviously safe
way to do it than the original patch.  And objtool still doesn't report
any warnings.

Fixes: ef0f3ed5 (x86/asm/power: Create stack frames in hibernate_asm_64.S)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=150021


Cc: 4.6+ <stable@vger.kernel.org> # 4.6+
Reported-by: default avatarAndre Reinke <andre.reinke@mailbox.org>
Tested-by: default avatarAndre Reinke <andre.reinke@mailbox.org>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      4ce827b4
  5. Jul 22, 2016
    • Chen Yu's avatar
      PM / hibernate: Introduce test_resume mode for hibernation · fe12c00d
      Chen Yu authored 
      

test_resume mode is to verify if the snapshot data
written to swap device can be successfully restored
to memory. It is useful to ease the debugging process
on hibernation, since this mode can not only bypass
the BIOSes/bootloader, but also the system re-initialization.

To avoid the risk to break the filesystm on persistent storage,
this patch resumes the image with tasks frozen.

For example:
echo test_resume > /sys/power/disk
echo disk > /sys/power/state

[  187.306470] PM: Image saving progress:  70%
[  187.395298] PM: Image saving progress:  80%
[  187.476697] PM: Image saving progress:  90%
[  187.554641] PM: Image saving done.
[  187.558896] PM: Wrote 594600 kbytes in 0.90 seconds (660.66 MB/s)
[  187.566000] PM: S|
[  187.589742] PM: Basic memory bitmaps freed
[  187.594694] PM: Checking hibernation image
[  187.599865] PM: Image signature found, resuming
[  187.605209] PM: Loading hibernation image.
[  187.665753] PM: Basic memory bitmaps created
[  187.691397] PM: Using 3 thread(s) for decompression.
[  187.691397] PM: Loading and decompressing image data (148650 pages)...
[  187.889719] PM: Image loading progress:   0%
[  188.100452] PM: Image loading progress:  10%
[  188.244781] PM: Image loading progress:  20%
[  189.057305] PM: Image loading done.
[  189.068793] PM: Image successfully loaded

Suggested-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarChen Yu <yu.c.chen@intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      fe12c00d
  7. Jul 16, 2016
    • Rafael J. Wysocki's avatar
      x86 / hibernate: Use hlt_play_dead() when resuming from hibernation · 406f992e
      Rafael J. Wysocki authored 
      On Intel hardware, native_play_dead() uses mwait_play_dead() by
default and only falls back to the other methods if that fails.
That also happens during resume from hibernation, when the restore
(boot) kernel runs disable_nonboot_cpus() to take all of the CPUs
except for the boot one offline.

However, that is problematic, because the address passed to
__monitor() in mwait_play_dead() is likely to be written to in the
last phase of hibernate image restoration and that causes the "dead"
CPU to start executing instructions again.  Unfortunately, the page
containing the address in that CPU's instruction pointer may not be
valid any more at that point.

First, that page may have been overwritten with image kernel memory
contents already, so the instructions the CPU attempts to execute may
simply be invalid.  Second, the page tables previously used by that
CPU may have been overwritten by image kernel memory contents, so the
address in its instruction pointer is impossible to resolve then.

A report from Varun Koyyalagunta and investigation carried out by
Chen Yu show that the latter sometimes happens in practice.

To prevent it from happening, temporarily change the smp_ops.play_dead
pointer during resume from hibernation so that it points to a special
"play dead" routine which uses hlt_play_dead() and avoids the
inadvertent "revivals" of "dead" CPUs this way.

A slightly unpleasant consequence of this change is that if the
system is hibernated with one or more CPUs offline, it will generally
draw more power after resume than it did before hibernation, because
the physical state entered by CPUs via hlt_play_dead() is higher-power
than the mwait_play_dead() one in the majority of cases.  It is
possible to work around this, but it is unclear how much of a problem
that's going to be in practice, so the workaround will be implemented
later if it turns out to be necessary.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=106371


Reported-by: default avatarVarun Koyyalagunta <cpudebug@centtech.com>
Original-by: default avatarChen Yu <yu.c.chen@intel.com>
Tested-by: default avatarChen Yu <yu.c.chen@intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
      406f992e
  9. Jul 10, 2016
  11. Jul 09, 2016
  13. Jul 02, 2016
    • Rafael J. Wysocki's avatar
      PM / hibernate: Recycle safe pages after image restoration · 307c5971
      Rafael J. Wysocki authored 
      

One of the memory bitmaps used by the hibernation image restoration
code is freed after the image has been loaded.

That is not quite efficient, though, because the memory pages used
for building that bitmap are known to be safe (ie. they were not
used by the image kernel before hibernation) and the arch-specific
code finalizing the image restoration may need them.  In that case
it needs to allocate those pages again via the memory management
subsystem, check if they are really safe again by consulting the
other bitmaps and so on.

To avoid that, recycle those pages by putting them into the global
list of known safe pages so that they can be given to the arch code
right away when necessary.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      307c5971
    • Rafael J. Wysocki's avatar
      PM / hibernate: Simplify mark_unsafe_pages() · 6dbecfd3
      Rafael J. Wysocki authored 
      

Rework mark_unsafe_pages() to use a simpler method of clearing
all bits in free_pages_map and to set the bits for the "unsafe"
pages (ie. pages that were used by the image kernel before
hibernation) with the help of duplicate_memory_bitmap().

For this purpose, move the pfn_valid() check from mark_unsafe_pages()
to unpack_orig_pfns() where the "unsafe" pages are discovered.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      6dbecfd3
    • Rafael J. Wysocki's avatar
      PM / hibernate: Do not free preallocated safe pages during image restore · 9c744481
      Rafael J. Wysocki authored 
      

The core image restoration code preallocates some safe pages
(ie. pages that weren't used by the image kernel before hibernation)
for future use before allocating the bulk of memory for loading the
image data.  Those safe pages are then freed so they can be allocated
again (with the memory management subsystem's help).  That's done to
ensure that there will be enough safe pages for temporary data
structures needed during image restoration.

However, it is not really necessary to free those pages after they
have been allocated.  They can be added to the (global) list of
safe pages right away and then picked up from there when needed
without freeing.

That reduces the overhead related to using safe pages, especially
in the arch-specific code, so modify the code accordingly.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      9c744481
    • Roger Lu's avatar
      PM / suspend: show workqueue state in suspend flow · 7b776af6
      Roger Lu authored 
      

If freezable workqueue aborts suspend flow, show
workqueue state for debug purpose.

Signed-off-by: default avatarRoger Lu <roger.lu@mediatek.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      7b776af6
  15. Jul 01, 2016
    • Rafael J. Wysocki's avatar
      x86/power/64: Fix kernel text mapping corruption during image restoration · 65c0554b
      Rafael J. Wysocki authored 
      Logan Gunthorpe reports that hibernation stopped working reliably for
him after commit ab76f7b4 (x86/mm: Set NX on gap between __ex_table
and rodata).

That turns out to be a consequence of a long-standing issue with the
64-bit image restoration code on x86, which is that the temporary
page tables set up by it to avoid page tables corruption when the
last bits of the image kernel's memory contents are copied into
their original page frames re-use the boot kernel's text mapping,
but that mapping may very well get corrupted just like any other
part of the page tables.  Of course, if that happens, the final
jump to the image kernel's entry point will go to nowhere.

The exact reason why commit ab76f7b4 matters here is that it
sometimes causes a PMD of a large page to be split into PTEs
that are allocated dynamically and get corrupted during image
restoration as described above.

To fix that issue note that the code copying the last bits of the
image kernel's memory contents to the page frames occupied by them
previoulsy doesn't use the kernel text mapping, because it runs from
a special page covered by the identity mapping set up for that code
from scratch.  Hence, the kernel text mapping is only needed before
that code starts to run and then it will only be used just for the
final jump to the image kernel's entry point.

Accordingly, the temporary page tables set up in swsusp_arch_resume()
on x86-64 need to contain the kernel text mapping too.  That mapping
is only going to be used for the final jump to the image kernel, so
it only needs to cover the image kernel's entry point, because the
first thing the image kernel does after getting control back is to
switch over to its own original page tables.  Moreover, the virtual
address of the image kernel's entry point in that mapping has to be
the same as the one mapped by the image kernel's page tables.

With that in mind, modify the x86-64's arch_hibernation_header_save()
and arch_hibernation_header_restore() routines to pass the physical
address of the image kernel's entry point (in addition to its virtual
address) to the boot kernel (a small piece of assembly code involved
in passing the entry point's virtual address to the image kernel is
not necessary any more after that, so drop it).  Update RESTORE_MAGIC
too to reflect the image header format change.

Next, in set_up_temporary_mappings(), use the physical and virtual
addresses of the image kernel's entry point passed in the image
header to set up a minimum kernel text mapping (using memory pages
that won't be overwritten by the image kernel's memory contents) that
will map those addresses to each other as appropriate.

This makes the concern about the possible corruption of the original
boot kernel text mapping go away and if the the minimum kernel text
mapping used for the final jump marks the image kernel's entry point
memory as executable, the jump to it is guaraneed to succeed.

Fixes: ab76f7b4 (x86/mm: Set NX on gap between __ex_table and rodata)
Link: http://marc.info/?l=linux-pm&m=146372852823760&w=2


Reported-by: default avatarLogan Gunthorpe <logang@deltatee.com>
Reported-and-tested-by: default avatarBorislav Petkov <bp@suse.de>
Tested-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      65c0554b
  17. Jun 28, 2016
  19. Jun 27, 2016
  21. Jun 25, 2016