linux-toradex.git/mm/Makefile, branch v4.9.96

Disable the __builtin_return_address() warning globally after all

2016-10-12T17:23:41+00:00

This affectively reverts commit 377ccbb48373 ("Makefile: Mute warning
for __builtin_return_address(>0) for tracing only") because it turns out
that it really isn't tracing only - it's all over the tree.

We already also had the warning disabled separately for mm/usercopy.c
(which this commit also removes), and it turns out that we will also
want to disable it for get_lock_parent_ip(), that is used for at least
TRACE_IRQFLAGS.  Which (when enabled) ends up being all over the tree.

Steven Rostedt had a patch that tried to limit it to just the config
options that actually triggered this, but quite frankly, the extra
complexity and abstraction just isn't worth it.  We have never actually
had a case where the warning is actually useful, so let's just disable
it globally and not worry about it.

Acked-by: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: Andrew Morton 
Cc: Ingo Molnar 
Cc: Peter Anvin 
Signed-off-by: Linus Torvalds

Merge tag 'usercopy-v4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2016-08-08T21:48:14+00:00

Pull usercopy protection from Kees Cook:
 "Tbhis implements HARDENED_USERCOPY verification of copy_to_user and
  copy_from_user bounds checking for most architectures on SLAB and
  SLUB"

* tag 'usercopy-v4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  mm: SLUB hardened usercopy support
  mm: SLAB hardened usercopy support
  s390/uaccess: Enable hardened usercopy
  sparc/uaccess: Enable hardened usercopy
  powerpc/uaccess: Enable hardened usercopy
  ia64/uaccess: Enable hardened usercopy
  arm64/uaccess: Enable hardened usercopy
  ARM: uaccess: Enable hardened usercopy
  x86/uaccess: Enable hardened usercopy
  mm: Hardened usercopy
  mm: Implement stack frame object validation
  mm: Add is_migrate_cma_page

thp: extract khugepaged from mm/huge_memory.c

2016-07-26T23:19:19+00:00

khugepaged implementation grew to the point when it deserve separate
file in source.

Let's move it to mm/khugepaged.c.

Link: http://lkml.kernel.org/r/1466021202-61880-32-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: Hardened usercopy

2016-07-26T21:41:47+00:00

This is the start of porting PAX_USERCOPY into the mainline kernel. This
is the first set of features, controlled by CONFIG_HARDENED_USERCOPY. The
work is based on code by PaX Team and Brad Spengler, and an earlier port
from Casey Schaufler. Additional non-slab page tests are from Rik van Riel.

This patch contains the logic for validating several conditions when
performing copy_to_user() and copy_from_user() on the kernel object
being copied to/from:
- address range doesn't wrap around
- address range isn't NULL or zero-allocated (with a non-zero copy size)
- if on the slab allocator:
  - object size must be less than or equal to copy size (when check is
    implemented in the allocator, which appear in subsequent patches)
- otherwise, object must not span page allocations (excepting Reserved
  and CMA ranges)
- if on the stack
  - object must not extend before/after the current process stack
  - object must be contained by a valid stack frame (when there is
    arch/build support for identifying stack frames)
- object must not overlap with kernel text

Signed-off-by: Kees Cook 
Tested-by: Valdis Kletnieks 
Tested-by: Michael Ellerman

z3fold: the 3-fold allocator for compressed pages

2016-05-21T00:58:30+00:00

This patch introduces z3fold, a special purpose allocator for storing
compressed pages.  It is designed to store up to three compressed pages
per physical page.  It is a ZBUD derivative which allows for higher
compression ratio keeping the simplicity and determinism of its
predecessor.

This patch comes as a follow-up to the discussions at the Embedded Linux
Conference in San-Diego related to the talk [1].  The outcome of these
discussions was that it would be good to have a compressed page
allocator as stable and deterministic as zbud with with higher
compression ratio.

To keep the determinism and simplicity, z3fold, just like zbud, always
stores an integral number of compressed pages per page, but it can store
up to 3 pages unlike zbud which can store at most 2.  Therefore the
compression ratio goes to around 2.6x while zbud's one is around 1.7x.

The patch is based on the latest linux.git tree.

This version has been updated after testing on various simulators (e.g.
ARM Versatile Express, MIPS Malta, x86_64/Haswell) and basing on
comments from Dan Streetman [3].

[1] https://openiotelc2016.sched.org/event/6DAC/swapping-and-embedded-compression-relieves-the-pressure-vitaly-wool-softprise-consulting-ou
[2] https://lkml.org/lkml/2016/4/21/799
[3] https://lkml.org/lkml/2016/5/4/852

Link: http://lkml.kernel.org/r/20160509151753.ec3f9fda3c9898d31ff52a32@gmail.com
Signed-off-by: Vitaly Wool 
Cc: Seth Jennings 
Cc: Dan Streetman 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, kasan: SLAB support

2016-03-25T23:37:42+00:00

Add KASAN hooks to SLAB allocator.

This patch is based on the "mm: kasan: unified support for SLUB and SLAB
allocators" patch originally prepared by Dmitry Chernenkov.

Signed-off-by: Alexander Potapenko 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: David Rientjes 
Cc: Joonsoo Kim 
Cc: Andrey Konovalov 
Cc: Dmitry Vyukov 
Cc: Andrey Ryabinin 
Cc: Steven Rostedt 
Cc: Konstantin Serebryany 
Cc: Dmitry Chernenkov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel: add kcov code coverage

2016-03-22T22:36:02+00:00

kcov provides code coverage collection for coverage-guided fuzzing
(randomized testing).  Coverage-guided fuzzing is a testing technique
that uses coverage feedback to determine new interesting inputs to a
system.  A notable user-space example is AFL
(http://lcamtuf.coredump.cx/afl/).  However, this technique is not
widely used for kernel testing due to missing compiler and kernel
support.

kcov does not aim to collect as much coverage as possible.  It aims to
collect more or less stable coverage that is function of syscall inputs.
To achieve this goal it does not collect coverage in soft/hard
interrupts and instrumentation of some inherently non-deterministic or
non-interesting parts of kernel is disbled (e.g.  scheduler, locking).

Currently there is a single coverage collection mode (tracing), but the
API anticipates additional collection modes.  Initially I also
implemented a second mode which exposes coverage in a fixed-size hash
table of counters (what Quentin used in his original patch).  I've
dropped the second mode for simplicity.

This patch adds the necessary support on kernel side.  The complimentary
compiler support was added in gcc revision 231296.

We've used this support to build syzkaller system call fuzzer, which has
found 90 kernel bugs in just 2 months:

  https://github.com/google/syzkaller/wiki/Found-Bugs

We've also found 30+ bugs in our internal systems with syzkaller.
Another (yet unexplored) direction where kcov coverage would greatly
help is more traditional "blob mutation".  For example, mounting a
random blob as a filesystem, or receiving a random blob over wire.

Why not gcov.  Typical fuzzing loop looks as follows: (1) reset
coverage, (2) execute a bit of code, (3) collect coverage, repeat.  A
typical coverage can be just a dozen of basic blocks (e.g.  an invalid
input).  In such context gcov becomes prohibitively expensive as
reset/collect coverage steps depend on total number of basic
blocks/edges in program (in case of kernel it is about 2M).  Cost of
kcov depends only on number of executed basic blocks/edges.  On top of
that, kernel requires per-thread coverage because there are always
background threads and unrelated processes that also produce coverage.
With inlined gcov instrumentation per-thread coverage is not possible.

kcov exposes kernel PCs and control flow to user-space which is
insecure.  But debugfs should not be mapped as user accessible.

Based on a patch by Quentin Casasnovas.

[akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode']
[akpm@linux-foundation.org: unbreak allmodconfig]
[akpm@linux-foundation.org: follow x86 Makefile layout standards]
Signed-off-by: Dmitry Vyukov 
Reviewed-by: Kees Cook 
Cc: syzkaller 
Cc: Vegard Nossum 
Cc: Catalin Marinas 
Cc: Tavis Ormandy 
Cc: Will Deacon 
Cc: Quentin Casasnovas 
Cc: Kostya Serebryany 
Cc: Eric Dumazet 
Cc: Alexander Potapenko 
Cc: Kees Cook 
Cc: Bjorn Helgaas 
Cc: Sasha Levin 
Cc: David Drysdale 
Cc: Ard Biesheuvel 
Cc: Andrey Ryabinin 
Cc: Kirill A. Shutemov 
Cc: Jiri Slaby 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/page_ref: add tracepoint to track down page reference manipulation

2016-03-17T22:09:34+00:00

CMA allocation should be guaranteed to succeed by definition, but,
unfortunately, it would be failed sometimes.  It is hard to track down
the problem, because it is related to page reference manipulation and we
don't have any facility to analyze it.

This patch adds tracepoints to track down page reference manipulation.
With it, we can find exact reason of failure and can fix the problem.
Following is an example of tracepoint output.  (note: this example is
stale version that printing flags as the number.  Recent version will
print it as human readable string.)

<...>-9018  [004]    92.678375: page_ref_set:         pfn=0x17ac9 flags=0x0 count=1 mapcount=0 mapping=(nil) mt=4 val=1
<...>-9018  [004]    92.678378: kernel_stack:
 => get_page_from_freelist (ffffffff81176659)
 => __alloc_pages_nodemask (ffffffff81176d22)
 => alloc_pages_vma (ffffffff811bf675)
 => handle_mm_fault (ffffffff8119e693)
 => __do_page_fault (ffffffff810631ea)
 => trace_do_page_fault (ffffffff81063543)
 => do_async_page_fault (ffffffff8105c40a)
 => async_page_fault (ffffffff817581d8)
[snip]
<...>-9018  [004]    92.678379: page_ref_mod:         pfn=0x17ac9 flags=0x40048 count=2 mapcount=1 mapping=0xffff880015a78dc1 mt=4 val=1
[snip]
...
...
<...>-9131  [001]    93.174468: test_pages_isolated:  start_pfn=0x17800 end_pfn=0x17c00 fin_pfn=0x17ac9 ret=fail
[snip]
<...>-9018  [004]    93.174843: page_ref_mod_and_test: pfn=0x17ac9 flags=0x40068 count=0 mapcount=0 mapping=0xffff880015a78dc1 mt=4 val=-1 ret=1
 => release_pages (ffffffff8117c9e4)
 => free_pages_and_swap_cache (ffffffff811b0697)
 => tlb_flush_mmu_free (ffffffff81199616)
 => tlb_finish_mmu (ffffffff8119a62c)
 => exit_mmap (ffffffff811a53f7)
 => mmput (ffffffff81073f47)
 => do_exit (ffffffff810794e9)
 => do_group_exit (ffffffff81079def)
 => SyS_exit_group (ffffffff81079e74)
 => entry_SYSCALL_64_fastpath (ffffffff817560b6)

This output shows that problem comes from exit path.  In exit path, to
improve performance, pages are not freed immediately.  They are gathered
and processed by batch.  During this process, migration cannot be
possible and CMA allocation is failed.  This problem is hard to find
without this page reference tracepoint facility.

Enabling this feature bloat kernel text 30 KB in my configuration.

   text    data     bss     dec     hex filename
12127327        2243616 1507328 15878271         f2487f vmlinux_disabled
12157208        2258880 1507328 15923416         f2f8d8 vmlinux_enabled

Note that, due to header file dependency problem between mm.h and
tracepoint.h, this feature has to open code the static key functions for
tracepoints.  Proposed by Steven Rostedt in following link.

https://lkml.org/lkml/2015/12/9/699

[arnd@arndb.de: crypto/async_pq: use __free_page() instead of put_page()]
[iamjoonsoo.kim@lge.com: fix build failure for xtensa]
[akpm@linux-foundation.org: tweak Kconfig text, per Vlastimil]
Signed-off-by: Joonsoo Kim 
Acked-by: Michal Nazarewicz 
Acked-by: Vlastimil Babka 
Cc: Minchan Kim 
Cc: Mel Gorman 
Cc: "Kirill A. Shutemov" 
Cc: Sergey Senozhatsky 
Acked-by: Steven Rostedt 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/page_poison.c: enable PAGE_POISONING as a separate option

2016-03-15T23:55:16+00:00

Page poisoning is currently set up as a feature if architectures don't
have architecture debug page_alloc to allow unmapping of pages.  It has
uses apart from that though.  Clearing of the pages on free provides an
increase in security as it helps to limit the risk of information leaks.
Allow page poisoning to be enabled as a separate option independent of
kernel_map pages since the two features do separate work.  Because of
how hiberanation is implemented, the checks on alloc cannot occur if
hibernation is enabled.  The runtime alloc checks can also be enabled
with an option when !HIBERNATION.

Credit to Grsecurity/PaX team for inspiring this work

Signed-off-by: Laura Abbott 
Cc: Rafael J. Wysocki 
Cc: "Kirill A. Shutemov" 
Cc: Vlastimil Babka 
Cc: Michal Hocko 
Cc: Kees Cook 
Cc: Mathias Krause 
Cc: Dave Hansen 
Cc: Jianyu Zhan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'media/v4.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media

2015-09-11T23:42:39+00:00

Pull media updates from Mauro Carvalho Chehab:
 "A series of patches that move part of the code used to allocate memory
  from the media subsystem to the mm subsystem"

[ The mm parts have been acked by VM people, and the series was
  apparently in -mm for a while   - Linus ]

* tag 'media/v4.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
  [media] drm/exynos: Convert g2d_userptr_get_dma_addr() to use get_vaddr_frames()
  [media] media: vb2: Remove unused functions
  [media] media: vb2: Convert vb2_dc_get_userptr() to use frame vector
  [media] media: vb2: Convert vb2_vmalloc_get_userptr() to use frame vector
  [media] media: vb2: Convert vb2_dma_sg_get_userptr() to use frame vector
  [media] vb2: Provide helpers for mapping virtual addresses
  [media] media: omap_vout: Convert omap_vout_uservirt_to_phys() to use get_vaddr_pfns()
  [media] mm: Provide new get_vaddr_frames() helper
  [media] vb2: Push mmap_sem down to memops