Commit Graph

616081 Commits

Author SHA1 Message Date
Peter Zijlstra 64a5e3cb30 locking/qspinlock: Improve readability
Restructure pv_queued_spin_steal_lock() as I found it hard to read.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <waiman.long@hpe.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-08-10 14:16:02 +02:00
Pan Xinhui c2ace36b88 locking/pvqspinlock: Fix a bug in qstat_read()
It's obviously wrong to set stat to NULL. So lets remove it.
Otherwise it is always zero when we check the latency of kick/wake.

Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <Waiman.Long@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1468405414-3700-1-git-send-email-xinhui.pan@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-08-10 14:13:29 +02:00
Wanpeng Li 229ce63157 locking/pvqspinlock: Fix double hash race
When the lock holder vCPU is racing with the queue head:

   CPU 0 (lock holder)    CPU1 (queue head)
   ===================    =================
   spin_lock();           spin_lock();
    pv_kick_node():        pv_wait_head_or_lock():
                            if (!lp) {
                             lp = pv_hash(lock, pn);
                             xchg(&l->locked, _Q_SLOW_VAL);
                            }
                            WRITE_ONCE(pn->state, vcpu_halted);
     cmpxchg(&pn->state,
      vcpu_halted, vcpu_hashed);
     WRITE_ONCE(l->locked, _Q_SLOW_VAL);
     (void)pv_hash(lock, pn);

In this case, lock holder inserts the pv_node of queue head into the
hash table and set _Q_SLOW_VAL unnecessary. This patch avoids it by
restoring/setting vcpu_hashed state after failing adaptive locking
spinning.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <Waiman.Long@hpe.com>
Link: http://lkml.kernel.org/r/1468484156-4521-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-08-10 14:13:28 +02:00
pan xinhui 2db34e8bf9 locking/qrwlock: Fix write unlock bug on big endian systems
This patch aims to get rid of endianness in queued_write_unlock(). We
want to set  __qrwlock->wmode to NULL, however the address is not
&lock->cnts in big endian machine. That causes queued_write_unlock()
write NULL to the wrong field of __qrwlock.

So implement __qrwlock_write_byte() which returns the correct
__qrwlock->wmode address.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman.Long@hpe.com
Cc: arnd@arndb.de
Cc: boqun.feng@gmail.com
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1468835259-4486-1-git-send-email-xinhui.pan@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-08-10 14:13:27 +02:00
Ingo Molnar a2071cd765 Merge branch 'linus' into locking/urgent, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-08-10 14:11:54 +02:00
Linus Torvalds a0cba2179e Revert "printk: create pr_<level> functions"
This reverts commit 874f9c7da9.

Geert Uytterhoeven reports:
 "This change seems to have an (unintendent?) side-effect.

  Before, pr_*() calls without a trailing newline characters would be
  printed with a newline character appended, both on the console and in
  the output of the dmesg command.

  After this commit, no new line character is appended, and the output
  of the next pr_*() call of the same type may be appended, like in:

    - Truncating RAM at 0x0000000040000000-0x00000000c0000000 to -0x0000000070000000
    - Ignoring RAM at 0x0000000200000000-0x0000000240000000 (!CONFIG_HIGHMEM)
    + Truncating RAM at 0x0000000040000000-0x00000000c0000000 to -0x0000000070000000Ignoring RAM at 0x0000000200000000-0x0000000240000000 (!CONFIG_HIGHMEM)"

Joe Perches says:
 "No, that is not intentional.

  The newline handling code inside vprintk_emit is a bit involved and
  for now I suggest a revert until this has all the same behavior as
  earlier"

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Requested-by: Joe Perches <joe@perches.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-09 10:48:18 -07:00
Linus Torvalds 84bd8d33a9 Merge tag 'trace-v4.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fix from Steven Rostedt:
 "Fix tick_stop tracepoint symbols for user export.

  Luiz Capitulino noticed that the tick_stop tracepoint wasn't being
  parsed properly by the tracing user space tools.

  This was due to the TRACE_DEFINE_ENUM() being set to a define, when it
  should have been set to the enum itself.  The define was of the MASK
  that used the BIT to shift.  The BIT was the enum and by adding that,
  everything gets converted nicely.  The MASK is still kept just in case
  it gets converted to an enum in the future"

* tag 'trace-v4.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix tick_stop tracepoint symbols for user export
2016-08-09 10:34:09 -07:00
Linus Torvalds b79f34d6ae Merge tag 'gcc-plugin-infrastructure-v4.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc plugin improvements from Kees Cook:
 "Several fixes/improvements for the gcc plugin infrastructure:

   - fix a problem with gcc plugins interfering with cc-option tests.

   - abort more gracefully when gcc plugin headers or compiler support
     is missing.

   - improve the gcc plugin rule generation to be more dynamic, pass
     arguments, and build from subdirectories"

* tag 'gcc-plugin-infrastructure-v4.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  gcc-plugins: Add support for plugin subdirectories
  gcc-plugins: Automate make rule generation
  gcc-plugins: Add support for passing plugin arguments
  gcc-plugins: abort builds cleanly when not supported
  kbuild: no gcc-plugins during cc-option tests
2016-08-09 10:30:07 -07:00
Linus Torvalds e1d009eab4 Merge tag 'platform-drivers-x86-v4.8-3' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86
Pull x86 platform driver update from Darren Hart:
 "dell-wmi: ignore battery remove/insert event"

* tag 'platform-drivers-x86-v4.8-3' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86:
  dell-wmi: Ignore WMI event 0xe00e
2016-08-09 10:26:14 -07:00
Linus Torvalds cb0d93aaf0 Merge tag 'drm-fixes-for-4.8-rc2' of git://people.freedesktop.org/~airlied/linux
Pull drm fixes from Dave Airlie:
 "This contains a bunch of amdgpu fixes, and some i915 regression fixes.

  It also contains some fixes for an older regression with some EDID
  changes and some 6bpc panels.

  Then there are the lockdep, cirrus and rcar-du regression fixes from
  this window"

* tag 'drm-fixes-for-4.8-rc2' of git://people.freedesktop.org/~airlied/linux:
  drm/cirrus: Fix NULL pointer dereference when registering the fbdev
  drm/edid: Set 8 bpc color depth for displays with "DFP 1.x compliant TMDS".
  drm/i915/dp: Revert "drm/i915/dp: fall back to 18 bpp when sink capability is unknown"
  drm/edid: Add 6 bpc quirk for display AEO model 0.
  drm: Paper over locking inversion after registration rework
  drm: rcar-du: Link HDMI encoder with bridge
  drm/ttm: Wait for a BO to become idle before unbinding it from GTT
  drm/i915/fbdev: Check for the framebuffer before use
  drm/amdgpu: update golden setting of polaris10
  drm/amdgpu: update golden setting of stoney
  drm/amdgpu: update golden setting of polaris11
  drm/amdgpu: update golden setting of carrizo
  drm/amdgpu: update golden setting of iceland
  drm/amd/amdgpu: change pptable output format from ASCII to binary
  drm/amdgpu/ci: add mullins to default case for smc ucode
  drm/amdgpu/gmc7: add missing mullins case
  drm/i915: Never fully mask the the EI up rps interrupt on SNB/IVB
  drm/i915: Wait up to 3ms for the pcu to ack the cdclk change request on SKL
2016-08-09 10:20:21 -07:00
Brian King a3d1ddd932 ipr: Fix sync scsi scan
Commit b195d5e2bf ("ipr: Wait to do async scan until scsi host is
initialized") fixed async scan for ipr, but broke sync scan for ipr.

This fixes sync scan back up.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Reported-and-tested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-09 10:17:42 -07:00
Vladimir Davydov c4159a75b6 mm: memcontrol: only mark charged pages with PageKmemcg
To distinguish non-slab pages charged to kmemcg we mark them PageKmemcg,
which sets page->_mapcount to -512.  Currently, we set/clear PageKmemcg
in __alloc_pages_nodemask()/free_pages_prepare() for any page allocated
with __GFP_ACCOUNT, including those that aren't actually charged to any
cgroup, i.e. allocated from the root cgroup context.  To avoid overhead
in case cgroups are not used, we only do that if memcg_kmem_enabled() is
true.  The latter is set iff there are kmem-enabled memory cgroups
(online or offline).  The root cgroup is not considered kmem-enabled.

As a result, if a page is allocated with __GFP_ACCOUNT for the root
cgroup when there are kmem-enabled memory cgroups and is freed after all
kmem-enabled memory cgroups were removed, e.g.

  # no memory cgroups has been created yet, create one
  mkdir /sys/fs/cgroup/memory/test
  # run something allocating pages with __GFP_ACCOUNT, e.g.
  # a program using pipe
  dmesg | tail
  # remove the memory cgroup
  rmdir /sys/fs/cgroup/memory/test

we'll get bad page state bug complaining about page->_mapcount != -1:

  BUG: Bad page state in process swapper/0  pfn:1fd945c
  page:ffffea007f651700 count:0 mapcount:-511 mapping:          (null) index:0x0
  flags: 0x1000000000000000()

To avoid that, let's mark with PageKmemcg only those pages that are
actually charged to and hence pin a non-root memory cgroup.

Fixes: 4949148ad4 ("mm: charge/uncharge kmemcg from generic page allocator paths")
Reported-and-tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-09 10:14:10 -07:00
Steven Rostedt (Red Hat) c87edb3611 tracing: Fix tick_stop tracepoint symbols for user export
The symbols used in the tick_stop tracepoint were not being converted
properly into integers in the trace_stop format file. Instead we had this:

print fmt: "success=%d dependency=%s", REC->success,
    __print_symbolic(REC->dependency, { 0, "NONE" },
     { (1 << TICK_DEP_BIT_POSIX_TIMER), "POSIX_TIMER" },
     { (1 << TICK_DEP_BIT_PERF_EVENTS), "PERF_EVENTS" },
     { (1 << TICK_DEP_BIT_SCHED), "SCHED" },
     { (1 << TICK_DEP_BIT_CLOCK_UNSTABLE), "CLOCK_UNSTABLE" })

User space tools have no idea how to parse "TICK_DEP_BIT_SCHED" or the other
symbols used to do the bit shifting. The reason is that the conversion was
done with using the TICK_DEP_MASK_* symbols which are just macros that
convert to the BIT shift itself (with the exception of NONE, which was
converted properly, because it doesn't use bits, and is defined as zero).

The TICK_DEP_BIT_* needs to be denoted by TRACE_DEFINE_ENUM() in order to
have this properly converted for user space tools to parse this event.

Cc: stable@vger.kernel.org
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Fixes: e6e6cc22e0 ("nohz: Use enum code for tick stop failure tracing message")
Reported-by: Luiz Capitulino <lcapitulino@redhat.com>
Tested-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2016-08-09 09:51:23 -04:00
Boris Brezillon 36e9d08b58 drm/cirrus: Fix NULL pointer dereference when registering the fbdev
cirrus_modeset_init() is initializing/registering the emulated fbdev
and, since commit c61b93fe51 ("drm/atomic: Fix remaining places where
!funcs->best_encoder is valid"), DRM internals can access/test some of
the fields in mode_config->funcs as part of the fbdev registration
process.
Make sure dev->mode_config.funcs is properly set to avoid dereferencing
a NULL pointer.

Reported-by: Mike Marshall <hubcap@omnibond.com>
Reported-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Fixes: c61b93fe51 ("drm/atomic: Fix remaining places where !funcs->best_encoder is valid")
Signed-off-by: Dave Airlie <airlied@redhat.com>
2016-08-09 13:01:47 +10:00
Emese Revfy caefd8c9a9 gcc-plugins: Add support for plugin subdirectories
This adds support for building more complex gcc plugins that live in a
subdirectory instead of just in a single source file.

Reported-by: PaX Team <pageexec@freemail.hu>
Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: clarified commit message]
Signed-off-by: Kees Cook <keescook@chromium.org>
2016-08-08 17:53:05 -07:00
Emese Revfy 7040c83bfb gcc-plugins: Automate make rule generation
There's no reason to repeat the same names in the Makefile when the .so
files have already been listed. The .o list can be generated from them.

Reported-by: PaX Team <pageexec@freemail.hu>
Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: clarified commit message]
Signed-off-by: Kees Cook <keescook@chromium.org>
2016-08-08 17:52:20 -07:00
Emese Revfy 65d59ec8ad gcc-plugins: Add support for passing plugin arguments
The latent_entropy plugin needs to pass arguments, so this adds the
support.

Signed-off-by: Emese Revfy <re.emese@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
2016-08-08 17:49:05 -07:00
Kees Cook ed58c0e9ee gcc-plugins: abort builds cleanly when not supported
When the compiler doesn't support gcc plugins (either due to missing
headers or too old a version), report the problem and abort the build
instead of emitting a warning and letting the build founder with arcane
compiler errors.

Signed-off-by: Kees Cook <keescook@chromium.org>
2016-08-08 17:49:05 -07:00
Emese Revfy d26e941492 kbuild: no gcc-plugins during cc-option tests
The gcc-plugins arguments should not be included when performing
cc-option tests.

Steps to reproduce:
1) make mrproper
2) make defconfig
3) enable GCC_PLUGINS, GCC_PLUGIN_CYC_COMPLEXITY
4) enable FUNCTION_TRACER (it will select other options as well)
5) make && make modules

Build errors:
MODPOST 18 modules
ERROR: "__fentry__" [net/netfilter/xt_nat.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_mark.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_addrtype.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_LOG.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_sip.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_irc.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_ftp.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat.ko] undefined!

Reported-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: renamed variable, clarified commit message]
Signed-off-by: Kees Cook <keescook@chromium.org>
2016-08-08 17:49:05 -07:00
Mario Kleiner 210a021dab drm/edid: Set 8 bpc color depth for displays with "DFP 1.x compliant TMDS".
According to E-EDID spec 1.3, table 3.9, a digital video sink with the
"DFP 1.x compliant TMDS" bit set is "signal compatible with VESA DFP 1.x
TMDS CRGB, 1 pixel / clock, up to 8 bits / color MSB aligned".

For such displays, the DFP spec 1.0, section 3.10 "EDID support" says:

"If the DFP monitor only supports EDID 1.X (1.1, 1.2, etc.)
 without extensions, the host will make the following assumptions:

 1. 24-bit MSB-aligned RGB TFT
 2. DE polarity is active high
 3. H and V syncs are active high
 4. Established CRT timings will be used
 5. Dithering will not be enabled on the host"

So if we don't know the bit depth of the display from additional
colorimetry info we should assume 8 bpc / 24 bpp by default.

This patch adds info->bpc = 8 assignement for that case.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2016-08-09 08:56:04 +10:00
Mario Kleiner 196f954e25 drm/i915/dp: Revert "drm/i915/dp: fall back to 18 bpp when sink capability is unknown"
This reverts commit 013dd9e038
("drm/i915/dp: fall back to 18 bpp when sink capability is unknown")

This commit introduced a regression into stable kernels,
as it reduces output color depth to 6 bpc for any video
sink connected to a Displayport connector if that sink
doesn't report a specific color depth via EDID, or if
our EDID parser doesn't actually recognize the proper
bpc from EDID.

Affected are active DisplayPort->VGA converters and
active DisplayPort->DVI converters. Both should be
able to handle 8 bpc, but are degraded to 6 bpc with
this patch.

The reverted commit was meant to fix
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=105331

A followup patch implements a fix for that specific bug,
which is caused by a faulty EDID of the affected DP panel
by adding a new EDID quirk for that panel.

DP 18 bpp fallback handling and other improvements to
DP sink bpc detection will be handled for future
kernels in a separate series of patches.

Please backport to stable.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Cc: stable@vger.kernel.org
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2016-08-09 08:56:01 +10:00
Mario Kleiner e10aec652f drm/edid: Add 6 bpc quirk for display AEO model 0.
Bugzilla https://bugzilla.kernel.org/show_bug.cgi?id=105331
reports that the "AEO model 0" display is driven with 8 bpc
without dithering by default, which looks bad because that
panel is apparently a 6 bpc DP panel with faulty EDID.

A fix for this was made by commit 013dd9e038
("drm/i915/dp: fall back to 18 bpp when sink capability is unknown").

That commit triggers new regressions in precision for DP->DVI and
DP->VGA displays. A patch is out to revert that commit, but it will
revert video output for the AEO model 0 panel to 8 bpc without
dithering.

The EDID 1.3 of that panel, as decoded from the xrandr output
attached to that bugzilla bug report, is somewhat faulty, and beyond
other problems also sets the "DFP 1.x compliant TMDS" bit, which
according to DFP spec means to drive the panel with 8 bpc and
no dithering in absence of other colorimetry information.

Try to make the original bug reporter happy despite the
faulty EDID by adding a quirk to mark that panel as 6 bpc,
so 6 bpc output with dithering creates a nice picture.

Tested by injecting the edid from the fdo bug into a DP connector
via drm_kms_helper.edid_firmware and verifying the 6 bpc + dithering
is selected.

This patch should be backported to stable.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: stable@vger.kernel.org
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2016-08-09 08:56:00 +10:00
Linus Torvalds 81abf25258 Merge tag 'lkdtm-v4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull lkdtm update from Kees Cook:
 "Fix rebuild problem with LKDTM's rodata test"

[ This, and the usercopy branch, both came in before the merge window
  closed, but ended up in my 'need to look more' queue and thus got
  merged only after rc1 was out ]

* tag 'lkdtm-v4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  lkdtm: Fix targets for objcopy usage
  lkdtm: fix false positive warning from -Wmaybe-uninitialized
2016-08-08 15:39:24 -07:00
Linus Torvalds 1eccfa090e Merge tag 'usercopy-v4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
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
2016-08-08 14:48:14 -07:00
Linus Torvalds 1bd4403d86 unsafe_[get|put]_user: change interface to use a error target label
When I initially added the unsafe_[get|put]_user() helpers in commit
5b24a7a2aa ("Add 'unsafe' user access functions for batched
accesses"), I made the mistake of modeling the interface on our
traditional __[get|put]_user() functions, which return zero on success,
or -EFAULT on failure.

That interface is fairly easy to use, but it's actually fairly nasty for
good code generation, since it essentially forces the caller to check
the error value for each access.

In particular, since the error handling is already internally
implemented with an exception handler, and we already use "asm goto" for
various other things, we could fairly easily make the error cases just
jump directly to an error label instead, and avoid the need for explicit
checking after each operation.

So switch the interface to pass in an error label, rather than checking
the error value in the caller.  Best do it now before we start growing
more users (the signal handling code in particular would be a good place
to use the new interface).

So rather than

	if (unsafe_get_user(x, ptr))
		... handle error ..

the interface is now

	unsafe_get_user(x, ptr, label);

where an error during the user mode fetch will now just cause a jump to
'label' in the caller.

Right now the actual _implementation_ of this all still ends up being a
"if (err) goto label", and does not take advantage of any exception
label tricks, but for "unsafe_put_user()" in particular it should be
fairly straightforward to convert to using the exception table model.

Note that "unsafe_get_user()" is much harder to convert to a clever
exception table model, because current versions of gcc do not allow the
use of "asm goto" (for the exception) with output values (for the actual
value to be fetched).  But that is hopefully not a limitation in the
long term.

[ Also note that it might be a good idea to switch unsafe_get_user() to
  actually _return_ the value it fetches from user space, but this
  commit only changes the error handling semantics ]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-08 13:02:01 -07:00