0day-ci / linux

With this patch applied pahole stats look like:

/* size: 840, cachelines: 14, members: 40 */
/* sum members: 833, holes: 1, sum holes: 7 */
/* bit holes: 1, sum bit holes: 28 bits */
/* last cacheline: 8 bytes */

No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>

The sectorsize member of btrfs_block_group_cache is unused. So remove it, this
reduces the number of holes in the struct.

With patch:
/* size: 856, cachelines: 14, members: 40 */
/* sum members: 837, holes: 4, sum holes: 19 */
/* bit holes: 1, sum bit holes: 29 bits */
/* last cacheline: 24 bytes */

Without patch:
/* size: 864, cachelines: 14, members: 41 */
/* sum members: 841, holes: 5, sum holes: 23 */
/* bit holes: 1, sum bit holes: 29 bits */
/* last cacheline: 32 bytes */

Signed-off-by: Nikolay Borisov <nborisov@suse.com>

Stack guard page is a useful feature to reduce a risk of stack smashing
into a different mapping. We have been using a single page gap which
is sufficient to prevent having stack adjacent to a different mapping.
But this seems to be insufficient in the light of the stack usage in
userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
which is 256kB or stack strings with MAX_ARG_STRLEN.

This will become especially dangerous for suid binaries and the default
no limit for the stack size limit because those applications can be
tricked to consume a large portion of the stack and a single glibc call
could jump over the guard page. These attacks are not theoretical,
unfortunatelly.

Make those attacks less probable by increasing the stack guard gap
to 1MB (on systems with 4k pages; but make it depend on the page size
because systems with larger base pages might cap stack allocations in
the PAGE_SIZE units) which should cover larger alloca() and VLA stack
allocations. It is obviously not a full fix because the problem is
somehow inherent, but it should reduce attack space a lot.

One could argue that the gap size should be configurable from userspace,
but that can be done later when somebody finds that the new 1MB is wrong
for some special case applications.  For now, add a kernel command line
option (stack_guard_gap) to specify the stack gap size (in page units).

Implementation wise, first delete all the old code for stack guard page:
because although we could get away with accounting one extra page in a
stack vma, accounting a larger gap can break userspace - case in point,
a program run with "ulimit -S -v 20000" failed when the 1MB gap was
counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
and strict non-overcommit mode.

Instead of keeping gap inside the stack vma, maintain the stack guard
gap as a gap between vmas: using vm_start_gap() in place of vm_start
(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
places which need to respect the gap - mainly arch_get_unmapped_area(),
and and the vma tree's subtree_gap support for that.

Original-patch-by: Oleg Nesterov <oleg@redhat.com>
Original-patch-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

…/git/arm/arm-soc

Pull ARM SoC fixes from Olof Johansson:
 "Stream of fixes has slowed down, only a few this week:

   - Some DT fixes for Allwinner platforms, and addition of a clock to
     the R_CCU clock controller that had been missed.

   - A couple of small DT fixes for am335x-sl50"

* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  arm64: allwinner: a64: Add PLL_PERIPH0 clock to the R_CCU
  ARM: sunxi: h3-h5: Add PLL_PERIPH0 clock to the R_CCU
  ARM: dts: am335x-sl50: Fix cannot claim requested pins for spi0
  ARM: dts: am335x-sl50: Fix card detect pin for mmc1
  arm64: allwinner: h5: Remove syslink to shared DTSI
  ARM: sunxi: h3/h5: fix the compatible of R_CCU

…nux/kernel/git/sunxi/linux into fixes

Allwinner fixes for 4.12

A few fixes around the PRCM support that got in 4.12 with a wrong
compatible, and a missing clock in the binding.

* tag 'sunxi-fixes-for-4.12' of https://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux:
  arm64: allwinner: a64: Add PLL_PERIPH0 clock to the R_CCU
  ARM: sunxi: h3-h5: Add PLL_PERIPH0 clock to the R_CCU
  arm64: allwinner: h5: Remove syslink to shared DTSI
  ARM: sunxi: h3/h5: fix the compatible of R_CCU

Signed-off-by: Olof Johansson <olof@lixom.net>

…/linux/kernel/git/tmlind/linux-omap into fixes

Two fixes for am335x-sl50 to fix a boot time error
for claiming SPI pins, and to fix a SDIO card detect
pin for production version of the device.

* tag 'omap-for-v4.12/fixes-sl50' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
  ARM: dts: am335x-sl50: Fix cannot claim requested pins for spi0
  ARM: dts: am335x-sl50: Fix card detect pin for mmc1

Signed-off-by: Olof Johansson <olof@lixom.net>

…t/mst/vhost

Pull virtio bugfix from Michael Tsirkin:
 "It turns out balloon does not handle IOMMUs correctly. We should fix
  that at some point, for now let's just disable this configuration"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio_balloon: disable VIOMMU support

…linux/kernel/git/wsa/linux

Pull i2c fixes from Wolfram Sang:
 "Two driver bugfixes"

* 'i2c/for-current-fixed' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: ismt: fix wrong device address when unmap the data buffer
  i2c: rcar: use correct length when unmapping DMA

…ream-linus

Pull MIPS fixes from Ralf Baechle:

 - Three highmem fixes:
    + Fixed mapping initialization
    + Adjust the pkmap location
    + Ensure we use at most one page for PTEs

 - Fix makefile dependencies for .its targets to depend on vmlinux

 - Fix reversed condition in BNEZC and JIALC software branch emulation

 - Only flush initialized flush_insn_slot to avoid NULL pointer
   dereference

 - perf: Remove incorrect odd/even counter handling for I6400

 - ftrace: Fix init functions tracing

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
  MIPS: .its targets depend on vmlinux
  MIPS: Fix bnezc/jialc return address calculation
  MIPS: kprobes: flush_insn_slot should flush only if probe initialised
  MIPS: ftrace: fix init functions tracing
  MIPS: mm: adjust PKMAP location
  MIPS: highmem: ensure that we don't use more than one page for PTEs
  MIPS: mm: fixed mappings: correct initialisation
  MIPS: perf: Remove incorrect odd/even counter handling for I6400

virtio balloon bypasses the DMA API entirely so does not support the
VIOMMU right now.  It's not clear we need that support, for now let's
just make sure we don't pretend to support it.

Cc: stable@vger.kernel.org
Cc: Wei Wang <wei.w.wang@intel.com>
Fixes: 1a93769 ("virtio: new feature to detect IOMMU device quirk")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

…inux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:
 "Two fixlets for x86:

   - Handle WARN_ONs proper with the new UD based WARN implementation

   - Disable 1G mappings when 2M mappings are disabled by kmemleak or
     debug_pagealloc. Otherwise 1G mappings might still be used,
     confusing the debug mechanisms"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: Disable 1GB direct mappings when disabling 2MB mappings
  x86/debug: Handle early WARN_ONs proper

…m/linux/kernel/git/tip/tip

Pull timer fixes from Thomas Gleixner:
 "Three fixlets for timers:

   - Two hot-fixes for the alarmtimer based posix timers, which prevent
     a nasty DOS by self rescheduling timers. The proper cleanup of that
     mess is queued for 4.13

   - Make a function static"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick/broadcast: Make tick_broadcast_setup_oneshot() static
  alarmtimer: Rate limit periodic intervals
  alarmtimer: Prevent overflow of relative timers

…/linux/kernel/git/tip/tip

Pull scheduler fixes from Thomas Gleixner:
 "Two small fixes for the schedulre core:

   - Use the proper switch_mm() variant in idle_task_exit() because that
     code is not called with interrupts disabled.

   - Fix a confusing typo in a printk"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Idle_task_exit() shouldn't use switch_mm_irqs_off()
  sched/fair: Fix typo in printk message

…linux/kernel/git/tip/tip

Pull perf fixes from Thomas Gleixner:
 "Three fixes for the perf user space side:

   - Fix the probing of precise_ip level, which got broken recently for
     x86.

   - Unbreak the ARCH=x86_64 build

   - Report module before trying to unwind into the module code, which
     avoids broken stack frames displayed"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf unwind: Report module before querying isactivation in dwfl unwind
  perf tools: Fix build with ARCH=x86_64
  perf evsel: Fix probing of precise_ip level for default cycles event

…inux/kernel/git/tip/tip

Pull irq fix from Thomas Gleixner:
 "Add a missing resource release to an error path"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Release resources in __setup_irq() error path

…linux/kernel/git/tip/tip

Pull objtool fix from Thomas Gleixner:
 "A single fix which adds fortify_panic to the list of no return
  functions"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Add fortify_panic as __noreturn function

…nux/kernel/git/j.anaszewski/linux-leds

Pull LED fixes from Jacek Anaszewski:
 "Two LED fixes:

   - fix signal source assignment for leds-bcm6328

   - revert patch that intended to fix LED behavior on suspend but it
     had a side effect preventing suspend at all due to uevent being
     sent on trigger removal"

* tag 'led_fixes_for_4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds:
  Revert "leds: handle suspend/resume in heartbeat trigger"
  leds: bcm6328: fix signal source assignment for leds 4 to 7

…/git/gregkh/usb

Pull USB fixes from Greg KH:
 "Here are some small gadget and xhci USB fixes for 4.12-rc6.

  Nothing major, but one of the gadget patches does fix a reported oops,
  and the xhci ones resolve reported problems. All have been in
  linux-next with no reported issues"

* tag 'usb-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  USB: gadgetfs, dummy-hcd, net2280: fix locking for callbacks
  usb: xhci: ASMedia ASM1042A chipset need shorts TX quirk
  usb: xhci: Fix USB 3.1 supported protocol parsing
  USB: gadget: fix GPF in gadgetfs
  usb: gadget: composite: make sure to reactivate function on unbind

…rnel/git/gregkh/staging

Pull staging and IIO fixes from Greg KH:
 "Here are some small staging and IIO driver fixes for 4.12-rc6.

  Nothing huge, just a few small driver fixes for reported issues. All
  have been in linux-next with no reported issues"

* tag 'staging-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  Staging: rtl8723bs: fix an error code in isFileReadable()
  iio: buffer-dmaengine: Add missing header buffer_impl.h
  iio: buffer-dma: Add missing header buffer_impl.h
  iio: adc: meson-saradc: fix potential crash in meson_sar_adc_clear_fifo
  iio: adc: mxs-lradc: Fix return value check in mxs_lradc_adc_probe()
  iio: imu: inv_mpu6050: add accel lpf setting for chip >= MPU6500
  staging: iio: ad7152: Fix deadlock in ad7152_write_raw_samp_freq()

Pull ceph fixes from Ilya Dryomov:
 "A fix for an old ceph ->fh_to_* bug from Luis and two timestamp fixups
  from Zheng, prompted by the ongoing y2038 work"

* tag 'ceph-for-4.12-rc6' of git://github.com/ceph/ceph-client:
  ceph: unify inode i_ctime update
  ceph: use current_kernel_time() to get request time stamp
  ceph: check i_nlink while converting a file handle to dentry

…fs-linux

Pull xfs fix from Darrick Wong:
 "One more bugfix for you for 4.12-rc6 to fix something that came up in
  an earlier rc:

   - Fix some bogus ASSERT failures on CONFIG_SMP=n and CONFIG_XFS_DEBUG=y"

* tag 'xfs-4.12-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: fix spurious spin_is_locked() assert failures on non-smp kernels

…/git/viro/vfs

Pull ufs fixes from Al Viro:
 "Fix assorted ufs bugs: a couple of deadlocks, fs corruption in
  truncate(), oopsen on tail unpacking and truncate when racing with
  vmscan, mild fs corruption (free blocks stats summary buggered, *BSD
  fsck would complain and fix), several instances of broken logics
  around reserved blocks (starting with "check almost never triggers
  when it should" and then there are issues with sufficiently large
  UFS2)"

[ Note: ufs hasn't gotten any loving in a long time, because nobody
  really seems to use it. These ufs fixes are triggered by people
  actually caring now, not some sudden influx of new bugs.  - Linus ]

* 'ufs-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  ufs_truncate_blocks(): fix the case when size is in the last direct block
  ufs: more deadlock prevention on tail unpacking
  ufs: avoid grabbing ->truncate_mutex if possible
  ufs_get_locked_page(): make sure we have buffer_heads
  ufs: fix s_size/s_dsize users
  ufs: fix reserved blocks check
  ufs: make ufs_freespace() return signed
  ufs: fix logics in "ufs: make fsck -f happy"

…/git/viro/vfs

Pull vfs fixes from Al Viro:
 "A couple of fixes; a leak in mntns_install() caught by Andrei (this
  cycle regression) + d_invalidate() softlockup fix - that had been
  reported by a bunch of people lately, but the problem is pretty old"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: don't forget to put old mntns in mntns_install
  Hang/soft lockup in d_invalidate with simultaneous calls

…ernel/git/helgaas/pci

Pull PCI fixes from Bjorn Helgaas:

 - fix another PCI_ENDPOINT build error (merged for v4.12)

 - fix error codes added to config accessors for v4.12

* tag 'pci-v4.12-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI: endpoint: Select CRC32 to fix test build error
  PCI: Make error code types consistent in pci_{read,write}_config_*

Pull fbdev fixes from Bartlomiej Zolnierkiewicz:

 - fix udlfb driver to stop spamming logs (Mike Gerow)

 - add missing endianness conversions in smscufx & udlfb drivers (Johan
   Hovold)

 - fix few gcc warnings/errors (Arnd Bergmann)

* tag 'fbdev-v4.12-rc6' of git://github.com/bzolnier/linux:
  video: fbdev: udlfb: drop log level for blanking
  video: fbdev: via: remove possibly unused variables
  video: fbdev: add missing USB-descriptor endianness conversions
  video: fbdev: avoid int-in-bool-context warning

Merge misc fixes from Andrew Morton:
 "5 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm: correct the comment when reclaimed pages exceed the scanned pages
  userfaultfd: shmem: handle coredumping in handle_userfault()
  mm: numa: avoid waiting on freed migrated pages
  swap: cond_resched in swap_cgroup_prepare()
  mm/memory-failure.c: use compound_head() flags for huge pages

Commit e1587a4 ("mm: vmpressure: fix sending wrong events on
underflow") declared that reclaimed pages exceed the scanned pages due
to the thp reclaim.

That is incorrect because THP will be spilt to normal page and loop
again, which will result in the scanned pages increment.

[akpm@linux-foundation.org: tweak comment text]
Link: http://lkml.kernel.org/r/1496824266-25235-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhongjiang <zhongjiang@huawei.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Anon and hugetlbfs handle FOLL_DUMP set by get_dump_page() internally to
__get_user_pages().

shmem as opposed has no special FOLL_DUMP handling there so
handle_mm_fault() is invoked without mmap_sem and ends up calling
handle_userfault() that isn't expecting to be invoked without mmap_sem
held.

This makes handle_userfault() fail immediately if invoked through
shmem_vm_ops->fault during coredumping and solves the problem.

The side effect is a BUG_ON with no lock held triggered by the
coredumping process which exits.  Only 4.11 is affected, pre-4.11 anon
memory holes are skipped in __get_user_pages by checking FOLL_DUMP
explicitly against empty pagetables (mm/gup.c:no_page_table()).

It's zero cost as we already had a check for current->flags to prevent
futex to trigger userfaults during exit (PF_EXITING).

Link: http://lkml.kernel.org/r/20170615214838.27429-1-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: <stable@vger.kernel.org>	[4.11+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In do_huge_pmd_numa_page(), we attempt to handle a migrating thp pmd by
waiting until the pmd is unlocked before we return and retry.  However,
we can race with migrate_misplaced_transhuge_page():

    // do_huge_pmd_numa_page                // migrate_misplaced_transhuge_page()
    // Holds 0 refs on page                 // Holds 2 refs on page

    vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
    /* ... */
    if (pmd_trans_migrating(*vmf->pmd)) {
            page = pmd_page(*vmf->pmd);
            spin_unlock(vmf->ptl);
                                            ptl = pmd_lock(mm, pmd);
                                            if (page_count(page) != 2)) {
                                                    /* roll back */
                                            }
                                            /* ... */
                                            mlock_migrate_page(new_page, page);
                                            /* ... */
                                            spin_unlock(ptl);
                                            put_page(page);
                                            put_page(page); // page freed here
            wait_on_page_locked(page);
            goto out;
    }

This can result in the freed page having its waiters flag set
unexpectedly, which trips the PAGE_FLAGS_CHECK_AT_PREP checks in the
page alloc/free functions.  This has been observed on arm64 KVM guests.

We can avoid this by having do_huge_pmd_numa_page() take a reference on
the page before dropping the pmd lock, mirroring what we do in
__migration_entry_wait().

When we hit the race, migrate_misplaced_transhuge_page() will see the
reference and abort the migration, as it may do today in other cases.

Fixes: b891663 ("mm: Prevent parallel splits during THP migration")
Link: http://lkml.kernel.org/r/1497349722-6731-2-git-send-email-will.deacon@arm.com
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Steve Capper <steve.capper@arm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

I saw need_resched() warnings when swapping on large swapfile (TBs)
because continuously allocating many pages in swap_cgroup_prepare() took
too long.

We already cond_resched when freeing page in swap_cgroup_swapoff().  Do
the same for the page allocation.

Link: http://lkml.kernel.org/r/20170604200109.17606-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memory_failure() chooses a recovery action function based on the page
flags.  For huge pages it uses the tail page flags which don't have
anything interesting set, resulting in:

> Memory failure: 0x9be3b4: Unknown page state
> Memory failure: 0x9be3b4: recovery action for unknown page: Failed

Instead, save a copy of the head page's flags if this is a huge page,
this means if there are no relevant flags for this tail page, we use the
head pages flags instead.  This results in the me_huge_page() recovery
action being called:

> Memory failure: 0x9b7969: recovery action for huge page: Delayed

For hugepages that have not yet been allocated, this allows the hugepage
to be dequeued.

Fixes: 524fca1 ("HWPOISON: fix misjudgement of page_action() for errors on mlocked pages")
Link: http://lkml.kernel.org/r/20170524130204.21845-1-james.morse@arm.com
Signed-off-by: James Morse <james.morse@arm.com>
Tested-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

…el/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:
 "Three small fixes for recently merged code:

   - remove a spurious WARN_ON when a PCI device has no of_node, it's
     allowed in some circumstances for there to be no of_node.

   - fix the offset for store EOI MMIOs in the XIVE interrupt
     controller.

   - fix non-const WARN_ONs which were becoming BUGs due to them losing
     BUGFLAG_WARNING in a recent cleanup patch.

  Thanks to: Alexey Kardashevskiy, Alistair Popple, Benjamin
  Herrenschmidt"

* tag 'powerpc-4.12-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/debug: Add missing warn flag to WARN_ON's non-builtin path
  powerpc/xive: Fix offset for store EOI MMIOs
  powerpc/npu-dma: Remove spurious WARN_ON when a PCI device has no of_node

…rg/pub/scm/linux/kernel/git/acme/linux into perf/urgent

Pull perf/urgent fixes from Arnaldo Carvalho de Melo:

- Fix probing of precise_ip level for default cycles event, that
  got broken recently on x86_64 when its arch code started
  considering invalid requesting precise samples when not sampling
  (i.e. when attr.sample_period == 0).

  This also fixes another problem in s/390 where the precision
  probing with sample_period == 0 returned precise_ip > 0, that
  then, when setting up the real cycles event (not probing) would
  return EOPNOTSUPP for precise_ip > 0 (as determined previously
  by probing) and sample_period > 0.

  These problems resulted in attr_precise not being set to the
  highest precision available on x86.64 when no event was specified,
  i.e. the canonical:

	perf record ./workload

  would end up using attr.precise_ip = 0. As a workaround this would
  need to be done:

	perf record -e cycles:P ./workload

  And on s/390 it would plain not work, requiring using:

        perf record -e cycles ./workload

  as a workaround.  (Arnaldo Carvalho de Melo)

- Fix perf build with ARCH=x86_64, when ARCH should be transformed
  into ARCH=x86, just like with the main kernel Makefile and
  tools/objtool's, i.e. use SRCARCH. (Jiada Wang)

- Avoid accessing uninitialized data structures when unwinding with
  elfutils's libdw, making it more closely mimic libunwind's unwinder.
  (Milian Wolff)

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

The PC returned by dwfl_frame_pc() may map into a not-yet-reported
module. We have to report it before we continue unwinding. But when we
query for the isactivation flag in dwfl_frame_pc, libdw will actually do
one more unwinding step internally which can then break and lead to
missed frames or broken stacks.

With libunwind we get e.g.:

~~~~~
  heaptrack_gui  2228 135073.400474:     613969 cycles:
	          108c8e [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          1093bc [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          109e7b QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0)
	          1470ff [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          147f67 QSystemLocale::query (/usr/lib/libQt5Core.so.5.8.0)
	          109fbf QLocalePrivate::updateSystemPrivate (/usr/lib/libQt5Core.so.5.8.0)
	          10aa27 QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0)
	          1e02c3 [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          2113bb [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          211505 [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          1b5df0 QFileInfo::exists (/usr/lib/libQt5Core.so.5.8.0)
	           92eb2 [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	           93423 [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	           93d2a QLibraryInfo::location (/usr/lib/libQt5Core.so.5.8.0)
	          2170af [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          297c53 QCoreApplicationPrivate::init (/usr/lib/libQt5Core.so.5.8.0)
	           f7cde QGuiApplicationPrivate::init (/usr/lib/libQt5Gui.so.5.8.0)
	          1589e8 QApplicationPrivate::init (/usr/lib/libQt5Widgets.so.5.8.0)
	           78622 main (/home/milian/projects/compiled/other/bin/heaptrack_gui)
	           20439 __libc_start_main (/usr/lib/libc-2.25.so)
	           78299 _start (/home/milian/projects/compiled/other/bin/heaptrack_gui)

  heaptrack_gui  2228 135073.401156:     569521 cycles:
	          131633 QString::endsWith (/usr/lib/libQt5Core.so.5.8.0)
	          1a0701 QDir::cleanPath (/usr/lib/libQt5Core.so.5.8.0)
	          21b82d [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          1b3727 QFileInfo::canonicalFilePath (/usr/lib/libQt5Core.so.5.8.0)
	          2780c7 QFactoryLoader::update (/usr/lib/libQt5Core.so.5.8.0)
	          279525 QFactoryLoader::QFactoryLoader (/usr/lib/libQt5Core.so.5.8.0)
	           e5bd0 QPlatformIntegrationFactory::create (/usr/lib/libQt5Gui.so.5.8.0)
	           f5a1c QGuiApplicationPrivate::createPlatformIntegration (/usr/lib/libQt5Gui.so.5.8.0)
	           f650c QGuiApplicationPrivate::createEventDispatcher (/usr/lib/libQt5Gui.so.5.8.0)
	          298524 QCoreApplicationPrivate::init (/usr/lib/libQt5Core.so.5.8.0)
	           f7cde QGuiApplicationPrivate::init (/usr/lib/libQt5Gui.so.5.8.0)
	          1589e8 QApplicationPrivate::init (/usr/lib/libQt5Widgets.so.5.8.0)
	           78622 main (/home/milian/projects/compiled/other/bin/heaptrack_gui)
	           20439 __libc_start_main (/usr/lib/libc-2.25.so)
	           78299 _start (/home/milian/projects/compiled/other/bin/heaptrack_gui)
~~~~~

Note the two frames 1589e8 and 78622 in the first sample. These are
missing when unwinding with libdw. The second sample's breakage is
more obvious:

~~~~~
  heaptrack_gui  2228 135073.400474:     613969 cycles:
	          108c8e [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          1093bc [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          109e7b QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0)
	          1470ff [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          147f67 QSystemLocale::query (/usr/lib/libQt5Core.so.5.8.0)
	          109fbf QLocalePrivate::updateSystemPrivate (/usr/lib/libQt5Core.so.5.8.0)
	          10aa27 QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0)
	          1e02c3 [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          2113bb [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          211505 [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          1b5df0 QFileInfo::exists (/usr/lib/libQt5Core.so.5.8.0)
	           92eb2 [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	           93423 [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	           93d2a QLibraryInfo::location (/usr/lib/libQt5Core.so.5.8.0)
	          2170af [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          297c53 QCoreApplicationPrivate::init (/usr/lib/libQt5Core.so.5.8.0)
	           f7cde QGuiApplicationPrivate::init (/usr/lib/libQt5Gui.so.5.8.0)
	           20439 __libc_start_main (/usr/lib/libc-2.25.so)
	           78299 _start (/home/milian/projects/compiled/other/bin/heaptrack_gui)

heaptrack_gui  2228 135073.401156:     569521 cycles:
	          131633 QString::endsWith (/usr/lib/libQt5Core.so.5.8.0)
	          1a0701 QDir::cleanPath (/usr/lib/libQt5Core.so.5.8.0)
	          21b82d [unknown] (/usr/lib/libQt5Core.so.5.8.0)
	          1b3727 QFileInfo::canonicalFilePath (/usr/lib/libQt5Core.so.5.8.0)
	          2780c7 QFactoryLoader::update (/usr/lib/libQt5Core.so.5.8.0)
	          279525 QFactoryLoader::QFactoryLoader (/usr/lib/libQt5Core.so.5.8.0)
	           e5bd0 QPlatformIntegrationFactory::create (/usr/lib/libQt5Gui.so.5.8.0)
	          723dbf [unknown] ([unknown])
~~~~~

This patch fixes this issue and the libdw unwinder mimicks the libunwind
behavior more closely.

Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
Acked-by: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20170602143753.16907-2-milian.wolff@kdab.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>