Cheers for reporting this. I managed to reproduce the build failure with
gcc version 6.3.0 20170516 (Debian 6.3.0-18+deb9u1).

The code in question is the arm64 versions of smp_load_acquire() and
smp_store_release(). Unlike other architectures, these are not built
around READ_ONCE() and WRITE_ONCE() since we have instructions we can
use instead of fences. Bringing our macros up-to-date with those (i.e.
tweaking the union initialisation and using the special "uXX_alias_t"
types) appears to fix the issue for me.

Committer notes:

Testing it in the systems previously failing:

  # time dm android-ndk:r12b-arm \
         android-ndk:r15c-arm \
         debian:experimental-x-arm64 \
         ubuntu:14.04.4-x-linaro-arm64 \
         ubuntu:16.04-x-arm \
         ubuntu:16.04-x-arm64 \
         ubuntu:18.04-x-arm \
         ubuntu:18.04-x-arm64
    1 android-ndk:r12b-arm          : Ok   arm-linux-androideabi-gcc (GCC) 4.9.x 20150123 (prerelease)
    2 android-ndk:r15c-arm          : Ok   arm-linux-androideabi-gcc (GCC) 4.9.x 20150123 (prerelease)
    3 debian:experimental-x-arm64   : Ok   aarch64-linux-gnu-gcc (Debian 8.2.0-7) 8.2.0
    4 ubuntu:14.04.4-x-linaro-arm64 : Ok   aarch64-linux-gnu-gcc (Linaro GCC 5.5-2017.10) 5.5.0
    5 ubuntu:16.04-x-arm            : Ok   arm-linux-gnueabihf-gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
    6 ubuntu:16.04-x-arm64          : Ok   aarch64-linux-gnu-gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
    7 ubuntu:18.04-x-arm            : Ok   arm-linux-gnueabihf-gcc (Ubuntu/Linaro 7.3.0-27ubuntu1~18.04) 7.3.0
    8 ubuntu:18.04-x-arm64          : Ok   aarch64-linux-gnu-gcc (Ubuntu/Linaro 7.3.0-27ubuntu1~18.04) 7.3.0
Reported-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: NDaniel Borkmann <daniel@iogearbox.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20181031174408.GA27871@arm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Merge tag 'perf-urgent-for-mingo-4.20-20181031' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/urgent

Pull perf/urgent improvements and fixes from Arnaldo Carvalho de Melo:

- Fixes dealing with the removal of the fallback to looking up samples
  marked as userspace in the kernel maps, done recently:

  - For intel-pt, that was setting the synthesized header misc field
    as PERF_RECORD_MISC_USER, depending thus on the fallback to take
    place, now it sets as USER or KERNEL according to x86 specific
    knowledge. Also now it inserts the PERF_CONTEXT_{USER,KERNEL} into
    the PERF_SAMPLE_CALLCHAINs it synthesizes from hw traces (Adrian Hunter)

  - Similar fixes for the cs-etm ARM HW trace code, that used the Intel PT
    model as a starting point (Leo Yan)

  - For the "caller" callchain order, where the callchain returned by the
    kernel was simply reversed without taking into account the
    PERF_CONTEXT_{USER,KERNEL,etc} markers from where to define if an entry
    was for kernel or userspace, working just because the map lookup fallback
    was in place (David S. Miller)

- Allow for selecting if 'overwrite' mode should be used in 'perf top' and
  make the default for it not to be used. This is due to problems with the
  current implementation where the pausing used ends up making 'perf top'
  miss PERF_RECORD_{MMAP,FORK,EXEC,etc} events, which with short lifetime
  threads workloads leads quickly to many "unknown" maps (and thus symbols)
  to appear in the UI. Workloads with long thread lifetimes and with few
  metadata events can still use --overwrite to take advantage of the
  overwrite mode (Arnaldo Carvalho de Melo)

- Start 'perf top''s display thread earlier, so that the screen doesn't
  remain blank for too long at tool start (David S. Miller)

- Don't clone maps from parent when synthesizing forks, to avoid the inevitable
  flurry of overlapping maps as we process the synthesized MMAP2 events that get
  delivered shortly thereafter. (David S. Miller)

- Take pgoff into account when reporting elf to libdwfl, now the unwinding
  results are the same with elfutils's libdwfl and libunwind (Milian Wolff)

- Update lotsa kernel ABI headers (Arnaldo Carvalho de Melo)

- 'perf trace' syscall arg beautification improvements to allow for
  handling args such as mount's 'flags', where maks have to be ignored
  before considering what is left, that, if only zeroes, is suppressed
  like other args without such masks (Arnaldo Carvalho de Melo)

- Beautify mount's 'source' and 'flags' args (Arnaldo Carvalho de Melo)

- Generate mmap's flags bit constants from linux/mman.h and all the
  arch specific mman.h files, so that no changes in the main 'perf trace'
  source files is required when new flags get added (Arnaldo Carvalho de Melo)

- Consider syscall aliases, so that 'perf trace -e umount' works and we don't
  have to use 'umount2' (that works as well, just not required) (Arnaldo Carvalho de Melo)
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

In the absence of a fallback, samples must provide a correct cpumode for
the 'ip'. Do that now there is no fallback.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Reviewed-by: NJiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: stable@vger.kernel.org # 4.19
Link: http://lkml.kernel.org/r/20181031091043.23465-6-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

In the absence of a fallback, callchains must encode also the callchain
context. Do that now there is no fallback.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Reviewed-by: NJiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: stable@vger.kernel.org # 4.19
Link: http://lkml.kernel.org/r/100ea2ec-ed14-b56d-d810-e0a6d2f4b069@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

When synthesizing FORK events, we are trying to create thread objects
for the already running tasks on the machine.

Normally, for a kernel FORK event, we want to clone the parent's maps
because that is what the kernel just did.

But when synthesizing, this should not be done.  If we do, we end up
with overlapping maps as we process the sythesized MMAP2 events that
get delivered shortly thereafter.

Use the FORK event misc flags in an internal way to signal this
situation, so we can elide the map clone when appropriate.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joe Mario <jmario@redhat.com>
Link: http://lkml.kernel.org/r/20181030.222404.2085088822877051075.davem@davemloft.net
[ Added comment about flag use in machine__process_fork_event(),
  use ternary op in thread__clone_map_groups() as suggested by Jiri ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

If events are coming in at a rate such that the event processing thread
can barely keep up, our initial run of the event ring will almost never
terminate and this delays the starting of the display thread.

The screen basically stays black until the event thread can get out of
it's endless loop.

Therefore, start the display thread before we start processing the ring
buffer.

This also make sure that we always have the user requested real time
setting engaged when processing the ring.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20181030.223003.2242527041807905962.davem@davemloft.netSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To pick the changes from:

  9163a0fc ("net: bridge: add support for per-port vlan stats")

And silence this build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/if_link.h' differs from latest version at 'include/uapi/linux/if_link.h'

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Leblond <eric@regit.org>
Cc: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Link: https://lkml.kernel.org/n/tip-7p53ghippywz7fqkwo3nkzet@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Picking the changes from:

  89d35528 ("netlink: Add new socket option to enable strict checking on dumps")

To silence this build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/netlink.h' differs from latest version at 'include/uapi/linux/netlink.h'

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Leblond <eric@regit.org>
Link: https://lkml.kernel.org/n/tip-1xymkfjpmhxfzrs46t8z8mjw@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

For powerpc, s390, x86 and the main uapi linux/kvm.h header, none of
them entail changes in tooling.

Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-avn7iy8f4tcm2y40sbsdk31m@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To pick up the changes from:

  20916d46 ("mm/hugetlb: add mmap() encodings for 32MB and 512MB page sizes")

That do not entail changes in in tools, this just shows that we have to
consider bits [26:31] of flags to beautify that in tools like 'perf
trace'

This silences this perf build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/mman.h' differs from latest version at 'include/uapi/linux/mman.h'
  diff -u tools/include/uapi/linux/mman.h include/uapi/linux/mman.h

Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-3rvc39lon93kgt5pl31d8g4x@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Instead of requiring us to go on and edit sources to add new flag.

  # perf trace -e *mmap sleep 0.1
     0.025 ( 0.005 ms): sleep/29876 mmap(len: 163746, prot: READ, flags: PRIVATE, fd: 3) = 0x7faa68ad1000
     0.059 ( 0.004 ms): sleep/29876 mmap(len: 8192, prot: READ|WRITE, flags: PRIVATE|ANONYMOUS) = 0x7faa68acf000
     0.069 ( 0.006 ms): sleep/29876 mmap(len: 3889792, prot: EXEC|READ, flags: PRIVATE|DENYWRITE, fd: 3) = 0x7faa6851f000
     0.086 ( 0.009 ms): sleep/29876 mmap(addr: 0x7faa688cb000, len: 24576, prot: READ|WRITE, flags: PRIVATE|FIXED|DENYWRITE, fd: 3, off: 1753088) = 0x7faa688cb000
     0.101 ( 0.005 ms): sleep/29876 mmap(addr: 0x7faa688d1000, len: 14976, prot: READ|WRITE, flags: PRIVATE|FIXED|ANONYMOUS) = 0x7faa688d1000
     0.348 ( 0.005 ms): sleep/29876 mmap(len: 111950656, prot: READ, flags: PRIVATE, fd: 3) = 0x7faa61a5b000
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-ggmoy6vxoygh5yim890ht0kf@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Now when we run 'make -C tools/perf O=/tmp/build/perf' we end up with:

  $ cat /tmp/build/perf/trace/beauty/generated/mmap_flags_array.c
  static const char *mmap_flags[] = {
	[ilog2(0x40) + 1] = "32BIT",
	[ilog2(0x01) + 1] = "SHARED",
	[ilog2(0x02) + 1] = "PRIVATE",
	[ilog2(0x10) + 1] = "FIXED",
	[ilog2(0x20) + 1] = "ANONYMOUS",
	[ilog2(0x100000) + 1] = "FIXED_NOREPLACE",
	[ilog2(0x0100) + 1] = "GROWSDOWN",
	[ilog2(0x0800) + 1] = "DENYWRITE",
	[ilog2(0x1000) + 1] = "EXECUTABLE",
	[ilog2(0x2000) + 1] = "LOCKED",
	[ilog2(0x4000) + 1] = "NORESERVE",
	[ilog2(0x8000) + 1] = "POPULATE",
	[ilog2(0x10000) + 1] = "NONBLOCK",
	[ilog2(0x20000) + 1] = "STACK",
	[ilog2(0x40000) + 1] = "HUGETLB",
	[ilog2(0x80000) + 1] = "SYNC",
  };
  $

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-t3fn7u3tjsupio6e6vkufx9m@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

It'll use tools/{arch}/*,include copies of mman.h to generate a table to
be used by tools, initially by the 'mmap' beautifiers in 'perf trace',
but that could also be used to translate from a string constant to the
integer value to be used in a eBPF or tracefs tracepoint filter.

Tested for all archs using:

$ for arch in `ls tools/arch/` ; \
	do echo $arch ; tools/perf/trace/beauty/mmap_flags.sh $arch ; \
   done | less

Example for alpha, an oddball, doesn't include any header, defines all
its stuff:

  $ tools/perf/trace/beauty/mmap_flags.sh alpha
  static const char *mmap_flags[] = {
	[ilog2(0x10) + 1] = "ANONYMOUS",
	[ilog2(0x02000) + 1] = "DENYWRITE",
	[ilog2(0x04000) + 1] = "EXECUTABLE",
	[ilog2(0x100) + 1] = "FIXED",
	[ilog2(0x01000) + 1] = "GROWSDOWN",
	[ilog2(0x100000) + 1] = "HUGETLB",
	[ilog2(0x08000) + 1] = "LOCKED",
	[ilog2(0x40000) + 1] = "NONBLOCK",
	[ilog2(0x10000) + 1] = "NORESERVE",
	[ilog2(0x20000) + 1] = "POPULATE",
	[ilog2(0x02) + 1] = "PRIVATE",
	[ilog2(0x01) + 1] = "SHARED",
	[ilog2(0x80000) + 1] = "STACK",
  };
  $

Common case, my workstation, defines one entry (MAP_32BIT), then
includes mman.h, which gets it to include mman-common.h too:

  $ tools/perf/trace/beauty/mmap_flags.sh
  static const char *mmap_flags[] = {
	[ilog2(0x40) + 1] = "32BIT",
	[ilog2(0x01) + 1] = "SHARED",
	[ilog2(0x02) + 1] = "PRIVATE",
	[ilog2(0x10) + 1] = "FIXED",
	[ilog2(0x20) + 1] = "ANONYMOUS",
	[ilog2(0x100000) + 1] = "FIXED_NOREPLACE",
	[ilog2(0x0100) + 1] = "GROWSDOWN",
	[ilog2(0x0800) + 1] = "DENYWRITE",
	[ilog2(0x1000) + 1] = "EXECUTABLE",
	[ilog2(0x2000) + 1] = "LOCKED",
	[ilog2(0x4000) + 1] = "NORESERVE",
	[ilog2(0x8000) + 1] = "POPULATE",
	[ilog2(0x10000) + 1] = "NONBLOCK",
	[ilog2(0x20000) + 1] = "STACK",
	[ilog2(0x40000) + 1] = "HUGETLB",
	[ilog2(0x80000) + 1] = "SYNC",
  };
  $ uname -m
  x86_64
  $

Sparc, that defines a bunch then includes just mman-common.h:

  $ tools/perf/trace/beauty/mmap_flags.sh sparc
  static const char *mmap_flags[] = {
	[ilog2(0x0800) + 1] = "DENYWRITE",
	[ilog2(0x1000) + 1] = "EXECUTABLE",
	[ilog2(0x0200) + 1] = "GROWSDOWN",
	[ilog2(0x40000) + 1] = "HUGETLB",
	[ilog2(0x100) + 1] = "LOCKED",
	[ilog2(0x10000) + 1] = "NONBLOCK",
	[ilog2(0x40) + 1] = "NORESERVE",
	[ilog2(0x8000) + 1] = "POPULATE",
	[ilog2(0x20000) + 1] = "STACK",
	[ilog2(0x01) + 1] = "SHARED",
	[ilog2(0x02) + 1] = "PRIVATE",
	[ilog2(0x10) + 1] = "FIXED",
	[ilog2(0x20) + 1] = "ANONYMOUS",
	[ilog2(0x100000) + 1] = "FIXED_NOREPLACE",
  };
  [acme@jouet perf]$

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-xydeh491z8fkgglcmqnl5thj@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To silence this perf build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/sound/asound.h' differs from latest version at 'include/uapi/sound/asound.h'
  diff -u tools/include/uapi/sound/asound.h include/uapi/sound/asound.h

Due to this cset:

  a9840151 ("ALSA: timer: fix wrong comment to refer to 'SNDRV_TIMER_PSFLG_*'")

Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: Takashi Iwai <tiwai@suse.de>
Link: https://lkml.kernel.org/n/tip-76gsvs0w2g0x723ivqa2xua3@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To get the changes in:

  82b355d1 ("y2038: Remove newstat family from default syscall set")

Which will make the syscall table used by 'perf trace' for arm64 to be
updated from the changes in that patch.

This silences these perf build warnings:

  Warning: Kernel ABI header at 'tools/arch/arm64/include/uapi/asm/unistd.h' differs from latest version at 'arch/arm64/include/uapi/asm/unistd.h'
  diff -u tools/arch/arm64/include/uapi/asm/unistd.h arch/arm64/include/uapi/asm/unistd.h
  Warning: Kernel ABI header at 'tools/include/uapi/asm-generic/unistd.h' differs from latest version at 'include/uapi/asm-generic/unistd.h'
  diff -u tools/include/uapi/asm-generic/unistd.h include/uapi/asm-generic/unistd.h

Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-3euy7c4yy5mvnp5bm16t9vqg@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To silence this perf build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/fs.h' differs from latest version at 'include/uapi/linux/fs.h'
  diff -u tools/include/uapi/linux/fs.h include/uapi/linux/fs.h

Due to just two comments added by:

  Fixes: 578bdaab ("crypto: speck - remove Speck")

So nothing that entails changes in tools/, that so far uses fs.h to
generate the mount and umount syscalls 'flags' argument integer->string
tables with:

  $ tools/perf/trace/beauty/mount_flags.sh
  static const char *mount_flags[] = {
	[4096 ? (ilog2(4096) + 1) : 0] = "BIND",
<SNIP>
	[30 + 1] = "ACTIVE",
	[31 + 1] = "NOUSER",
  };
  $
  # trace -e mount,umount mount --bind /proc /mnt
     1.228 ( 2.581 ms): mount/1068 mount(dev_name: /mnt, dir_name: 0x55f011c354a0, type: 0x55f011c38170, flags: BIND) = 0
  # trace -e mount,umount umount /proc /mnt
  umount: /proc: target is busy.
     1.587 ( 0.010 ms): umount/1070 umount2(name: /proc) = -1 EBUSY Device or resource busy
     1.799 (12.660 ms): umount/1070 umount2(name: /mnt) = 0
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Link: https://lkml.kernel.org/n/tip-c00bqzclscgah26z2g5zxm73@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

When processing using 'perf report -g caller', which is the default, we
ended up reverting the callchain entries received from the kernel, but
simply reverting throws away the information that tells that from a
point onwards the addresses are for userspace, kernel, guest kernel,
guest user, hypervisor.

The idea is that if we are walking backwards, for each cluster of
non-cpumode entries we have to first scan backwards for the next one and
use that for the cluster.

This seems silly and more expensive than it needs to be but it is enough
for a initial fix.

The code here is really complicated because it is intimately intertwined
with the lbr and branch handling, as well as this callchain order,
further fixes will be needed to properly take into account the cpumode
in those cases.

Another problem with ORDER_CALLER is that the NULL "0" IP that is at the
end of most callchains shows up at the top of the histogram because
every callchain contains it and with ORDER_CALLER it is the first entry.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Souvik Banerjee <souvik1997@gmail.com>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: stable@vger.kernel.org # 4.19
Link: https://lkml.kernel.org/n/tip-2wt3ayp6j2y2f2xowixa8y6y@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Since commit edeb0c90 ("perf tools: Stop fallbacking to kallsyms for
vdso symbols lookup"), the kernel address cannot be properly parsed to
kernel symbol with command 'perf script -k vmlinux'.  The reason is
CoreSight samples is always to set CPU mode as PERF_RECORD_MISC_USER,
thus it fails to find corresponding map/dso in below flows:

  process_sample_event()
    `-> machine__resolve()
	  `-> thread__find_map(thread, sample->cpumode, sample->ip, al);

In this flow it needs to pass argument 'sample->cpumode' to tell what's
the CPU mode, before it always passed PERF_RECORD_MISC_USER but without
any failure until the commit edeb0c90 ("perf tools: Stop fallbacking
to kallsyms for vdso symbols lookup") has been merged.  The reason is
even with the wrong CPU mode the function thread__find_map() firstly
fails to find map but it will rollback to find kernel map for vdso
symbols lookup.  In the latest code it has removed the fallback code,
thus if CPU mode is PERF_RECORD_MISC_USER then it cannot find map
anymore with kernel address.

This patch is to correct samples CPU mode setting, it creates a new
helper function cs_etm__cpu_mode() to tell what's the CPU mode based on
the address with the info from machine structure; this patch has a bit
extension to check not only kernel and user mode, but also check for
host/guest and hypervisor mode.  Finally this patch uses the function in
instruction and branch samples and also apply in cs_etm__mem_access()
for a minor polishing.
Signed-off-by: NLeo Yan <leo.yan@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Miller <davem@davemloft.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: stable@kernel.org # v4.19
Link: http://lkml.kernel.org/r/1540883908-17018-1-git-send-email-leo.yan@linaro.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

libdwfl parses an ELF file itself and creates mappings for the
individual sections. perf on the other hand sees raw mmap events which
represent individual sections. When we encounter an address pointing
into a mapping with pgoff != 0, we must take that into account and
report the file at the non-offset base address.

This fixes unwinding with libdwfl in some cases. E.g. for a file like:

```

using namespace std;

mutex g_mutex;

double worker()
{
    lock_guard<mutex> guard(g_mutex);
    uniform_real_distribution<double> uniform(-1E5, 1E5);
    default_random_engine engine;
    double s = 0;
    for (int i = 0; i < 1000; ++i) {
        s += norm(complex<double>(uniform(engine), uniform(engine)));
    }
    cout << s << endl;
    return s;
}

int main()
{
    vector<std::future<double>> results;
    for (int i = 0; i < 10000; ++i) {
        results.push_back(async(launch::async, worker));
    }
    return 0;
}
```

Compile it with `g++ -g -O2 -lpthread cpp-locking.cpp  -o cpp-locking`,
then record it with `perf record --call-graph dwarf -e
sched:sched_switch`.

When you analyze it with `perf script` and libunwind, you should see:

```
cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0 next_prio=120
        ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb1670208 schedule+0x28 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb16737cc rwsem_down_read_failed+0xec (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb1665e04 call_rwsem_down_read_failed+0x14 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb1672a03 down_read+0x13 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb106bd85 __do_page_fault+0x445 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb18015f5 page_fault+0x45 (/lib/modules/4.14.78-1-lts/build/vmlinux)
            7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so)
            7f38e4252d0b arena_get2.part.4+0x2fb (/usr/lib/libc-2.28.so)
            7f38e4255b1c tcache_init.part.6+0xec (/usr/lib/libc-2.28.so)
            7f38e42569e5 __GI___libc_malloc+0x115 (inlined)
            7f38e4241790 __GI__IO_file_doallocate+0x90 (inlined)
            7f38e424fbbf __GI__IO_doallocbuf+0x4f (inlined)
            7f38e424ee47 __GI__IO_file_overflow+0x197 (inlined)
            7f38e424df36 _IO_new_file_xsputn+0x116 (inlined)
            7f38e4242bfb __GI__IO_fwrite+0xdb (inlined)
            7f38e463fa6d std::basic_streambuf<char, std::char_traits<char> >::sputn(char const*, long)+0x1cd (inlined)
            7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> >::_M_put(char const*, long)+0x1cd (inlined)
            7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::__write<char>(std::ostreambuf_iterator<char, std::char_traits<char> >, char const*, int)+0x1cd (inlined)
            7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::_M_insert_float<double>(std::ostreambuf_iterator<c>
            7f38e464bd70 std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, double) const+0x90 (inl>
            7f38e464bd70 std::ostream& std::ostream::_M_insert<double>(double)+0x90 (/usr/lib/libstdc++.so.6.0.25)
            563b9cb502f7 std::ostream::operator<<(double)+0xb7 (inlined)
            563b9cb502f7 worker()+0xb7 (/ssd/milian/projects/kdab/rnd/hotspot/build/tests/test-clients/cpp-locking/cpp-locking)
            563b9cb506fb double std::__invoke_impl<double, double (*)()>(std::__invoke_other, double (*&&)())+0x2b (inlined)
            563b9cb506fb std::__invoke_result<double (*)()>::type std::__invoke<double (*)()>(double (*&&)())+0x2b (inlined)
            563b9cb506fb decltype (__invoke((_S_declval<0ul>)())) std::thread::_Invoker<std::tuple<double (*)()> >::_M_invoke<0ul>(std::_Index_tuple<0ul>)+0x2b (inlined)
            563b9cb506fb std::thread::_Invoker<std::tuple<double (*)()> >::operator()()+0x2b (inlined)
            563b9cb506fb std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<double>, std::__future_base::_Result_base::_Deleter>, std::thread::_Invoker<std::tuple<double (*)()> >, dou>
            563b9cb506fb std::_Function_handler<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> (), std::__future_base::_Task_setter<std::unique_ptr<std::__future_>
            563b9cb507e8 std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>::operator()() const+0x28 (inlined)
            563b9cb507e8 std::__future_base::_State_baseV2::_M_do_set(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*)+0x28 (/ssd/milian/>
            7f38e46d24fe __pthread_once_slow+0xbe (/usr/lib/libpthread-2.28.so)
            563b9cb51149 __gthread_once+0xe9 (inlined)
            563b9cb51149 void std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*)>
            563b9cb51149 std::__future_base::_State_baseV2::_M_set_result(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>, bool)+0xe9 (inlined)
            563b9cb51149 std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<double (*)()> >&&)::{lambda()#1}::op>
            563b9cb51149 void std::__invoke_impl<void, std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<double>
            563b9cb51149 std::__invoke_result<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<double (*)()> >>
            563b9cb51149 decltype (__invoke((_S_declval<0ul>)())) std::thread::_Invoker<std::tuple<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_>
            563b9cb51149 std::thread::_Invoker<std::tuple<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<dou>
            563b9cb51149 std::thread::_State_impl<std::thread::_Invoker<std::tuple<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread>
            7f38e45f0062 execute_native_thread_routine+0x12 (/usr/lib/libstdc++.so.6.0.25)
            7f38e46caa9c start_thread+0xfc (/usr/lib/libpthread-2.28.so)
            7f38e42ccb22 __GI___clone+0x42 (inlined)
```

Before this patch, using libdwfl, you would see:

```
cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0 next_prio=120
        ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb1670208 schedule+0x28 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb16737cc rwsem_down_read_failed+0xec (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb1665e04 call_rwsem_down_read_failed+0x14 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb1672a03 down_read+0x13 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb106bd85 __do_page_fault+0x445 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb18015f5 page_fault+0x45 (/lib/modules/4.14.78-1-lts/build/vmlinux)
            7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so)
        a041161e77950c5c [unknown] ([unknown])
```

With this patch applied, we get a bit further in unwinding:

```
cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0 next_prio=120
        ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb1670208 schedule+0x28 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb16737cc rwsem_down_read_failed+0xec (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb1665e04 call_rwsem_down_read_failed+0x14 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb1672a03 down_read+0x13 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb106bd85 __do_page_fault+0x445 (/lib/modules/4.14.78-1-lts/build/vmlinux)
        ffffffffb18015f5 page_fault+0x45 (/lib/modules/4.14.78-1-lts/build/vmlinux)
            7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so)
            7f38e4252d0b arena_get2.part.4+0x2fb (/usr/lib/libc-2.28.so)
            7f38e4255b1c tcache_init.part.6+0xec (/usr/lib/libc-2.28.so)
            7f38e42569e5 __GI___libc_malloc+0x115 (inlined)
            7f38e4241790 __GI__IO_file_doallocate+0x90 (inlined)
            7f38e424fbbf __GI__IO_doallocbuf+0x4f (inlined)
            7f38e424ee47 __GI__IO_file_overflow+0x197 (inlined)
            7f38e424df36 _IO_new_file_xsputn+0x116 (inlined)
            7f38e4242bfb __GI__IO_fwrite+0xdb (inlined)
            7f38e463fa6d std::basic_streambuf<char, std::char_traits<char> >::sputn(char const*, long)+0x1cd (inlined)
            7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> >::_M_put(char const*, long)+0x1cd (inlined)
            7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::__write<char>(std::ostreambuf_iterator<char, std::char_traits<char> >, char const*, int)+0x1cd (inlined)
            7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::_M_insert_float<double>(std::ostreambuf_iterator<c>
            7f38e464bd70 std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, double) const+0x90 (inl>
            7f38e464bd70 std::ostream& std::ostream::_M_insert<double>(double)+0x90 (/usr/lib/libstdc++.so.6.0.25)
            563b9cb502f7 std::ostream::operator<<(double)+0xb7 (inlined)
            563b9cb502f7 worker()+0xb7 (/ssd/milian/projects/kdab/rnd/hotspot/build/tests/test-clients/cpp-locking/cpp-locking)
        6eab825c1ee3e4ff [unknown] ([unknown])
```

Note that the backtrace is still stopping too early, when compared to
the nice results obtained via libunwind. It's unclear so far what the
reason for that is.

Committer note:

Further comment by Milian on the thread started on the Link: tag below:

 ---
The remaining issue is due to a bug in elfutils:

https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html

With both patches applied, libunwind and elfutils produce the same output for
the above scenario.
 ---
Signed-off-by: NMilian Wolff <milian.wolff@kdab.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20181029141644.3907-1-milian.wolff@kdab.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Enabling --overwrite mode allows us to to use just the most recent
records, which helps in high core count machines such as Knights
Landing/Mill, but right now is being disabled by default as the pausing
used in this technique is leading to loss of metadata events such as
PERF_RECORD_MMAP which makes 'perf top' unable to resolve samples,
leading to lots of unknown samples appearing on the UI.

Enabling this may be useful if you are in such machines and profiling a
workload that doesn't creates short lived threads and/or doesn't uses
many executable mmap operations.

Work is being planed to solve this situation, till then, this will
remain disabled by default.
Reported-by: NDavid Miller <davem@davemloft.net>
Acked-by: NKan Liang <kan.liang@intel.com>
Link: https://lkml.kernel.org/r/4f84468f-37d9-cf1b-12c1-514ef74b6a48@linux.intel.com
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: ebebbf08 ("perf top: Switch default mode to overwrite mode")
Link: https://lkml.kernel.org/n/tip-ehvf77vi1si9409r7p4wx788@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

In ebebbf08 ("perf top: Switch default mode to overwrite mode") we
forgot to leave a way to disable that new default, add a --overwrite
option that can be disabled using --no-overwrite, since the code already
in such a way that we can readily disable this mode.

This is useful when investigating bugs with this mode like the recent
report from David Miller where lots of unknown symbols appear due to
disabling the events while processing them which disables all record
types, not just PERF_RECORD_SAMPLE, which makes it impossible to resolve
maps when we lose PERF_RECORD_MMAP records.

This can be easily seen while building a kernel, when there are lots of
short lived processes.
Reported-by: NDavid Miller <davem@davemloft.net>
Acked-by: NKan Liang <kan.liang@intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: ebebbf08 ("perf top: Switch default mode to overwrite mode")
Link: https://lkml.kernel.org/n/tip-oqgsz2bq4kgrnnajrafcdhie@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The pathname beautifiers so far support just one augmented pathname per
syscall, so do it just for mount's first arg, later this will get fixed.

With:

  # perf probe -l
  probe:vfs_getname    (on getname_flags:73@acme/git/linux/fs/namei.c with pathname)
  #

Later this will get added to augmented_syscalls.c (eBPF):

In one xterm:

  # perf trace -e mount,umount
  2687.331 ( 3.544 ms): mount/8892 mount(dev_name: /mnt, dir_name: 0x561f9ac184a0, type: 0x561f9ac1b170, flags: BIND) = 0
  3912.126 ( 8.807 ms): umount/8895 umount2(name: /mnt) = 0
  ^C#

In the other:

  $ sudo mount --bind /proc /mnt
  $ sudo umount /mnt

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Benjamin Peterson <benjamin@python.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-qsvhrm2es635cl4zicqjeth2@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

By using the SCA_FILENAME beautifier, that works when either the
probe:vfs_getname probe is in place or with the eBPF program
tools/perf/examples/bpf/augmented_syscalls.c:

  # perf probe -l
  probe:vfs_getname (on getname_flags:73@acme/git/linux/fs/namei.c with pathname)
  # perf trace -e umount
  9630.332 ( 9.521 ms): umount/8082 umount2(name: /mnt) = 0
  #

The augmented syscalls one will be done in the next patch.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Benjamin Peterson <benjamin@python.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-hegbzlpd2nrn584l5jxn7sy2@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

When trying to trace the 'umount' syscall on x86_64 I noticed that it
was failing:

  # trace -e umount umount /mnt
  event syntax error: 'umount'
                       \___ parser error
  Run 'perf list' for a list of valid events

   Usage: perf trace [<options>] [<command>]
      or: perf trace [<options>] -- <command> [<options>]
      or: perf trace record [<options>] [<command>]
      or: perf trace record [<options>] -- <command> [<options>]

      -e, --event <event>   event/syscall selector. use 'perf list' to list available events
  #

This is because in the x86-64 we have it just as 'umount2':

  $ grep umount arch/x86/entry/syscalls/syscall_64.tbl
  166	common	umount2			__x64_sys_umount
  $

So if the syscall name fails, try fallbacking to looking at the aliases
we have in the syscall_fmts table to then re-lookup, now:

  # trace -e umount umount -f /mnt
  umount: /mnt: not mounted.
     1.759 ( 0.004 ms): umount/18365 umount2(name: 0x55fbfcbc4480, flags: 1) = -1 EINVAL Invalid argument
  #

Time to beautify the flags arg :-)

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Benjamin Peterson <benjamin@python.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-ukweodgzbmjd25lfkgryeft1@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

  # trace -e mount mount -o ro -t debugfs nodev /mnt
     0.000 ( 1.040 ms): mount/27235 mount(dev_name: 0x5601cc8c64e0, dir_name: 0x5601cc8c6500, type: 0x5601cc8c6480, flags: RDONLY) = 0
  # trace -e mount mount -o remount,relatime -t debugfs nodev /mnt
     0.000 ( 2.946 ms): mount/27262 mount(dev_name: 0x55f4a73d64e0, dir_name: 0x55f4a73d6500, type: 0x55f4a73d6480, flags: REMOUNT|RELATIME) = 0
  # trace -e mount mount -o remount,strictatime -t debugfs nodev /mnt
     0.000 ( 2.934 ms): mount/27265 mount(dev_name: 0x5617f71d94e0, dir_name: 0x5617f71d9500, type: 0x5617f71d9480, flags: REMOUNT|STRICTATIME) = 0
  # trace -e mount mount -o remount,suid,silent -t debugfs nodev /mnt
     0.000 ( 0.049 ms): mount/27273 mount(dev_name: 0x55ad65df24e0, dir_name: 0x55ad65df2500, type: 0x55ad65df2480, flags: REMOUNT|SILENT) = 0
  # trace -e mount mount -o remount,rw,sync,lazytime -t debugfs nodev /mnt
     0.000 ( 2.684 ms): mount/27281 mount(dev_name: 0x561216055530, dir_name: 0x561216055550, type: 0x561216055510, flags: SYNCHRONOUS|REMOUNT|LAZYTIME) = 0
  # trace -e mount mount -o remount,dirsync -t debugfs nodev /mnt
     0.000 ( 3.512 ms): mount/27314 mount(dev_name: 0x55c4e7188480, dir_name: 0x55c4e7188530, type: 0x55c4e71884a0, flags: REMOUNT|DIRSYNC, data: 0x55c4e71884e0) = 0
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Benjamin Peterson <benjamin@python.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-i5ncao73c0bd02qprgrq6wb9@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Take mount's 'flags' arg, to cope with this semantic, as defined in do_mount in fs/namespace.c:

  /*
   * Pre-0.97 versions of mount() didn't have a flags word.  When the
   * flags word was introduced its top half was required to have the
   * magic value 0xC0ED, and this remained so until 2.4.0-test9.
   * Therefore, if this magic number is present, it carries no
   * information and must be discarded.
   */

We need to mask this arg, and then see if it is zero, when we simply
don't print the arg name and value.

The next patch will use this for mount's 'flag' arg.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Benjamin Peterson <benjamin@python.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-btue14k5jemayuykfrwsnh85@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Generalizing pkey_alloc__scnprintf_access_rights(), so that we can use
it with other flags-like arguments, such as mount's mountflags argument.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Benjamin Peterson <benjamin@python.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-o3ymi3104m8moaz9865g09w9@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The intention is to have this as a library, since it is not perf
specific at all.

I did the switch for the files where I'm the only contributor, with the
exception of a few lines changed by Jiri Olsa.
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-a04q6chdyjknm1hr305ulx8h@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

It'll use tools/include copy of linux/fs.h to generate a table to be
used by tools, initially by the 'mount' and 'umount' beautifiers in
'perf trace', but that could also be used to translate from a string
constant to the integer value to be used in a eBPF or tracefs tracepoint
filter.

When used without any args it produces:

  $ tools/perf/trace/beauty/mount_flags.sh
  static const char *mount_flags[] = {
	[1 ? (ilog2(1) + 1) : 0] = "RDONLY",
	[2 ? (ilog2(2) + 1) : 0] = "NOSUID",
	[4 ? (ilog2(4) + 1) : 0] = "NODEV",
	[8 ? (ilog2(8) + 1) : 0] = "NOEXEC",
	[16 ? (ilog2(16) + 1) : 0] = "SYNCHRONOUS",
	[32 ? (ilog2(32) + 1) : 0] = "REMOUNT",
	[64 ? (ilog2(64) + 1) : 0] = "MANDLOCK",
	[128 ? (ilog2(128) + 1) : 0] = "DIRSYNC",
	[1024 ? (ilog2(1024) + 1) : 0] = "NOATIME",
	[2048 ? (ilog2(2048) + 1) : 0] = "NODIRATIME",
	[4096 ? (ilog2(4096) + 1) : 0] = "BIND",
	[8192 ? (ilog2(8192) + 1) : 0] = "MOVE",
	[16384 ? (ilog2(16384) + 1) : 0] = "REC",
	[32768 ? (ilog2(32768) + 1) : 0] = "SILENT",
	[16 + 1] = "POSIXACL",
	[17 + 1] = "UNBINDABLE",
	[18 + 1] = "PRIVATE",
	[19 + 1] = "SLAVE",
	[20 + 1] = "SHARED",
	[21 + 1] = "RELATIME",
	[22 + 1] = "KERNMOUNT",
	[23 + 1] = "I_VERSION",
	[24 + 1] = "STRICTATIME",
	[25 + 1] = "LAZYTIME",
	[26 + 1] = "SUBMOUNT",
	[27 + 1] = "NOREMOTELOCK",
	[28 + 1] = "NOSEC",
	[29 + 1] = "BORN",
	[30 + 1] = "ACTIVE",
	[31 + 1] = "NOUSER",
  };
  $

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Benjamin Peterson <benjamin@python.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-mgutbbkmip9gfnmd28ikg7xt@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

We'll use it to create tables for the 'flags' argument to the 'mount'
and 'umount' syscalls.

Add it to check_headers.sh so that when a new protocol gets added we get
a notification during the build process.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Benjamin Peterson <benjamin@python.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-yacf9jvkwfwg2g95r2us3xb3@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Replace a bunch of spaces with tab, cleans up indentation
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-janitors@vger.kernel.org
Link: http://lkml.kernel.org/r/20181029233211.21475-1-colin.king@canonical.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Signed-off-by: NIngo Molnar <mingo@kernel.org>

Commit 9ee3e066 ("HID: i2c-hid: override HID descriptors for certain
devices") added a new dmi_system_id quirk table to override certain HID
report descriptors for some systems that lack them.

But the table wasn't properly terminated, causing the dmi matching to
walk off into la-la-land, and starting to treat random data as dmi
descriptor pointers, causing boot-time oopses if you were at all
unlucky.

Terminate the array.

We really should have some way to just statically check that arrays that
should be terminated by an empty entry actually are so.  But the HID
people really should have caught this themselves, rather than have me
deal with an oops during the merge window.  Tssk, tssk.

Cc: Julian Sax <jsbc@gmx.de>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Merge updates from Andrew Morton:

 - a few misc things

 - ocfs2 updates

 - most of MM

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (132 commits)
  hugetlbfs: dirty pages as they are added to pagecache
  mm: export add_swap_extent()
  mm: split SWP_FILE into SWP_ACTIVATED and SWP_FS
  tools/testing/selftests/vm/map_fixed_noreplace.c: add test for MAP_FIXED_NOREPLACE
  mm: thp: relocate flush_cache_range() in migrate_misplaced_transhuge_page()
  mm: thp: fix mmu_notifier in migrate_misplaced_transhuge_page()
  mm: thp: fix MADV_DONTNEED vs migrate_misplaced_transhuge_page race condition
  mm/kasan/quarantine.c: make quarantine_lock a raw_spinlock_t
  mm/gup: cache dev_pagemap while pinning pages
  Revert "x86/e820: put !E820_TYPE_RAM regions into memblock.reserved"
  mm: return zero_resv_unavail optimization
  mm: zero remaining unavailable struct pages
  tools/testing/selftests/vm/gup_benchmark.c: add MAP_HUGETLB option
  tools/testing/selftests/vm/gup_benchmark.c: add MAP_SHARED option
  tools/testing/selftests/vm/gup_benchmark.c: allow user specified file
  tools/testing/selftests/vm/gup_benchmark.c: fix 'write' flag usage
  mm/gup_benchmark.c: add additional pinning methods
  mm/gup_benchmark.c: time put_page()
  mm: don't raise MEMCG_OOM event due to failed high-order allocation
  mm/page-writeback.c: fix range_cyclic writeback vs writepages deadlock
  ...

Pull networking fixes from David Miller:
 "What better way to start off a weekend than with some networking bug
  fixes:

  1) net namespace leak in dump filtering code of ipv4 and ipv6, fixed
     by David Ahern and Bjørn Mork.

  2) Handle bad checksums from hardware when using CHECKSUM_COMPLETE
     properly in UDP, from Sean Tranchetti.

  3) Remove TCA_OPTIONS from policy validation, it turns out we don't
     consistently use nested attributes for this across all packet
     schedulers. From David Ahern.

  4) Fix SKB corruption in cadence driver, from Tristram Ha.

  5) Fix broken WoL handling in r8169 driver, from Heiner Kallweit.

  6) Fix OOPS in pneigh_dump_table(), from Eric Dumazet"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (28 commits)
  net/neigh: fix NULL deref in pneigh_dump_table()
  net: allow traceroute with a specified interface in a vrf
  bridge: do not add port to router list when receives query with source 0.0.0.0
  net/smc: fix smc_buf_unuse to use the lgr pointer
  ipv6/ndisc: Preserve IPv6 control buffer if protocol error handlers are called
  net/{ipv4,ipv6}: Do not put target net if input nsid is invalid
  lan743x: Remove SPI dependency from Microchip group.
  drivers: net: remove <net/busy_poll.h> inclusion when not needed
  net: phy: genphy_10g_driver: Avoid NULL pointer dereference
  r8169: fix broken Wake-on-LAN from S5 (poweroff)
  octeontx2-af: Use GFP_ATOMIC under spin lock
  net: ethernet: cadence: fix socket buffer corruption problem
  net/ipv6: Allow onlink routes to have a device mismatch if it is the default route
  net: sched: Remove TCA_OPTIONS from policy
  ice: Poll for link status change
  ice: Allocate VF interrupts and set queue map
  ice: Introduce ice_dev_onetime_setup
  net: hns3: Fix for warning uninitialized symbol hw_err_lst3
  octeontx2-af: Copy the right amount of memory
  net: udp: fix handling of CHECKSUM_COMPLETE packets
  ...

Pull sparc fixes from David Miller:
 "Some more sparc fixups, mostly aimed at getting the allmodconfig build
  up and clean again"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
  sparc64: Rework xchg() definition to avoid warnings.
  sparc64: Export __node_distance.
  sparc64: Make corrupted user stacks more debuggable.

Some test systems were experiencing negative huge page reserve counts and
incorrect file block counts.  This was traced to /proc/sys/vm/drop_caches
removing clean pages from hugetlbfs file pagecaches.  When non-hugetlbfs
explicit code removes the pages, the appropriate accounting is not
performed.

This can be recreated as follows:
 fallocate -l 2M /dev/hugepages/foo
 echo 1 > /proc/sys/vm/drop_caches
 fallocate -l 2M /dev/hugepages/foo
 grep -i huge /proc/meminfo
   AnonHugePages:         0 kB
   ShmemHugePages:        0 kB
   HugePages_Total:    2048
   HugePages_Free:     2047
   HugePages_Rsvd:    18446744073709551615
   HugePages_Surp:        0
   Hugepagesize:       2048 kB
   Hugetlb:         4194304 kB
 ls -lsh /dev/hugepages/foo
   4.0M -rw-r--r--. 1 root root 2.0M Oct 17 20:05 /dev/hugepages/foo

To address this issue, dirty pages as they are added to pagecache.  This
can easily be reproduced with fallocate as shown above.  Read faulted
pages will eventually end up being marked dirty.  But there is a window
where they are clean and could be impacted by code such as drop_caches.
So, just dirty them all as they are added to the pagecache.

Link: http://lkml.kernel.org/r/b5be45b8-5afe-56cd-9482-28384699a049@oracle.com
Fixes: 6bda666a ("hugepages: fold find_or_alloc_pages into huge_no_page()")
Signed-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Acked-by: NMihcla Hocko <mhocko@suse.com>
Reviewed-by: NKhalid Aziz <khalid.aziz@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Btrfs currently does not support swap files because swap's use of bmap
does not work with copy-on-write and multiple devices.  See 35054394
("Btrfs: stop providing a bmap operation to avoid swapfile corruptions").

However, the swap code has a mechanism for the filesystem to manually add
swap extents using add_swap_extent() from the ->swap_activate() aop.
iomap has done this since 67482129 ("iomap: add a swapfile activation
function").  Btrfs will do the same in a later patch, so export
add_swap_extent().

Link: http://lkml.kernel.org/r/bb1208575e02829aae51b538709476964f97b1ea.1536704650.git.osandov@fb.comSigned-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: David Sterba <dsterba@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The SWP_FILE flag serves two purposes: to make swap_{read,write}page() go
through the filesystem, and to make swapoff() call ->swap_deactivate().
For Btrfs, we want the latter but not the former, so split this flag into
two.  This makes us always call ->swap_deactivate() if ->swap_activate()
succeeded, not just if it didn't add any swap extents itself.

This also resolves the issue of the very misleading name of SWP_FILE,
which is only used for swap files over NFS.

Link: http://lkml.kernel.org/r/6d63d8668c4287a4f6d203d65696e96f80abdfc7.1536704650.git.osandov@fb.comSigned-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Sterba <dsterba@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a test for MAP_FIXED_NOREPLACE, based on some code originally by Jann
Horn.  This would have caught the overlap bug reported by Daniel Micay.

I originally suggested to Michal that we create MAP_FIXED_NOREPLACE, but
instead of writing a selftest I spent my time bike-shedding whether it
should be called MAP_FIXED_SAFE/NOCLOBBER/WEAK/NEW ..  mea culpa.

Link: http://lkml.kernel.org/r/20181013133929.28653-1-mpe@ellerman.id.auSigned-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Reviewed-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NKhalid Aziz <khalid.aziz@oracle.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Jann Horn <jannh@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Jason Evans <jasone@google.com>
Cc: David Goldblatt <davidtgoldblatt@gmail.com>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>