linux-toradex.git/kernel/events, branch v4.4.77

perf/core: Drop kernel samples even though :u is specified

2017-06-14T11:16:25+00:00

commit cc1582c231ea041fbc68861dfaf957eaf902b829 upstream.

When doing sampling, for example:

  perf record -e cycles:u ...

On workloads that do a lot of kernel entry/exits we see kernel
samples, even though :u is specified. This is due to skid existing.

This might be a security issue because it can leak kernel addresses even
though kernel sampling support is disabled.

The patch drops the kernel samples if exclude_kernel is specified.

For example, test on Haswell desktop:

  perf record -e cycles:u 
  perf report --stdio

Before patch applied:

    99.77%  mgen     mgen              [.] buf_read
     0.20%  mgen     mgen              [.] rand_buf_init
     0.01%  mgen     [kernel.vmlinux]  [k] apic_timer_interrupt
     0.00%  mgen     mgen              [.] last_free_elem
     0.00%  mgen     libc-2.23.so      [.] __random_r
     0.00%  mgen     libc-2.23.so      [.] _int_malloc
     0.00%  mgen     mgen              [.] rand_array_init
     0.00%  mgen     [kernel.vmlinux]  [k] page_fault
     0.00%  mgen     libc-2.23.so      [.] __random
     0.00%  mgen     libc-2.23.so      [.] __strcasestr
     0.00%  mgen     ld-2.23.so        [.] strcmp
     0.00%  mgen     ld-2.23.so        [.] _dl_start
     0.00%  mgen     libc-2.23.so      [.] sched_setaffinity@@GLIBC_2.3.4
     0.00%  mgen     ld-2.23.so        [.] _start

We can see kernel symbols apic_timer_interrupt and page_fault.

After patch applied:

    99.79%  mgen     mgen           [.] buf_read
     0.19%  mgen     mgen           [.] rand_buf_init
     0.00%  mgen     libc-2.23.so   [.] __random_r
     0.00%  mgen     mgen           [.] rand_array_init
     0.00%  mgen     mgen           [.] last_free_elem
     0.00%  mgen     libc-2.23.so   [.] vfprintf
     0.00%  mgen     libc-2.23.so   [.] rand
     0.00%  mgen     libc-2.23.so   [.] __random
     0.00%  mgen     libc-2.23.so   [.] _int_malloc
     0.00%  mgen     libc-2.23.so   [.] _IO_doallocbuf
     0.00%  mgen     ld-2.23.so     [.] do_lookup_x
     0.00%  mgen     ld-2.23.so     [.] open_verify.constprop.7
     0.00%  mgen     ld-2.23.so     [.] _dl_important_hwcaps
     0.00%  mgen     libc-2.23.so   [.] sched_setaffinity@@GLIBC_2.3.4
     0.00%  mgen     ld-2.23.so     [.] _start

There are only userspace symbols.

Signed-off-by: Jin Yao 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Cc: acme@kernel.org
Cc: jolsa@kernel.org
Cc: kan.liang@intel.com
Cc: mark.rutland@arm.com
Cc: will.deacon@arm.com
Cc: yao.jin@intel.com
Link: http://lkml.kernel.org/r/1495706947-3744-1-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

perf/core: Fix concurrent sys_perf_event_open() vs. 'move_group' race

2017-04-30T03:49:29+00:00

commit 321027c1fe77f892f4ea07846aeae08cefbbb290 upstream.

Di Shen reported a race between two concurrent sys_perf_event_open()
calls where both try and move the same pre-existing software group
into a hardware context.

The problem is exactly that described in commit:

  f63a8daa5812 ("perf: Fix event->ctx locking")

... where, while we wait for a ctx->mutex acquisition, the event->ctx
relation can have changed under us.

That very same commit failed to recognise sys_perf_event_context() as an
external access vector to the events and thereby didn't apply the
established locking rules correctly.

So while one sys_perf_event_open() call is stuck waiting on
mutex_lock_double(), the other (which owns said locks) moves the group
about. So by the time the former sys_perf_event_open() acquires the
locks, the context we've acquired is stale (and possibly dead).

Apply the established locking rules as per perf_event_ctx_lock_nested()
to the mutex_lock_double() for the 'move_group' case. This obviously means
we need to validate state after we acquire the locks.

Reported-by: Di Shen (Keen Lab)
Tested-by: John Dias 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Min Chong 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Fixes: f63a8daa5812 ("perf: Fix event->ctx locking")
Link: http://lkml.kernel.org/r/20170106131444.GZ3174@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar 
[bwh: Backported to 4.4:
 - Test perf_event::group_flags instead of group_caps
 - Adjust context]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

perf/core: Fix event inheritance on fork()

2017-03-26T10:13:18+00:00

commit e7cc4865f0f31698ef2f7aac01a50e78968985b7 upstream.

While hunting for clues to a use-after-free, Oleg spotted that
perf_event_init_context() can loose an error value with the result
that fork() can succeed even though we did not fully inherit the perf
event context.

Spotted-by: Oleg Nesterov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Dmitry Vyukov 
Cc: Frederic Weisbecker 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Mathieu Desnoyers 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Cc: oleg@redhat.com
Fixes: 889ff0150661 ("perf/core: Split context's event group list into pinned and non-pinned lists")
Link: http://lkml.kernel.org/r/20170316125823.190342547@infradead.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

perf/core: Fix PERF_RECORD_MMAP2 prot/flags for anonymous memory

2017-02-09T07:02:45+00:00

commit 0b3589be9b98994ce3d5aeca52445d1f5627c4ba upstream.

Andres reported that MMAP2 records for anonymous memory always have
their protection field 0.

Turns out, someone daft put the prot/flags generation code in the file
branch, leaving them unset for anonymous memory.

Reported-by: Andres Freund 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Don Zickus 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: acme@kernel.org
Cc: anton@ozlabs.org
Cc: namhyung@kernel.org
Fixes: f972eb63b100 ("perf: Pass protection and flags bits through mmap2 interface")
Link: http://lkml.kernel.org/r/20170126221508.GF6536@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

perf/core: Fix pmu::filter_match for SW-led groups

2016-10-07T13:23:41+00:00

commit 2c81a6477081966fe80b8c6daa68459bca896774 upstream.

The following commit:

  66eb579e66ec ("perf: allow for PMU-specific event filtering")

added the pmu::filter_match() callback. This was intended to
avoid HW constraints on events from resulting in extremely
pessimistic scheduling.

However, pmu::filter_match() is only called for the leader of each event
group. When the leader is a SW event, we do not filter the groups, and
may fail at pmu::add() time, and when this happens we'll give up on
scheduling any event groups later in the list until they are rotated
ahead of the failing group.

This can result in extremely sub-optimal event scheduling behaviour,
e.g. if running the following on a big.LITTLE platform:

$ taskset -c 0 ./perf stat \
 -e 'a57{context-switches,armv8_cortex_a57/config=0x11/}' \
 -e 'a53{context-switches,armv8_cortex_a53/config=0x11/}' \
 ls

           context-switches                                              (0.00%)
           armv8_cortex_a57/config=0x11/                                 (0.00%)
                24      context-switches                                              (37.36%)
          57589154      armv8_cortex_a53/config=0x11/                                 (37.36%)

Here the 'a53' event group was always eligible to be scheduled, but
the 'a57' group never eligible to be scheduled, as the task was always
affine to a Cortex-A53 CPU. The SW (group leader) event in the 'a57'
group was eligible, but the HW event failed at pmu::add() time,
resulting in ctx_flexible_sched_in giving up on scheduling further
groups with HW events.

One way of avoiding this is to check pmu::filter_match() on siblings
as well as the group leader. If any of these fail their
pmu::filter_match() call, we must skip the entire group before
attempting to add any events.

Signed-off-by: Mark Rutland 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Fixes: 66eb579e66ec ("perf: allow for PMU-specific event filtering")
Link: http://lkml.kernel.org/r/1465917041-15339-1-git-send-email-mark.rutland@arm.com
[ Small readability edits. ]
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

uprobes: Fix the memcg accounting

2016-09-15T06:27:53+00:00

commit 6c4687cc17a788a6dd8de3e27dbeabb7cbd3e066 upstream.

__replace_page() wronlgy calls mem_cgroup_cancel_charge() in "success" path,
it should only do this if page_check_address() fails.

This means that every enable/disable leads to unbalanced mem_cgroup_uncharge()
from put_page(old_page), it is trivial to underflow the page_counter->count
and trigger OOM.

Reported-and-tested-by: Brenden Blanco 
Signed-off-by: Oleg Nesterov 
Reviewed-by: Johannes Weiner 
Acked-by: Michal Hocko 
Cc: Alexander Shishkin 
Cc: Alexei Starovoitov 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Vladimir Davydov 
Fixes: 00501b531c47 ("mm: memcontrol: rewrite charge API")
Link: http://lkml.kernel.org/r/20160817153629.GB29724@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

bpf, perf: delay release of BPF prog after grace period

2016-07-11T16:31:11+00:00

[ Upstream commit ceb56070359b7329b5678b5d95a376fcb24767be ]

Commit dead9f29ddcc ("perf: Fix race in BPF program unregister") moved
destruction of BPF program from free_event_rcu() callback to __free_event(),
which is problematic if used with tail calls: if prog A is attached as
trace event directly, but at the same time present in a tail call map used
by another trace event program elsewhere, then we need to delay destruction
via RCU grace period since it can still be in use by the program doing the
tail call (the prog first needs to be dropped from the tail call map, then
trace event with prog A attached destroyed, so we get immediate destruction).

Fixes: dead9f29ddcc ("perf: Fix race in BPF program unregister")
Signed-off-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Cc: Jann Horn 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

perf/core: Fix perf_event_open() vs. execve() race

2016-06-01T19:15:47+00:00

commit 79c9ce57eb2d5f1497546a3946b4ae21b6fdc438 upstream.

Jann reported that the ptrace_may_access() check in
find_lively_task_by_vpid() is racy against exec().

Specifically:

  perf_event_open()		execve()

  ptrace_may_access()
				commit_creds()
  ...				if (get_dumpable() != SUID_DUMP_USER)
				  perf_event_exit_task();
  perf_install_in_context()

would result in installing a counter across the creds boundary.

Fix this by wrapping lots of perf_event_open() in cred_guard_mutex.
This should be fine as perf_event_exit_task() is already called with
cred_guard_mutex held, so all perf locks already nest inside it.

Reported-by: Jann Horn 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Signed-off-by: Ingo Molnar 
Signed-off-by: He Kuang 
Signed-off-by: Greg Kroah-Hartman

perf/core: Disable the event on a truncated AUX record

2016-05-19T00:06:48+00:00

commit 9f448cd3cbcec8995935e60b27802ae56aac8cc0 upstream.

When the PMU driver reports a truncated AUX record, it effectively means
that there is no more usable room in the event's AUX buffer (even though
there may still be some room, so that perf_aux_output_begin() doesn't take
action). At this point the consumer still has to be woken up and the event
has to be disabled, otherwise the event will just keep spinning between
perf_aux_output_begin() and perf_aux_output_end() until its context gets
unscheduled.

Again, for cpu-wide events this means never, so once in this condition,
they will be forever losing data.

Fix this by disabling the event and waking up the consumer in case of a
truncated AUX record.

Reported-by: Markus Metzger 
Signed-off-by: Alexander Shishkin 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Borislav Petkov 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/1462886313-13660-3-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

perf: Cure event->pending_disable race

2016-04-20T06:42:14+00:00

commit 28a967c3a2f99fa3b5f762f25cb2a319d933571b upstream.

Because event_sched_out() checks event->pending_disable _before_
actually disabling the event, it can happen that the event fires after
it checks but before it gets disabled.

This would leave event->pending_disable set and the queued irq_work
will try and process it.

However, if the event trigger was during schedule(), the event might
have been de-scheduled by the time the irq_work runs, and
perf_event_disable_local() will fail.

Fix this by checking event->pending_disable _after_ we call
event->pmu->del(). This depends on the latter being a compiler
barrier, such that the compiler does not lift the load and re-creates
the problem.

Tested-by: Alexander Shishkin 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.040469884@infradead.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman