linux-toradex.git/kernel/events/core.c, branch v4.19-rc5

perf/core: Force USER_DS when recording user stack data

2018-09-10T12:01:46+00:00

Perf can record user stack data in response to a synchronous request, such
as a tracepoint firing. If this happens under set_fs(KERNEL_DS), then we
end up reading user stack data using __copy_from_user_inatomic() under
set_fs(KERNEL_DS). I think this conflicts with the intention of using
set_fs(KERNEL_DS). And it is explicitly forbidden by hardware on ARM64
when both CONFIG_ARM64_UAO and CONFIG_ARM64_PAN are used.

So fix this by forcing USER_DS when recording user stack data.

Signed-off-by: Yabin Cui 
Acked-by: Peter Zijlstra (Intel) 
Cc: 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: 88b0193d9418 ("perf/callchain: Force USER_DS when invoking perf_callchain_user()")
Link: http://lkml.kernel.org/r/20180823225935.27035-1-yabinc@google.com
Signed-off-by: Ingo Molnar

Merge tag 'perf-urgent-for-mingo-4.19-20180903' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/urgent

2018-09-09T19:36:31+00:00

Pull perf/urgent fixes from Arnaldo Carvalho de Melo:

Kernel:

- Modify breakpoint fixes (Jiri Olsa)

perf annotate:

- Fix parsing aarch64 branch instructions after objdump update (Kim Phillips)

- Fix parsing indirect calls in 'perf annotate' (Martin Liška)

perf probe:

- Ignore SyS symbols irrespective of endianness on PowerPC (Sandipan Das)

perf trace:

- Fix include path for asm-generic/unistd.h on arm64 (Kim Phillips)

Core libraries:

- Fix potential null pointer dereference in perf_evsel__new_idx() (Hisao Tanabe)

- Use fixed size string for comms instead of scanf("%m"), that is
  not present in the bionic libc and leads to a crash (Chris Phlipot)

- Fix bad memory access in trace info on 32-bit systems, we were reading
  8 bytes from a 4-byte long variable when saving the command line in the
  perf.data file.  (Chris Phlipot)

Build system:

- Streamline bpf examples and headers installation, clarifying
  some install messages. (Arnaldo Carvalho de Melo)

Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Ingo Molnar

perf/hw_breakpoint: Simplify breakpoint enable in perf_event_modify_breakpoint

2018-08-30T17:49:24+00:00

We can safely enable the breakpoint back for both the fail and success
paths by checking only the bp->attr.disabled, which either holds the new
'requested' disabled state or the original breakpoint state.

Committer testing:

At the end of the series, the 'perf test' entry introduced as the first
patch now runs to completion without finding the fixed issues:

  # perf test "bp modify"
  62: x86 bp modify                                         : Ok
  #

In verbose mode:

  # perf test -v "bp modify"
  62: x86 bp modify                                         :
  --- start ---
  test child forked, pid 5161
  rip 5950a0, bp_1 0x5950a0
  in bp_1
  rip 5950a0, bp_1 0x5950a0
  in bp_1
  test child finished with 0
  ---- end ----
  x86 bp modify: Ok

Suggested-by: Oleg Nesterov 
Acked-by: Oleg Nesterov 
Signed-off-by: Jiri Olsa 
Tested-by: Arnaldo Carvalho de Melo 
Cc: Alexander Shishkin 
Cc: David Ahern 
Cc: Milind Chabbi 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20180827091228.2878-6-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2018-08-21T20:47:29+00:00

Pull core signal handling updates from Eric Biederman:
 "It was observed that a periodic timer in combination with a
  sufficiently expensive fork could prevent fork from every completing.
  This contains the changes to remove the need for that restart.

  This set of changes is split into several parts:

   - The first part makes PIDTYPE_TGID a proper pid type instead
     something only for very special cases. The part starts using
     PIDTYPE_TGID enough so that in __send_signal where signals are
     actually delivered we know if the signal is being sent to a a group
     of processes or just a single process.

   - With that prep work out of the way the logic in fork is modified so
     that fork logically makes signals received while it is running
     appear to be received after the fork completes"

* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (22 commits)
  signal: Don't send signals to tasks that don't exist
  signal: Don't restart fork when signals come in.
  fork: Have new threads join on-going signal group stops
  fork: Skip setting TIF_SIGPENDING in ptrace_init_task
  signal: Add calculate_sigpending()
  fork: Unconditionally exit if a fatal signal is pending
  fork: Move and describe why the code examines PIDNS_ADDING
  signal: Push pid type down into complete_signal.
  signal: Push pid type down into __send_signal
  signal: Push pid type down into send_signal
  signal: Pass pid type into do_send_sig_info
  signal: Pass pid type into send_sigio_to_task & send_sigurg_to_task
  signal: Pass pid type into group_send_sig_info
  signal: Pass pid and pid type into send_sigqueue
  posix-timers: Noralize good_sigevent
  signal: Use PIDTYPE_TGID to clearly store where file signals will be sent
  pid: Implement PIDTYPE_TGID
  pids: Move the pgrp and session pid pointers from task_struct to signal_struct
  kvm: Don't open code task_pid in kvm_vcpu_ioctl
  pids: Compute task_tgid using signal->leader_pid
  ...

Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2018-08-14T23:39:13+00:00

Pull arm64 updates from Will Deacon:
 "A bunch of good stuff in here. Worth noting is that we've pulled in
  the x86/mm branch from -tip so that we can make use of the core
  ioremap changes which allow us to put down huge mappings in the
  vmalloc area without screwing up the TLB. Much of the positive
  diffstat is because of the rseq selftest for arm64.

  Summary:

   - Wire up support for qspinlock, replacing our trusty ticket lock
     code

   - Add an IPI to flush_icache_range() to ensure that stale
     instructions fetched into the pipeline are discarded along with the
     I-cache lines

   - Support for the GCC "stackleak" plugin

   - Support for restartable sequences, plus an arm64 port for the
     selftest

   - Kexec/kdump support on systems booting with ACPI

   - Rewrite of our syscall entry code in C, which allows us to zero the
     GPRs on entry from userspace

   - Support for chained PMU counters, allowing 64-bit event counters to
     be constructed on current CPUs

   - Ensure scheduler topology information is kept up-to-date with CPU
     hotplug events

   - Re-enable support for huge vmalloc/IO mappings now that the core
     code has the correct hooks to use break-before-make sequences

   - Miscellaneous, non-critical fixes and cleanups"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (90 commits)
  arm64: alternative: Use true and false for boolean values
  arm64: kexec: Add comment to explain use of __flush_icache_range()
  arm64: sdei: Mark sdei stack helper functions as static
  arm64, kaslr: export offset in VMCOREINFO ELF notes
  arm64: perf: Add cap_user_time aarch64
  efi/libstub: Only disable stackleak plugin for arm64
  arm64: drop unused kernel_neon_begin_partial() macro
  arm64: kexec: machine_kexec should call __flush_icache_range
  arm64: svc: Ensure hardirq tracing is updated before return
  arm64: mm: Export __sync_icache_dcache() for xen-privcmd
  drivers/perf: arm-ccn: Use devm_ioremap_resource() to map memory
  arm64: Add support for STACKLEAK gcc plugin
  arm64: Add stack information to on_accessible_stack
  drivers/perf: hisi: update the sccl_id/ccl_id when MT is supported
  arm64: fix ACPI dependencies
  rseq/selftests: Add support for arm64
  arm64: acpi: fix alignment fault in accessing ACPI
  efi/arm: map UEFI memory map even w/o runtime services enabled
  efi/arm: preserve early mapping of UEFI memory map longer for BGRT
  drivers: acpi: add dependency of EFI for arm64
  ...

arm64: perf: Add cap_user_time aarch64

2018-07-31T09:14:00+00:00

It is useful to get the running time of a thread.  Doing so in an
efficient manner can be important for performance of user applications.
Avoiding system calls in `clock_gettime` when handling
CLOCK_THREAD_CPUTIME_ID is important.  Other clocks are handled in the
VDSO, but CLOCK_THREAD_CPUTIME_ID falls back on the system call.

CLOCK_THREAD_CPUTIME_ID is not handled in the VDSO since it would have
costs associated with maintaining updated user space accessible time
offsets.  These offsets have to be updated everytime the a thread is
scheduled/descheduled.  However, for programs regularly checking the
running time of a thread, this is a performance improvement.

This patch takes a middle ground, and adds support for cap_user_time an
optional feature of the perf_event API.  This way costs are only
incurred when the perf_event api is enabled.  This is done the same way
as it is in x86.

Ultimately this allows calculating the thread running time in userspace
on aarch64 as follows (adapted from perf_event_open manpage):

u32 seq, time_mult, time_shift;
u64 running, count, time_offset, quot, rem, delta;
struct perf_event_mmap_page *pc;
pc = buf;  // buf is the perf event mmaped page as documented in the API.

if (pc->cap_usr_time) {
    do {
        seq = pc->lock;
        barrier();
        running = pc->time_running;

        count = readCNTVCT_EL0();  // Read ARM hardware clock.
        time_offset = pc->time_offset;
        time_mult   = pc->time_mult;
        time_shift  = pc->time_shift;

        barrier();
    } while (pc->lock != seq);

    quot = (count >> time_shift);
    rem = count & (((u64)1 << time_shift) - 1);
    delta = time_offset + quot * time_mult +
            ((rem * time_mult) >> time_shift);

    running += delta;
    // running now has the current nanosecond level thread time.
}

Summary of changes in the patch:

For aarch64 systems, make arch_perf_update_userpage update the timing
information stored in the perf_event page.  Requiring the following
calculations:
  - Calculate the appropriate time_mult, and time_shift factors to convert
    ticks to nano seconds for the current clock frequency.
  - Adjust the mult and shift factors to avoid shift factors of 32 bits.
    (possibly unnecessary)
  - The time_offset userspace should apply when doing calculations:
    negative the current sched time (now), because time_running and
    time_enabled fields of the perf_event page have just been updated.
Toggle bits to appropriate values:
  - Enable cap_user_time

Signed-off-by: Michael O'Farrell 
Signed-off-by: Will Deacon

Merge branch 'perf/urgent' into perf/core, to pick up fixes

2018-07-25T09:47:02+00:00

Signed-off-by: Ingo Molnar

perf/core: Fix crash when using HW tracing kernel filters

2018-07-25T09:46:22+00:00

In function perf_event_parse_addr_filter(), the path::dentry of each struct
perf_addr_filter is left unassigned (as it should be) when the pattern
being parsed is related to kernel space.  But in function
perf_addr_filter_match() the same dentries are given to d_inode() where
the value is not expected to be NULL, resulting in the following splat:

  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000058
  pc : perf_event_mmap+0x2fc/0x5a0
  lr : perf_event_mmap+0x2c8/0x5a0
  Process uname (pid: 2860, stack limit = 0x000000001cbcca37)
  Call trace:
   perf_event_mmap+0x2fc/0x5a0
   mmap_region+0x124/0x570
   do_mmap+0x344/0x4f8
   vm_mmap_pgoff+0xe4/0x110
   vm_mmap+0x2c/0x40
   elf_map+0x60/0x108
   load_elf_binary+0x450/0x12c4
   search_binary_handler+0x90/0x290
   __do_execve_file.isra.13+0x6e4/0x858
   sys_execve+0x3c/0x50
   el0_svc_naked+0x30/0x34

This patch is fixing the problem by introducing a new check in function
perf_addr_filter_match() to see if the filter's dentry is NULL.

Signed-off-by: Mathieu Poirier 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Cc: acme@kernel.org
Cc: miklos@szeredi.hu
Cc: namhyung@kernel.org
Cc: songliubraving@fb.com
Fixes: 9511bce9fe8e ("perf/core: Fix bad use of igrab()")
Link: http://lkml.kernel.org/r/1531782831-1186-1-git-send-email-mathieu.poirier@linaro.org
Signed-off-by: Ingo Molnar

perf/x86/intel: Fix unwind errors from PEBS entries (mk-II)

2018-07-25T09:46:21+00:00

Vince reported the perf_fuzzer giving various unwinder warnings and
Josh reported:

> Deja vu.  Most of these are related to perf PEBS, similar to the
> following issue:
>
>   b8000586c90b ("perf/x86/intel: Cure bogus unwind from PEBS entries")
>
> This is basically the ORC version of that.  setup_pebs_sample_data() is
> assembling a franken-pt_regs which ORC isn't happy about.  RIP is
> inconsistent with some of the other registers (like RSP and RBP).

And where the previous unwinder only needed BP,SP ORC also requires
IP. But we cannot spoof IP because then the sample will get displaced,
entirely negating the point of PEBS.

So cure the whole thing differently by doing the unwind early; this
does however require a means to communicate we did the unwind early.
We (ab)use an unused sample_type bit for this, which we set on events
that fill out the data->callchain before the normal
perf_prepare_sample().

Debugged-by: Josh Poimboeuf 
Reported-by: Vince Weaver 
Tested-by: Josh Poimboeuf 
Tested-by: Prashant Bhole 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Signed-off-by: Ingo Molnar

pid: Implement PIDTYPE_TGID

2018-07-21T15:43:12+00:00

Everywhere except in the pid array we distinguish between a tasks pid and
a tasks tgid (thread group id).  Even in the enumeration we want that
distinction sometimes so we have added __PIDTYPE_TGID.  With leader_pid
we almost have an implementation of PIDTYPE_TGID in struct signal_struct.

Add PIDTYPE_TGID as a first class member of the pid_type enumeration and
into the pids array.  Then remove the __PIDTYPE_TGID special case and the
leader_pid in signal_struct.

The net size increase is just an extra pointer added to struct pid and
an extra pair of pointers of an hlist_node added to task_struct.

The effect on code maintenance is the removal of a number of special
cases today and the potential to remove many more special cases as
PIDTYPE_TGID gets used to it's fullest.  The long term potential
is allowing zombie thread group leaders to exit, which will remove
a lot more special cases in the code.

Signed-off-by: "Eric W. Biederman"