Impact: feature

This patch sets a C-like output for the function graph tracing.
For this aim, we now call two handler for each function: one on the entry
and one other on return. This way we can draw a well-ordered call stack.

The pid of the previous trace is loosely stored to be compared against
the one of the current trace to see if there were a context switch.

Without this little feature, the call tree would seem broken at
some locations.
We could use the sched_tracer to capture these sched_events but this
way of processing is much more simpler.

2 spaces have been chosen for indentation to fit the screen while deep
calls. The time of execution in nanosecs is printed just after closed
braces, it seems more easy this way to find the corresponding function.
If the time was printed as a first column, it would be not so easy to
find the corresponding function if it is called on a deep depth.

I plan to output the return value but on 32 bits CPU, the return value
can be 32 or 64, and its difficult to guess on which case we are.
I don't know what would be the better solution on X86-32: only print
eax (low-part) or even edx (high-part).

Actually it's thee same problem when a function return a 8 bits value, the
high part of eax could contain junk values...

Here is an example of trace:

sys_read() {
  fget_light() {
  } 526
  vfs_read() {
    rw_verify_area() {
      security_file_permission() {
        cap_file_permission() {
        } 519
      } 1564
    } 2640
    do_sync_read() {
      pipe_read() {
        __might_sleep() {
        } 511
        pipe_wait() {
          prepare_to_wait() {
          } 760
          deactivate_task() {
            dequeue_task() {
              dequeue_task_fair() {
                dequeue_entity() {
                  update_curr() {
                    update_min_vruntime() {
                    } 504
                  } 1587
                  clear_buddies() {
                  } 512
                  add_cfs_task_weight() {
                  } 519
                  update_min_vruntime() {
                  } 511
                } 5602
                dequeue_entity() {
                  update_curr() {
                    update_min_vruntime() {
                    } 496
                  } 1631
                  clear_buddies() {
                  } 496
                  update_min_vruntime() {
                  } 527
                } 4580
                hrtick_update() {
                  hrtick_start_fair() {
                  } 488
                } 1489
              } 13700
            } 14949
          } 16016
          msecs_to_jiffies() {
          } 496
          put_prev_task_fair() {
          } 504
          pick_next_task_fair() {
          } 489
          pick_next_task_rt() {
          } 496
          pick_next_task_fair() {
          } 489
          pick_next_task_idle() {
          } 489

------------8<---------- thread 4 ------------8<----------

finish_task_switch() {
} 1203
do_softirq() {
  __do_softirq() {
    __local_bh_disable() {
    } 669
    rcu_process_callbacks() {
      __rcu_process_callbacks() {
        cpu_quiet() {
          rcu_start_batch() {
          } 503
        } 1647
      } 3128
      __rcu_process_callbacks() {
      } 542
    } 5362
    _local_bh_enable() {
    } 587
  } 8880
} 9986
kthread_should_stop() {
} 669
deactivate_task() {
  dequeue_task() {
    dequeue_task_fair() {
      dequeue_entity() {
        update_curr() {
          calc_delta_mine() {
          } 511
          update_min_vruntime() {
          } 511
        } 2813
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

This patch changes the name of the "return function tracer" into
function-graph-tracer which is a more suitable name for a tracing
which makes one able to retrieve the ordered call stack during
the code flow.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: add new ftrace plugin

A prototype for a BTS ftrace plug-in.

The tracer collects branch trace in a cyclic buffer for each cpu.

The tracer is not configurable and the trace for each snapshot is
appended when doing cat /debug/tracing/trace.

This is a proof of concept that will be extended with future patches
to become a (hopefully) useful tool.
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add a callback to allow an ftrace plug-in to write its own header.

Move the call to trace->open() up a few lines.

The changes are required by the BTS ftrace plug-in.
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: restructure DS memory allocation to be done by the usage site of DS

Require pre-allocated buffers in ds.h.

Move the BTS buffer allocation for ptrace into ptrace.c.
The pointer to the allocated buffer is stored in the traced task's
task_struct together with the handle returned by ds_request_bts().

Removes memory accounting code.
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: generalize the DS code to shared buffers

Change the in-kernel ds.h interface to identify the tracer via a
handle returned on ds_request_~().

Tracers used to be identified via their task_struct.

The changes are required to allow DS to be shared between different
tasks, which is needed for perfmon2 and for ftrace.

For ptrace, the handle is stored in the traced task's task_struct.
This should probably go into a (arch-specific) ptrace context some
time.
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This pulls together all the topic branches that are needed
for the DS/BTS/PEBS tracing work.

Impact: fix sleeping-with-spinlock-held bugs/crashes

- Turn a wrmsr to write the DS_AREA MSR into a wrmsrl.
- Use irqsave variants of spinlocks.
- Do not allocate memory while holding spinlocks.
Reported-by: NStephane Eranian <eranian@googlemail.com>
Reported-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix DS hw enablement on 64-bit x86

Fix the PEBS record size in the DS configuration.
Reported-by: NStephane Eranian <eranian@googlemail.com>
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Replace a macro with a static inline function.
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Move the CONFIG guard from the .c file into the makefile.
Reported-by: NAndi Kleen <andi-suse@firstfloor.org>
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix theoretical option string parsing overflow

Since bridge is unsigned, it would seem better to use simple_strtoul that
simple_strtol.

A simplified version of the semantic patch that makes this change is as
follows: (http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@r2@
long e;
position p;
@@

e = simple_strtol@p(...)

@@
position p != r2.p;
type T;
T e;
@@

e =
- simple_strtol@p
+ simple_strtoul
  (...)
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Cc: muli@il.ibm.com
Cc: jdmason@kudzu.us
Cc: discuss@x86-64.org
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix with certain compilers

GCC can decide to use %dil when "r" is used, which is not valid for
setnz.

This bug was brought out by Stephen Rothwell's merging of the
branch tracer into linux-next.

[ Thanks to Uros Bizjak for recommending 'q' over 'Q' ]
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Stephen Rothwell reported tht this warning started triggering in
linux-next:

  In file included from init/main.c:27:
  include/linux/tty.h: In function ‘tty_kref_get’:
  include/linux/tty.h:330: warning: ‘______f’ is static but declared in inline function ‘tty_kref_get’ which is not static

Which gcc emits for 'extern inline' functions that nevertheless define
static variables. Change it to 'static inline', which is the norm
in the kernel anyway.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Merge branches 'tracing/branch-tracer', 'tracing/fastboot', 'tracing/ftrace', 'tracing/function-return-tracer', 'tracing/power-tracer', 'tracing/powerpc', 'tracing/ring-buffer', 'tracing/stack-tracer' and 'tracing/urgent' into tracing/core

Impact: use standard docbook tags
Reported-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NTörök Edwin <edwintorok@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: avoid losing some traces when a task is freed

do_exit() is not the last function called when a task finishes.
There are still some functions which are to be called such as
ree_task().  So we delay the freeing of the return stack to the
last moment.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: update documentation

Update to reflect the current state of the tracing framework:

 - "none" tracer has been replaced by "nop" tracer
 - tracing_enabled must be toggled when changing buffer size
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix mmiotrace overrun tracing

When ftrace framework moved to use the ring buffer facility, the buffer
overrun detection was broken after 2.6.27 by commit

| commit 3928a8a2
| Author: Steven Rostedt <rostedt@goodmis.org>
| Date:   Mon Sep 29 23:02:41 2008 -0400
|
|     ftrace: make work with new ring buffer
|
|     This patch ports ftrace over to the new ring buffer.

The detection is now fixed by using the ring buffer API.

When mmiotrace detects a buffer overrun, it will report the number of
lost events. People reading an mmiotrace log must know if something was
missed, otherwise the data may not make sense.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix a crash

While I killed the cat process, I got sometimes the following (but rare)
crash:

[   65.689027] Pid: 2969, comm: cat Not tainted (2.6.28-rc6-tip #83) AMILO Li 2727
[   65.689027] EIP: 0060:[<00000000>] EFLAGS: 00010082 CPU: 1
[   65.689027] EIP is at 0x0
[   65.689027] EAX: 00000000 EBX: f66cd780 ECX: c019a64a EDX: f66cd780
[   65.689027] ESI: 00000286 EDI: f66cd780 EBP: f630be2c ESP: f630be24
[   65.689027]  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
[   65.689027] Process cat (pid: 2969, ti=f630a000 task=f66cd780 task.ti=f630a000)
[   65.689027] Stack:
[   65.689027]  00000012 f630bd54 f630be7c c012c853 00000000 c0133cc9 f66cda54 f630be5c
[   65.689027]  f630be68 f66cda54 f66cd88c f66cd878 f7070000 00000001 f630be90 c0135dbc
[   65.689027]  f614a614 f630be68 f630be68 f65ba200 00000002 f630bf10 f630be90 c012cad6
[   65.689027] Call Trace:
[   65.689027]  [<c012c853>] ? do_exit+0x603/0x850
[   65.689027]  [<c0133cc9>] ? next_signal+0x9/0x40
[   65.689027]  [<c0135dbc>] ? dequeue_signal+0x8c/0x180
[   65.689027]  [<c012cad6>] ? do_group_exit+0x36/0x90
[   65.689027]  [<c013709c>] ? get_signal_to_deliver+0x20c/0x390
[   65.689027]  [<c0102b69>] ? do_notify_resume+0x99/0x8b0
[   65.689027]  [<c02e6d1a>] ? tty_ldisc_deref+0x5a/0x80
[   65.689027]  [<c014db9b>] ? trace_hardirqs_on+0xb/0x10
[   65.689027]  [<c02e6d1a>] ? tty_ldisc_deref+0x5a/0x80
[   65.689027]  [<c02e39b0>] ? n_tty_write+0x0/0x340
[   65.689027]  [<c02e1812>] ? redirected_tty_write+0x82/0x90
[   65.689027]  [<c019ee99>] ? vfs_write+0x99/0xd0
[   65.689027]  [<c02e1790>] ? redirected_tty_write+0x0/0x90
[   65.689027]  [<c019f342>] ? sys_write+0x42/0x70
[   65.689027]  [<c01035ca>] ? work_notifysig+0x13/0x19
[   65.689027] Code:  Bad EIP value.
[   65.689027] EIP: [<00000000>] 0x0 SS:ESP 0068:f630be24

This is because on do_exit(), kfree is called to free the return addresses stack
but kfree is traced and stored its return address in this stack.
This patch fixes it.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Merge branch 'ppc/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/powerpc

Impact: fix Xen guest boot failure

commit eefb47f6 ("xen: use
spin_lock_nest_lock when pinning a pagetable") changed xen_pgd_walk to
walk over mm->pgd rather than taking pgd as an argument.

This breaks xen_mm_(un)pin_all() because it makes init_mm.pgd readonly
instead of the pgd we are interested in and therefore the pin subsequently
fails.

(XEN) mm.c:2280:d15 Bad type (saw 00000000e8000001 != exp 0000000060000000) for mfn bc464 (pfn 21ca7)
(XEN) mm.c:2665:d15 Error while pinning mfn bc464

[   14.586913] 1 multicall(s) failed: cpu 0
[   14.586926] Pid: 14, comm: kstop/0 Not tainted 2.6.28-rc5-x86_32p-xenU-00172-gee2f6cc7 #200
[   14.586940] Call Trace:
[   14.586955]  [<c030c17a>] ? printk+0x18/0x1e
[   14.586972]  [<c0103df3>] xen_mc_flush+0x163/0x1d0
[   14.586986]  [<c0104bc1>] __xen_pgd_pin+0xa1/0x110
[   14.587000]  [<c015a330>] ? stop_cpu+0x0/0xf0
[   14.587015]  [<c0104d7b>] xen_mm_pin_all+0x4b/0x70
[   14.587029]  [<c022bcb9>] xen_suspend+0x39/0xe0
[   14.587042]  [<c015a330>] ? stop_cpu+0x0/0xf0
[   14.587054]  [<c015a3cd>] stop_cpu+0x9d/0xf0
[   14.587067]  [<c01417cd>] run_workqueue+0x8d/0x150
[   14.587080]  [<c030e4b3>] ? _spin_unlock_irqrestore+0x23/0x40
[   14.587094]  [<c014558a>] ? prepare_to_wait+0x3a/0x70
[   14.587107]  [<c0141918>] worker_thread+0x88/0xf0
[   14.587120]  [<c01453c0>] ? autoremove_wake_function+0x0/0x50
[   14.587133]  [<c0141890>] ? worker_thread+0x0/0xf0
[   14.587146]  [<c014509c>] kthread+0x3c/0x70
[   14.587157]  [<c0145060>] ? kthread+0x0/0x70
[   14.587170]  [<c0109d1b>] kernel_thread_helper+0x7/0x10
[   14.587181]   call  1/3: op=14 arg=[c0415000] result=0
[   14.587192]   call  2/3: op=14 arg=[e1ca2000] result=0
[   14.587204]   call  3/3: op=26 arg=[c1808860] result=-22
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Acked-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix race

vma->vm_file reference is only stable while holding the mmap_sem,
so move usage of it to within the critical section.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Merge branch 'oprofile-for-tip' of git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile into x86/urgent

Impact: fix MSIx not enough irq numbers available regression

The manual revert of the sparse_irq patches missed to bring the number
of possible irqs back to the .27 status. This resulted in a regression
when two multichannel network cards were placed in a system with only
one IO_APIC - causing the networking driver to not have the right
IRQ and the device not coming up.

Remove the dynamic allocation logic leftovers and simply return
NR_IRQS in probe_nr_irqs() for now.

   Fixes: http://lkml.org/lkml/2008/11/19/354Reported-by: NJesper Dangaard Brouer <hawk@diku.dk>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NJesper Dangaard Brouer <hawk@diku.dk>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

User stack tracing is just implemented for x86, but it is not x86 specific.

Introduce a generic config flag, that is currently enabled only for x86.
When other arches implement it, they will have to
SELECT USER_STACKTRACE_SUPPORT.
Signed-off-by: NTörök Edwin <edwintorok@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix refcounting/object-access bug

Hold mmap_sem while looking up/accessing vma.
Hold the RCU lock while using the task we looked up.
Signed-off-by: NTörök Edwin <edwintorok@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup
Signed-off-by: NTörök Edwin <edwintorok@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix compiler warning

The ftrace_pointers used in the branch profiler are constant values.
They should never change. But the compiler complains when they are
passed into the debugfs_create_file as a data pointer, because the
function discards the qualifier.

This patch typecasts the parameter to debugfs_create_file back to
a void pointer. To remind the callbacks that they are pointing to
a constant value, I also modified the callback local pointers to
be const struct ftrace_pointer * as well.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: add new API to disable all of ftrace on anomalies

It case of a serious anomaly being detected (like something caught by
lockdep) it is a good idea to disable all tracing immediately, without
grabing any locks.

This patch adds ftrace_off_permanent that disables the tracers, function
tracing and ring buffers without a way to enable them again. This should
only be used when something serious has been detected.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: feature to permanently disable ring buffer

This patch adds a API to the ring buffer code that will permanently
disable the ring buffer from ever recording. This should only be
called when some serious anomaly is detected, and the system
may be in an unstable state. When that happens, shutting down the
recording to the ring buffers may be appropriate.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: extend scripts/recordmcount.pl to ARM

Arm uses %progbits instead of @progbits and requires only 4 byte alignment.

[ Thanks to Sam Ravnborg for mentioning that ARM uses %progbits ]
Signed-off-by: NJim Radford <radford@galvanix.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: extend scripts/recordmcount.pl with default alignment for SH

Set $alignment=2 for the sh architecture so that a ".align 2" directive
will be emitted for all __mcount_loc sections. Fix a whitspace error
while I'm here (converted spaces to tabs).
Signed-off-by: NMatt Fleming <mjf@gentoo.org>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: feature to profile if statements

This patch adds a branch profiler for all if () statements.
The results will be found in:

  /debugfs/tracing/profile_branch

For example:

   miss      hit    %        Function                  File              Line
 ------- ---------  -        --------                  ----              ----
       0        1 100 x86_64_start_reservations      head64.c             127
       0        1 100 copy_bootdata                  head64.c             69
       1        0   0 x86_64_start_kernel            head64.c             111
      32        0   0 set_intr_gate                  desc.h               319
       1        0   0 reserve_ebda_region            head.c               51
       1        0   0 reserve_ebda_region            head.c               47
       0        1 100 reserve_ebda_region            head.c               42
       0        0   X maxcpus                        main.c               165

Miss means the branch was not taken. Hit means the branch was taken.
The percent is the percentage the branch was taken.

This adds a significant amount of overhead and should only be used
by those analyzing their system.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup on output of branch profiler

When a branch has not been taken, it does not make sense to show
a percentage incorrect or hit. This patch changes the behaviour
to print out a 'X' when the branch has not been executed yet.

For example:

 correct incorrect  %        Function                  File              Line
 ------- ---------  -        --------                  ----              ----
    2096        0   0 do_arch_prctl                  process_64.c         832
       0        0   X do_arch_prctl                  process_64.c         804
    2604        0   0 IS_ERR                         err.h                34
  130228     5765   4 __switch_to                    process_64.c         673
       0        0   X enable_TSC                     process_64.c         448
       0        0   X disable_TSC                    process_64.c         431
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: clean up to make one profiler of like and unlikely tracer

The likely and unlikely profiler prints out the file and line numbers
of the annotated branches that it is profiling. It shows the number
of times it was correct or incorrect in its guess. Having two
different files or sections for that matter to tell us if it was a
likely or unlikely is pretty pointless. We really only care if
it was correct or not.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: clean up of branch check

The unlikely/likely profiler does an extra assign of the f.line.
This is not needed since it is already calculated at compile time.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup of recordmcount.pl

Now that more architectures are being ported to the MCOUNT_RECORD
method, there is no reason to have each declare their own arch
specific variable if most of them share the same value. This patch
creates a set of default values for the arch specific variables
based off of i386.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: Add PowerPC port to recordmcount.pl script

This patch updates the recordmcount.pl script to process
PowerPC.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>