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  1. 07 May, 2012 1 commit
  3. 04 May, 2012 1 commit
  5. 28 Apr, 2012 2 commits
    • Steven Rostedt's avatar
      ftrace/x86: Remove the complex ftrace NMI handling code · 4a6d70c9
      Steven Rostedt authored 
      As ftrace function tracing would require modifying code that could
be executed in NMI context, which is not stopped with stop_machine(),
ftrace had to do a complex algorithm with various stages of setup
and memory barriers to make it work.

With the new breakpoint method, this is no longer required. The changes
to the code can be done without any problem in NMI context, as well as
without stop machine altogether. Remove the complex code as it is
no longer needed.

Also, a lot of the notrace annotations could be removed from the
NMI code as it is now safe to trace them. With the exception of
do_nmi itself, which does some special work to handle running in
the debug stack. The breakpoint method can cause NMIs to double
nest the debug stack if it's not setup properly, and that is done
in do_nmi(), thus that function must not be traced.

(Note the arch sh may want to do the same)

Cc: Paul Mundt <lethal@linux-sh.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      4a6d70c9
    • Steven Rostedt's avatar
      ftrace/x86: Have arch x86_64 use breakpoints instead of stop machine · 08d636b6
      Steven Rostedt authored 
      This method changes x86 to add a breakpoint to the mcount locations
instead of calling stop machine.

Now that iret can be handled by NMIs, we perform the following to
update code:

1) Add a breakpoint to all locations that will be modified

2) Sync all cores

3) Update all locations to be either a nop or call (except breakpoint
   op)

4) Sync all cores

5) Remove the breakpoint with the new code.

6) Sync all cores

[
  Added updates that Masami suggested:
   Use unlikely(modifying_ftrace_code) in int3 trap to keep kprobes efficient.
   Don't use NOTIFY_* in ftrace handler in int3 as it is not a notifier.
]

Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      08d636b6
  7. 27 Apr, 2012 1 commit
    • Ingo Molnar's avatar
      Merge tag 'perf-annotate-for-mingo' of... · 1fa2e84d
      Ingo Molnar authored 
      Merge tag 'perf-annotate-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Annotation improvements:

Now the default annotate browser uses a much more compact format, implementing
suggestions made made by several people, notably Linus.

Here is part of the new __list_del_entry() annotation:

__list_del_entry
    8.47 │      push   %rbp
    8.47 │      mov    (%rdi),%rdx
   20.34 │      mov    $0xdead000000100100,%rcx
    3.39 │      mov    0x8(%rdi),%rax
    0.00 │      mov    %rsp,%rbp
    1.69 │      cmp    %rcx,%rdx
    0.00 │      je     43
    1.69 │      mov    $0xdead000000200200,%rcx
    3.39 │      cmp    %rcx,%rax
    0.00 │      je     a3
    5.08 │      mov    (%rax),%r8
   18.64 │      cmp    %r8,%rdi
    0.00 │      jne    84
    1.69 │      mov    0x8(%rdx),%r8
   25.42 │      cmp    %r8,%rdi
    0.00 │      jne    65
    1.69 │      mov    %rax,0x8(%rdx)
    0.00 │      mov    %rdx,(%rax)
    0.00 │      leaveq
    0.00 │      retq
    0.00 │ 43:  mov    %rdx,%r8
    0.00 │      mov    %rdi,%rcx
    0.00 │      mov    $0xffffffff817cd6a8,%rdx
    0.00 │      mov    $0x31,%esi
    0.00 │      mov    $0xffffffff817cd6e0,%rdi
    0.00 │      xor    %eax,%eax
    0.00 │      callq  ffffffff8104eab0 <warn_slowpath_fmt>
    0.00 │      leaveq
    0.00 │      retq
    0.00 │ 65:  mov    %rdi,%rcx
    0.00 │      mov    $0xffffffff817cd780,%rdx
    0.00 │      mov    $0x3a,%esi
    0.00 │      mov    $0xffffffff817cd6e0,%rdi
    0.00 │      xor    %eax,%eax
    0.00 │      callq  ffffffff8104eab0 <warn_slowpath_fmt>
    0.00 │      leaveq
    0.00 │      retq

The infrastructure is there to provide formatters for any instruction,
like the one I'll do for call functions to elide the address.

Further fixes on top of the first iteration:

- Sometimes a jump points to an offset with no instructions, make the
  mark jump targets function handle that, for now just ignoring such
  jump targets, more investigation is needed to figure out how to cope
  with that.

- Handle jump targets that are outside the function, for now just don't
  try to draw the connector arrow, right thing seems to be to mark this
  jump with a -> (right arrow) and handle it like a callq.
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      1fa2e84d
  9. 26 Apr, 2012 4 commits
  11. 25 Apr, 2012 5 commits
  13. 24 Apr, 2012 4 commits
    • Arnaldo Carvalho de Melo's avatar
      perf annotate browser: Initial loop detection · a3f895be
      Arnaldo Carvalho de Melo authored 
      Simple algorithm, just look for the next backward jump that points to
before the cursor.

Then draw an arrow connecting the jump to its target.

Do this as you move the cursor, entering/exiting possible loops.

Ex (graph chars replaced to avoid mail encoding woes):

avc_has_perm_flags
    0.00 |         nopl   0x0(%rax)
    5.36 |+-> 68:  mov    (%rax),%rax
    5.15 ||        test   %rax,%rax
    0.00 ||      v je     130
    2.96 ||   74:  cmp    -0x20(%rax),%ebx
   47.38 ||        lea    -0x20(%rax),%rcx
    0.28 ||      ^ jne    68
    3.16 ||        cmp    -0x18(%rax),%dx
    0.00 |+------^ jne    68
    4.92 |         cmp    0x4(%rcx),%r13d
    0.00 |       v jne    68
    1.15 |         test   %rcx,%rcx
    0.00 |       v je     130
Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-5gairf6or7dazlx3ocxwvftm@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      a3f895be
    • Vaibhav Nagarnaik's avatar
      ring-buffer: Add per_cpu ring buffer control files · 438ced17
      Vaibhav Nagarnaik authored 
      Add a debugfs entry under per_cpu/ folder for each cpu called
buffer_size_kb to control the ring buffer size for each CPU
independently.

If the global file buffer_size_kb is used to set size, the individual
ring buffers will be adjusted to the given size. The buffer_size_kb will
report the common size to maintain backward compatibility.

If the buffer_size_kb file under the per_cpu/ directory is used to
change buffer size for a specific CPU, only the size of the respective
ring buffer is updated. When tracing/buffer_size_kb is read, it reports
'X' to indicate that sizes of per_cpu ring buffers are not equivalent.

Link: http://lkml.kernel.org/r/1328212844-11889-1-git-send-email-vnagarnaik@google.com

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Justin Teravest <teravest@google.com>
Signed-off-by: default avatarVaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      438ced17
    • Dan Carpenter's avatar
      tracing: Remove an unneeded check in trace_seq_buffer() · 5a26c8f0
      Dan Carpenter authored 
      memcpy() returns a pointer to "bug".  Hopefully, it's not NULL here or
we would already have Oopsed.

Link: http://lkml.kernel.org/r/20120420063145.GA22649@elgon.mountain

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      5a26c8f0
    • Steven Rostedt's avatar
      tracing: Add percpu buffers for trace_printk() · 07d777fe
      Steven Rostedt authored 
      Currently, trace_printk() uses a single buffer to write into
to calculate the size and format needed to save the trace. To
do this safely in an SMP environment, a spin_lock() is taken
to only allow one writer at a time to the buffer. But this could
also affect what is being traced, and add synchronization that
would not be there otherwise.

Ideally, using percpu buffers would be useful, but since trace_printk()
is only used in development, having per cpu buffers for something
never used is a waste of space. Thus, the use of the trace_bprintk()
format section is changed to be used for static fmts as well as dynamic ones.
Then at boot up, we can check if the section that holds the trace_printk
formats is non-empty, and if it does contain something, then we
know a trace_printk() has been added to the kernel. At this time
the trace_printk per cpu buffers are allocated. A check is also
done at module load time in case a module is added that contains a
trace_printk().

Once the buffers are allocated, they are never freed. If you use
a trace_printk() then you should know what you are doing.

A buffer is made for each type of context:

  normal
  softirq
  irq
  nmi

The context is checked and the appropriate buffer is used.
This allows for totally lockless usage of trace_printk(),
and they no longer even disable interrupts.
Requested-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      07d777fe
  15. 21 Apr, 2012 22 commits
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