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  1. 21 1月, 2017 1 次提交
  3. 25 12月, 2016 1 次提交
  5. 16 11月, 2016 1 次提交
  7. 15 11月, 2016 3 次提交
  9. 02 9月, 2016 1 次提交
  11. 05 7月, 2016 1 次提交
  13. 20 6月, 2016 1 次提交
  15. 21 5月, 2016 1 次提交
    • S
      ftrace: Don't disable irqs when taking the tasklist_lock read_lock · 6112a300
      由 Soumya PN 提交于 
      In ftrace.c inside the function alloc_retstack_tasklist() (which will be
invoked when function_graph tracing is on) the tasklist_lock is being
held as reader while iterating through a list of threads. Here the lock
is being held as reader with irqs disabled. The tasklist_lock is never
write_locked in interrupt context so it is safe to not disable interrupts
for the duration of read_lock in this block which, can be significant,
given the block of code iterates through all threads. Hence changing the
code to call read_lock() and read_unlock() instead of read_lock_irqsave()
and read_unlock_irqrestore().

A similar change was made in commits: 8063e41d ("tracing: Change
syscall_*regfunc() to check PF_KTHREAD and use for_each_process_thread()")'
and 3472eaa1 ("sched: normalize_rt_tasks(): Don't use _irqsave for
tasklist_lock, use task_rq_lock()")'

Link: http://lkml.kernel.org/r/1463500874-77480-1-git-send-email-soumya.p.n@hpe.comSigned-off-by: NSoumya PN <soumya.p.n@hpe.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      6112a300
  17. 27 4月, 2016 1 次提交
    • T
      ftrace: Match dot symbols when searching functions on ppc64 · 7132e2d6
      由 Thiago Jung Bauermann 提交于 
      In the ppc64 big endian ABI, function symbols point to function
descriptors. The symbols which point to the function entry points
have a dot in front of the function name. Consequently, when the
ftrace filter mechanism searches for the symbol corresponding to
an entry point address, it gets the dot symbol.

As a result, ftrace filter users have to be aware of this ABI detail on
ppc64 and prepend a dot to the function name when setting the filter.

The perf probe command insulates the user from this by ignoring the dot
in front of the symbol name when matching function names to symbols,
but the sysfs interface does not. This patch makes the ftrace filter
mechanism do the same when searching symbols.

Fixes the following failure in ftracetest's kprobe_ftrace.tc:

  .../kprobe_ftrace.tc: line 9: echo: write error: Invalid argument

That failure is on this line of kprobe_ftrace.tc:

  echo _do_fork > set_ftrace_filter

This is because there's no _do_fork entry in the functions list:

  # cat available_filter_functions | grep _do_fork
  ._do_fork

This change introduces no regressions on the perf and ftracetest
testsuite results.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: NThiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      7132e2d6
  19. 14 4月, 2016 1 次提交
  21. 23 3月, 2016 1 次提交
  23. 18 3月, 2016 3 次提交
  25. 18 2月, 2016 1 次提交
  27. 08 1月, 2016 2 次提交
    • Q
      ftrace: Fix the race between ftrace and insmod · 5156dca3
      由 Qiu Peiyang 提交于 
      We hit ftrace_bug report when booting Android on a 64bit ATOM SOC chip.
Basically, there is a race between insmod and ftrace_run_update_code.

After load_module=>ftrace_module_init, another thread jumps in to call
ftrace_run_update_code=>ftrace_arch_code_modify_prepare
                        =>set_all_modules_text_rw, to change all modules
as RW. Since the new module is at MODULE_STATE_UNFORMED, the text attribute
is not changed. Then, the 2nd thread goes ahead to change codes.
However, load_module continues to call complete_formation=>set_section_ro_nx,
then 2nd thread would fail when probing the module's TEXT.

The patch fixes it by using notifier to delay the enabling of ftrace
records to the time when module is at state MODULE_STATE_COMING.

Link: http://lkml.kernel.org/r/567CE628.3000609@intel.comSigned-off-by: NQiu Peiyang <peiyangx.qiu@intel.com>
Signed-off-by: NZhang Yanmin <yanmin.zhang@intel.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      5156dca3
    • S
      ftrace: Add infrastructure for delayed enabling of module functions · b7ffffbb
      由 Steven Rostedt (Red Hat) 提交于 
      Qiu Peiyang pointed out that there's a race when enabling function tracing
and loading a module. In order to make the modifications of converting nops
in the prologue of functions into callbacks, the text needs to be converted
from read-only to read-write. When enabling function tracing, the text
permission is updated, the functions are modified, and then they are put
back.

When loading a module, the updates to convert function calls to mcount is
done before the module text is set to read-only. But after it is done, the
module text is visible by the function tracer. Thus we have the following
race:

	CPU 0			CPU 1
	-----			-----
   start function tracing
   set text to read-write
			     load_module
			     add functions to ftrace
			     set module text read-only

   update all functions to callbacks
   modify module functions too
   < Can't it's read-only >

When this happens, ftrace detects the issue and disables itself till the
next reboot.

To fix this, a new DISABLED flag is added for ftrace records, which all
module functions get when they are added. Then later, after the module code
is all set, the records will have the DISABLED flag cleared, and they will
be enabled if any callback wants all functions to be traced.

Note, this doesn't add the delay to later. It simply changes the
ftrace_module_init() to do both the setting of DISABLED records, and then
immediately calls the enable code. This helps with testing this new code as
it has the same behavior as previously. Another change will come after this
to have the ftrace_module_enable() called after the text is set to
read-only.

Cc: Qiu Peiyang <peiyangx.qiu@intel.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      b7ffffbb
  29. 24 12月, 2015 6 次提交
  31. 26 11月, 2015 3 次提交
    • S
      ftrace: Show all tramps registered to a record on ftrace_bug() · 39daa7b9
      由 Steven Rostedt (Red Hat) 提交于 
      When an anomaly is detected in the function call modification code,
ftrace_bug() is called to disable function tracing as well as give any
information that may help debug the problem. Currently, only the first found
trampoline that is attached to the failed record is reported. Instead, show
all trampolines that are hooked to it.

Also, not only show the ops pointer but also report the function it calls.

While at it, add this info to the enabled_functions debug file too.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      39daa7b9
    • S
      ftrace: Add variable ftrace_expected for archs to show expected code · b05086c7
      由 Steven Rostedt (Red Hat) 提交于 
      When an anomaly is found while modifying function code, ftrace_bug() is
called which disables the function tracing infrastructure and reports
information about what failed. If the code that is to be replaced does not
match what is expected, then actual code is shown. Currently there is no
arch generic way to show what was expected.

Add a new variable pointer calld ftrace_expected that the arch code can set
to point to what it expected so that ftrace_bug() can report the actual text
as well as the text that was expected to be there.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      b05086c7
    • S
      ftrace: Add new type to distinguish what kind of ftrace_bug() · 02a392a0
      由 Steven Rostedt (Red Hat) 提交于 
      The ftrace function hook utility has several internal checks to make sure
that whatever it modifies is exactly what it expects to be modifying. This
is essential as modifying running code can be extremely dangerous to the
system.

When an anomaly is detected, ftrace_bug() is called which sends a splat to
the console and disables function tracing. There's some extra information
that is printed to help diagnose the issue.

One thing that is missing though is output of what ftrace was doing at the
time of the crash. Was it updating a call site or perhaps converting a call
site to a nop? A new global enum variable is created to state what ftrace
was doing at the time of the anomaly, and this is reported in ftrace_bug().
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      02a392a0
  33. 21 10月, 2015 2 次提交
    • D
      ftrace: add module globbing · 0b507e1e
      由 Dmitry Safonov 提交于 
      Extend module command for function filter selection with globbing.
It uses the same globbing as function filter.

  sh# echo '*alloc*:mod:*' > set_ftrace_filter

Will trace any function with the letters 'alloc' in the name in any
module but not in kernel.

  sh# echo '!*alloc*:mod:ipv6' >> set_ftrace_filter

Will prevent from tracing functions with 'alloc' in the name from module
ipv6 (do not forget to append to set_ftrace_filter file).

  sh# echo '*alloc*:mod:!ipv6' > set_ftrace_filter

Will trace functions with 'alloc' in the name from kernel and any
module except ipv6.

  sh# echo '*alloc*:mod:!*' > set_ftrace_filter

Will trace any function with the letters 'alloc' in the name only from
kernel, but not from any module.

  sh# echo '*:mod:!*' > set_ftrace_filter
or
  sh# echo ':mod:!' > set_ftrace_filter

Will trace every function in the kernel, but will not trace functions
from any module.

  sh# echo '*:mod:*' > set_ftrace_filter
or
  sh# echo ':mod:' > set_ftrace_filter

As the opposite will trace all functions from all modules, but not from
kernel.

  sh# echo '*:mod:*snd*' > set_ftrace_filter

Will trace your sound drivers only (if any).

Link: http://lkml.kernel.org/r/1443545176-3215-4-git-send-email-0x7f454c46@gmail.comSigned-off-by: NDmitry Safonov <0x7f454c46@gmail.com>
[ Made format changes ]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      0b507e1e
    • D
      ftrace: Introduce ftrace_glob structure · 3ba00929
      由 Dmitry Safonov 提交于 
      ftrace_match parameters are very related and I reduce the number of local
variables & parameters with it.
This is also preparation for module globbing as it would introduce more
realated variables & parameters.

Link: http://lkml.kernel.org/r/1443545176-3215-3-git-send-email-0x7f454c46@gmail.comSigned-off-by: NDmitry Safonov <0x7f454c46@gmail.com>
[ Made some formatting changes ]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      3ba00929
  35. 16 10月, 2015 1 次提交
  37. 14 10月, 2015 1 次提交
  39. 06 10月, 2015 1 次提交
  41. 01 10月, 2015 2 次提交
  43. 25 7月, 2015 1 次提交
  45. 21 7月, 2015 1 次提交
  47. 03 4月, 2015 1 次提交
  49. 09 3月, 2015 2 次提交
    • S
      ftrace: Fix ftrace enable ordering of sysctl ftrace_enabled · 524a3868
      由 Steven Rostedt (Red Hat) 提交于 
      Some archs (specifically PowerPC), are sensitive with the ordering of
the enabling of the calls to function tracing and setting of the
function to use to be traced.

That is, update_ftrace_function() sets what function the ftrace_caller
trampoline should call. Some archs require this to be set before
calling ftrace_run_update_code().

Another bug was discovered, that ftrace_startup_sysctl() called
ftrace_run_update_code() directly. If the function the ftrace_caller
trampoline changes, then it will not be updated. Instead a call
to ftrace_startup_enable() should be called because it tests to see
if the callback changed since the code was disabled, and will
tell the arch to update appropriately. Most archs do not need this
notification, but PowerPC does.

The problem could be seen by the following commands:

 # echo 0 > /proc/sys/kernel/ftrace_enabled
 # echo function > /sys/kernel/debug/tracing/current_tracer
 # echo 1 > /proc/sys/kernel/ftrace_enabled
 # cat /sys/kernel/debug/tracing/trace

The trace will show that function tracing was not active.

Cc: stable@vger.kernel.org # 2.6.27+
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      524a3868
    • P
      ftrace: Fix en(dis)able graph caller when en(dis)abling record via sysctl · 1619dc3f
      由 Pratyush Anand 提交于 
      When ftrace is enabled globally through the proc interface, we must check if
ftrace_graph_active is set. If it is set, then we should also pass the
FTRACE_START_FUNC_RET command to ftrace_run_update_code(). Similarly, when
ftrace is disabled globally through the proc interface, we must check if
ftrace_graph_active is set. If it is set, then we should also pass the
FTRACE_STOP_FUNC_RET command to ftrace_run_update_code().

Consider the following situation.

 # echo 0 > /proc/sys/kernel/ftrace_enabled

After this ftrace_enabled = 0.

 # echo function_graph > /sys/kernel/debug/tracing/current_tracer

Since ftrace_enabled = 0, ftrace_enable_ftrace_graph_caller() is never
called.

 # echo 1 > /proc/sys/kernel/ftrace_enabled

Now ftrace_enabled will be set to true, but still
ftrace_enable_ftrace_graph_caller() will not be called, which is not
desired.

Further if we execute the following after this:
  # echo nop > /sys/kernel/debug/tracing/current_tracer

Now since ftrace_enabled is set it will call
ftrace_disable_ftrace_graph_caller(), which causes a kernel warning on
the ARM platform.

On the ARM platform, when ftrace_enable_ftrace_graph_caller() is called,
it checks whether the old instruction is a nop or not. If it's not a nop,
then it returns an error. If it is a nop then it replaces instruction at
that address with a branch to ftrace_graph_caller.
ftrace_disable_ftrace_graph_caller() behaves just the opposite. Therefore,
if generic ftrace code ever calls either ftrace_enable_ftrace_graph_caller()
or ftrace_disable_ftrace_graph_caller() consecutively two times in a row,
then it will return an error, which will cause the generic ftrace code to
raise a warning.

Note, x86 does not have an issue with this because the architecture
specific code for ftrace_enable_ftrace_graph_caller() and
ftrace_disable_ftrace_graph_caller() does not check the previous state,
and calling either of these functions twice in a row has no ill effect.

Link: http://lkml.kernel.org/r/e4fbe64cdac0dd0e86a3bf914b0f83c0b419f146.1425666454.git.panand@redhat.com

Cc: stable@vger.kernel.org # 2.6.31+
Signed-off-by: NPratyush Anand <panand@redhat.com>
[
  removed extra if (ftrace_start_up) and defined ftrace_graph_active as 0
  if CONFIG_FUNCTION_GRAPH_TRACER is not set.
]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      1619dc3f