linux-stable.git/kernel/trace/ftrace.c, branch v3.4.41

tracing: Fix double free when function profile init failed

2013-04-17T04:27:26+00:00

commit 83e03b3fe4daffdebbb42151d5410d730ae50bd1 upstream.

On the failure path, stat->start and stat->pages will refer same page.
So it'll attempt to free the same page again and get kernel panic.

Link: http://lkml.kernel.org/r/1364820385-32027-1-git-send-email-namhyung@kernel.org

Signed-off-by: Namhyung Kim 
Cc: Frederic Weisbecker 
Cc: Namhyung Kim 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

ftrace: Consistently restore trace function on sysctl enabling

2013-04-12T16:38:45+00:00

commit 5000c418840b309251c5887f0b56503aae30f84c upstream.

If we reenable ftrace via syctl, we currently set ftrace_trace_function
based on the previous simplistic algorithm. This is inconsistent with
what update_ftrace_function does. So better call that helper instead.

Link: http://lkml.kernel.org/r/5151D26F.1070702@siemens.com

Signed-off-by: Jan Kiszka 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix free of probe entry by calling call_rcu_sched()

2013-03-28T19:12:06+00:00

commit 740466bc89ad8bd5afcc8de220f715f62b21e365 upstream.

Because function tracing is very invasive, and can even trace
calls to rcu_read_lock(), RCU access in function tracing is done
with preempt_disable_notrace(). This requires a synchronize_sched()
for updates and not a synchronize_rcu().

Function probes (traceon, traceoff, etc) must be freed after
a synchronize_sched() after its entry has been removed from the
hash. But call_rcu() is used. Fix this by using call_rcu_sched().

Also fix the usage to use hlist_del_rcu() instead of hlist_del().

Signed-off-by: Steven Rostedt 
Cc: Paul McKenney 
Signed-off-by: Greg Kroah-Hartman

ftrace: Call ftrace cleanup module notifier after all other notifiers

2013-03-03T22:06:38+00:00

commit 8c189ea64eea01ca20d102ddb74d6936dd16c579 upstream.

Commit: c1bf08ac "ftrace: Be first to run code modification on modules"

changed ftrace module notifier's priority to INT_MAX in order to
process the ftrace nops before anything else could touch them
(namely kprobes). This was the correct thing to do.

Unfortunately, the ftrace module notifier also contains the ftrace
clean up code. As opposed to the set up code, this code should be
run *after* all the module notifiers have run in case a module is doing
correct clean-up and unregisters its ftrace hooks. Basically, ftrace
needs to do clean up on module removal, as it needs to know about code
being removed so that it doesn't try to modify that code. But after it
removes the module from its records, if a ftrace user tries to remove
a probe, that removal will fail due as the record of that code segment
no longer exists.

Nothing really bad happens if the probe removal is called after ftrace
did the clean up, but the ftrace removal function will return an error.
Correct code (such as kprobes) will produce a WARN_ON() if it fails
to remove the probe. As people get annoyed by frivolous warnings, it's
best to do the ftrace clean up after everything else.

By splitting the ftrace_module_notifier into two notifiers, one that
does the module load setup that is run at high priority, and the other
that is called for module clean up that is run at low priority, the
problem is solved.

Reported-by: Frank Ch. Eigler 
Acked-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

ftrace: Be first to run code modification on modules

2013-01-28T04:47:42+00:00

commit c1bf08ac26e92122faab9f6c32ea8aba94612dae upstream.

If some other kernel subsystem has a module notifier, and adds a kprobe
to a ftrace mcount point (now that kprobes work on ftrace points),
when the ftrace notifier runs it will fail and disable ftrace, as well
as kprobes that are attached to ftrace points.

Here's the error:

 WARNING: at kernel/trace/ftrace.c:1618 ftrace_bug+0x239/0x280()
 Hardware name: Bochs
 Modules linked in: fat(+) stap_56d28a51b3fe546293ca0700b10bcb29__8059(F) nfsv4 auth_rpcgss nfs dns_resolver fscache xt_nat iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack lockd sunrpc ppdev parport_pc parport microcode virtio_net i2c_piix4 drm_kms_helper ttm drm i2c_core [last unloaded: bid_shared]
 Pid: 8068, comm: modprobe Tainted: GF            3.7.0-0.rc8.git0.1.fc19.x86_64 #1
 Call Trace:
  [] warn_slowpath_common+0x7f/0xc0
  [] ? __probe_kernel_read+0x46/0x70
  [] ? 0xffffffffa017ffff
  [] ? 0xffffffffa017ffff
  [] warn_slowpath_null+0x1a/0x20
  [] ftrace_bug+0x239/0x280
  [] ftrace_process_locs+0x376/0x520
  [] ftrace_module_notify+0x47/0x50
  [] notifier_call_chain+0x4d/0x70
  [] __blocking_notifier_call_chain+0x58/0x80
  [] blocking_notifier_call_chain+0x16/0x20
  [] sys_init_module+0x73/0x220
  [] system_call_fastpath+0x16/0x1b
 ---[ end trace 9ef46351e53bbf80 ]---
 ftrace failed to modify [] init_once+0x0/0x20 [fat]
  actual: cc:bb:d2:4b:e1

A kprobe was added to the init_once() function in the fat module on load.
But this happened before ftrace could have touched the code. As ftrace
didn't run yet, the kprobe system had no idea it was a ftrace point and
simply added a breakpoint to the code (0xcc in the cc:bb:d2:4b:e1).

Then when ftrace went to modify the location from a call to mcount/fentry
into a nop, it didn't see a call op, but instead it saw the breakpoint op
and not knowing what to do with it, ftrace shut itself down.

The solution is to simply give the ftrace module notifier the max priority.
This should have been done regardless, as the core code ftrace modification
also happens very early on in boot up. This makes the module modification
closer to core modification.

Link: http://lkml.kernel.org/r/20130107140333.593683061@goodmis.org

Acked-by: Masami Hiramatsu 
Reported-by: Frank Ch. Eigler 
Signed-off-by: Steven Rostedt

ftrace: Clear bits properly in reset_iter_read()

2012-12-17T18:37:46+00:00

commit 70f77b3f7ec010ff9624c1f2e39a81babc9e2429 upstream.

There is a typo here where '&' is used instead of '|' and it turns the
statement into a noop.  The original code is equivalent to:

	iter->flags &= ~((1 << 2) & (1 << 4));

Link: http://lkml.kernel.org/r/20120609161027.GD6488@elgon.mountain

Signed-off-by: Dan Carpenter 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

ftrace: Fix function_graph for archs that test ftrace_trace_function

2012-03-13T19:07:37+00:00

When CONFIG_DYNAMIC_FTRACE is not set, some archs (ARM) test
the variable function_trace_function to determine if it should
call the function tracer. If it is not set to ftrace_stub, then
it will call the function and return, and not call the function
graph tracer.

But some of these archs (ARM) do not have the assembly code
to test if function tracing is enabled or not (quick stop of tracing)
and it calls the helper routine ftrace_test_stop_func() instead.

If function tracer is enabled and then disabled, the variable
ftrace_trace_function is still set to the helper routine
ftrace_test_stop_func(), and not to ftrace_stub. This will
prevent the function graph tracer from ever running.

Output before patch
/debug/tracing # echo function > current_tracer
/debug/tracing # echo function_graph > current_tracer
/debug/tracing # cat trace

Output after patch
/debug/tracing # echo function > current_tracer
/debug/tracing # echo function_graph > current_tracer
/debug/tracing # cat trace
0) ! 253.375 us | } /* irq_enter */
0) | generic_handle_irq() {
0) | handle_fasteoi_irq() {
0) 9.208 us | _raw_spin_lock();
0) | handle_irq_event() {
0) | handle_irq_event_percpu() {

Signed-off-by: Rajesh Bhagat 
Signed-off-by: Steven Rostedt

ftrace, perf: Add filter support for function trace event

2012-02-21T16:08:30+00:00

Adding support to filter function trace event via perf
interface. It is now possible to use filter interface
in the perf tool like:

  perf record -e ftrace:function --filter="(ip == mm_*)" ls

The filter syntax is restricted to the the 'ip' field only,
and following operators are accepted '==' '!=' '||', ending
up with the filter strings like:

  ip == f1[, ]f2 ... || ip != f3[, ]f4 ...

with comma ',' or space ' ' as a function separator. If the
space ' ' is used as a separator, the right side of the
assignment needs to be enclosed in double quotes '"', e.g.:

  perf record -e ftrace:function --filter '(ip == do_execve,sys_*,ext*)' ls
  perf record -e ftrace:function --filter '(ip == "do_execve,sys_*,ext*")' ls
  perf record -e ftrace:function --filter '(ip == "do_execve sys_* ext*")' ls

The '==' operator adds trace filter with same effect as would
be added via set_ftrace_filter file.

The '!=' operator adds trace filter with same effect as would
be added via set_ftrace_notrace file.

The right side of the '!=', '==' operators is list of functions
or regexp. to be added to filter separated by space.

The '||' operator is used for connecting multiple filter definitions
together. It is possible to have more than one '==' and '!='
operators within one filter string.

Link: http://lkml.kernel.org/r/1329317514-8131-8-git-send-email-jolsa@redhat.com

Signed-off-by: Jiri Olsa 
Signed-off-by: Steven Rostedt

ftrace: Add enable/disable ftrace_ops control interface

2012-02-21T16:08:23+00:00

Adding a way to temporarily enable/disable ftrace_ops. The change
follows the same way as 'global' ftrace_ops are done.

Introducing 2 global ftrace_ops - control_ops and ftrace_control_list
which take over all ftrace_ops registered with FTRACE_OPS_FL_CONTROL
flag. In addition new per cpu flag called 'disabled' is also added to
ftrace_ops to provide the control information for each cpu.

When ftrace_ops with FTRACE_OPS_FL_CONTROL is registered, it is
set as disabled for all cpus.

The ftrace_control_list contains all the registered 'control' ftrace_ops.
The control_ops provides function which iterates ftrace_control_list
and does the check for 'disabled' flag on current cpu.

Adding 3 inline functions:
  ftrace_function_local_disable/ftrace_function_local_enable
  - enable/disable the ftrace_ops on current cpu
  ftrace_function_local_disabled
  - get disabled ftrace_ops::disabled value for current cpu

Link: http://lkml.kernel.org/r/1329317514-8131-2-git-send-email-jolsa@redhat.com

Acked-by: Frederic Weisbecker 
Signed-off-by: Jiri Olsa 
Signed-off-by: Steven Rostedt

tracing/trivial: Use kcalloc instead of kzalloc to allocate array

2012-02-13T18:48:11+00:00

The advantage of kcalloc is, that will prevent integer overflows which could
result from the multiplication of number of elements and size and it is also
a bit nicer to read.

The semantic patch that makes this change is available
in https://lkml.org/lkml/2011/11/25/107

Link: http://lkml.kernel.org/r/1322600880.1534.347.camel@localhost.localdomain

Signed-off-by: Thomas Meyer 
Signed-off-by: Steven Rostedt