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commit 613f04a0f51e6e68ac6fe571ab79da3c0a5eb4da upstream.
The latency tracers require the buffers to be in overwrite mode,
otherwise they get screwed up. Force the buffers to stay in overwrite
mode when latency tracers are enabled.
Added a flag_changed() method to the tracer structure to allow
the tracers to see what flags are being changed, and also be able
to prevent the change from happing.
[Backported for 3.4-stable. Re-added current_trace NULL checks; removed
allocated_snapshot field; adapted to tracing_trace_options_write without
trace_set_options.]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Lingzhu Xiang <lxiang@redhat.com>
Reviewed-by: CAI Qian <caiqian@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 69d34da2984c95b33ea21518227e1f9470f11d95 upstream.
Seems that the tracer flags have never been protected from
synchronous writes. Luckily, admins don't usually modify the
tracing flags via two different tasks. But if scripts were to
be used to modify them, then they could get corrupted.
Move the trace_types_lock that protects against tracers changing
to also protect the flags being set.
[Backported for 3.4, 3.0-stable. Moved return to after unlock.]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Lingzhu Xiang <lxiang@redhat.com>
Reviewed-by: CAI Qian <caiqian@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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 <rostedt@goodmis.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 2721e72dd10f71a3ba90f59781becf02638aa0d9 upstream.
Although the swap is wrapped with a spin_lock, the assignment
of the temp buffer used to swap is not within that lock.
It needs to be moved into that lock, otherwise two swaps
happening on two different CPUs, can end up using the wrong
temp buffer to assign in the swap.
Luckily, all current callers of the swap function appear to have
their own locks. But in case something is added that allows two
different callers to call the swap, then there's a chance that
this race can trigger and corrupt the buffers.
New code is coming soon that will allow for this race to trigger.
I've Cc'd stable, so this bug will not show up if someone backports
one of the changes that can trigger this bug.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit db05021d49a994ee40a9735d9c3cb0060c9babb8 upstream.
The prompt to enable DYNAMIC_FTRACE (the ability to nop and
enable function tracing at run time) had a confusing statement:
"enable/disable ftrace tracepoints dynamically"
This was written before tracepoints were added to the kernel,
but now that tracepoints have been added, this is very confusing
and has confused people enough to give wrong information during
presentations.
Not only that, I looked at the help text, and it still references
that dreaded daemon that use to wake up once a second to update
the nop locations and brick NICs, that hasn't been around for over
five years.
Time to bring the text up to the current decade.
Reported-by: Ezequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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 <fche@redhat.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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:
[<ffffffff8105e70f>] warn_slowpath_common+0x7f/0xc0
[<ffffffff81134106>] ? __probe_kernel_read+0x46/0x70
[<ffffffffa0180000>] ? 0xffffffffa017ffff
[<ffffffffa0180000>] ? 0xffffffffa017ffff
[<ffffffff8105e76a>] warn_slowpath_null+0x1a/0x20
[<ffffffff810fd189>] ftrace_bug+0x239/0x280
[<ffffffff810fd626>] ftrace_process_locs+0x376/0x520
[<ffffffff810fefb7>] ftrace_module_notify+0x47/0x50
[<ffffffff8163912d>] notifier_call_chain+0x4d/0x70
[<ffffffff810882f8>] __blocking_notifier_call_chain+0x58/0x80
[<ffffffff81088336>] blocking_notifier_call_chain+0x16/0x20
[<ffffffff810c2a23>] sys_init_module+0x73/0x220
[<ffffffff8163d719>] system_call_fastpath+0x16/0x1b
---[ end trace 9ef46351e53bbf80 ]---
ftrace failed to modify [<ffffffffa0180000>] 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 <masami.hiramatsu.pt@hitachi.com>
Reported-by: Frank Ch. Eigler <fche@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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commit 9366c1ba13fbc41bdb57702e75ca4382f209c82f upstream.
The function rb_check_pages() was added to make sure the ring buffer's
pages were sane. This check is done when the ring buffer size is modified
as well as when the iterator is released (closing the "trace" file),
as that was considered a non fast path and a good place to do a sanity
check.
The problem is that the check does not have any locks around it.
If one process were to read the trace file, and another were to read
the raw binary file, the check could happen while the reader is reading
the file.
The issues with this is that the check requires to clear the HEAD page
before doing the full check and it restores it afterward. But readers
require the HEAD page to exist before it can read the buffer, otherwise
it gives a nasty warning and disables the buffer.
By adding the reader lock around the check, this keeps the race from
happening.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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 <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 71babb2705e2203a64c27ede13ae3508a0d2c16c upstream.
According to Documentation/trace/ftrace.txt:
tracing_cpumask:
This is a mask that lets the user only trace
on specified CPUS. The format is a hex string
representing the CPUS.
The tracing_cpumask currently doesn't affect the tracing state of
per-CPU ring buffers.
This patch enables/disables CPU recording as its corresponding bit in
tracing_cpumask is set/unset.
Link: http://lkml.kernel.org/r/1336096792-25373-3-git-send-email-vnagarnaik@google.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Laurent Chavey <chavey@google.com>
Cc: Justin Teravest <teravest@google.com>
Cc: David Sharp <dhsharp@google.com>
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 01de982abf8c9e10fc3089e10585cd2cc914bdab upstream.
8 hex characters tell only half the tale for 64 bit CPUs,
so use the appropriate length.
Link: http://lkml.kernel.org/r/1332411501-8059-2-git-send-email-wolfgang.mauerer@siemens.com
Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 30fb6aa74011dcf595f306ca2727254d708b786e upstream.
Multiple users of the function tracer can register their functions
with the ftrace_ops structure. The accounting within ftrace will
update the counter on each function record that is being traced.
When the ftrace_ops filtering adds or removes functions, the
function records will be updated accordingly if the ftrace_ops is
still registered.
When a ftrace_ops is removed, the counter of the function records,
that the ftrace_ops traces, are decremented. When they reach zero
the functions that they represent are modified to stop calling the
mcount code.
When changes are made, the code is updated via stop_machine() with
a command passed to the function to tell it what to do. There is an
ENABLE and DISABLE command that tells the called function to enable
or disable the functions. But the ENABLE is really a misnomer as it
should just update the records, as records that have been enabled
and now have a count of zero should be disabled.
The DISABLE command is used to disable all functions regardless of
their counter values. This is the big off switch and is not the
complement of the ENABLE command.
To make matters worse, when a ftrace_ops is unregistered and there
is another ftrace_ops registered, neither the DISABLE nor the
ENABLE command are set when calling into the stop_machine() function
and the records will not be updated to match their counter. A command
is passed to that function that will update the mcount code to call
the registered callback directly if it is the only one left. This
means that the ftrace_ops that is still registered will have its callback
called by all functions that have been set for it as well as the ftrace_ops
that was just unregistered.
Here's a way to trigger this bug. Compile the kernel with
CONFIG_FUNCTION_PROFILER set and with CONFIG_FUNCTION_GRAPH not set:
CONFIG_FUNCTION_PROFILER=y
# CONFIG_FUNCTION_GRAPH is not set
This will force the function profiler to use the function tracer instead
of the function graph tracer.
# cd /sys/kernel/debug/tracing
# echo schedule > set_ftrace_filter
# echo function > current_tracer
# cat set_ftrace_filter
schedule
# cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 692/68108025 #P:4
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
kworker/0:2-909 [000] .... 531.235574: schedule <-worker_thread
<idle>-0 [001] .N.. 531.235575: schedule <-cpu_idle
kworker/0:2-909 [000] .... 531.235597: schedule <-worker_thread
sshd-2563 [001] .... 531.235647: schedule <-schedule_hrtimeout_range_clock
# echo 1 > function_profile_enabled
# echo 0 > function_porfile_enabled
# cat set_ftrace_filter
schedule
# cat trace
# tracer: function
#
# entries-in-buffer/entries-written: 159701/118821262 #P:4
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
<idle>-0 [002] ...1 604.870655: local_touch_nmi <-cpu_idle
<idle>-0 [002] d..1 604.870655: enter_idle <-cpu_idle
<idle>-0 [002] d..1 604.870656: atomic_notifier_call_chain <-enter_idle
<idle>-0 [002] d..1 604.870656: __atomic_notifier_call_chain <-atomic_notifier_call_chain
The same problem could have happened with the trace_probe_ops,
but they are modified with the set_frace_filter file which does the
update at closure of the file.
The simple solution is to change ENABLE to UPDATE and call it every
time an ftrace_ops is unregistered.
Link: http://lkml.kernel.org/r/1323105776-26961-3-git-send-email-jolsa@redhat.com
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 072126f4529196f71a97960248bca54fd4554c2d upstream.
Currently, if set_ftrace_filter() is called when the ftrace_ops is
active, the function filters will not be updated. They will only be updated
when tracing is disabled and re-enabled.
Update the functions immediately during set_ftrace_filter().
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 41fb61c2d08107ce96a5dcb3a6289b2afd3e135c upstream.
Whenever the hash of the ftrace_ops is updated, the record counts
must be balance. This requires disabling the records that are set
in the original hash, and then enabling the records that are set
in the updated hash.
Moving the update into ftrace_hash_move() removes the bug where the
hash was updated but the records were not, which results in ftrace
triggering a warning and disabling itself because the ftrace_ops filter
is updated while the ftrace_ops was registered, and then the failure
happens when the ftrace_ops is unregistered.
The current code will not trigger this bug, but new code will.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit cb59974742aea24adf6637eb0c4b8e7b48bca6fb upstream.
Fix a bug introduced by e9dbfae5, which prevents event_subsystem from
ever being released.
Ref_count was added to keep track of subsystem users, not for counting
events. Subsystem is created with ref_count = 1, so there is no need to
increment it for every event, we have nr_events for that. Fix this by
touching ref_count only when we actually have a new user -
subsystem_open().
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Link: http://lkml.kernel.org/r/1320052062-7846-1-git-send-email-idryomov@gmail.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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ftrace_event_call->filter
commit d3d9acf646679c1981032b0985b386d12fccc60c upstream.
ftrace_event_call->filter is sched RCU protected but didn't use
rcu_assign_pointer(). Use it.
TODO: Add proper __rcu annotation to call->filter and all its users.
-v2: Use RCU_INIT_POINTER() for %NULL clearing as suggested by Eric.
Link: http://lkml.kernel.org/r/20111123164949.GA29639@google.com
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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commit 436fc280261dcfce5af38f08b89287750dc91cd2 upstream.
The trace_pipe_raw handler holds a cached page from the time the file
is opened to the time it is closed. The cached page is used to handle
the case of the user space buffer being smaller than what was read from
the ring buffer. The left over buffer is held in the cache so that the
next read will continue where the data left off.
After EOF is returned (no more data in the buffer), the index of
the cached page is set to zero. If a user app reads the page again
after EOF, the check in the buffer will see that the cached page
is less than page size and will return the cached page again. This
will cause reading the trace_pipe_raw again after EOF to return
duplicate data, making the output look like the time went backwards
but instead data is just repeated.
The fix is to not reset the index right after all data is read
from the cache, but to reset it after all data is read and more
data exists in the ring buffer.
Reported-by: Jeremy Eder <jeder@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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commit f7bc8b61f65726ff98f52e286b28e294499d7a08 upstream.
Enabling function tracer to trace all functions, then load a module and
then disable function tracing will cause ftrace to fail.
This can also happen by enabling function tracing on the command line:
ftrace=function
and during boot up, modules are loaded, then you disable function tracing
with 'echo nop > current_tracer' you will trigger a bug in ftrace that
will shut itself down.
The reason is, the new ftrace code keeps ref counts of all ftrace_ops that
are registered for tracing. When one or more ftrace_ops are registered,
all the records that represent the functions that the ftrace_ops will
trace have a ref count incremented. If this ref count is not zero,
when the code modification runs, that function will be enabled for tracing.
If the ref count is zero, that function will be disabled from tracing.
To make sure the accounting was working, FTRACE_WARN_ON()s were added
to updating of the ref counts.
If the ref count hits its max (> 2^30 ftrace_ops added), or if
the ref count goes below zero, a FTRACE_WARN_ON() is triggered which
disables all modification of code.
Since it is common for ftrace_ops to trace all functions in the kernel,
instead of creating > 20,000 hash items for the ftrace_ops, the hash
count is just set to zero, and it represents that the ftrace_ops is
to trace all functions. This is where the issues arrise.
If you enable function tracing to trace all functions, and then add
a module, the modules function records do not get the ref count updated.
When the function tracer is disabled, all function records ref counts
are subtracted. Since the modules never had their ref counts incremented,
they go below zero and the FTRACE_WARN_ON() is triggered.
The solution to this is rather simple. When modules are loaded, and
their functions are added to the the ftrace pool, look to see if any
ftrace_ops are registered that trace all functions. And for those,
update the ref count for the module function records.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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commit 43dd61c9a09bd413e837df829e6bfb42159be52a upstream.
The new code that allows different utilities to pick and choose
what functions they trace broke the :mod: hook that allows users
to trace only functions of a particular module.
The reason is that the :mod: hook bypasses the hash that is setup
to allow individual users to trace their own functions and uses
the global hash directly. But if the global hash has not been
set up, it will cause a bug:
echo '*:mod:radeon' > /sys/kernel/debug/set_ftrace_filter
produces:
[drm:drm_mode_getfb] *ERROR* invalid framebuffer id
[drm:radeon_crtc_page_flip] *ERROR* failed to reserve new rbo buffer before flip
BUG: unable to handle kernel paging request at ffffffff8160ec90
IP: [<ffffffff810d9136>] add_hash_entry+0x66/0xd0
PGD 1a05067 PUD 1a09063 PMD 80000000016001e1
Oops: 0003 [#1] SMP Jul 7 04:02:28 phyllis kernel: [55303.858604] CPU 1
Modules linked in: cryptd aes_x86_64 aes_generic binfmt_misc rfcomm bnep ip6table_filter hid radeon r8169 ahci libahci mii ttm drm_kms_helper drm video i2c_algo_bit intel_agp intel_gtt
Pid: 10344, comm: bash Tainted: G WC 3.0.0-rc5 #1 Dell Inc. Inspiron N5010/0YXXJJ
RIP: 0010:[<ffffffff810d9136>] [<ffffffff810d9136>] add_hash_entry+0x66/0xd0
RSP: 0018:ffff88003a96bda8 EFLAGS: 00010246
RAX: ffff8801301735c0 RBX: ffffffff8160ec80 RCX: 0000000000306ee0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880137c92940
RBP: ffff88003a96bdb8 R08: ffff880137c95680 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff81c9df78
R13: ffff8801153d1000 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f329c18a700(0000) GS:ffff880137c80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffff8160ec90 CR3: 000000003002b000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process bash (pid: 10344, threadinfo ffff88003a96a000, task ffff88012fcfc470)
Stack:
0000000000000fd0 00000000000000fc ffff88003a96be38 ffffffff810d92f5
ffff88011c4c4e00 ffff880000000000 000000000b69f4d0 ffffffff8160ec80
ffff8800300e6f06 0000000081130295 0000000000000282 ffff8800300e6f00
Call Trace:
[<ffffffff810d92f5>] match_records+0x155/0x1b0
[<ffffffff810d940c>] ftrace_mod_callback+0xbc/0x100
[<ffffffff810dafdf>] ftrace_regex_write+0x16f/0x210
[<ffffffff810db09f>] ftrace_filter_write+0xf/0x20
[<ffffffff81166e48>] vfs_write+0xc8/0x190
[<ffffffff81167001>] sys_write+0x51/0x90
[<ffffffff815c7e02>] system_call_fastpath+0x16/0x1b
Code: 48 8b 33 31 d2 48 85 f6 75 33 49 89 d4 4c 03 63 08 49 8b 14 24 48 85 d2 48 89 10 74 04 48 89 42 08 49 89 04 24 4c 89 60 08 31 d2
RIP [<ffffffff810d9136>] add_hash_entry+0x66/0xd0
RSP <ffff88003a96bda8>
CR2: ffffffff8160ec90
---[ end trace a5d031828efdd88e ]---
Reported-by: Brian Marete <marete@toshnix.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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commit 40ee4dffff061399eb9358e0c8fcfbaf8de4c8fe upstream.
The "enable" file for the event system can be removed when a module
is unloaded and the event system only has events from that module.
As the event system nr_events count goes to zero, it may be freed
if its ref_count is also set to zero.
Like the "filter" file, the "enable" file may be opened by a task and
referenced later, after a module has been unloaded and the events for
that event system have been removed.
Although the "filter" file referenced the event system structure,
the "enable" file only references a pointer to the event system
name. Since the name is freed when the event system is removed,
it is possible that an access to the "enable" file may reference
a freed pointer.
Update the "enable" file to use the subsystem_open() routine that
the "filter" file uses, to keep a reference to the event system
structure while the "enable" file is opened.
Reported-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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commit e9dbfae53eeb9fc3d4bb7da3df87fa9875f5da02 upstream.
The event system is freed when its nr_events is set to zero. This happens
when a module created an event system and then later the module is
removed. Modules may share systems, so the system is allocated when
it is created and freed when the modules are unloaded and all the
events under the system are removed (nr_events set to zero).
The problem arises when a task opened the "filter" file for the
system. If the module is unloaded and it removed the last event for
that system, the system structure is freed. If the task that opened
the filter file accesses the "filter" file after the system has
been freed, the system will access an invalid pointer.
By adding a ref_count, and using it to keep track of what
is using the event system, we can free it after all users
are finished with the event system.
Reported-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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The fix to fix the printk_formats of modules broke the
printk_formats of trace_printks in the kernel.
The update of what to show via the seq_file was only updated
if the passed in fmt was NULL, which happens only on the first
iteration. The result was showing the first format every time
instead of iterating through the available formats.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Revert the commit that removed the disabling of interrupts around
the initial modifying of mcount callers to nops, and update the comment.
The original comment was outdated and stated that the interrupts were
being disabled to prevent kstop machine, which was required with the
old ftrace daemon, but was no longer the case.
What the comment failed to mention was that interrupts needed to be
disabled to keep interrupts from preempting the modifying of the code
and then executing the code that was partially modified.
Revert the commit and update the comment.
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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With gcc 4.6, the self test kprobe function:
kprobe_trace_selftest_target()
is optimized such that kallsyms does not list it. The kprobes
test uses this function to insert a probe and test it. But
it will fail the test if the function is not listed in kallsyms.
Adding a __used annotation keeps the symbol in the kallsyms table.
Suggested-by: David Daney <ddaney@caviumnetworks.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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kernel/trace/ftrace.c: In function 'ftrace_regex_write.clone.15':
kernel/trace/ftrace.c:2743:6: warning: 'ret' may be used uninitialized in this
function
Signed-off-by: GuoWen Li <guowen.li.linux@gmail.com>
Link: http://lkml.kernel.org/r/201106011918.47939.guowen.li.linux@gmail.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Witold reported a reboot caused by the selftests of the dynamic function
tracer. He sent me a config and I used ktest to do a config_bisect on it
(as my config did not cause the crash). It pointed out that the problem
config was CONFIG_PROVE_RCU.
What happened was that if multiple callbacks are attached to the
function tracer, we iterate a list of callbacks. Because the list is
managed by synchronize_sched() and preempt_disable, the access to the
pointers uses rcu_dereference_raw().
When PROVE_RCU is enabled, the rcu_dereference_raw() calls some
debugging functions, which happen to be traced. The tracing of the debug
function would then call rcu_dereference_raw() which would then call the
debug function and then... well you get the idea.
I first wrote two different patches to solve this bug.
1) add a __rcu_dereference_raw() that would not do any checks.
2) add notrace to the offending debug functions.
Both of these patches worked.
Talking with Paul McKenney on IRC, he suggested to add recursion
detection instead. This seemed to be a better solution, so I decided to
implement it. As the task_struct already has a trace_recursion to detect
recursion in the ring buffer, and that has a very small number it
allows, I decided to use that same variable to add flags that can detect
the recursion inside the infrastructure of the function tracer.
I plan to change it so that the task struct bit can be checked in
mcount, but as that requires changes to all archs, I will hold that off
to the next merge window.
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1306348063.1465.116.camel@gandalf.stny.rr.com
Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Filesystem, like Btrfs, has some "ULL" macros, and when these macros are passed
to tracepoints'__print_symbolic(), there will be 64->32 truncate WARNINGS during
compiling on 32bit box.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Link: http://lkml.kernel.org/r/4DACE6E0.7000507@cn.fujitsu.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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When dynamic ftrace is not configured, the ops->flags still needs
to have its FTRACE_OPS_FL_ENABLED bit set in ftrace_startup().
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The self tests for event tracer does not check if the function
tracing was successfully activated. It needs to before it continues
the tests, otherwise the wrong errors may be reported.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The register_ftrace_function() returns an error code on failure
except if the call to ftrace_startup() fails. Add a error return to
ftrace_startup() if it fails to start, allowing register_ftrace_funtion()
to return a proper error value.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (60 commits)
sched: Fix and optimise calculation of the weight-inverse
sched: Avoid going ahead if ->cpus_allowed is not changed
sched, rt: Update rq clock when unthrottling of an otherwise idle CPU
sched: Remove unused parameters from sched_fork() and wake_up_new_task()
sched: Shorten the construction of the span cpu mask of sched domain
sched: Wrap the 'cfs_rq->nr_spread_over' field with CONFIG_SCHED_DEBUG
sched: Remove unused 'this_best_prio arg' from balance_tasks()
sched: Remove noop in alloc_rt_sched_group()
sched: Get rid of lock_depth
sched: Remove obsolete comment from scheduler_tick()
sched: Fix sched_domain iterations vs. RCU
sched: Next buddy hint on sleep and preempt path
sched: Make set_*_buddy() work on non-task entities
sched: Remove need_migrate_task()
sched: Move the second half of ttwu() to the remote cpu
sched: Restructure ttwu() some more
sched: Rename ttwu_post_activation() to ttwu_do_wakeup()
sched: Remove rq argument from ttwu_stat()
sched: Remove rq->lock from the first half of ttwu()
sched: Drop rq->lock from sched_exec()
...
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Fix rt_rq runtime leakage bug
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Add some basic sanity tests for multiple users of the function
tracer at startup.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Since users of the function tracer can now pick and choose which
functions they want to trace agnostically from other users of the
function tracer, we need to pass the ops struct to the ftrace_set_filter()
functions.
The functions ftrace_set_global_filter() and ftrace_set_global_notrace()
is added to keep the old filter functions which are used to modify
the generic function tracers.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Now that functions may be selected individually, it only makes sense
that we should allow dynamically allocated trace structures to
be traced. This will allow perf to allocate a ftrace_ops structure
at runtime and use it to pick and choose which functions that
structure will trace.
Note, a dynamically allocated ftrace_ops will always be called
indirectly instead of being called directly from the mcount in
entry.S. This is because there's no safe way to prevent mcount
from being preempted before calling the function, unless we
modify every entry.S to do so (not likely). Thus, dynamically allocated
functions will now be called by the ftrace_ops_list_func() that
loops through the ops that are allocated if there are more than
one op allocated at a time. This loop is protected with a
preempt_disable.
To determine if an ftrace_ops structure is allocated or not, a new
util function was added to the kernel/extable.c called
core_kernel_data(), which returns 1 if the address is between
_sdata and _edata.
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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ftrace_ops that are registered to trace functions can now be
agnostic to each other in respect to what functions they trace.
Each ops has their own hash of the functions they want to trace
and a hash to what they do not want to trace. A empty hash for
the functions they want to trace denotes all functions should
be traced that are not in the notrace hash.
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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When a hash is modified and might be in use, we need to perform
a schedule RCU operation on it, as the hashes will soon be used
directly in the function tracer callback.
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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This is a step towards each ops structure defining its own set
of functions to trace. As the current code with pid's and such
are specific to the global_ops, it is restructured to be used
with the global ops.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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In order to allow different ops to enable different functions,
the ftrace_startup() and ftrace_shutdown() functions need the
ops parameter passed to them.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Add the enabled_functions file that is used to show all the
functions that have been enabled for tracing as well as their
ref counts. This helps seeing if any function has been registered
and what functions are being traced.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Every function has its own record that stores the instruction
pointer and flags for the function to be traced. There are only
two flags: enabled and free. The enabled flag states that tracing
for the function has been enabled (actively traced), and the free
flag states that the record no longer points to a function and can
be used by new functions (loaded modules).
These flags are now moved to the MSB of the flags (actually just
the top 32bits). The rest of the bits (30 bits) are now used as
a ref counter. Everytime a tracer register functions to trace,
those functions will have its counter incremented.
When tracing is enabled, to determine if a function should be traced,
the counter is examined, and if it is non-zero it is set to trace.
When a ftrace_ops is registered to trace functions, its hashes
are examined. If the ftrace_ops filter_hash count is zero, then
all functions are set to be traced, otherwise only the functions
in the hash are to be traced. The exception to this is if a function
is also in the ftrace_ops notrace_hash. Then that function's counter
is not incremented for this ftrace_ops.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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When filtering, allocate a hash to insert the function records.
After the filtering is complete, assign it to the ftrace_ops structure.
This allows the ftrace_ops structure to have a much smaller array of
hash buckets instead of wasting a lot of memory.
A read only empty_hash is created to be the minimum size that any ftrace_ops
can point to.
When a new hash is created, it has the following steps:
o Allocate a default hash.
o Walk the function records assigning the filtered records to the hash
o Allocate a new hash with the appropriate size buckets
o Move the entries from the default hash to the new hash.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Combine the filter and notrace hashes to be accessed by a single entity,
the global_ops. The global_ops is a ftrace_ops structure that is passed
to different functions that can read or modify the filtering of the
function tracer.
The ftrace_ops structure was modified to hold a filter and notrace
hashes so that later patches may allow each ftrace_ops to have its own
set of rules to what functions may be filtered.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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When multiple users are allowed to have their own set of functions
to trace, having the FTRACE_FL_FILTER flag will not be enough to
handle the accounting of those users. Each user will need their own
set of functions.
Replace the FTRACE_FL_FILTER with a filter_hash instead. This is
temporary until the rest of the function filtering accounting
gets in.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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To prepare for the accounting system that will allow multiple users of
the function tracer, having the FTRACE_FL_NOTRACE as a flag in the
dyn_trace record does not make sense.
All ftrace_ops will soon have a hash of functions they should trace
and not trace. By making a global hash of functions not to trace makes
this easier for the transition.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Merge reason: pull in the latest fixes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This partially reverts commit e6e1e2593592a8f6f6380496655d8c6f67431266.
That commit changed the structure layout of the trace structure, which
in turn broke PowerTOP (1.9x generation) quite badly.
I appreciate not wanting to expose the variable in question, and
PowerTOP was not using it, so I've replaced the variable with just a
padding field - that way if in the future a new field is needed it can
just use this padding field.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into perf/core
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into perf/core
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The code used for matching functions is almost identical between normal
selecting of functions and using the :mod: feature of set_ftrace_notrace.
Consolidate the two users into one function.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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