I noticed that if I use dd to read the set_ftrace_filter file that the first
hash command is repeated.

 # cd /sys/kernel/debug/tracing
 # echo schedule > set_ftrace_filter
 # echo do_IRQ >> set_ftrace_filter
 # echo schedule:traceoff >> set_ftrace_filter
 # echo do_IRQ:traceoff >> set_ftrace_filter

 # cat set_ftrace_filter
 schedule
 do_IRQ
 schedule:traceoff:unlimited
 do_IRQ:traceoff:unlimited

 # dd if=set_ftrace_filter bs=1
 schedule
 do_IRQ
 schedule:traceoff:unlimited
 schedule:traceoff:unlimited
 do_IRQ:traceoff:unlimited
 98+0 records in
 98+0 records out
 98 bytes copied, 0.00265011 s, 37.0 kB/s

This is due to the way t_start() calls t_next() as well as the seq_file
calls t_next() and the state is slightly different between the two. Namely,
t_start() will call t_next() with a local "pos" variable.

By separating out the function listing from t_next() into its own function,
we can have better control of outputting the functions and the hash of
triggers. This simplifies the code.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

If all functions are enabled, there's a comment displayed in the file to
denote that:

  # cd /sys/kernel/debug/tracing
  # cat set_ftrace_filter
 #### all functions enabled ####

If a function trigger is set, those are displayed as well:

  # echo schedule:traceoff >> /debug/tracing/set_ftrace_filter
  # cat set_ftrace_filter
 #### all functions enabled ####
 schedule:traceoff:unlimited

But if you read that file with dd, the output can change:

  # dd if=/debug/tracing/set_ftrace_filter bs=1
 #### all functions enabled ####
 32+0 records in
 32+0 records out
 32 bytes copied, 7.0237e-05 s, 456 kB/s

This is because the "pos" variable is updated for the comment, but func_pos
is not. "func_pos" is used by the triggers (or hashes) to know how many
functions were printed and it bases its index from the pos - func_pos.
func_pos should be 1 to count for the comment printed. But since it is not,
t_hash_start() thinks that one trigger was already printed.

The cat gets to t_hash_start() via t_next() and not t_start() which updates
both pos and func_pos.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The loop in t_start() of calling t_next() will call t_hash_start() if the
pos is beyond the functions and enters the hash items. There's no reason to
check if p is NULL and call t_hash_start(), as that would be redundant.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Instead of testing if the hash to use is the filter_hash or the notrace_hash
at each iteration, do the test at open, and set the iter->hash to point to
the corresponding filter or notrace hash. Then use that directly instead of
testing which hash needs to be used each iteration.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The return status check of __seq_open_private() is rather strange:

	iter = __seq_open_private();
	if (iter) {
		/* do stuff */
	}

	return iter ? 0 : -ENOMEM;

It makes much more sense to do the return of failure right away:

	iter = __seq_open_private();
	if (!iter)
		return -ENOMEM;

	/* do stuff */

	return 0;

This clean up will make updates to this code a bit nicer.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Adding a hook into free_reserve_area() that informs ftrace that boot up init
text is being free, lets ftrace safely remove those init functions from its
records, which keeps ftrace from trying to modify text that no longer
exists.

Note, this still does not allow for tracing .init text of modules, as
modules require different work for freeing its init code.

Link: http://lkml.kernel.org/r/1488502497.7212.24.camel@linux.intel.com

Cc: linux-mm@kvack.org
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Requested-by: NTodd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Early trace callgraphs can be extremely large on systems with
several seconds of boot time. The max_depth parameter limits how
deep the graph trace goes and reduces the output size. This
parameter is the same as the max_graph_depth file in tracefs.

Link: http://lkml.kernel.org/r/1488499935-23216-1-git-send-email-todd.e.brandt@linux.intel.comSigned-off-by: NTodd Brandt <todd.e.brandt@linux.intel.com>
[ changed comments about debugfs to tracefs ]
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

On boot up, if the kernel command line sets a graph funtion with the kernel
command line options "ftrace_graph_filter" or "ftrace_graph_notrace" then it
updates the corresponding function graph hash, ftrace_graph_hash or
ftrace_graph_notrace_hash respectively. Unfortunately, at boot up, these
variables are pointers to the "EMPTY_HASH" which is a constant used as a
placeholder when a hash has no entities. The problem was that the comand
line version to set the hashes updated the actual EMPTY_HASH instead of
creating a new hash for the function graph. This broke the EMPTY_HASH
because not only did it modify a constant (not sure how that was allowed to
happen, except maybe because it was done at early boot, const variables were
still mutable), but it made the filters have functions listed in them when
they were actually empty.

The kernel command line function needs to allocate a new hash for the
function graph filters and assign the necessary variables to that new hash
instead.

Link: http://lkml.kernel.org/r/1488420091.7212.17.camel@linux.intel.com

Cc: Namhyung Kim <namhyung@kernel.org>
Fixes: b9b0c831 ("ftrace: Convert graph filter to use hash tables")
Reported-by: NTodd Brandt <todd.e.brandt@linux.intel.com>
Tested-by: NTodd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

We are going to split <linux/sched/task.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/task.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

There is no function 'ftrace_ops_recurs_func' existing in the current code,
it was renamed to ftrace_ops_assist_func() in commit c68c0fa2
("ftrace: Have ftrace_ops_get_func() handle RCU and PER_CPU flags too").
Update the comment to the correct function name.

Link: http://lkml.kernel.org/r/1487723366-14463-1-git-send-email-chuhu@redhat.comSigned-off-by: NChunyu Hu <chuhu@redhat.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Currently, only one function can be written to set_graph_function and
set_graph_notrace. The last function in the list will have saved, even
though other functions will be added then removed.

Change the behavior to be the same as set_ftrace_function as to allow
multiple functions to be written. If any one fails, none of them will be
added. The addition of the functions are done at the end when the file is
closed.
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The hashs ftrace_graph_hash and ftrace_graph_notrace_hash are modified
within the graph_lock being held. Holding a pointer to them and passing them
along can lead to a use of a stale pointer (fgd->hash). Move assigning the
pointer and its use to within the holding of the lock. Note, it's an
rcu_sched protected data, and other instances of referencing them are done
with preemption disabled. But the file manipuation code must be protected by
the lock.

The fgd->hash pointer is set to NULL when the lock is being released.
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Since reading the set_graph_functions uses seq functions, which sets the
file->private_data pointer to a seq_file descriptor. On writes the
ftrace_graph_data descriptor is set to file->private_data. But if the file
is opened for RDWR, the ftrace_graph_write() will incorrectly use the
file->private_data descriptor instead of
((struct seq_file *)file->private_data)->private pointer, and this can crash
the kernel.
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

fgd->hash is saved and then freed, but is never reset to either
ftrace_graph_hash nor ftrace_graph_notrace_hash. But if multiple writes are
performed, then the freed hash could be accessed again.

 # cd /sys/kernel/debug/tracing
 # head -1000 available_filter_functions > /tmp/funcs
 # cat /tmp/funcs > set_graph_function

Causes:

 general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
 Modules linked in:  [...]
 CPU: 2 PID: 1337 Comm: cat Not tainted 4.10.0-rc2-test-00010-g6b052e9 #32
 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
 task: ffff880113a12200 task.stack: ffffc90001940000
 RIP: 0010:free_ftrace_hash+0x7c/0x160
 RSP: 0018:ffffc90001943db0 EFLAGS: 00010246
 RAX: 6b6b6b6b6b6b6b6b RBX: 6b6b6b6b6b6b6b6b RCX: 6b6b6b6b6b6b6b6b
 RDX: 0000000000000002 RSI: 0000000000000001 RDI: ffff8800ce1e1d40
 RBP: ffff8800ce1e1d50 R08: 0000000000000000 R09: 0000000000006400
 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
 R13: ffff8800ce1e1d40 R14: 0000000000004000 R15: 0000000000000001
 FS:  00007f9408a07740(0000) GS:ffff88011e500000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000aee1f0 CR3: 0000000116bb4000 CR4: 00000000001406e0
 Call Trace:
  ? ftrace_graph_write+0x150/0x190
  ? __vfs_write+0x1f6/0x210
  ? __audit_syscall_entry+0x17f/0x200
  ? rw_verify_area+0xdb/0x210
  ? _cond_resched+0x2b/0x50
  ? __sb_start_write+0xb4/0x130
  ? vfs_write+0x1c8/0x330
  ? SyS_write+0x62/0xf0
  ? do_syscall_64+0xa3/0x1b0
  ? entry_SYSCALL64_slow_path+0x25/0x25
 Code: 01 48 85 db 0f 84 92 00 00 00 b8 01 00 00 00 d3 e0 85 c0 7e 3f 83 e8 01 48 8d 6f 10 45 31 e4 4c 8d 34 c5 08 00 00 00 49 8b 45 08 <4a> 8b 34 20 48 85 f6 74 13 48 8b 1e 48 89 ef e8 20 fa ff ff 48
 RIP: free_ftrace_hash+0x7c/0x160 RSP: ffffc90001943db0
 ---[ end trace 999b48216bf4b393 ]---
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

When the set_graph_function or set_graph_notrace contains no records, a
banner is displayed of either "#### all functions enabled ####" or
"#### all functions disabled ####" respectively. To tell the seq operations
to do this, (void *)1 is passed as a return value. Instead of using a
hardcoded meaningless variable, define it as a macro.
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

This is a micro-optimization, but as it has to deal with a fast path of the
function tracer, these optimizations can be noticed.

The ftrace_lookup_ip() returns true if the given ip is found in the hash. If
it's not found or the hash is NULL, it returns false. But there's some cases
that a NULL hash is a true, and the ftrace_hash_empty() is tested before
calling ftrace_lookup_ip() in those cases. But as ftrace_lookup_ip() tests
that first, that adds a few extra unneeded instructions in those cases.

A new static "always_inlined" function is created that does not perform the
hash empty test. This most only be used by callers that do the check first
anyway, as an empty or NULL hash could cause a crash if a lookup is
performed on it.

Also add kernel doc for the ftrace_lookup_ip() main function.
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Replace the couple of use cases that has small logic to produce the ftrace
function key id with a helper function. No need for duplicate code.
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Use ftrace_hash instead of a static array of a fixed size.  This is
useful when a graph filter pattern matches to a large number of
functions.  Now hash lookup is done with preemption disabled to protect
from the hash being changed/freed.

Link: http://lkml.kernel.org/r/20170120024447.26097-3-namhyung@kernel.orgSigned-off-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

It will be used when checking graph filter hashes later.

Link: http://lkml.kernel.org/r/20170120024447.26097-2-namhyung@kernel.orgSigned-off-by: NNamhyung Kim <namhyung@kernel.org>
[ Moved ftrace_hash dec and functions outside of FUNCTION_GRAPH define ]
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The __ftrace_hash_move() is to allocates properly-sized hash and move
entries in the src ftrace_hash.  It will be used to set function graph
filters which has nothing to do with the dyn_ftrace records.

Link: http://lkml.kernel.org/r/20170120024447.26097-1-namhyung@kernel.orgSigned-off-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

There is no point in having an extra type for extra confusion. u64 is
unambiguous.

Conversion was done with the following coccinelle script:

@rem@
@@
-typedef u64 cycle_t;

@fix@
typedef cycle_t;
@@
-cycle_t
+u64
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>

Currently the global_ops filtering hash is not available to outside users
registering for function tracing. Provide an API for those users to be
able to choose global filtering.

This is in preparation for pstore's ftrace feature to be able to
use the global filters.
Suggested-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: NJoel Fernandes <joelaf@google.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NKees Cook <keescook@chromium.org>

Use glob_match() to support flexible glob wildcards (*,?)
and character classes ([) for ftrace.
Since the full glob matching is slower than the current
partial matching routines(*pat, pat*, *pat*), this leaves
those routines and just add MATCH_GLOB for complex glob
expression.

e.g.
----
[root@localhost tracing]# echo 'sched*group' > set_ftrace_filter
[root@localhost tracing]# cat set_ftrace_filter
sched_free_group
sched_change_group
sched_create_group
sched_online_group
sched_destroy_group
sched_offline_group
[root@localhost tracing]# echo '[Ss]y[Ss]_*' > set_ftrace_filter
[root@localhost tracing]# head set_ftrace_filter
sys_arch_prctl
sys_rt_sigreturn
sys_ioperm
SyS_iopl
sys_modify_ldt
SyS_mmap
SyS_set_thread_area
SyS_get_thread_area
SyS_set_tid_address
sys_fork
----

Link: http://lkml.kernel.org/r/147566869501.29136.6462645009894738056.stgit@devboxAcked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

When a module is first loaded and its function ip records are added to the
ftrace list of functions to modify, they are set to DISABLED, as their text
is still in a read only state. When the module is fully loaded, and can be
updated, the flag is cleared, and if their's any functions that should be
tracing them, it is updated at that moment.

But there's several locations that do record accounting and should ignore
records that are marked as disabled, or they can cause issues.

Alexei already fixed one location, but others need to be addressed.

Cc: stable@vger.kernel.org
Fixes: b7ffffbb "ftrace: Add infrastructure for delayed enabling of module functions"
Reported-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

ftrace_shutdown() checks for sanity of ftrace records
and if dyn_ftrace->flags is not zero, it will warn.
It can happen that 'flags' are set to FTRACE_FL_DISABLED at this point,
since some module was loaded, but before ftrace_module_enable()
cleared the flags for this module.

In other words the module.c is doing:
ftrace_module_init(mod); // calls ftrace_update_code() that sets flags=FTRACE_FL_DISABLED
... // here ftrace_shutdown() is called that warns, since
err = prepare_coming_module(mod); // didn't have a chance to clear FTRACE_FL_DISABLED

Fix it by ignoring disabled records.
It's similar to what __ftrace_hash_rec_update() is already doing.

Link: http://lkml.kernel.org/r/1478560460-3818619-1-git-send-email-ast@fb.com

Cc: stable@vger.kernel.org
Fixes: b7ffffbb "ftrace: Add infrastructure for delayed enabling of module functions"
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The subtime is used only for function profiler with function graph
tracer enabled.  Move the definition of subtime under
CONFIG_FUNCTION_PROFILER to reduce the memory usage.  Also move the
initialization of subtime into the graph entry callback.

Link: http://lkml.kernel.org/r/20160831025529.24018-1-namhyung@kernel.org

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Commit 345ddcc8 ("ftrace: Have set_ftrace_pid use the bitmap like events
do") placed ftrace_init_tracefs into the instance creation, and encapsulated
the top level updating with an if conditional, as the top level only gets
updated at boot up. Unfortunately, this triggers section mismatch errors as
the init functions are called from a function that can be called later, and
the section mismatch logic is unaware of the if conditional that would
prevent it from happening at run time.

To make everyone happy, create a separate ftrace_init_tracefs_toplevel()
routine that only gets called by init functions, and this will be what calls
other init functions for the toplevel directory.

Link: http://lkml.kernel.org/r/20160704102139.19cbc0d9@gandalf.local.homeReported-by: Nkbuild test robot <fengguang.wu@intel.com>
Reported-by: NArnd Bergmann <arnd@arndb.de>
Fixes: 345ddcc8 ("ftrace: Have set_ftrace_pid use the bitmap like events do")
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Convert set_ftrace_pid to use the bitmap like set_event_pid does. This
allows for instances to use the pid filtering as well, and will allow for
function-fork option to set if the children of a traced function should be
traced or not.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

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>

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>

In order to support live patching on powerpc we would like to call
ftrace_location_range(), so make it global.
Signed-off-by: NTorsten Duwe <duwe@suse.de>
Signed-off-by: NBalbir Singh <bsingharora@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Use the more common logging method with the eventual goal of removing
pr_warning altogether.

Miscellanea:

 - Realign arguments
 - Coalesce formats
 - Add missing space between a few coalesced formats
Signed-off-by: NJoe Perches <joe@perches.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>	[kernel/power/suspend.c]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use kasprintf() instead of kmalloc() and snprintf().

Link: http://lkml.kernel.org/r/135a7bc36e51fd9eaa57124dd2140285b771f738.1458050835.git.geliangtang@163.comAcked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NGeliang Tang <geliangtang@163.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Currently dynamic ftrace calls are updated any time
the ftrace_ops is un/registered. If we do  this update
only when it's needed, we save lot of time for perf
system wide ftrace function sampling/counting.

The reason is that for system wide sampling/counting,
perf creates event for each cpu in the system.

Each event then registers separate copy of ftrace_ops,
which ends up in FTRACE_UPDATE_CALLS updates. On servers
with many cpus that means serious stall (240 cpus server):

Counting:
  # time ./perf stat -e ftrace:function -a sleep 1

   Performance counter stats for 'system wide':

              370,663      ftrace:function

          1.401427505 seconds time elapsed

  real    3m51.743s
  user    0m0.023s
  sys     3m48.569s

Sampling:
  # time ./perf record -e ftrace:function -a sleep 1
  [ perf record: Woken up 0 times to write data ]
  Warning:
  Processed 141200 events and lost 5 chunks!

  [ perf record: Captured and wrote 10.703 MB perf.data (135950 samples) ]

  real    2m31.429s
  user    0m0.213s
  sys     2m29.494s

There's no reason to do the FTRACE_UPDATE_CALLS update
for each event in perf case, because all the ftrace_ops
always share the same filter, so the updated calls are
always the same.

It's required that only first ftrace_ops registration
does the FTRACE_UPDATE_CALLS update (also sometimes
the second if the first one used the trampoline), but
the rest can be only cheaply linked into the ftrace_ops
list.

Counting:
  # time ./perf stat -e ftrace:function -a sleep 1

   Performance counter stats for 'system wide':

             398,571      ftrace:function

         1.377503733 seconds time elapsed

  real    0m2.787s
  user    0m0.005s
  sys     0m1.883s

Sampling:
  # time ./perf record -e ftrace:function -a sleep 1
  [ perf record: Woken up 0 times to write data ]
  Warning:
  Processed 261730 events and lost 9 chunks!

  [ perf record: Captured and wrote 19.907 MB perf.data (256293 samples) ]

  real    1m31.948s
  user    0m0.309s
  sys     1m32.051s

Link: http://lkml.kernel.org/r/1458138873-1553-6-git-send-email-jolsa@kernel.orgAcked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Change __ftrace_hash_rec_update to return true in case
we need to update dynamic ftrace call records. It return
false in case no update is needed.

Link: http://lkml.kernel.org/r/1458138873-1553-5-git-send-email-jolsa@kernel.orgAcked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Remove the ftrace module notifier in favor of directly calling
ftrace_module_enable() and ftrace_release_mod() in the module loader.
Hard-coding the function calls directly in the module loader removes
dependence on the module notifier call chain and provides better
visibility and control over what gets called when, which is important
to kernel utilities such as livepatch.

This fixes a notifier ordering issue in which the ftrace module notifier
(and hence ftrace_module_enable()) for coming modules was being called
after klp_module_notify(), which caused livepatch modules to initialize
incorrectly. This patch removes dependence on the module notifier call
chain in favor of hard coding the corresponding function calls in the
module loader. This ensures that ftrace and livepatch code get called in
the correct order on patch module load and unload.

Fixes: 5156dca3 ("ftrace: Fix the race between ftrace and insmod")
Signed-off-by: NJessica Yu <jeyu@redhat.com>
Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>
Reviewed-by: NPetr Mladek <pmladek@suse.cz>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: NMiroslav Benes <mbenes@suse.cz>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

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>

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>

The start and end variables were only used when ftrace_module_init() was
split up into multiple functions. No need to keep them around after the
merger.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Simple cleanup. No need for two functions here.
The whole work can simply be done inside 'ftrace_module_init'.

Link: http://lkml.kernel.org/r/1449067197-5718-1-git-send-email-abelvesa@linux.comSigned-off-by: NAbel Vesa <abelvesa@linux.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>