This is a tool that is intended to work around the fact that the
preemptoff, irqsoff, and preemptirqsoff tracers only work in
overwrite mode. The idea is to act randomly in such a way that we
do not systematically lose any latencies, so that if enough testing
is done, all latencies will be captured. If the same burst of
latencies is repeated, then sooner or later we will have captured all
the latencies.

It also works with the wakeup_dl, wakeup_rt, and wakeup tracers.
However, in that case it is probably not useful to use the random
sleep functionality.

The reason why it may be desirable to catch all latencies with a long
test campaign is that for some organizations, it's necessary to test
the kernel in the field and not practical for developers to work
iteratively with field testers. Because of cost and project schedules
it is not possible to start a new test campaign every time a latency
problem has been fixed.

It uses inotify to detect changes to /sys/kernel/tracing/trace.
When a latency is detected, it will either sleep or print
immediately, depending on a function that act as an unfair coin
toss.

If immediate print is chosen, it means that we open
/sys/kernel/tracing/trace and thereby cause a blackout period
that will hide any subsequent latencies.

If sleep is chosen, it means that we wait before opening
/sys/kernel/tracing/trace, by default for 1000 ms, to see if
there is another latency during this period. If there is, then we will
lose the previous latency. The coin will be tossed again with a
different probability, and we will either print the new latency, or
possibly a subsequent one.

The probability for the unfair coin toss is chosen so that there
is equal probability to obtain any of the latencies in a burst.
However, this assumes that we make an assumption of how many
latencies there can be. By default  the program assumes that there
are no more than 2 latencies in a burst, the probability of immediate
printout will be:

1/2 and 1

Thus, the probability of getting each of the two latencies will be 1/2.

If we ever find that there is more than one latency in a series,
meaning that we reach the probability of 1, then the table will be
expanded to:

1/3, 1/2, and 1

Thus, we assume that there are no more than three latencies and each
with a probability of 1/3 of being captured. If the probability of 1
is reached in the new table, that is we see more than two closely
occurring latencies, then the table will again be extended, and so
on.

On my systems, it seems like this scheme works fairly well, as
long as the latencies we trace are long enough, 300 us seems to be
enough. This userspace program receive the inotify event at the end
of a latency, and it has time until the end of the next latency
to react, that is to open /sys/kernel/tracing/trace. Thus,
if we trace latencies that are >300 us, then we have at least 300 us
to react.

The minimum latency will of course not be 300 us on all systems, it
will depend on the hardware, kernel version, workload and
configuration.

Example usage:

In one shell, give the following command:
sudo latency-collector -rvv -t preemptirqsoff -s 2000 -a 3

This will trace latencies > 2000us with the preemptirqsoff tracer,
using random sleep with maximum verbosity, with a probability
table initialized to a size of 3.

In another shell, generate a few bursts of latencies:

root@host:~# modprobe preemptirq_delay_test delay=3000 test_mode=alternate
burst_size=3
root@host:~# echo 1 > /sys/kernel/preemptirq_delay_test/trigger
root@host:~# echo 1 > /sys/kernel/preemptirq_delay_test/trigger
root@host:~# echo 1 > /sys/kernel/preemptirq_delay_test/trigger
root@host:~# echo 1 > /sys/kernel/preemptirq_delay_test/trigger

If all goes well, you should be getting stack traces that shows
all the different latencies, i.e. you should see all the three
functions preemptirqtest_0, preemptirqtest_1, preemptirqtest_2 in the
stack traces.

Link: https://lkml.kernel.org/r/20210212134421.172750-2-Viktor.Rosendahl@bmw.deSigned-off-by: Viktor Rosendahl <Viktor.Rosendahl@bmw.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Since the original behavior of the trace events is to hash the %p pointers,
make that the default, and have developers have to enable the option in
order to have them unhashed.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Add tracefs/options/hash-ptr option to show hashed pointer
value by %p in event printk format string.

For the security reason, normal printk will show the hashed
pointer value (encrypted by random number) with %p to printk
buffer to hide the real address. But the tracefs/trace always
shows real address for debug. To bridge those outputs, add an
option to switch the output format. Ftrace users can use it
to find the hashed value corresponding to the real address
in trace log.

Link: https://lkml.kernel.org/r/160277372504.29307.14909828808982012211.stgit@devnote2Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Update the comment of the 3rd stage of trace event macro
expansion code. Now there are 2 macros makes different
trace_raw_output_<call>() functions.

Link: https://lkml.kernel.org/r/160277371605.29307.8586817119278606720.stgit@devnote2Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

To help debugging kernel, show real address for trace event arguments
in tracefs/trace{,pipe} instead of hashed pointer value.

Since ftrace human-readable format uses vsprintf(), all %p are
translated to hash values instead of pointer address.

However, when debugging the kernel, raw address value gives a
hint when comparing with the memory mapping in the kernel.
(Those are sometimes used with crash log, which is not hashed too)
So converting %p with %px when calling trace_seq_printf().

Moreover, this is not improving the security because the tracefs
can be used only by root user and the raw address values are readable
from tracefs/percpu/cpu*/trace_pipe_raw file.

Link: https://lkml.kernel.org/r/160277370703.29307.5134475491761971203.stgit@devnote2Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Add a check confirming that '!event' alone will remove a synthetic
event.

Link: https://lkml.kernel.org/r/1dff3f03d18542cece08c10d6323d8a8dba11e42.1612208610.git.zanussi@kernel.orgSigned-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Some of the synthetic event errors and positions have changed in the
code - update those and add several more tests.

Also add a runtime check to ensure that the kernel supports dynamic
strings in synthetic events, which these tests require.

Link: https://lkml.kernel.org/r/51402656433455baead34f068c6e9466b64df9c0.1612208610.git.zanussi@kernel.org

Fixes: 81ff92a9 (selftests/ftrace: Add test case for synthetic event syntax errors)
Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The synthetic event parsing rework now requires semicolons between
synthetic event fields.  That requirement breaks existing users who
might already have used the old synthetic event command format, so
this adds an inner loop that can parse more than one field, if
present, between semicolons.  For each field, parse_synth_field()
checks in which version that field was introduced, using
check_field_version().  The caller, __create_synth_event() can then use
that version information to determine whether or not to enforce the
requirement on the command as a whole.

In the future, if/when new features are added, the requirement will be
that any field/string containing the new feature must use semicolons,
and the check_field_version() check can then check for those and
enforce it.  Using a version number allows this scheme to be extended
if necessary.

Link: https://lkml.kernel.org/r/74fcc500d561b40ce91c5ee94818c70c6b0c9330.1612208610.git.zanussi@kernel.org

[ zanussi: added check_field_version() comment from rostedt@goodmis.org ]
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Since array types are handled differently, errors referencing them
also need to be handled differently.  Add and use a new
INVALID_ARRAY_SPEC error.  Also add INVALID_CMD and INVALID_DYN_CMD to
catch and display the correct form for badly-formed commands, which
can also be used in place of CMD_INCOMPLETE, which is removed, and
remove CMD_TOO_LONG, since it's no longer used.

Link: https://lkml.kernel.org/r/b9dd434dc6458dcff11adc6ed616fe93a8794770.1612208610.git.zanussi@kernel.orgSigned-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Now that command parsing has been delegated to the create functions
and we're no longer constrained by argv_split(), we can modify the
synthetic event command parser to better match the higher-level
structure of the synthetic event commands, which is basically an event
name followed by a set of semicolon-separated fields.

Since we're also now passed the raw command, we can also save it
directly and can get rid of save_cmdstr().

Link: https://lkml.kernel.org/r/cb9e2be92d992ce59f2b4f132264a5d467f3933f.1612208610.git.zanussi@kernel.orgSigned-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Delegate command parsing to each create function so that the
command syntax can be customized.

This requires changes to the kprobe/uprobe/synthetic event handling,
which are also included here.

Link: https://lkml.kernel.org/r/e488726f49cbdbc01568618f8680584306c4c79f.1612208610.git.zanussi@kernel.orgSigned-off-by: Masami Hiramatsu <mhiramat@kernel.org>
[ zanussi@kernel.org: added synthetic event modifications ]
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Warn if the kprobe is reregistered, since there must be
a software bug (actively used resource must not be re-registered)
and caller must be fixed.

Link: https://lkml.kernel.org/r/161236436734.194052.4058506306336814476.stgit@devnote2Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@linux.ibm.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

ftrace_force_update() is committed by Commit e1c08bdd ("ftrace: force
recording") and removed by Commit cb7be3b2 ("ftrace: remove daemon").
Remove it in header file.

Link: https://lkml.kernel.org/r/1612409671-8249-1-git-send-email-hejinyang@loongson.cnSigned-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Restructure the code a bit to make it simpler, fix some formatting problems
and add READ_ONCE/WRITE_ONCE to make sure there's no compiler load/store
tearing to the variables that can be accessed across CPUs.

Started with Mathieu Desnoyers's patch:

  Link: https://lore.kernel.org/lkml/20210203175741.20665-1-mathieu.desnoyers@efficios.com/

And will keep his signature, but I will take the responsibility of this
being correct, and keep the authorship.

Link: https://lkml.kernel.org/r/20210204143004.61126582@gandalf.local.homeSigned-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

With static calls, a tracepoint can call the callback directly if there is
only one callback registered to that tracepoint. When there is more than
one, the static call will call the tracepoint's "iterator" function, which
needs to reload the tracepoint's "funcs" array again, as it could have
changed since the first time it was loaded.

But an arch without static calls is punished by having to load the
tracepoint's "funcs" array twice. Once in the DO_TRACE macro, and once
again in the iterator macro.

For archs without static calls, there's no reason to load the array macro
in the first place, since the iterator function will do it anyway.

Change the __DO_TRACE_CALL() macro to do the load and call of the
tracepoints funcs array only for architectures with static calls, and just
call the iterator function directly for architectures without static calls.

Link: https://lkml.kernel.org/r/20210208201050.909329787@goodmis.orgAcked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

While working on a clean up that would restructure the difference between
architectures that have static calls vs those that do not, I was stumbling
over the "data_args" parameter that includes "__data" in the arguments. The
issue was that one version didn't even need it, while the other one did.
Instead of injecting a "__data = NULL;" into the macro for the unneeded
version, just remove it completely.

The original idea behind data_args is that there may be a case of a
tracepoint with no arguments. But this is considered bad practice, and all
tracepoints should pass something to that location (that's what tracepoints
were created for).

Link: https://lkml.kernel.org/r/20210208201050.768074128@goodmis.orgAcked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The ftrace event subsystem is only created for showing the format files of
events created by the ftrace tracers, and are not trace events. The ftrace
subsystem currently has both the "enable" and "filter" files that in other
subsystems are used to enable/disable all events within the subsystem or set
a filter for all the subsystem events.

As ftrace subsystem events do not use enable or filter operations, these
files are useless in the ftrace subsystem. Remove them.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The kernel thread executing test can run on any cpu, which might be
different cpu latency tracer is running on, as a result, the
big latency caused by preemptirq delay test can't be detected.

Therefore, the argument cpu_affinity is added to be passed to test,
ensure it's running on the same cpu with latency tracer.

e.g.
cyclictest -p 90 -m -c 0 -i 1000 -a 3
modprobe preemptirq_delay_test test_mode=preempt delay=500 \
burst_size=3 cpu_affinity=3

Link: https://lkml.kernel.org/r/1611797713-20965-1-git-send-email-chensong_2000@189.cnSigned-off-by: Song Chen <chensong_2000@189.cn>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The list of tracepoint callbacks is managed by an array that is protected
by RCU. To update this array, a new array is allocated, the updates are
copied over to the new array, and then the list of functions for the
tracepoint is switched over to the new array. After a completion of an RCU
grace period, the old array is freed.

This process happens for both adding a callback as well as removing one.
But on removing a callback, if the new array fails to be allocated, the
callback is not removed, and may be used after it is freed by the clients
of the tracepoint.

There's really no reason to fail if the allocation for a new array fails
when removing a function. Instead, the function can simply be replaced by a
stub function that could be cleaned up on the next modification of the
array. That is, instead of calling the function registered to the
tracepoint, it would call a stub function in its place.

Link: https://lore.kernel.org/r/20201115055256.65625-1-mmullins@mmlx.us
Link: https://lore.kernel.org/r/20201116175107.02db396d@gandalf.local.home
Link: https://lore.kernel.org/r/20201117211836.54acaef2@oasis.local.home
Link: https://lkml.kernel.org/r/20201118093405.7a6d2290@gandalf.local.home

[ Note, this version does use undefined compiler behavior (assuming that
  a stub function with no parameters or return, can be called by a location
  that thinks it has parameters but still no return value. Static calls
  do the same thing, so this trick is not without precedent.

  There's another solution that uses RCU tricks and is more complex, but
  can be an alternative if this solution becomes an issue.

  Link: https://lore.kernel.org/lkml/20210127170721.58bce7cc@gandalf.local.home/
]

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@chromium.org>
Cc: netdev <netdev@vger.kernel.org>
Cc: bpf <bpf@vger.kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Florian Weimer <fw@deneb.enyo.de>
Fixes: 97e1c18e ("tracing: Kernel Tracepoints")
Reported-by: syzbot+83aa762ef23b6f0d1991@syzkaller.appspotmail.com
Reported-by: syzbot+d29e58bb557324e55e5e@syzkaller.appspotmail.com
Reported-by: Matt Mullins <mmullins@mmlx.us>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Matt Mullins <mmullins@mmlx.us>

Defining DEBUG should only be done in development.
So remove DEBUG.

Link: https://lkml.kernel.org/r/20210115153348.131791-1-trix@redhat.comSigned-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Add description for trace_array_put() parameter.

kernel/trace/trace.c:464: warning: Function parameter or member 'this_tr' not described in 'trace_array_put'

Link: https://lkml.kernel.org/r/20210112111202.23508-1-huobean@gmail.comSigned-off-by: Bean Huo <beanhuo@micron.com>
[ Merged as one of the original fixes was already fixed by someone else ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

s/controling/controlling/p

Link: https://lkml.kernel.org/r/20210112045008.29834-1-unixbhaskar@gmail.comSigned-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

There is a spelling mistake in the Kconfig help text. Fix it.

Link: https://lkml.kernel.org/r/20201216114051.12056-1-colin.king@canonical.comSigned-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

I can't imagine when or why `current' would return a NULL pointer. This
check was added in commit
      72829bc3 ("ftrace: move enums to ftrace.h and make helper function global")

but it doesn't give me hint why it was needed.

Assume `current' never returns a NULL pointer and remove the check.

Link: https://lkml.kernel.org/r/20210125194511.3924915-5-bigeasy@linutronix.deSigned-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

PREEMPT_RT does not report "serving softirq" because the tracing core
looks at the preemption counter while PREEMPT_RT does not update it
while processing softirqs in order to remain preemptible. The
information is stored somewhere else.
The in_serving_softirq() macro and the SOFTIRQ_OFFSET define are still
working but not on the preempt-counter.

Use in_serving_softirq() macro which works on PREEMPT_RT. On !PREEMPT_RT
the compiler (gcc-10 / clang-11) is smart enough to optimize the
in_serving_softirq() related read of the preemption counter away.
The only difference I noticed by using in_serving_softirq() on
!PREEMPT_RT is that gcc-10 implemented tracing_gen_ctx_flags() as
reading FLAG, jmp _tracing_gen_ctx_flags(). Without in_serving_softirq()
it inlined _tracing_gen_ctx_flags() into tracing_gen_ctx_flags().

Link: https://lkml.kernel.org/r/20210125194511.3924915-4-bigeasy@linutronix.deSigned-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Inline tracing_gen_ctx_flags(). This allows to have one ifdef
CONFIG_TRACE_IRQFLAGS_SUPPORT.

This requires to move `trace_flag_type' so tracing_gen_ctx_flags() can
use it.

Link: https://lkml.kernel.org/r/20210125194511.3924915-3-bigeasy@linutronix.deSuggested-by: Steven Rostedt <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/20210125140323.6b1ff20c@gandalf.local.homeSigned-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The state of the interrupts (irqflags) and the preemption counter are
both passed down to tracing_generic_entry_update(). Only one bit of
irqflags is actually required: The on/off state. The complete 32bit
of the preemption counter isn't needed. Just whether of the upper bits
(softirq, hardirq and NMI) are set and the preemption depth is needed.

The irqflags and the preemption counter could be evaluated early and the
information stored in an integer `trace_ctx'.
tracing_generic_entry_update() would use the upper bits as the
TRACE_FLAG_* and the lower 8bit as the disabled-preemption depth
(considering that one must be substracted from the counter in one
special cases).

The actual preemption value is not used except for the tracing record.
The `irqflags' variable is mostly used only for the tracing record. An
exception here is for instance wakeup_tracer_call() or
probe_wakeup_sched_switch() which explicilty disable interrupts and use
that `irqflags' to save (and restore) the IRQ state and to record the
state.

Struct trace_event_buffer has also the `pc' and flags' members which can
be replaced with `trace_ctx' since their actual value is not used
outside of trace recording.

This will reduce tracing_generic_entry_update() to simply assign values
to struct trace_entry. The evaluation of the TRACE_FLAG_* bits is moved
to _tracing_gen_ctx_flags() which replaces preempt_count() and
local_save_flags() invocations.

As an example, ftrace_syscall_enter() may invoke:
- trace_buffer_lock_reserve() -> … -> tracing_generic_entry_update()
- event_trigger_unlock_commit()
  -> ftrace_trace_stack() -> … -> tracing_generic_entry_update()
  -> ftrace_trace_userstack() -> … -> tracing_generic_entry_update()

In this case the TRACE_FLAG_* bits were evaluated three times. By using
the `trace_ctx' they are evaluated once and assigned three times.

A build with all tracers enabled on x86-64 with and without the patch:

    text     data      bss      dec      hex    filename
21970669 17084168  7639260 46694097  2c87ed1 vmlinux.old
21970293 17084168  7639260 46693721  2c87d59 vmlinux.new

text shrank by 379 bytes, data remained constant.

Link: https://lkml.kernel.org/r/20210125194511.3924915-2-bigeasy@linutronix.deSigned-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Remove the cpumask check, as we has done it at the beginning of
the function.
Also fix a typo. s/also the on the/also on the/

Link: https://lkml.kernel.org/r/20201224144634.3210-1-hqjagain@gmail.comSigned-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The cpu_buffer argument is not used inside the rb_inc_page() after
commit 3adc54fa ("ring-buffer: make the buffer a true circular link
list").
And cpu_buffer argument is not used inside the two functions too,
rb_is_head_page/rb_set_list_to_head.

Link: https://lkml.kernel.org/r/20201225140356.23008-1-hqjagain@gmail.comSigned-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Since commit b6f11df2 ("trace: Call tracing_reset_online_cpus before
tracer->init()"), get/put_cpu() are not needed anymore.
We can use raw_smp_processor_id() instead.

Link: https://lkml.kernel.org/r/20201230140521.31920-1-hqjagain@gmail.comSigned-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Update kernel-doc parameter after
commit b3b1e6ed ("ftrace: Create set_ftrace_notrace_pid to not trace tasks")
added @filtered_no_pids.

Link: https://lkml.kernel.org/r/20201231153558.4804-1-hqjagain@gmail.comSigned-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Attributing the function allows the compiler to more thoroughly
check the use of the function with -Wformat and similar flags.

Link: https://lkml.kernel.org/r/20201221162715.3757291-1-trix@redhat.comSigned-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

When executing a tracepoint, the tracepoint's func is dereferenced twice -
in __DO_TRACE() (where the returned pointer is checked) and later on in
__traceiter_##_name where the returned pointer is dereferenced without
checking which leads to races against tracepoint_removal_sync() and
crashes.

This adds a check before referencing the pointer in tracepoint_ptr_deref.

Link: https://lkml.kernel.org/r/20210202072326.120557-1-aik@ozlabs.ru

Cc: stable@vger.kernel.org
Fixes: d25e37d8 ("tracepoint: Optimize using static_call()")
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Our system encountered a re-init error when re-registering same kretprobe,
where the kretprobe_instance in rp->free_instances is illegally accessed
after re-init.

Implementation to avoid re-registration has been introduced for kprobe
before, but lags for register_kretprobe(). We must check if kprobe has
been re-registered before re-initializing kretprobe, otherwise it will
destroy the data struct of kretprobe registered, which can lead to memory
leak, system crash, also some unexpected behaviors.

We use check_kprobe_rereg() to check if kprobe has been re-registered
before running register_kretprobe()'s body, for giving a warning message
and terminate registration process.

Link: https://lkml.kernel.org/r/20210128124427.2031088-1-bobo.shaobowang@huawei.com

Cc: stable@vger.kernel.org
Fixes: 1f0ab409 ("kprobes: Prevent re-registration of the same kprobe")
[ The above commit should have been done for kretprobes too ]
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@linux.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Fix kprobe_on_func_entry() returns error code instead of false so that
register_kretprobe() can return an appropriate error code.

append_trace_kprobe() expects the kprobe registration returns -ENOENT
when the target symbol is not found, and it checks whether the target
module is unloaded or not. If the target module doesn't exist, it
defers to probe the target symbol until the module is loaded.

However, since register_kretprobe() returns -EINVAL instead of -ENOENT
in that case, it always fail on putting the kretprobe event on unloaded
modules. e.g.

Kprobe event:
/sys/kernel/debug/tracing # echo p xfs:xfs_end_io >> kprobe_events
[   16.515574] trace_kprobe: This probe might be able to register after target module is loaded. Continue.

Kretprobe event: (p -> r)
/sys/kernel/debug/tracing # echo r xfs:xfs_end_io >> kprobe_events
sh: write error: Invalid argument
/sys/kernel/debug/tracing # cat error_log
[   41.122514] trace_kprobe: error: Failed to register probe event
  Command: r xfs:xfs_end_io
             ^

To fix this bug, change kprobe_on_func_entry() to detect symbol lookup
failure and return -ENOENT in that case. Otherwise it returns -EINVAL
or 0 (succeeded, given address is on the entry).

Link: https://lkml.kernel.org/r/161176187132.1067016.8118042342894378981.stgit@devnote2

Cc: stable@vger.kernel.org
Fixes: 59158ec4 ("tracing/kprobes: Check the probe on unloaded module correctly")
Reported-by: Jianlin Lv <Jianlin.Lv@arm.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Eaerlier, tracing was disabled when reading the trace file. This behavior
was changed with:

commit 06e0a548 ("tracing: Do not disable tracing when reading the
trace file").

This doesn't seem to work with the latency tracers.

The above mentioned commit dit not only change the behavior but also added
an option to emulate the old behavior. The idea with this patch is to
enable this pause-on-trace option when the latency tracers are used.

Link: https://lkml.kernel.org/r/20210119164344.37500-2-Viktor.Rosendahl@bmw.de

Cc: stable@vger.kernel.org
Fixes: 06e0a548 ("tracing: Do not disable tracing when reading the trace file")
Signed-off-by: Viktor Rosendahl <Viktor.Rosendahl@bmw.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

On some archs, the idle task can call into cpu_suspend(). The cpu_suspend()
will disable or pause function graph tracing, as there's some paths in
bringing down the CPU that can have issues with its return address being
modified. The task_struct structure has a "tracing_graph_pause" atomic
counter, that when set to something other than zero, the function graph
tracer will not modify the return address.

The problem is that the tracing_graph_pause counter is initialized when the
function graph tracer is enabled. This can corrupt the counter for the idle
task if it is suspended in these architectures.

   CPU 1				CPU 2
   -----				-----
  do_idle()
    cpu_suspend()
      pause_graph_tracing()
          task_struct->tracing_graph_pause++ (0 -> 1)

				start_graph_tracing()
				  for_each_online_cpu(cpu) {
				    ftrace_graph_init_idle_task(cpu)
				      task-struct->tracing_graph_pause = 0 (1 -> 0)

      unpause_graph_tracing()
          task_struct->tracing_graph_pause-- (0 -> -1)

The above should have gone from 1 to zero, and enabled function graph
tracing again. But instead, it is set to -1, which keeps it disabled.

There's no reason that the field tracing_graph_pause on the task_struct can
not be initialized at boot up.

Cc: stable@vger.kernel.org
Fixes: 380c4b14 ("tracing/function-graph-tracer: append the tracing_graph_flag")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211339
Reported-by: pierre.gondois@arm.com
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Pull arch/sh updates from Rich Felker:
 "Cleanup and warning fixes"

* tag 'sh-for-5.11' of git://git.libc.org/linux-sh:
  sh/intc: Restore devm_ioremap() alignment
  sh: mach-sh03: remove duplicate include
  arch: sh: remove duplicate include
  sh: Drop ARCH_NR_GPIOS definition
  sh: Remove unused HAVE_COPY_THREAD_TLS macro
  sh: remove CONFIG_IDE from most defconfig
  sh: mm: Convert to DEFINE_SHOW_ATTRIBUTE
  sh: intc: Convert to DEFINE_SHOW_ATTRIBUTE
  arch/sh: hyphenate Non-Uniform in Kconfig prompt
  sh: dma: fix kconfig dependency for G2_DMA

Pull io_uring fixes from Jens Axboe:
 "Still need a final cancelation fix that isn't quite done done,
  expected in the next day or two. That said, this contains:

   - Wakeup fix for IOPOLL requests

   - SQPOLL split close op handling fix

   - Ensure that any use of io_uring fd itself is marked as inflight

   - Short non-regular file read fix (Pavel)

   - Fix up bad false positive warning (Pavel)

   - SQPOLL fixes (Pavel)

   - In-flight removal fix (Pavel)"

* tag 'io_uring-5.11-2021-01-24' of git://git.kernel.dk/linux-block:
  io_uring: account io_uring internal files as REQ_F_INFLIGHT
  io_uring: fix sleeping under spin in __io_clean_op
  io_uring: fix short read retries for non-reg files
  io_uring: fix SQPOLL IORING_OP_CLOSE cancelation state
  io_uring: fix skipping disabling sqo on exec
  io_uring: fix uring_flush in exit_files() warning
  io_uring: fix false positive sqo warning on flush
  io_uring: iopoll requests should also wake task ->in_idle state