linux-stable.git/kernel/trace/ftrace.c, branch v5.8.3

tracing: Use trace_sched_process_free() instead of exit() for pid tracing

2020-08-21T11:15:00+00:00

commit afcab636657421f7ebfa0783a91f90256bba0091 upstream.

On exit, if a process is preempted after the trace_sched_process_exit()
tracepoint but before the process is done exiting, then when it gets
scheduled in, the function tracers will not filter it properly against the
function tracing pid filters.

That is because the function tracing pid filters hooks to the
sched_process_exit() tracepoint to remove the exiting task's pid from the
filter list. Because the filtering happens at the sched_switch tracepoint,
when the exiting task schedules back in to finish up the exit, it will no
longer be in the function pid filtering tables.

This was noticeable in the notrace self tests on a preemptable kernel, as
the tests would fail as it exits and preempted after being taken off the
notrace filter table and on scheduling back in it would not be in the
notrace list, and then the ending of the exit function would trace. The test
detected this and would fail.

Cc: stable@vger.kernel.org
Cc: Namhyung Kim 
Fixes: 1e10486ffee0a ("ftrace: Add 'function-fork' trace option")
Fixes: c37775d57830a ("tracing: Add infrastructure to allow set_event_pid to follow children"
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Setup correct FTRACE_FL_REGS flags for module

2020-08-21T11:14:59+00:00

commit 8a224ffb3f52b0027f6b7279854c71a31c48fc97 upstream.

When module loaded and enabled, we will use __ftrace_replace_code
for module if any ftrace_ops referenced it found. But we will get
wrong ftrace_addr for module rec in ftrace_get_addr_new, because
rec->flags has not been setup correctly. It can cause the callback
function of a ftrace_ops has FTRACE_OPS_FL_SAVE_REGS to be called
with pt_regs set to NULL.
So setup correct FTRACE_FL_REGS flags for rec when we call
referenced_filters to find ftrace_ops references it.

Link: https://lkml.kernel.org/r/20200728180554.65203-1-zhouchengming@bytedance.com

Cc: stable@vger.kernel.org
Fixes: 8c4f3c3fa9681 ("ftrace: Check module functions being traced on reload")
Signed-off-by: Chengming Zhou 
Signed-off-by: Muchun Song 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Fix ftrace_trace_task return value

2020-08-19T06:26:53+00:00

[ Upstream commit c58b6b0372de0d4cd0536d6585addd1b36b151ae ]

I was attempting to use pid filtering with function_graph, but it wasn't
allowing anything to make it through.  Turns out ftrace_trace_task
returns false if ftrace_ignore_pid is not-empty, which isn't correct
anymore.  We're now setting it to FTRACE_PID_IGNORE if we need to ignore
that pid, otherwise it's set to the pid (which is weird considering the
name) or to FTRACE_PID_TRACE.  Fix the check to check for !=
FTRACE_PID_IGNORE.  With this we can now use function_graph with pid
filtering.

Link: https://lkml.kernel.org/r/20200725005048.1790-1-josef@toxicpanda.com

Fixes: 717e3f5ebc82 ("ftrace: Make function trace pid filtering a bit more exact")
Signed-off-by: Josef Bacik 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

ftrace: Fix maybe-uninitialized compiler warning

2020-06-17T21:13:18+00:00

During build compiler reports some 'false positive' warnings about
variables {'seq_ops', 'filtered_pids', 'other_pids'} may be used
uninitialized. This patch silences these warnings.
Also delete some useless spaces

Link: https://lkml.kernel.org/r/20200529141214.37648-1-pilgrimtao@gmail.com

Signed-off-by: Kaitao Cheng 
Signed-off-by: Steven Rostedt (VMware)

Merge tag 'trace-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2020-06-09T17:06:18+00:00

Pull tracing updates from Steven Rostedt:
 "No new features this release. Mostly clean ups, restructuring and
  documentation.

   - Have ftrace_bug() show ftrace errors before the WARN, as the WARN
     will reboot the box before the error messages are printed if
     panic_on_warn is set.

   - Have traceoff_on_warn disable tracing sooner (before prints)

   - Write a message to the trace buffer that its being disabled when
     disable_trace_on_warning() is set.

   - Separate out synthetic events from histogram code to let it be used
     by other parts of the kernel.

   - More documentation on histogram design.

   - Other small fixes and clean ups"

* tag 'trace-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Remove obsolete PREEMPTIRQ_EVENTS kconfig option
  tracing/doc: Fix ascii-art in histogram-design.rst
  tracing: Add a trace print when traceoff_on_warning is triggered
  ftrace,bug: Improve traceoff_on_warn
  selftests/ftrace: Distinguish between hist and synthetic event checks
  tracing: Move synthetic events to a separate file
  tracing: Fix events.rst section numbering
  tracing/doc: Fix typos in histogram-design.rst
  tracing: Add hist_debug trace event files for histogram debugging
  tracing: Add histogram-design document
  tracing: Check state.disabled in synth event trace functions
  tracing/probe: reverse arguments to list_add
  tools/bootconfig: Add a summary of test cases and return error
  ftrace: show debugging information when panic_on_warn set

kallsyms/printk: add loglvl to print_ip_sym()

2020-06-09T16:39:10+00:00

Patch series "Add log level to show_stack()", v3.

Add log level argument to show_stack().

Done in three stages:
1. Introducing show_stack_loglvl() for every architecture
2. Migrating old users with an explicit log level
3. Renaming show_stack_loglvl() into show_stack()

Justification:

- It's a design mistake to move a business-logic decision into platform
  realization detail.

- I have currently two patches sets that would benefit from this work:
  Removing console_loglevel jumps in sysrq driver [1] Hung task warning
  before panic [2] - suggested by Tetsuo (but he probably didn't realise
  what it would involve).

- While doing (1), (2) the backtraces were adjusted to headers and other
  messages for each situation - so there won't be a situation when the
  backtrace is printed, but the headers are missing because they have
  lesser log level (or the reverse).

- As the result in (2) plays with console_loglevel for kdb are removed.

The least important for upstream, but maybe still worth to note that every
company I've worked in so far had an off-list patch to print backtrace
with the needed log level (but only for the architecture they cared
about).  If you have other ideas how you will benefit from show_stack()
with a log level - please, reply to this cover letter.

See also discussion on v1:
https://lore.kernel.org/linux-riscv/20191106083538.z5nlpuf64cigxigh@pathway.suse.cz/

This patch (of 50):

print_ip_sym() needs to have a log level parameter to comply with other
parts being printed.  Otherwise, half of the expected backtrace would be
printed and other may be missing with some logging level.

The following callee(s) are using now the adjusted log level:
- microblaze/unwind: the same level as headers & userspace unwind.
  Note that pr_debug()'s there are for debugging the unwinder itself.
- nds32/traps: symbol addresses are printed with the same log level
  as backtrace headers.
- lockdep: ip for locking issues is printed with the same log level
  as other part of the warning.
- sched: ip where preemption was disabled is printed as error like
  the rest part of the message.
- ftrace: bug reports are now consistent in the log level being used.

Signed-off-by: Dmitry Safonov 
Signed-off-by: Andrew Morton 
Acked-by: Steven Rostedt (VMware) 
Cc: Albert Ou 
Cc: Ben Segall 
Cc: Dietmar Eggemann 
Cc: Greentime Hu 
Cc: Greg Kroah-Hartman 
Cc: Ingo Molnar 
Cc: James Hogan 
Cc: Juri Lelli 
Cc: Mel Gorman 
Cc: Michal Simek 
Cc: Palmer Dabbelt 
Cc: Paul Burton 
Cc: Paul Walmsley 
Cc: Peter Zijlstra 
Cc: Ralf Baechle 
Cc: Thomas Gleixner 
Cc: Vincent Chen 
Cc: Vincent Guittot 
Cc: Will Deacon 
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Dmitry Safonov 
Cc: Jiri Slaby 
Cc: Petr Mladek 
Cc: Sergey Senozhatsky 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Richard Henderson 
Cc: Vineet Gupta 
Cc: Russell King 
Cc: Catalin Marinas 
Cc: Aurelien Jacquiot 
Cc: Mark Salter 
Cc: Guo Ren 
Cc: Yoshinori Sato 
Cc: Brian Cain 
Cc: Fenghua Yu 
Cc: Tony Luck 
Cc: Geert Uytterhoeven 
Cc: Ley Foon Tan 
Cc: Jonas Bonn 
Cc: Stafford Horne 
Cc: Stefan Kristiansson 
Cc: Helge Deller 
Cc: "James E.J. Bottomley" 
Cc: Benjamin Herrenschmidt 
Cc: Michael Ellerman 
Cc: Paul Mackerras 
Cc: Christian Borntraeger 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: Rich Felker 
Cc: "David S. Miller" 
Cc: Anton Ivanov 
Cc: Jeff Dike 
Cc: Richard Weinberger 
Cc: Guan Xuetao 
Cc: Borislav Petkov 
Cc: "H. Peter Anvin" 
Cc: Chris Zankel 
Cc: Max Filippov 
Cc: Len Brown 
Cc: Pavel Machek 
Cc: "Rafael J. Wysocki" 
Cc: "Rafael J. Wysocki" 
Cc: Daniel Thompson 
Cc: Douglas Anderson 
Cc: Jason Wessel 
Link: http://lkml.kernel.org/r/20200418201944.482088-2-dima@arista.com
Signed-off-by: Linus Torvalds

ftrace: show debugging information when panic_on_warn set

2020-05-20T01:08:01+00:00

When an anomaly is detected in the function call modification
code, ftrace_bug() is called to disable function tracing as well
as give some warn and information that may help debug the problem.

But currently, we call FTRACE_WARN_ON_ONCE() first in ftrace_bug(),
so when panic_on_warn is set, we can't see the debugging information
here. Call FTRACE_WARN_ON_ONCE() at the end of ftrace_bug() to ensure
that the debugging information is displayed first.

after this patch, the dmesg looks like:

	------------[ ftrace bug ]------------
	ftrace failed to modify
	[] bcm2835_handle_irq+0x4/0x58
	 actual:   1f:20:03:d5
	Setting ftrace call site to call ftrace function
	ftrace record flags: 80000001
	 (1)
	 expected tramp: ffff80001009d6f0
	------------[ cut here ]------------
	WARNING: CPU: 2 PID: 1635 at kernel/trace/ftrace.c:2078 ftrace_bug+0x204/0x238
	Kernel panic - not syncing: panic_on_warn set ...
	CPU: 2 PID: 1635 Comm: sh Not tainted 5.7.0-rc5-00033-gb922183867f5 #14
	Hardware name: linux,dummy-virt (DT)
	Call trace:
	 dump_backtrace+0x0/0x1b0
	 show_stack+0x20/0x30
	 dump_stack+0xc0/0x10c
	 panic+0x16c/0x368
	 __warn+0x120/0x160
	 report_bug+0xc8/0x160
	 bug_handler+0x28/0x98
	 brk_handler+0x70/0xd0
	 do_debug_exception+0xcc/0x1ac
	 el1_sync_handler+0xe4/0x120
	 el1_sync+0x7c/0x100
	 ftrace_bug+0x204/0x238

Link: https://lkml.kernel.org/r/20200515100828.7091-1-cj.chengjian@huawei.com

Signed-off-by: Cheng Jian 
Signed-off-by: Steven Rostedt (VMware)

Merge tag 'noinstr-lds-2020-05-19' into core/rcu

2020-05-19T13:50:34+00:00

Get the noinstr section and annotation markers to base the RCU parts on.

ftrace: Use synchronize_rcu_tasks_rude() instead of ftrace_sync()

2020-04-27T18:03:53+00:00

This commit replaces the schedule_on_each_cpu(ftrace_sync) instances
with synchronize_rcu_tasks_rude().

Suggested-by: Steven Rostedt 
Cc: Ingo Molnar 
[ paulmck: Make Kconfig adjustments noted by kbuild test robot. ]
Signed-off-by: Paul E. McKenney

ftrace: Fix memory leak caused by not freeing entry in unregister_ftrace_direct()

2020-04-23T02:04:27+00:00

kmemleak reported the following:

unreferenced object 0xffff90d47127a920 (size 32):
  comm "modprobe", pid 1766, jiffies 4294792031 (age 162.568s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 22 01 00 00 00 00 ad de  ........".......
    00 78 12 a7 ff ff ff ff 00 00 b6 c0 ff ff ff ff  .x..............
  backtrace:
    [<00000000bb79e72e>] register_ftrace_direct+0xcb/0x3a0
    [<00000000295e4f79>] do_one_initcall+0x72/0x340
    [<00000000873ead18>] do_init_module+0x5a/0x220
    [<00000000974d9de5>] load_module+0x2235/0x2550
    [<0000000059c3d6ce>] __do_sys_finit_module+0xc0/0x120
    [<000000005a8611b4>] do_syscall_64+0x60/0x230
    [<00000000a0cdc49e>] entry_SYSCALL_64_after_hwframe+0x49/0xb3

The entry used to save the direct descriptor needs to be freed
when unregistering.

Signed-off-by: Steven Rostedt (VMware)