linux-toradex.git/kernel/trace, branch v6.14-rc3

ring-buffer: Update pages_touched to reflect persistent buffer content

2025-02-15T19:00:59+00:00

The pages_touched field represents the number of subbuffers in the ring
buffer that have content that can be read. This is used in accounting of
"dirty_pages" and "buffer_percent" to allow the user to wait for the
buffer to be filled to a certain amount before it reads the buffer in
blocking mode.

The persistent buffer never updated this value so it was set to zero, and
this accounting would take it as it had no content. This would cause user
space to wait for content even though there's enough content in the ring
buffer that satisfies the buffer_percent.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Vincent Donnefort 
Link: https://lore.kernel.org/20250214123512.0631436e@gandalf.local.home
Fixes: 5f3b6e839f3ce ("ring-buffer: Validate boot range memory events")
Signed-off-by: Steven Rostedt (Google)

tracing: Do not allow mmap() of persistent ring buffer

2025-02-15T18:59:52+00:00

When trying to mmap a trace instance buffer that is attached to
reserve_mem, it would crash:

 BUG: unable to handle page fault for address: ffffe97bd00025c8
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 2862f3067 P4D 2862f3067 PUD 0
 Oops: Oops: 0000 [#1] PREEMPT_RT SMP PTI
 CPU: 4 UID: 0 PID: 981 Comm: mmap-rb Not tainted 6.14.0-rc2-test-00003-g7f1a5e3fbf9e-dirty #233
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
 RIP: 0010:validate_page_before_insert+0x5/0xb0
 Code: e2 01 89 d0 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 <48> 8b 46 08 a8 01 75 67 66 90 48 89 f0 8b 50 34 85 d2 74 76 48 89
 RSP: 0018:ffffb148c2f3f968 EFLAGS: 00010246
 RAX: ffff9fa5d3322000 RBX: ffff9fa5ccff9c08 RCX: 00000000b879ed29
 RDX: ffffe97bd00025c0 RSI: ffffe97bd00025c0 RDI: ffff9fa5ccff9c08
 RBP: ffffb148c2f3f9f0 R08: 0000000000000004 R09: 0000000000000004
 R10: 0000000000000000 R11: 0000000000000200 R12: 0000000000000000
 R13: 00007f16a18d5000 R14: ffff9fa5c48db6a8 R15: 0000000000000000
 FS:  00007f16a1b54740(0000) GS:ffff9fa73df00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: ffffe97bd00025c8 CR3: 00000001048c6006 CR4: 0000000000172ef0
 Call Trace:
  
  ? __die_body.cold+0x19/0x1f
  ? __die+0x2e/0x40
  ? page_fault_oops+0x157/0x2b0
  ? search_module_extables+0x53/0x80
  ? validate_page_before_insert+0x5/0xb0
  ? kernelmode_fixup_or_oops.isra.0+0x5f/0x70
  ? __bad_area_nosemaphore+0x16e/0x1b0
  ? bad_area_nosemaphore+0x16/0x20
  ? do_kern_addr_fault+0x77/0x90
  ? exc_page_fault+0x22b/0x230
  ? asm_exc_page_fault+0x2b/0x30
  ? validate_page_before_insert+0x5/0xb0
  ? vm_insert_pages+0x151/0x400
  __rb_map_vma+0x21f/0x3f0
  ring_buffer_map+0x21b/0x2f0
  tracing_buffers_mmap+0x70/0xd0
  __mmap_region+0x6f0/0xbd0
  mmap_region+0x7f/0x130
  do_mmap+0x475/0x610
  vm_mmap_pgoff+0xf2/0x1d0
  ksys_mmap_pgoff+0x166/0x200
  __x64_sys_mmap+0x37/0x50
  x64_sys_call+0x1670/0x1d70
  do_syscall_64+0xbb/0x1d0
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

The reason was that the code that maps the ring buffer pages to user space
has:

	page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]);

And uses that in:

	vm_insert_pages(vma, vma->vm_start, pages, &nr_pages);

But virt_to_page() does not work with vmap()'d memory which is what the
persistent ring buffer has. It is rather trivial to allow this, but for
now just disable mmap() of instances that have their ring buffer from the
reserve_mem option.

If an mmap() is performed on a persistent buffer it will return -ENODEV
just like it would if the .mmap field wasn't defined in the
file_operations structure.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Vincent Donnefort 
Link: https://lore.kernel.org/20250214115547.0d7287d3@gandalf.local.home
Fixes: 9b7bdf6f6ece6 ("tracing: Have trace_printk not use binary prints if boot buffer")
Signed-off-by: Steven Rostedt (Google)

ring-buffer: Validate the persistent meta data subbuf array

2025-02-14T17:50:51+00:00

The meta data for a mapped ring buffer contains an array of indexes of all
the subbuffers. The first entry is the reader page, and the rest of the
entries lay out the order of the subbuffers in how the ring buffer link
list is to be created.

The validator currently makes sure that all the entries are within the
range of 0 and nr_subbufs. But it does not check if there are any
duplicates.

While working on the ring buffer, I corrupted this array, where I added
duplicates. The validator did not catch it and created the ring buffer
link list on top of it. Luckily, the corruption was only that the reader
page was also in the writer path and only presented corrupted data but did
not crash the kernel. But if there were duplicates in the writer side,
then it could corrupt the ring buffer link list and cause a crash.

Create a bitmask array with the size of the number of subbuffers. Then
clear it. When walking through the subbuf array checking to see if the
entries are within the range, test if its bit is already set in the
subbuf_mask. If it is, then there is duplicates and fail the validation.
If not, set the corresponding bit and continue.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Vincent Donnefort 
Link: https://lore.kernel.org/20250214102820.7509ddea@gandalf.local.home
Fixes: c76883f18e59b ("ring-buffer: Add test if range of boot buffer is valid")
Signed-off-by: Steven Rostedt (Google)

tracing: Have the error of __tracing_resize_ring_buffer() passed to user

2025-02-14T17:50:27+00:00

Currently if __tracing_resize_ring_buffer() returns an error, the
tracing_resize_ringbuffer() returns -ENOMEM. But it may not be a memory
issue that caused the function to fail. If the ring buffer is memory
mapped, then the resizing of the ring buffer will be disabled. But if the
user tries to resize the buffer, it will get an -ENOMEM returned, which is
confusing because there is plenty of memory. The actual error returned was
-EBUSY, which would make much more sense to the user.

Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers 
Cc: Vincent Donnefort 
Link: https://lore.kernel.org/20250213134132.7e4505d7@gandalf.local.home
Fixes: 117c39200d9d7 ("ring-buffer: Introducing ring-buffer mapping functions")
Signed-off-by: Steven Rostedt (Google) 
Reviewed-by: Masami Hiramatsu (Google)

ring-buffer: Unlock resize on mmap error

2025-02-14T17:50:05+00:00

Memory mapping the tracing ring buffer will disable resizing the buffer.
But if there's an error in the memory mapping like an invalid parameter,
the function exits out without re-enabling the resizing of the ring
buffer, preventing the ring buffer from being resized after that.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Vincent Donnefort 
Link: https://lore.kernel.org/20250213131957.530ec3c5@gandalf.local.home
Fixes: 117c39200d9d7 ("ring-buffer: Introducing ring-buffer mapping functions")
Signed-off-by: Steven Rostedt (Google)

fgraph: Fix set_graph_notrace with setting TRACE_GRAPH_NOTRACE_BIT

2025-02-08T13:36:45+00:00

The code was restructured where the function graph notrace code, that
would not trace a function and all its children is done by setting a
NOTRACE flag when the function that is not to be traced is hit.

There's a TRACE_GRAPH_NOTRACE_BIT which defines the bit in the flags and a
TRACE_GRAPH_NOTRACE which is the mask with that bit set. But the
restructuring used TRACE_GRAPH_NOTRACE_BIT when it should have used
TRACE_GRAPH_NOTRACE.

For example:

 # cd /sys/kernel/tracing
 # echo set_track_prepare stack_trace_save  > set_graph_notrace
 # echo function_graph > current_tracer
 # cat trace
[..]
 0)               |                          __slab_free() {
 0)               |                            free_to_partial_list() {
 0)               |                                  arch_stack_walk() {
 0)               |                                    __unwind_start() {
 0)   0.501 us    |                                      get_stack_info();

Where a non filter trace looks like:

 # echo > set_graph_notrace
 # cat trace
 0)               |                            free_to_partial_list() {
 0)               |                              set_track_prepare() {
 0)               |                                stack_trace_save() {
 0)               |                                  arch_stack_walk() {
 0)               |                                    __unwind_start() {

Where the filter should look like:

 # cat trace
 0)               |                            free_to_partial_list() {
 0)               |                              _raw_spin_lock_irqsave() {
 0)   0.350 us    |                                preempt_count_add();
 0)   0.351 us    |                                do_raw_spin_lock();
 0)   2.440 us    |                              }

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Link: https://lore.kernel.org/20250208001511.535be150@batman.local.home
Fixes: b84214890a9bc ("function_graph: Move graph notrace bit to shadow stack global var")
Signed-off-by: Steven Rostedt (Google)

treewide: const qualify ctl_tables where applicable

2025-01-28T12:48:37+00:00

Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.

Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide:
constify the ctl_table argument of proc_handlers") constified all the
proc_handlers.

Created this by running an spatch followed by a sed command:
Spatch:
    virtual patch

    @
    depends on !(file in "net")
    disable optional_qualifier
    @

    identifier table_name != {
      watchdog_hardlockup_sysctl,
      iwcm_ctl_table,
      ucma_ctl_table,
      memory_allocation_profiling_sysctls,
      loadpin_sysctl_table
    };
    @@

    + const
    struct ctl_table table_name [] = { ... };

sed:
    sed --in-place \
      -e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \
      kernel/utsname_sysctl.c

Reviewed-by: Song Liu 
Acked-by: Steven Rostedt (Google)  # for kernel/trace/
Reviewed-by: Martin K. Petersen  # SCSI
Reviewed-by: Darrick J. Wong  # xfs
Acked-by: Jani Nikula 
Acked-by: Corey Minyard 
Acked-by: Wei Liu 
Acked-by: Thomas Gleixner 
Reviewed-by: Bill O'Donnell 
Acked-by: Baoquan He 
Acked-by: Ashutosh Dixit 
Acked-by: Anna Schumaker 
Signed-off-by: Joel Granados

Merge tag 'trace-tools-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2025-01-26T22:25:58+00:00

Pull rv and tools/rtla updates from Steven Rostedt:

 - Add a test suite to test the tool

   Add a small test suite that can be used to test rtla's basic features
   to at least have something to test when applying changes.

 - Automate manual steps in monitor creation

   While creating a new monitor in RV, besides generating code from
   dot2k, there are a few manual steps which can be tedious and error
   prone, like adding the tracepoints, makefile lines and kconfig, or
   selecting events that start the monitor in the initial state.

   Updates were made to try and automate as much as possible among those
   steps to make creating a new RV monitor much quicker. It is still
   requires to select proper tracepoints, this step is harder to
   automate in a general way and, in several cases, would still need
   user intervention.

 - Have rtla timerlat hist and top set OSNOISE_WORKLOAD flag

   Have both rtla-timerlat-hist and rtla-timerlat-top set
   OSNOISE_WORKLOAD to the proper value ("on" when running with -k,
   "off" when running with -u) every time the option is available
   instead of setting it only when running with -u.

   This prevents rtla timerlat -k from giving no results when
   NO_OSNOISE_WORKLOAD is set, either manually or by an abnormally
   exited earlier run of rtla timerlat -u.

 - Stop rtla timerlat on signal properly when overloaded

   There is an issue where if rtla is run on machines with a high number
   of CPUs (100+), timerlat can generate more samples than rtla is able
   to process via tracefs_iterate_raw_events. This is especially common
   when the interval is set to 100us (rteval and cyclictest default) as
   opposed to the rtla default of 1000us, but also happens with the rtla
   default.

   Currently, this leads to rtla hanging and having to be terminated
   with SIGTERM. SIGINT setting stop_tracing is not enough, since more
   and more events are coming and tracefs_iterate_raw_events never
   exits.

   To fix this: Stop the timerlat tracer on SIGINT/SIGALRM to ensure no
   more events are generated when rtla is supposed to exit.

   Also on receiving SIGINT/SIGALRM twice, abort iteration immediately
   with tracefs_iterate_stop, making rtla exit right away instead of
   waiting for all events to be processed.

 - Account for missed events

   Due to tracefs buffer overflow, it can happen that rtla misses
   events, making the tracing results inaccurate.

   Count both the number of missed events and the total number of
   processed events, and display missed events as well as their
   percentage. The numbers are displayed for both osnoise and timerlat,
   even though for the earlier, missed events are generally not
   expected.

   For hist, the number is displayed at the end of the run; for top, it
   is displayed on each printing of the top table.

 - Changes to make osnoise more robust

   There was a dependency in the code that the first field of the
   osnoise_tool structure was the trace field. If that that ever
   changed, then the code work break. Change the code to encapsulate
   this dependency where the code that uses the structure does not have
   this dependency.

* tag 'trace-tools-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (22 commits)
  rtla: Report missed event count
  rtla: Add function to report missed events
  rtla: Count all processed events
  rtla: Count missed trace events
  tools/rtla: Add osnoise_trace_is_off()
  rtla/timerlat_top: Set OSNOISE_WORKLOAD for kernel threads
  rtla/timerlat_hist: Set OSNOISE_WORKLOAD for kernel threads
  rtla/osnoise: Distinguish missing workload option
  rtla/timerlat_top: Abort event processing on second signal
  rtla/timerlat_hist: Abort event processing on second signal
  rtla/timerlat_top: Stop timerlat tracer on signal
  rtla/timerlat_hist: Stop timerlat tracer on signal
  rtla: Add trace_instance_stop
  tools/rtla: Add basic test suite
  verification/dot2k: Implement event type detection
  verification/dot2k: Auto patch current kernel source
  verification/dot2k: Simplify manual steps in monitor creation
  rv: Simplify manual steps in monitor creation
  verification/dot2k: Add support for name and description options
  verification/dot2k: More robust template variables
  ...

Merge tag 'trace-rv-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2025-01-26T22:19:45+00:00

Pull runtime verifier and osnoise fixes from Steven Rostedt:

 - Reset idle tasks on reset for runtime verifier

   When the runtime verifier is reset, it resets the task's data that is
   being monitored. But it only iterates for_each_process() which does
   not include the idle tasks. As the idle tasks can be monitored, they
   need to be reset as well.

 - Fix the enabling and disabling of tracepoints in osnoise

   If timerlat is enabled and the WORKLOAD flag is not set, then the
   osnoise tracer will enable the migrate task tracepoint to monitor it
   for its own workload. The test to enable the tracepoint is done
   against user space modifiable parameters. On disabling of the tracer,
   those same parameters are used to determine if the tracepoint should
   be disabled. The problem is if user space were to modify the
   parameters after it enables the tracer then it may not disable the
   tracepoint.

   Instead, a static variable is used to keep track if the tracepoint
   was enabled or not. Then when the tracer shuts down, it will use this
   variable to decide to disable the tracepoint or not, instead of
   looking at the user space parameters.

* tag 'trace-rv-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing/osnoise: Fix resetting of tracepoints
  rv: Reset per-task monitors also for idle tasks

tracing/osnoise: Fix resetting of tracepoints

2025-01-24T20:20:44+00:00

If a timerlat tracer is started with the osnoise option OSNOISE_WORKLOAD
disabled, but then that option is enabled and timerlat is removed, the
tracepoints that were enabled on timerlat registration do not get
disabled. If the option is disabled again and timelat is started, then it
triggers a warning in the tracepoint code due to registering the
tracepoint again without ever disabling it.

Do not use the same user space defined options to know to disable the
tracepoints when timerlat is removed. Instead, set a global flag when it
is enabled and use that flag to know to disable the events.

 ~# echo NO_OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options
 ~# echo timerlat > /sys/kernel/tracing/current_tracer
 ~# echo OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options
 ~# echo nop > /sys/kernel/tracing/current_tracer
 ~# echo NO_OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options
 ~# echo timerlat > /sys/kernel/tracing/current_tracer

Triggers:

 ------------[ cut here ]------------
 WARNING: CPU: 6 PID: 1337 at kernel/tracepoint.c:294 tracepoint_add_func+0x3b6/0x3f0
 Modules linked in:
 CPU: 6 UID: 0 PID: 1337 Comm: rtla Not tainted 6.13.0-rc4-test-00018-ga867c441128e-dirty #73
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
 RIP: 0010:tracepoint_add_func+0x3b6/0x3f0
 Code: 48 8b 53 28 48 8b 73 20 4c 89 04 24 e8 23 59 11 00 4c 8b 04 24 e9 36 fe ff ff 0f 0b b8 ea ff ff ff 45 84 e4 0f 84 68 fe ff ff <0f> 0b e9 61 fe ff ff 48 8b 7b 18 48 85 ff 0f 84 4f ff ff ff 49 8b
 RSP: 0018:ffffb9b003a87ca0 EFLAGS: 00010202
 RAX: 00000000ffffffef RBX: ffffffff92f30860 RCX: 0000000000000000
 RDX: 0000000000000000 RSI: ffff9bf59e91ccd0 RDI: ffffffff913b6410
 RBP: 000000000000000a R08: 00000000000005c7 R09: 0000000000000002
 R10: ffffb9b003a87ce0 R11: 0000000000000002 R12: 0000000000000001
 R13: ffffb9b003a87ce0 R14: ffffffffffffffef R15: 0000000000000008
 FS:  00007fce81209240(0000) GS:ffff9bf6fdd00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055e99b728000 CR3: 00000001277c0002 CR4: 0000000000172ef0
 Call Trace:
  
  ? __warn.cold+0xb7/0x14d
  ? tracepoint_add_func+0x3b6/0x3f0
  ? report_bug+0xea/0x170
  ? handle_bug+0x58/0x90
  ? exc_invalid_op+0x17/0x70
  ? asm_exc_invalid_op+0x1a/0x20
  ? __pfx_trace_sched_migrate_callback+0x10/0x10
  ? tracepoint_add_func+0x3b6/0x3f0
  ? __pfx_trace_sched_migrate_callback+0x10/0x10
  ? __pfx_trace_sched_migrate_callback+0x10/0x10
  tracepoint_probe_register+0x78/0xb0
  ? __pfx_trace_sched_migrate_callback+0x10/0x10
  osnoise_workload_start+0x2b5/0x370
  timerlat_tracer_init+0x76/0x1b0
  tracing_set_tracer+0x244/0x400
  tracing_set_trace_write+0xa0/0xe0
  vfs_write+0xfc/0x570
  ? do_sys_openat2+0x9c/0xe0
  ksys_write+0x72/0xf0
  do_syscall_64+0x79/0x1c0
  entry_SYSCALL_64_after_hwframe+0x76/0x7e

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Tomas Glozar 
Cc: Gabriele Monaco 
Cc: Luis Goncalves 
Cc: John Kacur 
Link: https://lore.kernel.org/20250123204159.4450c88e@gandalf.local.home
Fixes: e88ed227f639e ("tracing/timerlat: Add user-space interface")
Signed-off-by: Steven Rostedt (Google)