Pull ring-buffer updates from Steven Rostedt

 - Do not invalidate entire buffer for invalid sub-buffers

   For the persistent ring buffer, if one sub-buffer is found to be
   invalid, it invalidates the entire per CPU ring buffer. This can lose
   a lot of valuable data if there's some corruption with the writes to
   the buffer not syncing properly on a hard crash. Instead, if a
   sub-buffer is found to be invalid, simply zero it out and mark it for
   "missed events".

   When the persistent ring buffer is read and a sub-buffer that was
   cleared due to being invalid on boot up is discovered, the output
   will show "[LOST EVENTS]" to let the user know that events were
   missing at that location. Displaying the events from valid buffers
   can still be useful.

 - Add a test to be able to test corrupted sub-buffers

   If a persistent ring buffer is created as "ptraingtest" and the new
   config that adds the test is enabled, when a panic happens, the
   kernel will randomly corrupt one of the per CPU ring buffers. On boot
   up, the sub-buffers with the corruption should be cleared and
   flagged. When reading this buffer, the missed events should should
   [LOST EVENTS].

 - Add commit number in the sub-buffer meta debug info

   The commit is used to know the content of a meta page. Add it to the
   buffer_meta file that is shown for each per CPU buffer.

 - Clean up the persistent ring buffer validation code

   Add some helper functions and make variable names more consistent.

* tag 'trace-ring-buffer-v7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Better comment the use of RB_MISSED_EVENTS
  ring-buffer: Show persistent buffer dropped events in trace_pipe file
  ring-buffer: Show persistent buffer dropped events in trace file
  ring-buffer: Have dropped subbuffers be persistent across reboots
  ring-buffer: Cleanup buffer_data_page related code
  ring-buffer: Cleanup persistent ring buffer validation
  ring-buffer: Show commit numbers in buffer_meta file
  ring-buffer: Add persistent ring buffer invalid-page inject test
  ring-buffer: Skip invalid sub-buffers when rewinding persistent ring buffer
  ring-buffer: Skip invalid sub-buffers when validating persistent ring buffer

Add a self-corrupting test for the persistent ring buffer.

This will inject an erroneous value to some sub-buffer pages (where
the index is even or multiples of 5) in the persistent ring buffer
when the kernel panics, and checks whether the number of detected
invalid pages and the total entry_bytes are the same as the recorded
values after reboot.

This ensures that the kernel can correctly recover a partially
corrupted persistent ring buffer after a reboot or panic.

The test only runs on the persistent ring buffer whose name is
"ptracingtest". The user has to fill it with events before a
kernel panic.

To run the test, enable CONFIG_RING_BUFFER_PERSISTENT_INJECT
and add the following kernel cmdline:

 reserve_mem=20M:2M:trace trace_instance=ptracingtest^traceoff@trace
 panic=1

Run the following commands after the 1st boot:

 cd /sys/kernel/tracing/instances/ptracingtest
 echo 1 > tracing_on
 echo 1 > events/enable
 sleep 3
 echo c > /proc/sysrq-trigger

After panic message, the kernel will reboot and run the verification
on the persistent ring buffer, e.g.

 Ring buffer meta [2] invalid buffer page detected
 Ring buffer meta [2] is from previous boot! (318 pages discarded)
 Ring buffer testing [2] invalid pages: PASSED (318/318)
 Ring buffer testing [2] entry_bytes: PASSED (1300476/1300476)

Link: https://patch.msgid.link/20260522171051.260140328@kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

trace_iterator_increment() is only called from trace_find_next_entry_inc().
It's a small enough function that really doesn't need to be separated.

Move the code from trace_iterator_increment() into
trace_find_next_entry_inc() and remove trace_iterator_increment().

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260521095026.20c9799d@gandalf.local.home
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

The events/ prefix should be removed, since synthetic_events
is now directly under the tracing root directory.

Cc: <mhiramat@kernel.org>
Cc: <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260521015211.111-1-ao.sun@transsion.com
Signed-off-by: Ao Sun <ao.sun@transsion.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Use krealloc_array() when growing tr->topts instead of open-coding the
size calculation in krealloc().

This makes the resize path use the helper intended for array allocations
and avoids manual multiplication of the element count and element size.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260519083409.3885032-1-pengyu@kylinos.cn
Signed-off-by: Yu Peng <pengyu@kylinos.cn>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Pull tracing updates from Steven Rostedt:

 - Fix printf format warning for bprintf

   sunrpc uses a trace_printk() that triggers a printf warning during
   the compile. Move the __printf() attribute around for when debugging
   is not enabled the warning will go away

 - Remove redundant check for EVENT_FILE_FL_FREED in
   event_filter_write()

   The FREED flag is checked in the call to event_file_file() and then
   checked again right afterward, which is unneeded

 - Clean up event_file_file() and event_file_data() helpers

   These helper functions played a different role in the past, but now
   with eventfs, the READ_ONCE() isn't needed. Simplify the code a bit
   and also add a warning to event_file_data() if the file or its data
   is not present

 - Remove updating file->private_data in tracing open

   All access to the file private data is handled by the helper
   functions, which do not use file->private_data. Stop updating it on
   open

 - Show ENUM names in function arguments via BTF in function tracing

   When showing the function arguments when func-args option is set for
   function tracing, if one of the arguments is found to be an enum,
   show the name of the enum instead of its number

 - Add new trace_call__##name() API for tracepoints

   Tracepoints are enabled via static_branch() blocks, where when not
   enabled, there's only a nop that is in the code where the execution
   will just skip over it. When tracing is enabled, the nop is converted
   to a direct jump to the tracepoint code. Sometimes more calculations
   are required to be performed to update the parameters of the
   tracepoint. In this case, trace_##name##_enabled() is called which is
   a static_branch() that gets enabled only when the tracepoint is
   enabled. This allows the extra calculations to also be skipped by the
   nop:

	if (trace_foo_enabled()) {
		x = bar();
		trace_foo(x);
	}

   Where the x=bar() is only performed when foo is enabled. The problem
   with this approach is that there's now two static_branch() calls. One
   for checking if the tracepoint is enabled, and then again to know if
   the tracepoint should be called. The second one is redundant

   Introduce trace_call__foo() that will call the foo() tracepoint
   directly without doing a static_branch():

	if (trace_foo_enabled()) {
		x = bar();
		trace_call__foo();
	}

 - Update various locations to use the new trace_call__##name() API

 - Move snapshot code out of trace.c

   Cleaning up trace.c to not be a "dump all", move the snapshot code
   out of it and into a new trace_snapshot.c file

 - Clean up some "%*.s" to "%*s"

 - Allow boot kernel command line options to be called multiple times

   Have options like:

	ftrace_filter=foo ftrace_filter=bar ftrace_filter=zoo

   Equal to:

	ftrace_filter=foo,bar,zoo

 - Fix ipi_raise event CPU field to be a CPU field

   The ipi_raise target_cpus field is defined as a __bitmask(). There is
   now a __cpumask() field definition. Update the field to use that

 - Have hist_field_name() use a snprintf() and not a series of strcat()

   It's safer to use snprintf() that a series of strcat()

 - Fix tracepoint regfunc balancing

   A tracepoint can define a "reg" and "unreg" function that gets called
   before the tracepoint is enabled, and after it is disabled
   respectively. But on error, after the "reg" func is called and the
   tracepoint is not enabled, the "unreg" function is not called to tear
   down what the "reg" function performed

 - Fix output that shows what histograms are enabled

   Event variables are displayed incorrectly in the histogram output

   Instead of "sched.sched_wakeup.$var", it is showing
   "$sched.sched_wakeup.var" where the '$' is in the incorrect location

 - Some other simple cleanups

* tag 'trace-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (24 commits)
  selftests/ftrace: Add test case for fully-qualified variable references
  tracing: Fix fully-qualified variable reference printing in histograms
  tracepoint: balance regfunc() on func_add() failure in tracepoint_add_func()
  tracing: Rebuild full_name on each hist_field_name() call
  tracing: Report ipi_raise target CPUs as cpumask
  tracing: Remove duplicate latency_fsnotify() stub
  tracing: Preserve repeated trace_trigger boot parameters
  tracing: Append repeated boot-time tracing parameters
  tracing: Remove spurious default precision from show_event_trigger/filter formats
  cpufreq: Use trace_call__##name() at guarded tracepoint call sites
  tracing: Remove tracing_alloc_snapshot() when snapshot isn't defined
  tracing: Move snapshot code out of trace.c and into trace_snapshot.c
  mm: damon: Use trace_call__##name() at guarded tracepoint call sites
  btrfs: Use trace_call__##name() at guarded tracepoint call sites
  spi: Use trace_call__##name() at guarded tracepoint call sites
  i2c: Use trace_call__##name() at guarded tracepoint call sites
  kernel: Use trace_call__##name() at guarded tracepoint call sites
  tracepoint: Add trace_call__##name() API
  tracing: trace_mmap.h: fix a kernel-doc warning
  tracing: Pretty-print enum parameters in function arguments
  ...

When the persistent ring buffer was first introduced, it did not make
sense to start tracing for it on the kernel command line. That's because
if there was a crash, the start of events would invalidate the events from
the previous boot that had the crash.

But now that there's a "backup" instance that can take a snapshot of the
persistent ring buffer when boot starts, it is possible to have the
persistent ring buffer start events at boot up and not lose the old events.

Update the code where the boot events start after all boot time instances
are created. This will allow the backup instance to copy the persistent
ring buffer from the previous boot, and allow the persistent ring buffer
to start tracing new events for the current boot.

  reserve_mem=100M:12M:trace trace_instance=boot_mapped^@trace,sched trace_instance=backup=boot_mapped

The above will create a boot_mapped persistent ring buffer and enabled the
scheduler events. If there's a crash, a "backup" instance will be created
holding the events of the persistent ring buffer from the previous boot,
while the persistent ring buffer will once again start tracing scheduler
events of the current boot.

Now the user doesn't have to remember to start the persistent ring buffer.
It will always have the events started at each boot.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/20260331163924.6ccb3896@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Since the backup instance is readonly, after reading all data via pipe, no
data is left on the instance. Thus it can be removed safely after closing
all files.  This also removes it if user resets the ring buffer manually
via 'trace' file.

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/177502547711.1311542.12572973358010839400.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Since there is no reason to reuse the backup instance, make it readonly
(but erasable).  Note that only backup instances are readonly, because
other trace instances will be empty unless it is writable.  Only backup
instances have copy entries from the original.

With this change, most of the trace control files are removed from the
backup instance, including eventfs enable/filter etc.

 # find /sys/kernel/tracing/instances/backup/events/ | wc -l
 4093
 # find /sys/kernel/tracing/instances/boot_map/events/ | wc -l
 9573

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/177502546939.1311542.1826814401724828930.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Some tracing boot parameters already accept delimited value lists, but
their __setup() handlers keep only the last instance seen at boot.
Make repeated instances append to the same boot-time buffer in the
format each parser already consumes.

Use a shared trace_append_boot_param() helper for the ftrace filters,
trace_options, and kprobe_event boot parameters.

This also lets Bootconfig array values work naturally when they expand
to repeated param=value entries.

Before this change, only the last instance from each repeated
parameter survived boot.

Link: https://patch.msgid.link/20260330181103.1851230-1-atwellwea@gmail.com
Signed-off-by: Wesley Atwell <atwellwea@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>