linux.git/kernel/trace/Makefile, branch v7.2-rc1

Merge tag 'trace-v7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-06-19T03:53:00+00:00

Pull tracing updates from Steven Rostedt:

 - Remove a redundant IS_ERR() check

   trace_pipe_open() already checks for IS_ERR() and does it again in
   the return path. Remove the return check.

 - Export seq_buf_putmem_hex() to allow kunit tests against them

   To add Kunit tests on seq_buf_putmem_hex(), it needs to be exported.

 - Replace strcat() and strcpy() with seq_buf() logic

   The code for synthetic events uses a series of strcat() and strcpy()
   which can be error prone. Replace them with seq_buf() logic that does
   all the necessary bound checking.

 - Add a lockdep rcu_is_watching() to trace_##event##_enabled() call

   The trace_##event##_enabled() is a static branch that is true if the
   "event" is enabled. But this can hide bugs if this logic is in a
   location where RCU is disabled and not "watching". It would only
   trigger if lockdep is enabled and the event is enabled.

   Add a "rcu_is_watching()" warning if lockdep is enabled in that
   helper function to trigger regardless if the event is enabled or not.

 - Remove the local variable in the trace_printk() macro

   For name space integrity, remove the _______STR variable in the
   trace_printk() macro for using the sizeof() macro directly.

 - Use guard()s for the trace_recursion_record.c file

 - Fix typo in a comment of eventfs_callback() kerneldoc

 - Use trace_call__##event() in events within trace_##event##_enabled()

   A couple of events are called within an if block guarded by
   trace_##event##_enabled(). That is a static key that is only enabled
   when the event is enabled. The trace_call_##event() calls the
   tracepoint code directly without adding a redundant static key for
   that check.

 - Allow perf to read synthetic events

   Currently, perf does not have the ability to enable a synthetic
   event. If it does, it will either cause a kernel warning or error
   with "No such device". Synthetic events are not much different than
   kprobes and perf can handle fine with a few modifications.

 - Replace printk(KERN_WARNING ...) with pr_warn()

 - Replace krealloc() on an array with krealloc_array()

 - Fix README file path name for synthetic events

 - Change tracing_map tracing_map_array to use a flexible array

   Instead of allocating a separate pointer to hold the pages field of
   tracing_map_array, allocate the pages field as a flexible array when
   allocating the structure.

 - Fold trace_iterator_increment() into trace_find_next_entry_inc()

   The function trace_iterator_increment() was only used by
   trace_find_next_entry_inc(). It's not big enough to be a helper
   function for one user. Fold it into its caller.

 - Make field_var_str field a flexible array of hist_elt_data

   Instead of allocating a separate pointer for the field_var_str array
   of the hist_elt_data structure, allocate it as a flexible array when
   allocating the structure.

 - Disable KCOV for trace_irqsoff.c

   Like trace_preemptirq.c, trace_irqsoff.c has code that will crash
   when KCOV is enabled on ARM. The irqsoff tracing can be called on ARM
   because the irqsoff tracing code can be run from early interrupt code
   and produce coverage unrelated to syscall inputs.

 - Fix warning in __unregister_ftrace_function() called by perf

   Perf calls unregister_ftrace_function() without checking if its
   ftrace_ops has already been unregistered. There's an error path where
   on clean up it will unregister the ftrace_ops even if it wasn't
   registered and causes a warning.

* tag 'trace-v7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  perf/ftrace: Fix WARNING in __unregister_ftrace_function
  tracing: Disable KCOV instrumentation for trace_irqsoff.o
  tracing: Turn hist_elt_data field_var_str into a flexible array
  tracing: Move trace_iterator_increment() into trace_find_next_entry_inc()
  tracing: Simplify pages allocation for tracing_map logic
  tracing: Fix README path for synthetic_events
  tracing: Use krealloc_array() for trace option array growth
  tracing/branch: Use pr_warn() instead of printk(KERN_WARNING)
  tracing: Allow perf to read synthetic events
  HID: Use trace_call__##name() at guarded tracepoint call sites
  cpufreq: amd-pstate: Use trace_call__##name() at guarded tracepoint call site
  tracefs: Fix typo in a comment of eventfs_callback() kerneldoc
  tracing: Switch trace_recursion_record.c code over to use guard()
  tracing: Remove local variable for argument detection from trace_printk()
  tracepoint: Add lockdep rcu_is_watching() check to trace_##name##_enabled()
  tracing: Bound synthetic-field strings with seq_buf
  seq_buf: Export seq_buf_putmem_hex() and add KUnit tests
  tracing: Remove redundant IS_ERR() check in trace_pipe_open()

tracing: Disable KCOV instrumentation for trace_irqsoff.o

2026-05-29T15:21:58+00:00

When KCOV runs its boot selftest with whole-kernel instrumentation
enabled, it sets current->kcov_mode to KCOV_MODE_TRACE_PC without
installing a coverage area. Any instrumented code accepted as task-context
coverage in that window dereferences current->kcov_area and crashes.

On ARMv5 Versatile PB with CONFIG_KCOV_SELFTEST=y,
CONFIG_KCOV_INSTRUMENT_ALL=y and CONFIG_IRQSOFF_TRACER=y, boot hits a
NULL pointer fault during the selftest:

  kcov: running self test
  Internal error: Oops: 5 [#1] ARM
  PC is at __sanitizer_cov_trace_pc+0x4c/0x90
  Kernel panic - not syncing: Fatal exception

A diagnostic run showed the unwanted coverage comes from the IRQs-off
tracer callbacks reached from ARM IRQ entry before hardirq context is
visible to KCOV:

  __sanitizer_cov_trace_pc from tracer_hardirqs_off+0x18/0x1cc
  tracer_hardirqs_off from trace_hardirqs_off+0x34/0x54
  trace_hardirqs_off from __irq_svc+0x58/0xb0
  __irq_svc from kcov_init+0x7c/0xdc

and similarly through tracer_hardirqs_on().

trace_preemptirq.o is already excluded because this tracing path can run
from early interrupt code and produce coverage unrelated to syscall
inputs. Exclude trace_irqsoff.o as well, instead of requiring users to
turn off CONFIG_KCOV_INSTRUMENT_ALL=y, which is the default whole-kernel
KCOV mode.

With the exclusion in place, the same ARMv5 Versatile PB QEMU test boots
through the KCOV selftest and reaches userspace.

Tested on ARMv5 Versatile PB QEMU with CONFIG_KCOV_SELFTEST=y,
CONFIG_KCOV_INSTRUMENT_ALL=y and CONFIG_IRQSOFF_TRACER=y.

Link: https://patch.msgid.link/20260525170428.67211-1-kmehltretter@gmail.com
Assisted-by: Codex:gpt-5
Signed-off-by: Karl Mehltretter 
Signed-off-by: Steven Rostedt

tracing: Create output file from cmd_check_undefined

2026-05-21T12:31:55+00:00

As the output file is currently never created, the check will run every
time, even if the inputs have not changed.

Create an empty output file which allows make to skip the execution when
it is not necessary.

Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Vincent Donnefort 
Cc: Marc Zyngier 
Cc: Arnd Bergmann 
Link: https://patch.msgid.link/20260520-tracing-ringbuffer-check-v1-1-d979cfab1338@weissschuh.net
Fixes: 1211907ac0b5 ("tracing: Generate undef symbols allowlist for simple_ring_buffer")
Fixes: 58b4bd18390e ("tracing: Adjust cmd_check_undefined to show unexpected undefined symbols")
Reviewed-by: Nathan Chancellor 
Tested-by: Nathan Chancellor 
Signed-off-by: Thomas Weißschuh 
Signed-off-by: Steven Rostedt

ring-buffer remote: Avoid unexpected symbol warnings (arm, s390)

2026-05-15T18:59:30+00:00

The now more verbose check found more architecture specific symbol
missing from the whitelist, during randconfig testing on s390
and 32-bit arm:

Unexpected symbols in kernel/trace/simple_ring_buffer.o:
         U __aeabi_unwind_cpp_pr1

Unexpected symbols in kernel/trace/simple_ring_buffer.o:
                 U __s390_indirect_jump_r1
                 U __s390_indirect_jump_r10
                 U __s390_indirect_jump_r14
                 U __s390_indirect_jump_r2
                 U __s390_indirect_jump_r5
                 U __s390_indirect_jump_r7
                 U __s390_indirect_jump_r8
                 U __s390_indirect_jump_r9
make[6]: *** [/home/arnd/arm-soc/kernel/trace/Makefile:160: kernel/trace/simple_ring_buffer.o.checked] Error 1

Add these to the list and keep it roughly sorted into sanitizer
and architecture symbols.

Cc: Masami Hiramatsu 
Cc: Marc Zyngier 
Cc: Nathan Chancellor 
Cc: Vincent Donnefort 
Cc: Mathieu Desnoyers 
Cc: Paolo Bonzini 
Link: https://patch.msgid.link/20260515105717.1023007-1-arnd@kernel.org
Fixes: 1211907ac0b5 ("tracing: Generate undef symbols allowlist for simple_ring_buffer")
Signed-off-by: Arnd Bergmann 
Signed-off-by: Steven Rostedt

tracing: Make undefsyms_base.c a first-class citizen

2026-04-22T15:24:41+00:00

Linus points out that dumping undefsyms_base.c form the Makefile
is rather ugly, and that a much better course of action would be
to have this file as a first-class citizen in the git tree.

This allows some extra cleanup in the Makefile, and the removal of
the .gitignore file in kernel/trace.

Cc: Marc Zyngier 
Cc: Arnd Bergmann 
Link: https://lore.kernel.org/r/CAHk-=wieqGd_XKpu8UxDoyADZx8TDe8CF3RmkUXt5N_9t5Pf_w@mail.gmail.com
Link: https://lore.kernel.org/all/20260421095446.2951646-1-maz@kernel.org/
Link: https://patch.msgid.link/20260421100455.324333-1-pbonzini@redhat.com
Reported-by: Linus Torvalds 
Reviewed-by: Nathan Chancellor 
Tested-by: Nathan Chancellor 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Steven Rostedt

Merge tag 'trace-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-04-17T16:43:12+00:00

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
  ...

tracing: Move snapshot code out of trace.c and into trace_snapshot.c

2026-03-26T14:24:40+00:00

The trace.c file was a dumping ground for most tracing code. Start
organizing it better by moving various functions out into their own files.
Move all the snapshot code, including the max trace code into its own
trace_snapshot.c file.

Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Link: https://patch.msgid.link/20260324140145.36352d6a@gandalf.local.home
Signed-off-by: Steven Rostedt (Google)

tracing: Adjust cmd_check_undefined to show unexpected undefined symbols

2026-03-23T09:22:22+00:00

When the check_undefined command in kernel/trace/Makefile fails, there
is no output, making it hard to understand why the build failed. Capture
the output of the $(NM) + grep command and print it when failing to make
it clearer what the problem is.

Fixes: a717943d8ecc ("tracing: Check for undefined symbols in simple_ring_buffer")
Signed-off-by: Nathan Chancellor 
Reviewed-by: Vincent Donnefort 
Acked-by: Arnd Bergmann 
Link: https://patch.msgid.link/20260320-cmd_check_undefined-verbose-v1-1-54fc5b061f94@kernel.org
Signed-off-by: Marc Zyngier

tracing: Restore accidentally removed SPDX tag

2026-03-18T07:05:11+00:00

Restore the SPDX tag that was accidentally dropped.

Fixes: 7e4b6c94300e3 ("tracing: add more symbols to whitelist")
Reported-by: Nathan Chancellor 
Cc: Arnd Bergmann 
Cc: Vincent Donnefort 
Cc: Steven Rostedt 
Reviewed-by: Steven Rostedt (Google) 
Link: https://patch.msgid.link/20260317194252.1890568-1-maz@kernel.org
Signed-off-by: Marc Zyngier

tracing: Generate undef symbols allowlist for simple_ring_buffer

2026-03-17T09:01:19+00:00

Compiler and tooling-generated symbols are difficult to maintain
across all supported architectures. Make the allowlist more robust by
replacing the harcoded list with a mechanism that automatically detects
these symbols.

This mechanism generates a C function designed to trigger common
compiler-inserted symbols.

Signed-off-by: Vincent Donnefort 
Reviewed-by: Nathan Chancellor 
Tested-by: Nathan Chancellor 
Acked-by: Steven Rostedt (Google) 
Tested-by: Arnd Bergmann 
Link: https://patch.msgid.link/20260316092845.3367411-1-vdonnefort@google.com
[maz: added __msan prefix to allowlist as pointed out by Arnd]
Signed-off-by: Marc Zyngier