Merge tag 'trace-ftrace-v7.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull ftrace updates from Steven Rostedt:

 - Have the stacktrace option work with func-args

   The func_stack_trace option has it's own ftrace handler and so does
   the func-args option. When they are both set, neither would run. The
   function tracer itself would error out.

   Allow the stacktrace and function args to work together.

 - Avoid BTF lookup in atomic context

   The ftrace_dump() can call function graph tracing output from an
   atomic context (like an NMI watchdog going off). The BTF lookup is
   not safe to call from atomic context. Have btf_find_func_proto()
   return if in atomic context.

 - Build trace_btf.c when CONFIG_DEBUG_INFO_BTF is enabled

   New code is depending on trace_btf.c but that only gets built when
   BPF_SYSCALL is also enabled. As the new code doesn't depend on that,
   have trace_btf.c get built with just DEBUG_INFO_BTF set.

 - Have function graph return values have BTF processing

   Have the return values printed by the function graph tracer use BTF
   to print the values in better format. For example, if it's a char,
   short, signed or unsigned, print according to the value defined by
   BTF.

 - Add a "max" field to the function profiler stats

   The function profiler shows all the functions run in the kernel, the
   number of times they are called, and the total time they took up.
   Also add a "max" field which holds the longest time a function ran
   for.

 - Fix memory leak in module with all skipped functions

   On module load, the ftrace entries are recorded to keep track of what
   functions can be traced or not. Some functions may be skipped for
   various reasons (some defined by the architecture). If all functions
   in the module are skipped, its data page is not freed and can leak.
   Catch this case and free the empty page.

 - Allow architectures to reject functions from being traced

   Allow architectures to skip a function address by returning zero from
   ftrace_call_adjust().

 - Initialize modname and offset in print_rec()

   The variables modname and offset are initialized by
   kallsyms_lookup(). If that fails, the values are not set, but the
   code continues to print other information. The modname and offset are
   used later, but if the kallsyms_lookup() failed, they will not be
   set.

   If a module is being loaded and unloaded at the same time as reading
   the available_filter_functions file, it can cause a fault due to the
   lookup failing and modname and offset being used uninitialized.

* tag 'trace-ftrace-v7.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ftrace: Initialize modname and offset in print_rec()
  ftrace: Let ftrace_call_adjust() reject a patch site
  ftrace: Do not leak a module's empty page group
  ftrace: Add max field to function profiler stats
  tracing: Update funcgraph-retval documentation
  fgraph: Enhance funcgraph-retval with BTF-based type-aware output
  ftrace: Build trace_btf.c when CONFIG_DEBUG_INFO_BTF is enabled
  tracing: Avoid BTF lookup in atomic context
  ftrace: Have stacktrace option work with func-args

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