[PATCH 00/10] ftrace: Add register_ftrace_direct()

[Steven Rostedt]

Alexei mentioned that he would like a way to access the ftrace fentry
code to jump directly to a custom eBPF trampoline instead of using
ftrace regs caller, as he said it would be faster.

I proposed a new register_ftrace_direct() function that would allow
this to happen and still work with the ftrace infrastructure. I posted
a proof of concept patch here:

 https://lore.kernel.org/r/20191023122307.756b4978@xxxxxxxxxxxxxxxxxx

This patch series is a more complete version, and the start of the
actual implementation. I haven't run it through my full test suite but
it passes my smoke tests and some other custom tests I built.

I also realized that I need to make the sample modules depend on X86_64
as it has inlined assembly in it that requires that dependency.

This is based on 5.4-rc6 plus the permanent patches that prevent
a ftrace_ops from being disabled by /proc/sys/kernel/ftrace_enabled

Below is the tree that contains this code.

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
ftrace/direct

Head SHA1: 9492654d091cb90a487ca669c58f802fa99bcd6f

Enjoy,

-- Steve


Steven Rostedt (VMware) (10):
      ftrace: Separate out the copying of a ftrace_hash from __ftrace_hash_move()
      ftrace: Separate out functionality from ftrace_location_range()
      ftrace: Add register_ftrace_direct()
      ftrace: Add ftrace_find_direct_func()
      ftrace: Add sample module that uses register_ftrace_direct()
      ftrace/selftest: Add tests to test register_ftrace_direct()
      ftrace: Add another example of register_ftrace_direct() use case
      ftrace/selftests: Update the direct call selftests to test two direct calls
      ftrace/x86: Add register_ftrace_direct() for custom trampolines
      ftrace/x86: Add a counter to test function_graph with direct

----
 arch/x86/Kconfig                                   |   1 +
 arch/x86/include/asm/ftrace.h                      |  13 +
 arch/x86/kernel/ftrace.c                           |  14 +
 arch/x86/kernel/ftrace_64.S                        |  33 +-
 include/linux/ftrace.h                             |  50 ++-
 kernel/trace/Kconfig                               |   8 +
 kernel/trace/ftrace.c                              | 420 +++++++++++++++++++--
 samples/Kconfig                                    |   7 +
 samples/Makefile                                   |   1 +
 samples/ftrace/Makefile                            |   4 +
 samples/ftrace/ftrace-direct-too.c                 |  51 +++
 samples/ftrace/ftrace-direct.c                     |  45 +++
 .../ftrace/test.d/direct/ftrace-direct.tc          |  69 ++++
 .../ftrace/test.d/direct/kprobe-direct.tc          |  84 +++++
 14 files changed, 759 insertions(+), 41 deletions(-)
 create mode 100644 samples/ftrace/Makefile
 create mode 100644 samples/ftrace/ftrace-direct-too.c
 create mode 100644 samples/ftrace/ftrace-direct.c
 create mode 100644 tools/testing/selftests/ftrace/test.d/direct/ftrace-direct.tc
 create mode 100644 tools/testing/selftests/ftrace/test.d/direct/kprobe-direct.tc