[PATCH bpf-next 0/3] uprobe: uretprobe speed up

[Jiri Olsa <jolsa@kernel.org>]

hi,
as part of the effort on speeding up the uprobes [0] coming with
return uprobe optimization by using syscall instead of the trap
on the uretprobe trampoline.

The speed up depends on instruction type that uprobe is installed
and depends on specific HW type, please check patch 1 for details.

I added extra bpf selftest to check on registers values before and
after uretprobe to make sure the syscall saves all the needed regs.

changes from RFC:
  - using __NR_uretprobe instead hardcoded syscall value [Andrii]
  - using __builtin_memcpy to copy registers [Andrii]
  - adding more comments
  - Oleg provided the code that enabled the syscall to take the
    sysret path, which made it lot faster [Oleg]
  - nocf_check attribute change was sent separatelly
  - added test for checking up changed registers in uprobe consumer

thanks,
jirka


[0] https://lore.kernel.org/bpf/ZeCXHKJ--iYYbmLj@krava/
---
Jiri Olsa (3):
      uprobe: Add uretprobe syscall to speed up return probe
      selftests/bpf: Add uretprobe syscall test for regs integrity
      selftests/bpf: Add uretprobe syscall test for regs changes

 arch/x86/entry/syscalls/syscall_64.tbl                  |   1 +
 arch/x86/kernel/uprobes.c                               |  83 ++++++++++++++++++++++++++++++++++
 include/linux/syscalls.h                                |   2 +
 include/linux/uprobes.h                                 |   2 +
 include/uapi/asm-generic/unistd.h                       |   5 ++-
 kernel/events/uprobes.c                                 |  18 ++++++--
 kernel/sys_ni.c                                         |   2 +
 tools/include/linux/compiler.h                          |   4 ++
 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c   | 119 ++++++++++++++++++++++++++++++++++++++++++++++++-
 tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c | 230 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/uprobe_syscall.c      |  15 +++++++
 11 files changed, 475 insertions(+), 6 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
 create mode 100644 tools/testing/selftests/bpf/progs/uprobe_syscall.c