[PATCHv4 bpf-next 0/6] bpf: Fixes for CONFIG_X86_KERNEL_IBT

[Jiri Olsa <jolsa@kernel.org>]

hi,
Martynas reported bpf_get_func_ip returning +4 address when
CONFIG_X86_KERNEL_IBT option is enabled and I found there are
some failing bpf tests when this option is enabled.

The CONFIG_X86_KERNEL_IBT option adds endbr instruction at the
function entry, so the idea is to 'fix' entry ip for kprobe_multi
and trampoline probes, because they are placed on the function
entry.

v4 changes:
  - used get_kernel_nofault to read previous instruction [Peter]
  - used movabs instruction in trampoline comment [Peter]
  - renamed fentry_ip argument in kprobe_multi_link_handler [Peter]

v3 changes:
  - using 'unused' bpf function to get IBT config option
    into selftest skeleton
  - rebased to current bpf-next/master
  - added ack/review from Masami

v2 changes:
  - change kprobes get_func_ip to return zero for kprobes
    attached within the function body [Andrii]
  - detect IBT config and properly test kprobe with offset 
    [Andrii]

v1 changes:
  - read previous instruction in kprobe_multi link handler
    and adjust entry_ip for CONFIG_X86_KERNEL_IBT option
  - split first patch into 2 separate changes
  - update changelogs

thanks,
jirka


---
Jiri Olsa (6):
      kprobes: Add new KPROBE_FLAG_ON_FUNC_ENTRY kprobe flag
      ftrace: Keep the resolved addr in kallsyms_callback
      bpf: Use given function address for trampoline ip arg
      bpf: Adjust kprobe_multi entry_ip for CONFIG_X86_KERNEL_IBT
      bpf: Return value in kprobe get_func_ip only for entry address
      selftests/bpf: Fix get_func_ip offset test for CONFIG_X86_KERNEL_IBT

 arch/x86/net/bpf_jit_comp.c                               | 11 +++++------
 include/linux/kprobes.h                                   |  1 +
 kernel/kprobes.c                                          |  6 +++++-
 kernel/trace/bpf_trace.c                                  | 25 ++++++++++++++++++++++---
 kernel/trace/ftrace.c                                     |  3 +--
 tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++-----------
 tools/testing/selftests/bpf/progs/get_func_ip_test.c      | 25 +++++++++++++------------
 tools/testing/selftests/bpf/progs/kprobe_multi.c          |  4 +---
 8 files changed, 96 insertions(+), 38 deletions(-)