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(-)
