hi,
sending 2 fixes to fix kernel support for loading
trampoline programs in bcc/bpftrace and allow to
unwind through trampoline/dispatcher.
Original rfc post [1].
Speedup output of perf bench while running klockstat.py
on kprobes vs trampolines:
Without:
$ perf bench sched messaging -l 50000
...
Total time: 18.571 [sec]
With current kprobe tracing:
$ perf bench sched messaging -l 50000
...
Total time: 183.395 [sec]
With kfunc tracing:
$ perf bench sched messaging -l 50000
...
Total time: 39.773 [sec]
v4 changes:
- rebased on latest bpf-next/master
- removed image tree mutex and use trampoline_mutex instead
- checking directly for string pointer in patch 1 [Alexei]
- skipped helpers patches, as they are no longer needed [Alexei]
v3 changes:
- added ack from John Fastabend for patch 1
- move out is_bpf_image_address from is_bpf_text_address call [David]
v2 changes:
- make the unwind work for dispatcher as well
- added test for allowed trampolines count
- used raw tp pt_regs nest-arrays for trampoline helpers
thanks,
jirka
[1] https://lore.kernel.org/netdev/20191229143740.29143-1-jolsa@xxxxxxxxxx/
---
Jiri Olsa (3):
bpf: Allow BTF ctx access for string pointers
bpf: Allow to resolve bpf trampoline and dispatcher in unwind
selftest/bpf: Add test for allowed trampolines count
include/linux/bpf.h | 12 +++++++++++-
kernel/bpf/btf.c | 16 ++++++++++++++++
kernel/bpf/dispatcher.c | 4 ++--
kernel/bpf/trampoline.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
kernel/extable.c | 7 +++++--
tools/testing/selftests/bpf/prog_tests/trampoline_count.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/progs/test_trampoline_count.c | 21 +++++++++++++++++++++
7 files changed, 242 insertions(+), 12 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/trampoline_count.c
create mode 100644 tools/testing/selftests/bpf/progs/test_trampoline_count.c
