[RFCv3 00/19] x86/ftrace/bpf: Add batch support for direct/tracing attach

Jiri Olsa
2021-06-05T11:10:48Z

hi,
saga continues.. ;-) previous post is in here [1]

After another discussion with Steven, he mentioned that if we fix
the ftrace graph problem with direct functions, he'd be open to
add batch interface for direct ftrace functions.

He already had prove of concept fix for that, which I took and broke
up into several changes. I added the ftrace direct batch interface
and bpf new interface on top of that.

It's not so many patches after all, so I thought having them all
together will help the review, because they are all connected.
However I can break this up into separate patchsets if necessary.

This patchset contains:

1) patches (1-4) that fix the ftrace graph tracing over the function
with direct trampolines attached
2) patches (5-8) that add batch interface for ftrace direct function
register/unregister/modify
3) patches (9-19) that add support to attach BPF program to multiple
functions

In nutshell:

Ad 1) moves the graph tracing setup before the direct trampoline
prepares the stack, so they don't clash

Ad 2) uses ftrace_ops interface to register direct function with
all functions in ftrace_ops filter.

Ad 3) creates special program and trampoline type to allow attachment
of multiple functions to single program.

There're more detailed desriptions in related changelogs.

I have working bpftrace multi attachment code on top this. I briefly
checked retsnoop and I think it could use the new API as well.

Also available at:
https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
bpf/batch

thanks,
jirka

[1] https://lore.kernel.org/bpf/20210413121516.1467989-1-jolsa@kernel.org/

---
Jiri Olsa (17):
x86/ftrace: Remove extra orig rax move
tracing: Add trampoline/graph selftest
ftrace: Add ftrace_add_rec_direct function
ftrace: Add multi direct register/unregister interface
ftrace: Add multi direct modify interface
ftrace/samples: Add multi direct interface test module
bpf, x64: Allow to use caller address from stack
bpf: Allow to store caller's ip as argument
bpf: Add support to load multi func tracing program
bpf: Add bpf_trampoline_alloc function
bpf: Add support to link multi func tracing program
libbpf: Add btf__find_by_pattern_kind function
libbpf: Add support to link multi func tracing program
selftests/bpf: Add fentry multi func test
selftests/bpf: Add fexit multi func test
selftests/bpf: Add fentry/fexit multi func test
selftests/bpf: Temporary fix for fentry_fexit_multi_test

Steven Rostedt (VMware) (2):
x86/ftrace: Remove fault protection code in prepare_ftrace_return
x86/ftrace: Make function graph use ftrace directly

arch/x86/include/asm/ftrace.h | 9 ++++--
arch/x86/kernel/ftrace.c | 71 ++++++++++++++++++++++-----------------------
arch/x86/kernel/ftrace_64.S | 30 +------------------
arch/x86/net/bpf_jit_comp.c | 31 ++++++++++++++------
include/linux/bpf.h | 14 +++++++++
include/linux/ftrace.h | 22 ++++++++++++++
include/uapi/linux/bpf.h | 12 ++++++++
kernel/bpf/btf.c | 5 ++++
kernel/bpf/syscall.c | 220 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
kernel/bpf/trampoline.c | 83 ++++++++++++++++++++++++++++++++++++++---------------
kernel/bpf/verifier.c | 3 +-
kernel/trace/fgraph.c | 8 ++++--
kernel/trace/ftrace.c | 211 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------------
kernel/trace/trace_selftest.c | 49 ++++++++++++++++++++++++++++++-
samples/ftrace/Makefile | 1 +
samples/ftrace/ftrace-direct-multi.c | 52 +++++++++++++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 12 ++++++++
tools/lib/bpf/bpf.c | 11 ++++++-
tools/lib/bpf/bpf.h | 4 ++-
tools/lib/bpf/btf.c | 68 +++++++++++++++++++++++++++++++++++++++++++
tools/lib/bpf/btf.h | 3 ++
tools/lib/bpf/libbpf.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/multi_check.h | 53 ++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/prog_tests/fentry_fexit_multi_test.c | 52 +++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/prog_tests/fentry_multi_test.c | 43 +++++++++++++++++++++++++++
tools/testing/selftests/bpf/prog_tests/fexit_multi_test.c | 44 ++++++++++++++++++++++++++++
tools/testing/selftests/bpf/progs/fentry_fexit_multi_test.c | 31 ++++++++++++++++++++
tools/testing/selftests/bpf/progs/fentry_multi_test.c | 20 +++++++++++++
tools/testing/selftests/bpf/progs/fexit_multi_test.c | 22 ++++++++++++++
29 files changed, 1121 insertions(+), 135 deletions(-)
create mode 100644 samples/ftrace/ftrace-direct-multi.c
create mode 100644 tools/testing/selftests/bpf/multi_check.h
create mode 100644 tools/testing/selftests/bpf/prog_tests/fentry_fexit_multi_test.c
create mode 100644 tools/testing/selftests/bpf/prog_tests/fentry_multi_test.c
create mode 100644 tools/testing/selftests/bpf/prog_tests/fexit_multi_test.c
create mode 100644 tools/testing/selftests/bpf/progs/fentry_fexit_multi_test.c
create mode 100644 tools/testing/selftests/bpf/progs/fentry_multi_test.c
create mode 100644 tools/testing/selftests/bpf/progs/fexit_multi_test.c