[PATCH bpf-next v3 0/5] writable contexts for bpf raw tracepoints

Matt Mullins
2019-04-19T21:04:48Z

This adds an opt-in interface for tracepoints to expose a writable context to
BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE programs that are attached, while
supporting read-only access from existing BPF_PROG_TYPE_RAW_TRACEPOINT
programs, as well as from non-BPF-based tracepoints.

The initial motivation is to support tracing that can be observed from the
remote end of an NBD socket, e.g. by adding flags to the struct nbd_request
header. Earlier attempts included adding an NBD-specific tracepoint fd, but in
code review, I was recommended to implement it more generically -- as a result,
this patchset is far simpler than my initial try.

v2->v3:
* Andrew addressed Josef's comments:
* C-style commenting in nbd.c
* Collapsed identical events into a single DECLARE_EVENT_CLASS.
This saves about 2kB of kernel text

v1->v2:
* add selftests
* sync tools/include/uapi/linux/bpf.h
* reject variable offset into the buffer
* add string representation of PTR_TO_TP_BUFFER to reg_type_str

Andrew Hall (1):
nbd: add tracepoints for send/receive timing

Matt Mullins (4):
bpf: add writable context for raw tracepoints
nbd: trace sending nbd requests
tools: sync bpf.h
selftests: bpf: test writable buffers in raw tps

MAINTAINERS | 1 +
drivers/block/nbd.c | 13 +++
include/linux/bpf.h | 2 +
include/linux/bpf_types.h | 1 +
include/linux/tracepoint-defs.h | 1 +
include/trace/bpf_probe.h | 27 ++++-
include/trace/events/bpf_test_run.h | 50 ++++++++
include/trace/events/nbd.h | 107 ++++++++++++++++++
include/uapi/linux/bpf.h | 1 +
kernel/bpf/syscall.c | 8 +-
kernel/bpf/verifier.c | 31 +++++
kernel/trace/bpf_trace.c | 21 ++++
net/bpf/test_run.c | 4 +
tools/include/uapi/linux/bpf.h | 1 +
tools/lib/bpf/libbpf.c | 1 +
tools/lib/bpf/libbpf_probes.c | 1 +
.../raw_tp_writable_reject_nbd_invalid.c | 40 +++++++
.../bpf/prog_tests/raw_tp_writable_test_run.c | 80 +++++++++++++
.../selftests/bpf/verifier/raw_tp_writable.c | 34 ++++++
19 files changed, 420 insertions(+), 4 deletions(-)
create mode 100644 include/trace/events/bpf_test_run.h
create mode 100644 include/trace/events/nbd.h
create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
create mode 100644 tools/testing/selftests/bpf/verifier/raw_tp_writable.c

--
2.17.1