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Subject[PATCH bpf-next 0/5] bpf, tracing: introduce bpf raw tracepoints
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This patch set is a different way to address the pressing need to access
task_struct pointers in sched tracepoints from bpf programs.

The first approach simply added these pointers to sched tracepoints:
https://lkml.org/lkml/2017/12/14/753
which Peter nacked.
Few options were discussed and eventually the discussion converged on
doing bpf specific tracepoint_probe_register() probe functions.
Details here:
https://lkml.org/lkml/2017/12/20/929

Patch 1 is kernel wide cleanup of pass-struct-by-value into
pass-struct-by-reference into tracepoints.

Patch 2 minor prep work to expose number of arguments passed
into tracepoints.

Patch 3 introduces BPF_RAW_TRACEPOINT api.
the auto-cleanup and multiple concurrent users are must have
features of tracing api. For bpf raw tracepoints it looks like:
// load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type
prog_fd = bpf_prog_load(...);

// receive anon_inode fd for given bpf_raw_tracepoint
raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception");

// attach bpf program to given tracepoint
bpf_prog_attach(prog_fd, raw_tp_fd, BPF_RAW_TRACEPOINT);

Ctrl-C of tracing daemon or cmdline tool will automatically
detach bpf program, unload it and unregister tracepoint probe.
More details in patch 3.

Patch 4, 5 - user space lib and tests

samples/bpf/test_overhead performance on 1 cpu:

tracepoint base kprobe+bpf tracepoint+bpf raw_tracepoint+bpf
task_rename 1.1M 769K 947K 1.0M
urandom_read 789K 697K 750K 755K

Alexei Starovoitov (5):
treewide: remove struct-pass-by-value from tracepoints arguments
tracepoint: compute num_args at build time
bpf: introduce BPF_RAW_TRACEPOINT
libbpf: add bpf_raw_tracepoint_open helper
samples/bpf: raw tracepoint test

arch/x86/xen/mmu_pv.c | 16 +--
drivers/gpu/drm/i915/i915_trace.h | 13 +-
drivers/infiniband/hw/hfi1/file_ops.c | 2 +-
drivers/infiniband/hw/hfi1/trace_ctxts.h | 12 +-
drivers/s390/cio/ioasm.c | 18 +--
drivers/s390/cio/trace.h | 50 ++++----
fs/dax.c | 2 +-
include/linux/bpf_types.h | 1 +
include/linux/trace_events.h | 57 +++++++++
include/linux/tracepoint-defs.h | 1 +
include/linux/tracepoint.h | 32 +++--
include/trace/bpf_probe.h | 87 +++++++++++++
include/trace/define_trace.h | 15 ++-
include/trace/events/f2fs.h | 2 +-
include/trace/events/fs_dax.h | 6 +-
include/trace/events/rcu.h | 4 +-
include/trace/events/xen.h | 32 ++---
include/uapi/linux/bpf.h | 11 ++
kernel/bpf/syscall.c | 108 ++++++++++++++++
kernel/rcu/tree.c | 10 +-
kernel/trace/bpf_trace.c | 211 +++++++++++++++++++++++++++++++
kernel/tracepoint.c | 27 ++--
net/wireless/trace.h | 2 +-
samples/bpf/Makefile | 1 +
samples/bpf/bpf_load.c | 13 ++
samples/bpf/test_overhead_raw_tp_kern.c | 17 +++
samples/bpf/test_overhead_user.c | 12 ++
sound/firewire/amdtp-stream-trace.h | 2 +-
tools/include/uapi/linux/bpf.h | 11 ++
tools/lib/bpf/bpf.c | 10 ++
tools/lib/bpf/bpf.h | 1 +
31 files changed, 677 insertions(+), 109 deletions(-)
create mode 100644 include/trace/bpf_probe.h
create mode 100644 samples/bpf/test_overhead_raw_tp_kern.c

--
2.9.5

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