[PATCH v7 bpf-next 00/10] bpf, tracing: introduce bpf raw tracepoints

Alexei Starovoitov
2018-03-28T02:10:55Z

v6->v7:
- adopted Steven's bpf_raw_tp_map section approach to find tracepoint
and corresponding bpf probe function instead of kallsyms approach.
dropped kernel_tracepoint_find_by_name() patch

v5->v6:
- avoid changing semantics of for_each_kernel_tracepoint() function, instead
introduce kernel_tracepoint_find_by_name() helper

v4->v5:
- adopted Daniel's fancy REPEAT macro in bpf_trace.c in patch 7

v3->v4:
- adopted Linus's CAST_TO_U64 macro to cast any integer, pointer, or small
struct to u64. That nicely reduced the size of patch 1

v2->v3:
- with Linus's suggestion introduced generic COUNT_ARGS and CONCATENATE macros
(or rather moved them from apparmor)
that cleaned up patches 6 and 7
- added patch 4 to refactor trace_iwlwifi_dev_ucode_error() from 17 args to 4
Now any tracepoint with >12 args will have build error

v1->v2:
- simplified api by combing bpf_raw_tp_open(name) + bpf_attach(prog_fd) into
bpf_raw_tp_open(name, prog_fd) as suggested by Daniel.
That simplifies bpf_detach as well which is now simple close() of fd.
- fixed memory leak in error path which was spotted by Daniel.
- fixed bpf_get_stackid(), bpf_perf_event_output() called from raw tracepoints
- added more tests
- fixed allyesconfig build caught by buildbot

v1:
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.

Patches 2 and 3 are minor cleanups to address allyesconfig build

Patch 4 refactor trace_iwlwifi_dev_ucode_error from 17 to 4 args

Patch 5 introduces COUNT_ARGS macro

Patch 6 minor prep work to expose number of arguments passed
into tracepoints.

Patch 7 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
// and attach bpf program to it
raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd);

Ctrl-C of tracing daemon or cmdline tool will automatically
detach bpf program, unload it and unregister tracepoint probe.
More details in patch 7.

Patch 8 - trivial support in libbpf
Patches 9, 10 - user space 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 (10):
treewide: remove large struct-pass-by-value from tracepoint arguments
net/mediatek: disambiguate mt76 vs mt7601u trace events
net/mac802154: disambiguate mac80215 vs mac802154 trace events
net/wireless/iwlwifi: fix iwlwifi_dev_ucode_error tracepoint
macro: introduce COUNT_ARGS() macro
tracepoint: compute num_args at build time
bpf: introduce BPF_RAW_TRACEPOINT
libbpf: add bpf_raw_tracepoint_open helper
samples/bpf: raw tracepoint test
selftests/bpf: test for bpf_get_stackid() from raw tracepoints

drivers/infiniband/hw/hfi1/file_ops.c | 2 +-
drivers/infiniband/hw/hfi1/trace_ctxts.h | 12 +-
drivers/net/wireless/intel/iwlwifi/dvm/main.c | 7 +-
.../wireless/intel/iwlwifi/iwl-devtrace-iwlwifi.h | 39 ++---
drivers/net/wireless/intel/iwlwifi/iwl-devtrace.c | 1 +
drivers/net/wireless/intel/iwlwifi/mvm/utils.c | 7 +-
drivers/net/wireless/mediatek/mt7601u/trace.h | 6 +-
include/asm-generic/vmlinux.lds.h | 10 ++
include/linux/bpf_types.h | 1 +
include/linux/kernel.h | 7 +
include/linux/trace_events.h | 42 +++++
include/linux/tracepoint-defs.h | 6 +
include/linux/tracepoint.h | 12 +-
include/trace/bpf_probe.h | 91 ++++++++++
include/trace/define_trace.h | 15 +-
include/trace/events/f2fs.h | 2 +-
include/uapi/linux/bpf.h | 11 ++
kernel/bpf/syscall.c | 78 +++++++++
kernel/trace/bpf_trace.c | 183 +++++++++++++++++++++
net/mac802154/trace.h | 8 +-
net/wireless/trace.h | 2 +-
samples/bpf/Makefile | 1 +
samples/bpf/bpf_load.c | 14 ++
samples/bpf/test_overhead_raw_tp_kern.c | 17 ++
samples/bpf/test_overhead_user.c | 12 ++
security/apparmor/include/path.h | 7 +-
sound/firewire/amdtp-stream-trace.h | 2 +-
tools/include/uapi/linux/bpf.h | 11 ++
tools/lib/bpf/bpf.c | 11 ++
tools/lib/bpf/bpf.h | 1 +
tools/testing/selftests/bpf/test_progs.c | 91 +++++++---
31 files changed, 619 insertions(+), 90 deletions(-)
create mode 100644 include/trace/bpf_probe.h
create mode 100644 samples/bpf/test_overhead_raw_tp_kern.c

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2.9.5