Merge branch 'bpf-raw-tracepoints'
Alexei Starovoitov says:
====================
v7->v8:
- moved 'u32 num_args' from 'struct tracepoint' into 'struct bpf_raw_event_map'
that increases memory overhead, but can be optimized/compressed later.
Now it's zero changes in tracepoint.[ch]
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 6
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 patch 6
- 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 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 6.
Patch 7 - trivial support in libbpf
Patches 8, 9 - 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
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
