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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>