perf record: Apply config to BPF objects before recording
bpf__apply_obj_config() is introduced as the core API to apply object config options to all BPF objects. This patch also does the real work for setting values for BPF_MAP_TYPE_PERF_ARRAY maps by inserting value stored in map's private field into the BPF map. This patch is required because we are not always able to set all BPF config during parsing. Further patch will set events created by perf to BPF_MAP_TYPE_PERF_EVENT_ARRAY maps, which is not exist until perf_evsel__open(). bpf_map_foreach_key() is introduced to iterate over each key needs to be configured. This function would be extended to support more map types and different key settings. In perf record, before start recording, call bpf__apply_config() to turn on all BPF config options. Test result: # cat ./test_bpf_map_1.c /************************ BEGIN **************************/ #include <uapi/linux/bpf.h> #define SEC(NAME) __attribute__((section(NAME), used)) struct bpf_map_def { unsigned int type; unsigned int key_size; unsigned int value_size; unsigned int max_entries; }; static void *(*map_lookup_elem)(struct bpf_map_def *, void *) = (void *)BPF_FUNC_map_lookup_elem; static int (*trace_printk)(const char *fmt, int fmt_size, ...) = (void *)BPF_FUNC_trace_printk; struct bpf_map_def SEC("maps") channel = { .type = BPF_MAP_TYPE_ARRAY, .key_size = sizeof(int), .value_size = sizeof(int), .max_entries = 1, }; SEC("func=sys_nanosleep") int func(void *ctx) { int key = 0; char fmt[] = "%d\n"; int *pval = map_lookup_elem(&channel, &key); if (!pval) return 0; trace_printk(fmt, sizeof(fmt), *pval); return 0; } char _license[] SEC("license") = "GPL"; int _version SEC("version") = LINUX_VERSION_CODE; /************************* END ***************************/ # echo "" > /sys/kernel/debug/tracing/trace # ./perf record -e './test_bpf_map_1.c/map:channel.value=11/' usleep 10 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.012 MB perf.data ] # cat /sys/kernel/debug/tracing/trace # tracer: nop # # entries-in-buffer/entries-written: 1/1 #P:8 [SNIP] # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | usleep-18593 [007] d... 2394714.395539: : 11 # ./perf record -e './test_bpf_map_1.c/map:channel.value=101/' usleep 10 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.012 MB perf.data ] # cat /sys/kernel/debug/tracing/trace # tracer: nop # # entries-in-buffer/entries-written: 1/1 #P:8 [SNIP] # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | usleep-18593 [007] d... 2394714.395539: : 11 usleep-19000 [006] d... 2394831.057840: : 101 Signed-off-by: NWang Nan <wangnan0@huawei.com> Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Cc: Cody P Schafer <dev@codyps.com> Cc: He Kuang <hekuang@huawei.com> Cc: Jeremie Galarneau <jeremie.galarneau@efficios.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Kirill Smelkov <kirr@nexedi.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1456132275-98875-6-git-send-email-wangnan0@huawei.comSigned-off-by: NHe Kuang <hekuang@huawei.com> Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
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