[RFC PATCH 00/13] perf tools: Support uBPF script

[Wang Nan <wangnan0@huawei.com>]

This patch set allows to perf invoke some user space BPF scripts on some
point. uBPF scripts and kernel BPF scripts reside in one BPF object.
They communicate with each other with BPF maps. uBPF scripts can invoke
helper functions provided by perf.

At least following new features can be achieved based on uBPF support:

 1) Report statistical result:
    Like DTrace, perf print statistical report before quit. No need to
    extract data using 'perf report'. Statistical method is controled by
    user.

 2) Control perf's behavior:
    Dynamically adjust period of different events. Policy is defined by
    user.

uBPF library is required before compile. It can be found from github:

 https://github.com/iovisor/ubpf.git

 Following is an example:

 Using BPF script attached at the bottom of this commit message, one
 can print histogram of write size before perf exit like this:

 # ~/perf record  -a -e ./test_ubpf.c &
 [1] 16800
 # dd if=/dev/zero of=/dev/null bs=512 count=5000
 5000+0 records in
 5000+0 records out
 2560000 bytes (2.6 MB) copied, 0.00552838 s, 463 MB/s
 # dd if=/dev/zero of=/dev/null bs=2048 count=5000
 5000+0 records in
 5000+0 records out
 10240000 bytes (10 MB) copied, 0.0188971 s, 542 MB/s
 # fg
 ^C         <--- *Press Ctrl-c*
 2^^0: 47
 2^^1: 13
 2^^2: 4
 2^^3: 130
 2^^4: 11
 2^^5: 1051
 2^^6: 486
 2^^7: 4863
 2^^8: 0
 2^^9: 5003
 2^^10: 4
 2^^11: 5003
 2^^12: 1
 2^^13: 0
 2^^14: 0
 2^^15: 0
 2^^16: 0
 2^^17: 0
 2^^18: 0
 2^^19: 0
 2^^20: 0
 [ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.788 MB perf.data ]

 Here is test_ubpf.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;
 };
 
 #define BPF_ANY 0
 
 static void *(*map_lookup_elem)(struct bpf_map_def *, void *) =
                 (void *)BPF_FUNC_map_lookup_elem;
 
 static inline unsigned int log2(unsigned int v)
 {
     unsigned int r;
     unsigned int shift;
     
     r = (v > 0xFFFF) << 4; v >>= r;
     shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
     shift = (v > 0xF) << 2; v >>= shift; r |= shift;
     shift = (v > 0x3) << 1; v >>= shift; r |= shift;
     r |= (v >> 1);
     return r;
 }
 
 static inline unsigned int log2l(unsigned long v)
 {
     unsigned int hi = v >> 32;
     if (hi)
         return log2(hi) + 32;
     else
         return log2(v);
 }
 
 struct bpf_map_def SEC("maps") my_hist_map = {
     .type = BPF_MAP_TYPE_ARRAY,
     .key_size = sizeof(int),
     .value_size = sizeof(long),
     .max_entries = 21,
 };
 
 SEC("sys_write=sys_write count")
 int sys_write(void *ctx, int err, long write_size)
 {
     long *value;
     int key = 0;
 
     if (err)
         return 0;
 
     key = log2l(write_size);
     if (key > 20)
         key = 20;
     value = map_lookup_elem(&my_hist_map, &key);
     if (!value)
         return 0;
     __sync_fetch_and_add(value, 1);
     return 0;
 }
 char _license[] SEC("license") = "GPL";
 u32 _version SEC("version") = LINUX_VERSION_CODE;
 
 /* Following ugly magic numbers can be find from tools/perf/util/ubpf-helpers-list.h */
 static int (*ubpf_memcmp)(void *s1, void *s2, unsigned int n) = (void *)1;
 static void (*ubpf_memcpy)(void *d, void *s, unsigned int size) = (void *)2;
 static int (*ubpf_strcmp)(void *s1, void *s2) = (void *)3;
 static int (*ubpf_printf)(char *fmt, ...) = (void *)4;
 static int (*ubpf_map_lookup_elem)(void *map_desc, void *key, void *value) = (void *)5;
 static int (*ubpf_map_update_elem)(void *map_desc, void *key, void *value, unsigned long long flags) = (void *)6;
 static int (*ubpf_map_get_next_key)(void *map_desc, void *key, void *value) = (void *)7;
 
 SEC("UBPF;perf_record_end")
 int perf_record_end(int samples)
 {
     int i, key;
     long value;
     char fmt[] = "2^^%d: %d\n";
 
     for (i = 0; i < 21; i++) {
         ubpf_map_lookup_elem(&my_hist_map, &i, &value);
         ubpf_printf(fmt, i, value);
     }
     return 0;
 }
 /************** END ***************/

Cc: Wang Nan <wangnan0@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>

Wang Nan (13):
  bpf tools: Add map related BPF helper
  tools: Add ubpf feature test
  bpf tools: Add ubpf include and makefile options
  bpf tools: Replace fd array to union array
  bpf tools: Save engine type in bpf_program
  bpf tools: Introduce ubpf_vm to program instance union
  bpf tools: Load ubpf program
  bpf tools: Add API for fetching ubpf_vm
  bpf tools: Register extern functions for ubpf programs
  perf tools: Register basic UBPF helpers
  perf bpf: Accept ubpf programs
  perf record: Add UBPF hooks at beginning and end of perf record
  perf tests: Add UBPF test case

 tools/build/Makefile.feature            |   6 +-
 tools/build/feature/Makefile            |   6 +-
 tools/build/feature/test-ubpf.c         |  11 ++
 tools/lib/bpf/Makefile                  |  16 +-
 tools/lib/bpf/bpf.c                     |  24 +++
 tools/lib/bpf/bpf.h                     |   2 +
 tools/lib/bpf/libbpf.c                  | 281 ++++++++++++++++++++++++++++----
 tools/lib/bpf/libbpf.h                  |  21 ++-
 tools/perf/Makefile.perf                |   2 +
 tools/perf/builtin-record.c             |   4 +
 tools/perf/config/Makefile              |   7 +
 tools/perf/perf.c                       |   3 +
 tools/perf/tests/Build                  |   8 +
 tools/perf/tests/bpf-script-test-ubpf.c |  68 ++++++++
 tools/perf/tests/bpf.c                  |  77 ++++++++-
 tools/perf/tests/llvm.c                 |   4 +
 tools/perf/tests/llvm.h                 |   2 +
 tools/perf/util/Build                   |   1 +
 tools/perf/util/bpf-loader.c            |  22 +++
 tools/perf/util/ubpf-helpers-list.h     |   7 +
 tools/perf/util/ubpf-helpers.c          |  66 ++++++++
 tools/perf/util/ubpf-helpers.h          |  21 +++
 tools/perf/util/ubpf-hooks-list.h       |  10 ++
 tools/perf/util/ubpf-hooks.c            |  81 +++++++++
 tools/perf/util/ubpf-hooks.h            |  35 ++++
 25 files changed, 745 insertions(+), 40 deletions(-)
 create mode 100644 tools/build/feature/test-ubpf.c
 create mode 100644 tools/perf/tests/bpf-script-test-ubpf.c
 create mode 100644 tools/perf/util/ubpf-helpers-list.h
 create mode 100644 tools/perf/util/ubpf-helpers.c
 create mode 100644 tools/perf/util/ubpf-helpers.h
 create mode 100644 tools/perf/util/ubpf-hooks-list.h
 create mode 100644 tools/perf/util/ubpf-hooks.c
 create mode 100644 tools/perf/util/ubpf-hooks.h

-- 
1.8.3.4