[PATCH bpf-next v2 0/9] bpf: add bpf_get_stack helper

[Yonghong Song <yhs@fb.com>]

Currently, stackmap and bpf_get_stackid helper are provided
for bpf program to get the stack trace. This approach has
a limitation though. If two stack traces have the same hash,
only one will get stored in the stackmap table regardless of
whether BPF_F_REUSE_STACKID is specified or not,
so some stack traces may be missing from user perspective.

This patch implements a new helper, bpf_get_stack, will
send stack traces directly to bpf program. The bpf program
is able to see all stack traces, and then can do in-kernel
processing or send stack traces to user space through
shared map or bpf_perf_event_output.

Patches #1 and #2 implemented the core kernel support.
Patches #3 and #4 are two verifier improves to make
bpf programming easier. Patch #5 synced the new helper
to tools headers. Patches #6 and #7 added a test in
samples/bpf by attaching to a kprobe. Patch #8 added
a verifier test in tools/bpf for new verifier change
and Patch #9 added a test by attaching to a tracepoint.

Changelogs:
  v1 -> v2:
    . fix compilation error when CONFIG_PERF_EVENTS is not enabled

Yonghong Song (9):
  bpf: change prototype for stack_map_get_build_id_offset
  bpf: add bpf_get_stack helper
  bpf/verifier: refine retval R0 state for bpf_get_stack helper
  bpf/verifier: improve register value range tracking with ARSH
  tools/bpf: add bpf_get_stack helper to tools headers
  samples/bpf: move common-purpose perf_event functions to bpf_load.c
  samples/bpf: add a test for bpf_get_stack helper
  tools/bpf: add a verifier test case for bpf_get_stack helper and ARSH
  tools/bpf: add a test_progs test case for bpf_get_stack helper

 include/linux/bpf.h                               |   1 +
 include/linux/filter.h                            |   3 +-
 include/uapi/linux/bpf.h                          |  19 ++-
 kernel/bpf/core.c                                 |   5 +
 kernel/bpf/stackmap.c                             |  80 ++++++++++--
 kernel/bpf/syscall.c                              |  10 ++
 kernel/bpf/verifier.c                             |  35 ++++-
 kernel/trace/bpf_trace.c                          |  50 +++++++-
 samples/bpf/Makefile                              |   4 +
 samples/bpf/bpf_load.c                            | 104 +++++++++++++++
 samples/bpf/bpf_load.h                            |   5 +
 samples/bpf/trace_get_stack_kern.c                |  86 +++++++++++++
 samples/bpf/trace_get_stack_user.c                | 150 ++++++++++++++++++++++
 samples/bpf/trace_output_user.c                   | 113 ++--------------
 tools/include/uapi/linux/bpf.h                    |  19 ++-
 tools/testing/selftests/bpf/bpf_helpers.h         |   2 +
 tools/testing/selftests/bpf/test_progs.c          |  41 +++++-
 tools/testing/selftests/bpf/test_stacktrace_map.c |  20 ++-
 tools/testing/selftests/bpf/test_verifier.c       |  45 +++++++
 19 files changed, 669 insertions(+), 123 deletions(-)
 create mode 100644 samples/bpf/trace_get_stack_kern.c
 create mode 100644 samples/bpf/trace_get_stack_user.c

-- 
2.9.5