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
