hi,
adding new helpers to access traced function arguments that
came out of the trampoline batch changes [1].
Get n-th argument of the traced function:
long bpf_get_func_arg(void *ctx, u32 n, u64 *value)
Get return value of the traced function:
long bpf_get_func_ret(void *ctx, u64 *value)
Get arguments count of the traced funtion:
long bpf_get_func_arg_cnt(void *ctx)
v2 changes:
- added acks
- updated stack diagram
- return -EOPNOTSUPP instead of -EINVAL in bpf_get_func_ret
- removed gpl_only for all helpers
- added verifier fix to allow proper arguments checks,
Andrii asked for checking also 'int *b' argument in
bpf_modify_return_test programs and it turned out that it's currently
not supported by verifier - we can't read argument that is int pointer,
so I had to add verifier change to allow that + adding verifier selftest
- checking all arguments in bpf_modify_return_test test programs
- moved helpers proto gets in tracing_prog_func_proto with attach type check
thanks,
jirka
[1] https://lore.kernel.org/bpf/20211118112455.475349-1-jolsa@xxxxxxxxxx/
---
Jiri Olsa (5):
bpf: Allow access to int pointer arguments in tracing programs
selftests/bpf: Add test to access int ptr argument in tracing program
bpf, x64: Replace some stack_size usage with offset variables
bpf: Add get_func_[arg|ret|arg_cnt] helpers
selftests/bpf: Add tests for get_func_[arg|ret|arg_cnt] helpers
arch/x86/net/bpf_jit_comp.c | 55 ++++++++++++++++++++++++++++++-----------
include/linux/bpf.h | 5 ++++
include/uapi/linux/bpf.h | 28 +++++++++++++++++++++
kernel/bpf/btf.c | 7 +++---
kernel/bpf/trampoline.c | 8 ++++++
kernel/bpf/verifier.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++++----
kernel/trace/bpf_trace.c | 55 ++++++++++++++++++++++++++++++++++++++++-
tools/include/uapi/linux/bpf.h | 28 +++++++++++++++++++++
tools/testing/selftests/bpf/prog_tests/get_func_args_test.c | 44 +++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/progs/get_func_args_test.c | 123 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/verifier/btf_ctx_access.c | 12 +++++++++
11 files changed, 418 insertions(+), 24 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/get_func_args_test.c
create mode 100644 tools/testing/selftests/bpf/progs/get_func_args_test.c
create mode 100644 tools/testing/selftests/bpf/verifier/btf_ctx_access.c
