bpf: Add helpers to access traced function arguments #2234
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As suggested by Andrii, adding variables for registers and ip address offsets, which makes the code more clear, rather than abusing single stack_size variable for everything. Also describing the stack layout in the comment. There is no function change. Suggested-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Andrii Nakryiko <andrii@kernel.org>
Adding following helpers for tracing programs: 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) The trampoline now stores number of arguments on ctx-8 address, so it's easy to verify argument index and find return value argument's position. Moving function ip address on the trampoline stack behind the number of functions arguments, so it's now stored on ctx-16 address if it's needed. All helpers above are inlined by verifier. Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Adding tests for get_func_[arg|ret|arg_cnt] helpers. Using these helpers in fentry/fexit/fmod_ret programs. Signed-off-by: Jiri Olsa <jolsa@kernel.org>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=590285 expired. Closing PR. |
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Pull request for series with
subject: bpf: Add helpers to access traced function arguments
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=590285