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| author | Daniel Borkmann <daniel@iogearbox.net> | 2019-01-07 22:57:17 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2019-01-07 15:52:00 -0800 |
| commit | a769fa7208b94f37b6240215dc6970f9d76fc58c (patch) | |
| tree | e14b9787e7429d0aee270c9321d9d252b30573d5 /Documentation | |
| parent | a8911d6d5878587767a78c6bde371298ca2a3be3 (diff) | |
| download | linux-a769fa7208b94f37b6240215dc6970f9d76fc58c.tar.bz2 | |
bpf, doc: update design qa to reflect kern_version requirement
Update the bpf_design_QA.rst to also reflect recent changes in
6c4fc209fcf9 ("bpf: remove useless version check for prog load").
Suggested-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/bpf/bpf_design_QA.rst | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/Documentation/bpf/bpf_design_QA.rst b/Documentation/bpf/bpf_design_QA.rst index 6780a6d81745..7cc9e368c1e9 100644 --- a/Documentation/bpf/bpf_design_QA.rst +++ b/Documentation/bpf/bpf_design_QA.rst @@ -157,12 +157,11 @@ Q: Does BPF have a stable ABI? ------------------------------ A: YES. BPF instructions, arguments to BPF programs, set of helper functions and their arguments, recognized return codes are all part -of ABI. However when tracing programs are using bpf_probe_read() helper -to walk kernel internal datastructures and compile with kernel -internal headers these accesses can and will break with newer -kernels. The union bpf_attr -> kern_version is checked at load time -to prevent accidentally loading kprobe-based bpf programs written -for a different kernel. Networking programs don't do kern_version check. +of ABI. However there is one specific exception to tracing programs +which are using helpers like bpf_probe_read() to walk kernel internal +data structures and compile with kernel internal headers. Both of these +kernel internals are subject to change and can break with newer kernels +such that the program needs to be adapted accordingly. Q: How much stack space a BPF program uses? ------------------------------------------- |