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authorDaniel Borkmann <daniel@iogearbox.net>2019-01-08 00:57:17 +0300
committerAlexei Starovoitov <ast@kernel.org>2019-01-08 02:52:00 +0300
commita769fa7208b94f37b6240215dc6970f9d76fc58c (patch)
treee14b9787e7429d0aee270c9321d9d252b30573d5 /Documentation/bpf/bpf_design_QA.rst
parenta8911d6d5878587767a78c6bde371298ca2a3be3 (diff)
downloadlinux-a769fa7208b94f37b6240215dc6970f9d76fc58c.tar.xz
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/bpf/bpf_design_QA.rst')
-rw-r--r--Documentation/bpf/bpf_design_QA.rst11
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?
-------------------------------------------