diff options
| author | Dave Thaler <dthaler@microsoft.com> | 2023-03-08 20:53:03 +0000 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-03-10 13:02:00 -0800 |
| commit | c1f9e14e3b676eb88fe1c9488c0b5f4fc9108a1c (patch) | |
| tree | c895db124ca1ed63b2683c3136c3a83f2fd7de0a /Documentation/bpf/clang-notes.rst | |
| parent | 74843b57ec70af7b67b7e6153374834ee18d139f (diff) | |
bpf, docs: Explain helper functions
Add brief text about existence of helper functions, with details to go in
separate psABI text.
Note that text about runtime functions (kfuncs) is part of a separate patch,
not this one.
Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Link: https://lore.kernel.org/r/20230308205303.1308-1-dthaler1968@googlemail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'Documentation/bpf/clang-notes.rst')
| -rw-r--r-- | Documentation/bpf/clang-notes.rst | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/bpf/clang-notes.rst b/Documentation/bpf/clang-notes.rst index 528feddf2db9..2c872a1ee08e 100644 --- a/Documentation/bpf/clang-notes.rst +++ b/Documentation/bpf/clang-notes.rst @@ -20,6 +20,12 @@ Arithmetic instructions For CPU versions prior to 3, Clang v7.0 and later can enable ``BPF_ALU`` support with ``-Xclang -target-feature -Xclang +alu32``. In CPU version 3, support is automatically included. +Jump instructions +================= + +If ``-O0`` is used, Clang will generate the ``BPF_CALL | BPF_X | BPF_JMP`` (0x8d) +instruction, which is not supported by the Linux kernel verifier. + Atomic operations ================= |