diff options
| author | Christoph Hellwig <hch@lst.de> | 2022-01-03 19:35:55 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-01-05 13:11:26 -0800 |
| commit | 9e533e22b5700097e84b8a841d9e1c251cc132c6 (patch) | |
| tree | 77d5f3699cf9fcf276b994d8164c4f86008f36ef /Documentation | |
| parent | 03c517ee9eedd95472c36c6291fc97368b48c9e4 (diff) | |
bpf, docs: Fully document the JMP opcodes
Add pseudo-code to document all the different BPF_JMP / BPF_JMP64
opcodes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220103183556.41040-6-hch@lst.de
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/bpf/instruction-set.rst | 34 |
1 files changed, 17 insertions, 17 deletions
diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst index efba4d193185..88e8d6a9195c 100644 --- a/Documentation/bpf/instruction-set.rst +++ b/Documentation/bpf/instruction-set.rst @@ -125,24 +125,24 @@ BPF_JMP32 uses 32-bit wide operands while BPF_JMP uses 64-bit wide operands for otherwise identical operations. The code field encodes the operation as below: - ======== ===== ========================= - code value description - ======== ===== ========================= - BPF_JA 0x00 BPF_JMP only - BPF_JEQ 0x10 - BPF_JGT 0x20 - BPF_JGE 0x30 - BPF_JSET 0x40 - BPF_JNE 0x50 jump '!=' - BPF_JSGT 0x60 signed '>' - BPF_JSGE 0x70 signed '>=' + ======== ===== ========================= ============ + code value description notes + ======== ===== ========================= ============ + BPF_JA 0x00 PC += off BPF_JMP only + BPF_JEQ 0x10 PC += off if dst == src + BPF_JGT 0x20 PC += off if dst > src unsigned + BPF_JGE 0x30 PC += off if dst >= src unsigned + BPF_JSET 0x40 PC += off if dst & src + BPF_JNE 0x50 PC += off if dst != src + BPF_JSGT 0x60 PC += off if dst > src signed + BPF_JSGE 0x70 PC += off if dst >= src signed BPF_CALL 0x80 function call - BPF_EXIT 0x90 function return - BPF_JLT 0xa0 unsigned '<' - BPF_JLE 0xb0 unsigned '<=' - BPF_JSLT 0xc0 signed '<' - BPF_JSLE 0xd0 signed '<=' - ======== ===== ========================= + BPF_EXIT 0x90 function / program return BPF_JMP only + BPF_JLT 0xa0 PC += off if dst < src unsigned + BPF_JLE 0xb0 PC += off if dst <= src unsigned + BPF_JSLT 0xc0 PC += off if dst < src signed + BPF_JSLE 0xd0 PC += off if dst <= src signed + ======== ===== ========================= ============ The eBPF program needs to store the return value into register R0 before doing a BPF_EXIT. |