diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/bpf/instruction-set.rst | 59 |
1 files changed, 37 insertions, 22 deletions
diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst index b44640589055..b77280eb926f 100644 --- a/Documentation/bpf/instruction-set.rst +++ b/Documentation/bpf/instruction-set.rst @@ -243,27 +243,29 @@ Jump instructions otherwise identical operations. The 'code' field encodes the operation as below: -======== ===== ========================= ============ -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 see `Helper functions`_ -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 -======== ===== ========================= ============ +======== ===== === =========================================== ========================================= +code value src description notes +======== ===== === =========================================== ========================================= +BPF_JA 0x0 0x0 PC += offset BPF_JMP only +BPF_JEQ 0x1 any PC += offset if dst == src +BPF_JGT 0x2 any PC += offset if dst > src unsigned +BPF_JGE 0x3 any PC += offset if dst >= src unsigned +BPF_JSET 0x4 any PC += offset if dst & src +BPF_JNE 0x5 any PC += offset if dst != src +BPF_JSGT 0x6 any PC += offset if dst > src signed +BPF_JSGE 0x7 any PC += offset if dst >= src signed +BPF_CALL 0x8 0x0 call helper function by address see `Helper functions`_ +BPF_CALL 0x8 0x1 call PC += offset see `Program-local functions`_ +BPF_CALL 0x8 0x2 call helper function by BTF ID see `Helper functions`_ +BPF_EXIT 0x9 0x0 return BPF_JMP only +BPF_JLT 0xa any PC += offset if dst < src unsigned +BPF_JLE 0xb any PC += offset if dst <= src unsigned +BPF_JSLT 0xc any PC += offset if dst < src signed +BPF_JSLE 0xd any PC += offset if dst <= src signed +======== ===== === =========================================== ========================================= The eBPF program needs to store the return value into register R0 before doing a -BPF_EXIT. +``BPF_EXIT``. Example: @@ -277,9 +279,22 @@ Helper functions ~~~~~~~~~~~~~~~~ Helper functions are a concept whereby BPF programs can call into a -set of function calls exposed by the runtime. Each helper -function is identified by an integer used in a ``BPF_CALL`` instruction. -The available helper functions may differ for each program type. +set of function calls exposed by the underlying platform. + +Historically, each helper function was identified by an address +encoded in the imm field. The available helper functions may differ +for each program type, but address values are unique across all program types. + +Platforms that support the BPF Type Format (BTF) support identifying +a helper function by a BTF ID encoded in the imm field, where the BTF ID +identifies the helper name and type. + +Program-local functions +~~~~~~~~~~~~~~~~~~~~~~~ +Program-local functions are functions exposed by the same BPF program as the +caller, and are referenced by offset from the call instruction, similar to +``BPF_JA``. A ``BPF_EXIT`` within the program-local function will return to +the caller. Load and store instructions =========================== |