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Diffstat (limited to 'Documentation/bpf')
| -rw-r--r-- | Documentation/bpf/standardization/instruction-set.rst | 184 |
1 files changed, 102 insertions, 82 deletions
diff --git a/Documentation/bpf/standardization/instruction-set.rst b/Documentation/bpf/standardization/instruction-set.rst index 6b11d1109f12..1602454fe7cf 100644 --- a/Documentation/bpf/standardization/instruction-set.rst +++ b/Documentation/bpf/standardization/instruction-set.rst @@ -32,7 +32,7 @@ Types This document refers to integer types with the notation `SN` to specify a type's signedness (`S`) and bit width (`N`), respectively. -.. table:: Meaning of signedness notation. +.. table:: Meaning of signedness notation ==== ========= S Meaning @@ -41,7 +41,7 @@ a type's signedness (`S`) and bit width (`N`), respectively. s signed ==== ========= -.. table:: Meaning of bit-width notation. +.. table:: Meaning of bit-width notation ===== ========= N Bit width @@ -263,18 +263,20 @@ Instruction classes The three least significant bits of the 'opcode' field store the instruction class: -===== ===== =============================== =================================== -class value description reference -===== ===== =============================== =================================== -LD 0x0 non-standard load operations `Load and store instructions`_ -LDX 0x1 load into register operations `Load and store instructions`_ -ST 0x2 store from immediate operations `Load and store instructions`_ -STX 0x3 store from register operations `Load and store instructions`_ -ALU 0x4 32-bit arithmetic operations `Arithmetic and jump instructions`_ -JMP 0x5 64-bit jump operations `Arithmetic and jump instructions`_ -JMP32 0x6 32-bit jump operations `Arithmetic and jump instructions`_ -ALU64 0x7 64-bit arithmetic operations `Arithmetic and jump instructions`_ -===== ===== =============================== =================================== +.. table:: Instruction class + + ===== ===== =============================== =================================== + class value description reference + ===== ===== =============================== =================================== + LD 0x0 non-standard load operations `Load and store instructions`_ + LDX 0x1 load into register operations `Load and store instructions`_ + ST 0x2 store from immediate operations `Load and store instructions`_ + STX 0x3 store from register operations `Load and store instructions`_ + ALU 0x4 32-bit arithmetic operations `Arithmetic and jump instructions`_ + JMP 0x5 64-bit jump operations `Arithmetic and jump instructions`_ + JMP32 0x6 32-bit jump operations `Arithmetic and jump instructions`_ + ALU64 0x7 64-bit arithmetic operations `Arithmetic and jump instructions`_ + ===== ===== =============================== =================================== Arithmetic and jump instructions ================================ @@ -292,6 +294,8 @@ For arithmetic and jump instructions (``ALU``, ``ALU64``, ``JMP`` and **s (source)** the source operand location, which unless otherwise specified is one of: + .. table:: Source operand location + ====== ===== ============================================== source value description ====== ===== ============================================== @@ -312,27 +316,29 @@ The 'code' field encodes the operation as below, where 'src' refers to the the source operand and 'dst' refers to the value of the destination register. -===== ===== ======= ========================================================== -name code offset description -===== ===== ======= ========================================================== -ADD 0x0 0 dst += src -SUB 0x1 0 dst -= src -MUL 0x2 0 dst \*= src -DIV 0x3 0 dst = (src != 0) ? (dst / src) : 0 -SDIV 0x3 1 dst = (src != 0) ? (dst s/ src) : 0 -OR 0x4 0 dst \|= src -AND 0x5 0 dst &= src -LSH 0x6 0 dst <<= (src & mask) -RSH 0x7 0 dst >>= (src & mask) -NEG 0x8 0 dst = -dst -MOD 0x9 0 dst = (src != 0) ? (dst % src) : dst -SMOD 0x9 1 dst = (src != 0) ? (dst s% src) : dst -XOR 0xa 0 dst ^= src -MOV 0xb 0 dst = src -MOVSX 0xb 8/16/32 dst = (s8,s16,s32)src -ARSH 0xc 0 :term:`sign extending<Sign Extend>` dst >>= (src & mask) -END 0xd 0 byte swap operations (see `Byte swap instructions`_ below) -===== ===== ======= ========================================================== +.. table:: Arithmetic instructions + + ===== ===== ======= ========================================================== + name code offset description + ===== ===== ======= ========================================================== + ADD 0x0 0 dst += src + SUB 0x1 0 dst -= src + MUL 0x2 0 dst \*= src + DIV 0x3 0 dst = (src != 0) ? (dst / src) : 0 + SDIV 0x3 1 dst = (src != 0) ? (dst s/ src) : 0 + OR 0x4 0 dst \|= src + AND 0x5 0 dst &= src + LSH 0x6 0 dst <<= (src & mask) + RSH 0x7 0 dst >>= (src & mask) + NEG 0x8 0 dst = -dst + MOD 0x9 0 dst = (src != 0) ? (dst % src) : dst + SMOD 0x9 1 dst = (src != 0) ? (dst s% src) : dst + XOR 0xa 0 dst ^= src + MOV 0xb 0 dst = src + MOVSX 0xb 8/16/32 dst = (s8,s16,s32)src + ARSH 0xc 0 :term:`sign extending<Sign Extend>` dst >>= (src & mask) + END 0xd 0 byte swap operations (see `Byte swap instructions`_ below) + ===== ===== ======= ========================================================== Underflow and overflow are allowed during arithmetic operations, meaning the 64-bit or 32-bit value will wrap. If BPF program execution would @@ -426,13 +432,15 @@ select what byte order the operation converts from or to. For ``ALU64``, the 1-bit source operand field in the opcode is reserved and MUST be set to 0. -===== ======== ===== ================================================= -class source value description -===== ======== ===== ================================================= -ALU TO_LE 0 convert between host byte order and little endian -ALU TO_BE 1 convert between host byte order and big endian -ALU64 Reserved 0 do byte swap unconditionally -===== ======== ===== ================================================= +.. table:: Byte swap instructions + + ===== ======== ===== ================================================= + class source value description + ===== ======== ===== ================================================= + ALU TO_LE 0 convert between host byte order and little endian + ALU TO_BE 1 convert between host byte order and big endian + ALU64 Reserved 0 do byte swap unconditionally + ===== ======== ===== ================================================= The 'imm' field encodes the width of the swap operations. The following widths are supported: 16, 32 and 64. Width 64 operations belong to the base64 @@ -468,27 +476,29 @@ otherwise identical operations, and indicates the base64 conformance group unless otherwise specified. The 'code' field encodes the operation as below: -======== ===== ======= ================================= =================================================== -code value src_reg description notes -======== ===== ======= ================================= =================================================== -JA 0x0 0x0 PC += offset {JA, K, JMP} only -JA 0x0 0x0 PC += imm {JA, K, JMP32} only -JEQ 0x1 any PC += offset if dst == src -JGT 0x2 any PC += offset if dst > src unsigned -JGE 0x3 any PC += offset if dst >= src unsigned -JSET 0x4 any PC += offset if dst & src -JNE 0x5 any PC += offset if dst != src -JSGT 0x6 any PC += offset if dst > src signed -JSGE 0x7 any PC += offset if dst >= src signed -CALL 0x8 0x0 call helper function by static ID {CALL, K, JMP} only, see `Helper functions`_ -CALL 0x8 0x1 call PC += imm {CALL, K, JMP} only, see `Program-local functions`_ -CALL 0x8 0x2 call helper function by BTF ID {CALL, K, JMP} only, see `Helper functions`_ -EXIT 0x9 0x0 return {CALL, K, JMP} only -JLT 0xa any PC += offset if dst < src unsigned -JLE 0xb any PC += offset if dst <= src unsigned -JSLT 0xc any PC += offset if dst < src signed -JSLE 0xd any PC += offset if dst <= src signed -======== ===== ======= ================================= =================================================== +.. table:: Jump instructions + + ======== ===== ======= ================================= =================================================== + code value src_reg description notes + ======== ===== ======= ================================= =================================================== + JA 0x0 0x0 PC += offset {JA, K, JMP} only + JA 0x0 0x0 PC += imm {JA, K, JMP32} only + JEQ 0x1 any PC += offset if dst == src + JGT 0x2 any PC += offset if dst > src unsigned + JGE 0x3 any PC += offset if dst >= src unsigned + JSET 0x4 any PC += offset if dst & src + JNE 0x5 any PC += offset if dst != src + JSGT 0x6 any PC += offset if dst > src signed + JSGE 0x7 any PC += offset if dst >= src signed + CALL 0x8 0x0 call helper function by static ID {CALL, K, JMP} only, see `Helper functions`_ + CALL 0x8 0x1 call PC += imm {CALL, K, JMP} only, see `Program-local functions`_ + CALL 0x8 0x2 call helper function by BTF ID {CALL, K, JMP} only, see `Helper functions`_ + EXIT 0x9 0x0 return {CALL, K, JMP} only + JLT 0xa any PC += offset if dst < src unsigned + JLE 0xb any PC += offset if dst <= src unsigned + JSLT 0xc any PC += offset if dst < src signed + JSLE 0xd any PC += offset if dst <= src signed + ======== ===== ======= ================================= =================================================== where 'PC' denotes the program counter, and the offset to increment by is in units of 64-bit instructions relative to the instruction following @@ -559,6 +569,8 @@ For load and store instructions (``LD``, ``LDX``, ``ST``, and ``STX``), the **mode** The mode modifier is one of: + .. table:: Mode modifier + ============= ===== ==================================== ============= mode modifier value description reference ============= ===== ==================================== ============= @@ -573,6 +585,8 @@ For load and store instructions (``LD``, ``LDX``, ``ST``, and ``STX``), the **sz (size)** The size modifier is one of: + .. table:: Size modifier + ==== ===== ===================== size value description ==== ===== ===================== @@ -641,14 +655,16 @@ The 'imm' field is used to encode the actual atomic operation. Simple atomic operation use a subset of the values defined to encode arithmetic operations in the 'imm' field to encode the atomic operation: -======== ===== =========== -imm value description -======== ===== =========== -ADD 0x00 atomic add -OR 0x40 atomic or -AND 0x50 atomic and -XOR 0xa0 atomic xor -======== ===== =========== +.. table:: Simple atomic operations + + ======== ===== =========== + imm value description + ======== ===== =========== + ADD 0x00 atomic add + OR 0x40 atomic or + AND 0x50 atomic and + XOR 0xa0 atomic xor + ======== ===== =========== ``{ATOMIC, W, STX}`` with 'imm' = ADD means:: @@ -662,6 +678,8 @@ XOR 0xa0 atomic xor In addition to the simple atomic operations, there also is a modifier and two complex atomic operations: +.. table:: Complex atomic operations + =========== ================ =========================== imm value description =========== ================ =========================== @@ -695,17 +713,19 @@ The following table defines a set of ``{IMM, DW, LD}`` instructions with opcode subtypes in the 'src_reg' field, using new terms such as "map" defined further below: -======= ========================================= =========== ============== -src_reg pseudocode imm type dst type -======= ========================================= =========== ============== -0x0 dst = (next_imm << 32) | imm integer integer -0x1 dst = map_by_fd(imm) map fd map -0x2 dst = map_val(map_by_fd(imm)) + next_imm map fd data address -0x3 dst = var_addr(imm) variable id data address -0x4 dst = code_addr(imm) integer code address -0x5 dst = map_by_idx(imm) map index map -0x6 dst = map_val(map_by_idx(imm)) + next_imm map index data address -======= ========================================= =========== ============== +.. table:: 64-bit immediate instructions + + ======= ========================================= =========== ============== + src_reg pseudocode imm type dst type + ======= ========================================= =========== ============== + 0x0 dst = (next_imm << 32) | imm integer integer + 0x1 dst = map_by_fd(imm) map fd map + 0x2 dst = map_val(map_by_fd(imm)) + next_imm map fd data address + 0x3 dst = var_addr(imm) variable id data address + 0x4 dst = code_addr(imm) integer code address + 0x5 dst = map_by_idx(imm) map index map + 0x6 dst = map_val(map_by_idx(imm)) + next_imm map index data address + ======= ========================================= =========== ============== where |