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dthalerdthaler
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Fix formatting
Signed-off-by: Dave Thaler <[email protected]>
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‎isa/kernel.org/instruction-set.rst

Lines changed: 133 additions & 133 deletions
Original file line numberDiff line numberDiff line change
@@ -27,10 +27,10 @@ all of which are 64-bits wide.
2727

2828
The eBPF calling convention is defined as:
2929

30-
* R0: return value from function calls, and exit value for eBPF programs
31-
* R1 - R5: arguments for function calls
32-
* R6 - R9: callee saved registers that function calls will preserve
33-
* R10: read-only frame pointer to access stack
30+
* R0: return value from function calls, and exit value for eBPF programs
31+
* R1 - R5: arguments for function calls
32+
* R6 - R9: callee saved registers that function calls will preserve
33+
* R10: read-only frame pointer to access stack
3434

3535
Registers R0 - R5 are scratch registers, meaning the BPF program needs to either
3636
spill them to the BPF stack or move them to callee saved registers if these
@@ -63,17 +63,17 @@ An eBPF program is a sequence of instructions.
6363

6464
eBPF has two instruction encodings:
6565

66-
* the basic instruction encoding, which uses 64 bits to encode an instruction
67-
* the wide instruction encoding, which appends a second 64-bit immediate (i.e.,
68-
constant) value after the basic instruction for a total of 128 bits.
66+
* the basic instruction encoding, which uses 64 bits to encode an instruction
67+
* the wide instruction encoding, which appends a second 64-bit immediate (i.e.,
68+
constant) value after the basic instruction for a total of 128 bits.
6969

7070
The basic instruction encoding is as follows:
7171

72-
============= ======= =============== ==================== ============
73-
32 bits (MSB) 16 bits 4 bits 4 bits 8 bits (LSB)
74-
============= ======= =============== ==================== ============
75-
imm offset src dst opcode
76-
============= ======= =============== ==================== ============
72+
============= ======= =============== ==================== ============
73+
32 bits (MSB) 16 bits 4 bits 4 bits 8 bits (LSB)
74+
============= ======= =============== ==================== ============
75+
imm offset src dst opcode
76+
============= ======= =============== ==================== ============
7777

7878
imm
7979
integer immediate value
@@ -97,11 +97,11 @@ As discussed below in `64-bit immediate instructions`_, some basic
9797
instructions denote that a 64-bit immediate value follows. Thus
9898
the wide instruction encoding is as follows:
9999

100-
================= =============
101-
64 bits (MSB) 64 bits (LSB)
102-
================= =============
103-
basic instruction imm64
104-
================= =============
100+
================= =============
101+
64 bits (MSB) 64 bits (LSB)
102+
================= =============
103+
basic instruction imm64
104+
================= =============
105105

106106
where MSB and LSB mean the most significant bits and least significant bits, respectively.
107107

@@ -115,18 +115,18 @@ The encoding of the 'opcode' field varies and can be determined from
115115
the three least significant bits (LSB) of the 'opcode' field which holds
116116
the "instruction class", as follows:
117117

118-
========= ===== =============================== ======= =================
119-
class value description version reference
120-
========= ===== =============================== ======= =================
121-
BPF_LD 0x00 non-standard load operations 1 `Load and store instructions`_
122-
BPF_LDX 0x01 load into register operations 1 `Load and store instructions`_
123-
BPF_ST 0x02 store from immediate operations 1 `Load and store instructions`_
124-
BPF_STX 0x03 store from register operations 1 `Load and store instructions`_
125-
BPF_ALU 0x04 32-bit arithmetic operations 3 `Arithmetic and jump instructions`_
126-
BPF_JMP 0x05 64-bit jump operations 1 `Arithmetic and jump instructions`_
127-
BPF_JMP32 0x06 32-bit jump operations 3 `Arithmetic and jump instructions`_
128-
BPF_ALU64 0x07 64-bit arithmetic operations 1 `Arithmetic and jump instructions`_
129-
========= ===== =============================== ======= =================
118+
========= ===== =============================== ======= =================
119+
class value description version reference
120+
========= ===== =============================== ======= =================
121+
BPF_LD 0x00 non-standard load operations 1 `Load and store instructions`_
122+
BPF_LDX 0x01 load into register operations 1 `Load and store instructions`_
123+
BPF_ST 0x02 store from immediate operations 1 `Load and store instructions`_
124+
BPF_STX 0x03 store from register operations 1 `Load and store instructions`_
125+
BPF_ALU 0x04 32-bit arithmetic operations 3 `Arithmetic and jump instructions`_
126+
BPF_JMP 0x05 64-bit jump operations 1 `Arithmetic and jump instructions`_
127+
BPF_JMP32 0x06 32-bit jump operations 3 `Arithmetic and jump instructions`_
128+
BPF_ALU64 0x07 64-bit arithmetic operations 1 `Arithmetic and jump instructions`_
129+
========= ===== =============================== ======= =================
130130

131131
where 'version' indicates the first ISA version in which support for the value was mandatory.
132132

@@ -136,11 +136,11 @@ Arithmetic and jump instructions
136136
For arithmetic and jump instructions (``BPF_ALU``, ``BPF_ALU64``, ``BPF_JMP`` and
137137
``BPF_JMP32``), the 8-bit 'opcode' field is divided into three parts:
138138

139-
============== ====== =================
140-
4 bits (MSB) 1 bit 3 bits (LSB)
141-
============== ====== =================
142-
code source instruction class
143-
============== ====== =================
139+
============== ====== =================
140+
4 bits (MSB) 1 bit 3 bits (LSB)
141+
============== ====== =================
142+
code source instruction class
143+
============== ====== =================
144144

145145
code
146146
the operation code, whose meaning varies by instruction class
@@ -176,24 +176,24 @@ versions.
176176

177177
The 4-bit 'code' field encodes the operation as follows:
178178

179-
======== ===== =================================================
180-
code value description
181-
======== ===== =================================================
182-
BPF_ADD 0x00 dst += src
183-
BPF_SUB 0x10 dst -= src
184-
BPF_MUL 0x20 dst \*= src
185-
BPF_DIV 0x30 dst /= src
186-
BPF_OR 0x40 dst \|= src
187-
BPF_AND 0x50 dst &= src
188-
BPF_LSH 0x60 dst <<= src
189-
BPF_RSH 0x70 dst >>= src
190-
BPF_NEG 0x80 dst = ~src
191-
BPF_MOD 0x90 dst %= src
192-
BPF_XOR 0xa0 dst ^= src
193-
BPF_MOV 0xb0 dst = src
194-
BPF_ARSH 0xc0 sign extending shift right
195-
BPF_END 0xd0 byte swap operations (see `Byte swap instructions`_ below)
196-
======== ===== =================================================
179+
======== ===== =================================================
180+
code value description
181+
======== ===== =================================================
182+
BPF_ADD 0x00 dst += src
183+
BPF_SUB 0x10 dst -= src
184+
BPF_MUL 0x20 dst \*= src
185+
BPF_DIV 0x30 dst /= src
186+
BPF_OR 0x40 dst \|= src
187+
BPF_AND 0x50 dst &= src
188+
BPF_LSH 0x60 dst <<= src
189+
BPF_RSH 0x70 dst >>= src
190+
BPF_NEG 0x80 dst = ~src
191+
BPF_MOD 0x90 dst %= src
192+
BPF_XOR 0xa0 dst ^= src
193+
BPF_MOV 0xb0 dst = src
194+
BPF_ARSH 0xc0 sign extending shift right
195+
BPF_END 0xd0 byte swap operations (see `Byte swap instructions`_ below)
196+
======== ===== =================================================
197197

198198
Underflow and overflow are allowed during arithmetic operations,
199199
meaning the 64-bit or 32-bit value will wrap.
@@ -242,12 +242,12 @@ Byte swap instructions use non-default semantics of the 1-bit 'source' field in
242242
the 'opcode' field. Instead of indicating the source operator, it is instead
243243
used to select what byte order the operation converts from or to:
244244

245-
========= ===== =================================================
246-
source value description
247-
========= ===== =================================================
248-
BPF_TO_LE 0x00 convert between host byte order and little endian
249-
BPF_TO_BE 0x08 convert between host byte order and big endian
250-
========= ===== =================================================
245+
========= ===== =================================================
246+
source value description
247+
========= ===== =================================================
248+
BPF_TO_LE 0x00 convert between host byte order and little endian
249+
BPF_TO_BE 0x08 convert between host byte order and big endian
250+
========= ===== =================================================
251251

252252
**Note**
253253

@@ -259,21 +259,21 @@ The 'imm' field encodes the width of the swap operations. The following widths
259259
are supported: 16, 32 and 64. The following table summarizes the resulting
260260
possibilities:
261261

262-
============================= ========= === ======== ==================
263-
opcode construction opcode imm mnemonic pseudocode
264-
============================= ========= === ======== ==================
265-
BPF_END | BPF_TO_LE | BPF_ALU 0xd4 16 le16 dst dst = htole16(dst)
266-
BPF_END | BPF_TO_LE | BPF_ALU 0xd4 32 le32 dst dst = htole32(dst)
267-
BPF_END | BPF_TO_LE | BPF_ALU 0xd4 64 le64 dst dst = htole64(dst)
268-
BPF_END | BPF_TO_BE | BPF_ALU 0xdc 16 be16 dst dst = htobe16(dst)
269-
BPF_END | BPF_TO_BE | BPF_ALU 0xdc 32 be32 dst dst = htobe32(dst)
270-
BPF_END | BPF_TO_BE | BPF_ALU 0xdc 64 be64 dst dst = htobe64(dst)
271-
============================= ========= === ======== ==================
262+
============================= ========= === ======== ==================
263+
opcode construction opcode imm mnemonic pseudocode
264+
============================= ========= === ======== ==================
265+
BPF_END | BPF_TO_LE | BPF_ALU 0xd4 16 le16 dst dst = htole16(dst)
266+
BPF_END | BPF_TO_LE | BPF_ALU 0xd4 32 le32 dst dst = htole32(dst)
267+
BPF_END | BPF_TO_LE | BPF_ALU 0xd4 64 le64 dst dst = htole64(dst)
268+
BPF_END | BPF_TO_BE | BPF_ALU 0xdc 16 be16 dst dst = htobe16(dst)
269+
BPF_END | BPF_TO_BE | BPF_ALU 0xdc 32 be32 dst dst = htobe32(dst)
270+
BPF_END | BPF_TO_BE | BPF_ALU 0xdc 64 be64 dst dst = htobe64(dst)
271+
============================= ========= === ======== ==================
272272

273273
where
274-
* mnenomic indicates a short form that might be displayed by some tools such as disassemblers
275-
* 'htoleNN()' indicates converting a NN-bit value from host byte order to little-endian byte order
276-
* 'htobeNN()' indicates converting a NN-bit value from host byte order to big-endian byte order
274+
* mnenomic indicates a short form that might be displayed by some tools such as disassemblers
275+
* 'htoleNN()' indicates converting a NN-bit value from host byte order to little-endian byte order
276+
* 'htobeNN()' indicates converting a NN-bit value from host byte order to big-endian byte order
277277

278278
Jump instructions
279279
-----------------
@@ -286,24 +286,24 @@ versions.
286286

287287
The 4-bit 'code' field encodes the operation as below, where PC is the program counter:
288288

289-
======== ===== ============================ ======= ============
290-
code value description version notes
291-
======== ===== ============================ ======= ============
292-
BPF_JA 0x00 PC += offset 1 BPF_JMP only
293-
BPF_JEQ 0x10 PC += offset if dst == src 1
294-
BPF_JGT 0x20 PC += offset if dst > src 1 unsigned
295-
BPF_JGE 0x30 PC += offset if dst >= src 1 unsigned
296-
BPF_JSET 0x40 PC += offset if dst & src 1
297-
BPF_JNE 0x50 PC += offset if dst != src 1
298-
BPF_JSGT 0x60 PC += offset if dst > src 1 signed
299-
BPF_JSGE 0x70 PC += offset if dst >= src 1 signed
300-
BPF_CALL 0x80 call function imm 1 see `Helper functions`_
301-
BPF_EXIT 0x90 function / program return 1 BPF_JMP only
302-
BPF_JLT 0xa0 PC += offset if dst < src 2 unsigned
303-
BPF_JLE 0xb0 PC += offset if dst <= src 2 unsigned
304-
BPF_JSLT 0xc0 PC += offset if dst < src 2 signed
305-
BPF_JSLE 0xd0 PC += offset if dst <= src 2 signed
306-
======== ===== ============================ ======= ============
289+
======== ===== ============================ ======= ============
290+
code value description version notes
291+
======== ===== ============================ ======= ============
292+
BPF_JA 0x00 PC += offset 1 BPF_JMP only
293+
BPF_JEQ 0x10 PC += offset if dst == src 1
294+
BPF_JGT 0x20 PC += offset if dst > src 1 unsigned
295+
BPF_JGE 0x30 PC += offset if dst >= src 1 unsigned
296+
BPF_JSET 0x40 PC += offset if dst & src 1
297+
BPF_JNE 0x50 PC += offset if dst != src 1
298+
BPF_JSGT 0x60 PC += offset if dst > src 1 signed
299+
BPF_JSGE 0x70 PC += offset if dst >= src 1 signed
300+
BPF_CALL 0x80 call function imm 1 see `Helper functions`_
301+
BPF_EXIT 0x90 function / program return 1 BPF_JMP only
302+
BPF_JLT 0xa0 PC += offset if dst < src 2 unsigned
303+
BPF_JLE 0xb0 PC += offset if dst <= src 2 unsigned
304+
BPF_JSLT 0xc0 PC += offset if dst < src 2 signed
305+
BPF_JSLE 0xd0 PC += offset if dst <= src 2 signed
306+
======== ===== ============================ ======= ============
307307

308308
where 'version' indicates the first ISA version in which the value was supported.
309309

@@ -330,11 +330,11 @@ Load and store instructions
330330
For load and store instructions (``BPF_LD``, ``BPF_LDX``, ``BPF_ST``, and ``BPF_STX``), the
331331
8-bit 'opcode' field is divided as:
332332

333-
============ ====== =================
334-
3 bits (MSB) 2 bits 3 bits (LSB)
335-
============ ====== =================
336-
mode size instruction class
337-
============ ====== =================
333+
============ ====== =================
334+
3 bits (MSB) 2 bits 3 bits (LSB)
335+
============ ====== =================
336+
mode size instruction class
337+
============ ====== =================
338338

339339
mode
340340
one of:
@@ -370,22 +370,22 @@ Regular load and store operations
370370
The ``BPF_MEM`` mode modifier is used to encode regular load and store
371371
instructions that transfer data between a register and memory.
372372

373-
============================= ========= ==================================
374-
opcode construction opcode pseudocode
375-
============================= ========= ==================================
376-
BPF_MEM | BPF_B | BPF_LDX 0x71 dst = *(uint8_t *) (src + offset)
377-
BPF_MEM | BPF_H | BPF_LDX 0x69 dst = *(uint16_t *) (src + offset)
378-
BPF_MEM | BPF_W | BPF_LDX 0x61 dst = *(uint32_t *) (src + offset)
379-
BPF_MEM | BPF_DW | BPF_LDX 0x79 dst = *(uint64_t *) (src + offset)
380-
BPF_MEM | BPF_B | BPF_ST 0x72 *(uint8_t *) (dst + offset) = imm
381-
BPF_MEM | BPF_H | BPF_ST 0x6a *(uint16_t *) (dst + offset) = imm
382-
BPF_MEM | BPF_W | BPF_ST 0x62 *(uint32_t *) (dst + offset) = imm
383-
BPF_MEM | BPF_DW | BPF_ST 0x7a *(uint64_t *) (dst + offset) = imm
384-
BPF_MEM | BPF_B | BPF_STX 0x73 *(uint8_t *) (dst + offset) = src
385-
BPF_MEM | BPF_H | BPF_STX 0x6b *(uint16_t *) (dst + offset) = src
386-
BPF_MEM | BPF_W | BPF_STX 0x63 *(uint32_t *) (dst + offset) = src
387-
BPF_MEM | BPF_DW | BPF_STX 0x7b *(uint64_t *) (dst + offset) = src
388-
============================= ========= ==================================
373+
============================= ========= ==================================
374+
opcode construction opcode pseudocode
375+
============================= ========= ==================================
376+
BPF_MEM | BPF_B | BPF_LDX 0x71 dst = *(uint8_t *) (src + offset)
377+
BPF_MEM | BPF_H | BPF_LDX 0x69 dst = *(uint16_t *) (src + offset)
378+
BPF_MEM | BPF_W | BPF_LDX 0x61 dst = *(uint32_t *) (src + offset)
379+
BPF_MEM | BPF_DW | BPF_LDX 0x79 dst = *(uint64_t *) (src + offset)
380+
BPF_MEM | BPF_B | BPF_ST 0x72 *(uint8_t *) (dst + offset) = imm
381+
BPF_MEM | BPF_H | BPF_ST 0x6a *(uint16_t *) (dst + offset) = imm
382+
BPF_MEM | BPF_W | BPF_ST 0x62 *(uint32_t *) (dst + offset) = imm
383+
BPF_MEM | BPF_DW | BPF_ST 0x7a *(uint64_t *) (dst + offset) = imm
384+
BPF_MEM | BPF_B | BPF_STX 0x73 *(uint8_t *) (dst + offset) = src
385+
BPF_MEM | BPF_H | BPF_STX 0x6b *(uint16_t *) (dst + offset) = src
386+
BPF_MEM | BPF_W | BPF_STX 0x63 *(uint32_t *) (dst + offset) = src
387+
BPF_MEM | BPF_DW | BPF_STX 0x7b *(uint64_t *) (dst + offset) = src
388+
============================= ========= ==================================
389389
390390
Atomic operations
391391
-----------------
@@ -397,8 +397,8 @@ by other eBPF programs or means outside of this specification.
397397
All atomic operations supported by eBPF are encoded as store operations
398398
that use the ``BPF_ATOMIC`` mode modifier as follows:
399399

400-
* ``BPF_ATOMIC | BPF_W | BPF_STX`` (0xc3) for 32-bit operations
401-
* ``BPF_ATOMIC | BPF_DW | BPF_STX`` (0xdb) for 64-bit operations
400+
* ``BPF_ATOMIC | BPF_W | BPF_STX`` (0xc3) for 32-bit operations
401+
* ``BPF_ATOMIC | BPF_DW | BPF_STX`` (0xdb) for 64-bit operations
402402

403403
Note that 8-bit (``BPF_B``) and 16-bit (``BPF_H``) wide atomic operations are not supported,
404404
nor is ``BPF_ATOMIC | <size> | BPF_ST``.
@@ -407,14 +407,14 @@ The 'imm' field is used to encode the actual atomic operation.
407407
Simple atomic operation use a subset of the values defined to encode
408408
arithmetic operations in the 'imm' field to encode the atomic operation:
409409

410-
======== ===== =========== =======
411-
imm value description version
412-
======== ===== =========== =======
413-
BPF_ADD 0x00 atomic add 1
414-
BPF_OR 0x40 atomic or 3
415-
BPF_AND 0x50 atomic and 3
416-
BPF_XOR 0xa0 atomic xor 3
417-
======== ===== =========== =======
410+
======== ===== =========== =======
411+
imm value description version
412+
======== ===== =========== =======
413+
BPF_ADD 0x00 atomic add 1
414+
BPF_OR 0x40 atomic or 3
415+
BPF_AND 0x50 atomic and 3
416+
BPF_XOR 0xa0 atomic xor 3
417+
======== ===== =========== =======
418418

419419
where 'version' indicates the first ISA version in which the value was supported.
420420

@@ -432,13 +432,13 @@ for ``BPF_ATOMIC | BPF_ADD``.
432432
In addition to the simple atomic operations above, there also is a modifier and
433433
two complex atomic operations:
434434

435-
=========== ================ =========================== =======
436-
imm value description version
437-
=========== ================ =========================== =======
438-
BPF_FETCH 0x01 modifier: return old value 3
439-
BPF_XCHG 0xe0 | BPF_FETCH atomic exchange 3
440-
BPF_CMPXCHG 0xf0 | BPF_FETCH atomic compare and exchange 3
441-
=========== ================ =========================== =======
435+
=========== ================ =========================== =======
436+
imm value description version
437+
=========== ================ =========================== =======
438+
BPF_FETCH 0x01 modifier: return old value 3
439+
BPF_XCHG 0xe0 | BPF_FETCH atomic exchange 3
440+
BPF_CMPXCHG 0xf0 | BPF_FETCH atomic compare and exchange 3
441+
=========== ================ =========================== =======
442442

443443
The ``BPF_FETCH`` modifier is optional for simple atomic operations, and
444444
always set for the complex atomic operations. If the ``BPF_FETCH`` flag
@@ -494,12 +494,12 @@ a register in addition to the immediate data.
494494

495495
These instructions have seven implicit operands:
496496

497-
* Register R6 is an implicit input that must contain a pointer to a
498-
context structure with a packet data pointer.
499-
* Register R0 is an implicit output which contains the data fetched from
500-
the packet.
501-
* Registers R1-R5 are scratch registers that are clobbered by the
502-
instruction.
497+
* Register R6 is an implicit input that must contain a pointer to a
498+
context structure with a packet data pointer.
499+
* Register R0 is an implicit output which contains the data fetched from
500+
the packet.
501+
* Registers R1-R5 are scratch registers that are clobbered by the
502+
instruction.
503503

504504
**Note**
505505

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