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linux/Documentation/bpf/instruction-set.rst

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bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
.. contents::
.. sectnum::
========================================
eBPF Instruction Set Specification, v1.0
========================================
This document specifies version 1.0 of the eBPF instruction set.
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Split the comparism to classic BPF from instruction-set.rst Split the introductory that explain eBPF vs classic BPF and how it maps to hardware from the instruction set specification into a standalone document. This duplicates a little bit of information but gives us a useful reference for the eBPF instrution set that is not encumbered by classic BPF. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-3-hch@lst.de
2021-12-23 13:19:04 +03:00
Registers and calling convention
================================
eBPF has 10 general purpose registers and a read-only frame pointer register,
all of which are 64-bits wide.
The eBPF calling convention is defined as:
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
* R0: return value from function calls, and exit value for eBPF programs
* R1 - R5: arguments for function calls
* R6 - R9: callee saved registers that function calls will preserve
* R10: read-only frame pointer to access stack
bpf, docs: Split the comparism to classic BPF from instruction-set.rst Split the introductory that explain eBPF vs classic BPF and how it maps to hardware from the instruction set specification into a standalone document. This duplicates a little bit of information but gives us a useful reference for the eBPF instrution set that is not encumbered by classic BPF. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-3-hch@lst.de
2021-12-23 13:19:04 +03:00
R0 - R5 are scratch registers and eBPF programs needs to spill/fill them if
necessary across calls.
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Add a setion to explain the basic instruction encoding The eBPF instruction set document does not currently document the basic instruction encoding. Add a section to do that. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-2-hch@lst.de
2022-01-03 21:35:51 +03:00
Instruction encoding
====================
bpf, docs: Better document the extended instruction format In addition to the normal 64-bit instruction encoding, eBPF also has a single instruction that uses a second 64-bit bits for a second immediate value. Instead of only documenting this format deep down in the document mention it in the instruction encoding section. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-5-hch@lst.de
2022-01-31 21:36:37 +03:00
eBPF has two instruction encodings:
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
* the basic instruction encoding, which uses 64 bits to encode an instruction
* the wide instruction encoding, which appends a second 64-bit immediate value
(imm64) after the basic instruction for a total of 128 bits.
bpf, docs: Better document the extended instruction format In addition to the normal 64-bit instruction encoding, eBPF also has a single instruction that uses a second 64-bit bits for a second immediate value. Instead of only documenting this format deep down in the document mention it in the instruction encoding section. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-5-hch@lst.de
2022-01-31 21:36:37 +03:00
The basic instruction encoding looks as follows:
bpf, docs: Add a setion to explain the basic instruction encoding The eBPF instruction set document does not currently document the basic instruction encoding. Add a section to do that. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-2-hch@lst.de
2022-01-03 21:35:51 +03:00
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
============= ======= =============== ==================== ============
32 bits (MSB) 16 bits 4 bits 4 bits 8 bits (LSB)
============= ======= =============== ==================== ============
immediate offset source register destination register opcode
============= ======= =============== ==================== ============
bpf, docs: Add a setion to explain the basic instruction encoding The eBPF instruction set document does not currently document the basic instruction encoding. Add a section to do that. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-2-hch@lst.de
2022-01-03 21:35:51 +03:00
Note that most instructions do not use all of the fields.
Unused fields shall be cleared to zero.
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
Instruction classes
bpf, docs: Add a setion to explain the basic instruction encoding The eBPF instruction set document does not currently document the basic instruction encoding. Add a section to do that. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-2-hch@lst.de
2022-01-03 21:35:51 +03:00
-------------------
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
The three LSB bits of the 'opcode' field store the instruction class:
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
========= ===== =============================== ===================================
class value description reference
========= ===== =============================== ===================================
BPF_LD 0x00 non-standard load operations `Load and store instructions`_
BPF_LDX 0x01 load into register operations `Load and store instructions`_
BPF_ST 0x02 store from immediate operations `Load and store instructions`_
BPF_STX 0x03 store from register operations `Load and store instructions`_
BPF_ALU 0x04 32-bit arithmetic operations `Arithmetic and jump instructions`_
BPF_JMP 0x05 64-bit jump operations `Arithmetic and jump instructions`_
BPF_JMP32 0x06 32-bit jump operations `Arithmetic and jump instructions`_
BPF_ALU64 0x07 64-bit arithmetic operations `Arithmetic and jump instructions`_
========= ===== =============================== ===================================
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
Arithmetic and jump instructions
================================
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
For arithmetic and jump instructions (``BPF_ALU``, ``BPF_ALU64``, ``BPF_JMP`` and
``BPF_JMP32``), the 8-bit 'opcode' field is divided into three parts:
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
============== ====== =================
4 bits (MSB) 1 bit 3 bits (LSB)
============== ====== =================
operation code source instruction class
============== ====== =================
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
The 4th bit encodes the source operand:
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
====== ===== ========================================
source value description
====== ===== ========================================
BPF_K 0x00 use 32-bit immediate as source operand
BPF_X 0x08 use 'src_reg' register as source operand
====== ===== ========================================
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
The four MSB bits store the operation code.
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Add subsections for ALU and JMP instructions Add a little more stucture to the ALU/JMP documentation with sections and improve the example text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-3-hch@lst.de
2022-01-03 21:35:52 +03:00
Arithmetic instructions
-----------------------
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
``BPF_ALU`` uses 32-bit wide operands while ``BPF_ALU64`` uses 64-bit wide operands for
bpf, docs: Add subsections for ALU and JMP instructions Add a little more stucture to the ALU/JMP documentation with sections and improve the example text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-3-hch@lst.de
2022-01-03 21:35:52 +03:00
otherwise identical operations.
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
The 'code' field encodes the operation as below:
======== ===== ==========================================================
code value description
======== ===== ==========================================================
BPF_ADD 0x00 dst += src
BPF_SUB 0x10 dst -= src
BPF_MUL 0x20 dst \*= src
BPF_DIV 0x30 dst /= src
BPF_OR 0x40 dst \|= src
BPF_AND 0x50 dst &= src
BPF_LSH 0x60 dst <<= src
BPF_RSH 0x70 dst >>= src
BPF_NEG 0x80 dst = ~src
BPF_MOD 0x90 dst %= src
BPF_XOR 0xa0 dst ^= src
BPF_MOV 0xb0 dst = src
BPF_ARSH 0xc0 sign extending shift right
BPF_END 0xd0 byte swap operations (see `Byte swap instructions`_ below)
======== ===== ==========================================================
``BPF_ADD | BPF_X | BPF_ALU`` means::
bpf, docs: Add subsections for ALU and JMP instructions Add a little more stucture to the ALU/JMP documentation with sections and improve the example text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-3-hch@lst.de
2022-01-03 21:35:52 +03:00
dst_reg = (u32) dst_reg + (u32) src_reg;
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
``BPF_ADD | BPF_X | BPF_ALU64`` means::
bpf, docs: Add subsections for ALU and JMP instructions Add a little more stucture to the ALU/JMP documentation with sections and improve the example text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-3-hch@lst.de
2022-01-03 21:35:52 +03:00
dst_reg = dst_reg + src_reg
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
``BPF_XOR | BPF_K | BPF_ALU`` means::
bpf, docs: Add subsections for ALU and JMP instructions Add a little more stucture to the ALU/JMP documentation with sections and improve the example text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-3-hch@lst.de
2022-01-03 21:35:52 +03:00
src_reg = (u32) src_reg ^ (u32) imm32
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
``BPF_XOR | BPF_K | BPF_ALU64`` means::
bpf, docs: Add subsections for ALU and JMP instructions Add a little more stucture to the ALU/JMP documentation with sections and improve the example text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-3-hch@lst.de
2022-01-03 21:35:52 +03:00
src_reg = src_reg ^ imm32
bpf, docs: Document the byte swapping instructions Add a section to document the byte swapping instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-2-hch@lst.de
2022-01-31 21:36:34 +03:00
Byte swap instructions
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
~~~~~~~~~~~~~~~~~~~~~~
bpf, docs: Document the byte swapping instructions Add a section to document the byte swapping instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-2-hch@lst.de
2022-01-31 21:36:34 +03:00
bpf, docs: Fix typo "BFP_ALU" to "BPF_ALU" "BFP" should be "BPF" Signed-off-by: Kosuke Fujimoto <fujimotokosuke0@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20220609083937.245749-1-fujimotoksouke0@gmail.com
2022-06-09 11:39:37 +03:00
The byte swap instructions use an instruction class of ``BPF_ALU`` and a 4-bit
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
'code' field of ``BPF_END``.
bpf, docs: Document the byte swapping instructions Add a section to document the byte swapping instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-2-hch@lst.de
2022-01-31 21:36:34 +03:00
bpf, docs: Remove duplicated word "instructions" The word "instructions" is duplicated, remove it. Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/1651139754-4838-2-git-send-email-yangtiezhu@loongson.cn
2022-04-28 12:55:52 +03:00
The byte swap instructions operate on the destination register
bpf, docs: Document the byte swapping instructions Add a section to document the byte swapping instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-2-hch@lst.de
2022-01-31 21:36:34 +03:00
only and do not use a separate source register or immediate value.
Delete duplicate words from kernel docs I have deleted duplicate words like to, guest, trace, when, we Signed-off-by: Akhil Raj <lf32.dev@gmail.com> Link: https://lore.kernel.org/r/20220829065239.4531-1-lf32.dev@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2022-08-29 09:52:39 +03:00
The 1-bit source operand field in the opcode is used to select what byte
bpf, docs: Document the byte swapping instructions Add a section to document the byte swapping instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-2-hch@lst.de
2022-01-31 21:36:34 +03:00
order the operation convert from or to:
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
========= ===== =================================================
source value description
========= ===== =================================================
BPF_TO_LE 0x00 convert between host byte order and little endian
BPF_TO_BE 0x08 convert between host byte order and big endian
========= ===== =================================================
bpf, docs: Document the byte swapping instructions Add a section to document the byte swapping instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-2-hch@lst.de
2022-01-31 21:36:34 +03:00
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
The 'imm' field encodes the width of the swap operations. The following widths
bpf, docs: Document the byte swapping instructions Add a section to document the byte swapping instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-2-hch@lst.de
2022-01-31 21:36:34 +03:00
are supported: 16, 32 and 64.
Examples:
``BPF_ALU | BPF_TO_LE | BPF_END`` with imm = 16 means::
dst_reg = htole16(dst_reg)
``BPF_ALU | BPF_TO_BE | BPF_END`` with imm = 64 means::
dst_reg = htobe64(dst_reg)
bpf, docs: Add subsections for ALU and JMP instructions Add a little more stucture to the ALU/JMP documentation with sections and improve the example text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-3-hch@lst.de
2022-01-03 21:35:52 +03:00
Jump instructions
-----------------
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
``BPF_JMP32`` uses 32-bit wide operands while ``BPF_JMP`` uses 64-bit wide operands for
bpf, docs: Add subsections for ALU and JMP instructions Add a little more stucture to the ALU/JMP documentation with sections and improve the example text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-3-hch@lst.de
2022-01-03 21:35:52 +03:00
otherwise identical operations.
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
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
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
======== ===== ========================= ============
bpf, docs: Split the comparism to classic BPF from instruction-set.rst Split the introductory that explain eBPF vs classic BPF and how it maps to hardware from the instruction set specification into a standalone document. This duplicates a little bit of information but gives us a useful reference for the eBPF instrution set that is not encumbered by classic BPF. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-3-hch@lst.de
2021-12-23 13:19:04 +03:00
bpf, docs: Add subsections for ALU and JMP instructions Add a little more stucture to the ALU/JMP documentation with sections and improve the example text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220103183556.41040-3-hch@lst.de
2022-01-03 21:35:52 +03:00
The eBPF program needs to store the return value into register R0 before doing a
BPF_EXIT.
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
Load and store instructions
===========================
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
For load and store instructions (``BPF_LD``, ``BPF_LDX``, ``BPF_ST``, and ``BPF_STX``), the
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
8-bit 'opcode' field is divided as:
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
============ ====== =================
3 bits (MSB) 2 bits 3 bits (LSB)
============ ====== =================
mode size instruction class
============ ====== =================
The mode modifier is one of:
============= ===== ==================================== =============
mode modifier value description reference
============= ===== ==================================== =============
BPF_IMM 0x00 64-bit immediate instructions `64-bit immediate instructions`_
BPF_ABS 0x20 legacy BPF packet access (absolute) `Legacy BPF Packet access instructions`_
BPF_IND 0x40 legacy BPF packet access (indirect) `Legacy BPF Packet access instructions`_
BPF_MEM 0x60 regular load and store operations `Regular load and store operations`_
BPF_ATOMIC 0xc0 atomic operations `Atomic operations`_
============= ===== ==================================== =============
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
The size modifier is one of:
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
============= ===== =====================
size modifier value description
============= ===== =====================
BPF_W 0x00 word (4 bytes)
BPF_H 0x08 half word (2 bytes)
BPF_B 0x10 byte
BPF_DW 0x18 double word (8 bytes)
============= ===== =====================
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Better document the regular load and store instructions Add a separate section and a little intro blurb for the regular load and store instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-3-hch@lst.de
2022-01-31 21:36:35 +03:00
Regular load and store operations
---------------------------------
The ``BPF_MEM`` mode modifier is used to encode regular load and store
instructions that transfer data between a register and memory.
``BPF_MEM | <size> | BPF_STX`` means::
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
*(size *) (dst_reg + off) = src_reg
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Better document the regular load and store instructions Add a separate section and a little intro blurb for the regular load and store instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-3-hch@lst.de
2022-01-31 21:36:35 +03:00
``BPF_MEM | <size> | BPF_ST`` means::
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
*(size *) (dst_reg + off) = imm32
bpf, docs: Better document the regular load and store instructions Add a separate section and a little intro blurb for the regular load and store instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-3-hch@lst.de
2022-01-31 21:36:35 +03:00
``BPF_MEM | <size> | BPF_LDX`` means::
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
dst_reg = *(size *) (src_reg + off)
bpf, docs: Better document the regular load and store instructions Add a separate section and a little intro blurb for the regular load and store instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-3-hch@lst.de
2022-01-31 21:36:35 +03:00
Where size is one of: ``BPF_B``, ``BPF_H``, ``BPF_W``, or ``BPF_DW``.
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
Atomic operations
-----------------
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Better document the atomic instructions Use proper tables and RST markup to document the atomic instructions in a structured way. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-6-hch@lst.de
2022-01-31 21:36:38 +03:00
Atomic operations are operations that operate on memory and can not be
interrupted or corrupted by other access to the same memory region
by other eBPF programs or means outside of this specification.
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Better document the atomic instructions Use proper tables and RST markup to document the atomic instructions in a structured way. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-6-hch@lst.de
2022-01-31 21:36:38 +03:00
All atomic operations supported by eBPF are encoded as store operations
that use the ``BPF_ATOMIC`` mode modifier as follows:
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
* ``BPF_ATOMIC | BPF_W | BPF_STX`` for 32-bit operations
* ``BPF_ATOMIC | BPF_DW | BPF_STX`` for 64-bit operations
* 8-bit and 16-bit wide atomic operations are not supported.
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
The 'imm' field is used to encode the actual atomic operation.
bpf, docs: Better document the atomic instructions Use proper tables and RST markup to document the atomic instructions in a structured way. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-6-hch@lst.de
2022-01-31 21:36:38 +03:00
Simple atomic operation use a subset of the values defined to encode
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
arithmetic operations in the 'imm' field to encode the atomic operation:
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
======== ===== ===========
imm value description
======== ===== ===========
BPF_ADD 0x00 atomic add
BPF_OR 0x40 atomic or
BPF_AND 0x50 atomic and
BPF_XOR 0xa0 atomic xor
======== ===== ===========
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
``BPF_ATOMIC | BPF_W | BPF_STX`` with 'imm' = BPF_ADD means::
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Better document the atomic instructions Use proper tables and RST markup to document the atomic instructions in a structured way. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-6-hch@lst.de
2022-01-31 21:36:38 +03:00
*(u32 *)(dst_reg + off16) += src_reg
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
``BPF_ATOMIC | BPF_DW | BPF_STX`` with 'imm' = BPF ADD means::
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Better document the atomic instructions Use proper tables and RST markup to document the atomic instructions in a structured way. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-6-hch@lst.de
2022-01-31 21:36:38 +03:00
*(u64 *)(dst_reg + off16) += src_reg
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Better document the atomic instructions Use proper tables and RST markup to document the atomic instructions in a structured way. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-6-hch@lst.de
2022-01-31 21:36:38 +03:00
In addition to the simple atomic operations, there also is a modifier and
two complex atomic operations:
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
=========== ================ ===========================
imm value description
=========== ================ ===========================
BPF_FETCH 0x01 modifier: return old value
BPF_XCHG 0xe0 | BPF_FETCH atomic exchange
BPF_CMPXCHG 0xf0 | BPF_FETCH atomic compare and exchange
=========== ================ ===========================
bpf, docs: Better document the atomic instructions Use proper tables and RST markup to document the atomic instructions in a structured way. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-6-hch@lst.de
2022-01-31 21:36:38 +03:00
The ``BPF_FETCH`` modifier is optional for simple atomic operations, and
always set for the complex atomic operations. If the ``BPF_FETCH`` flag
is set, then the operation also overwrites ``src_reg`` with the value that
was in memory before it was modified.
The ``BPF_XCHG`` operation atomically exchanges ``src_reg`` with the value
addressed by ``dst_reg + off``.
The ``BPF_CMPXCHG`` operation atomically compares the value addressed by
``dst_reg + off`` with ``R0``. If they match, the value addressed by
``dst_reg + off`` is replaced with ``src_reg``. In either case, the
value that was at ``dst_reg + off`` before the operation is zero-extended
and loaded back to ``R0``.
bpf, docs: Split general purpose eBPF documentation out of filter.rst filter.rst starts out documenting the classic BPF and then spills into introducing and documentating eBPF. Move the eBPF documentation into rwo new files under Documentation/bpf/ for the instruction set and the verifier and link to the BPF documentation from filter.rst. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211119163215.971383-6-hch@lst.de
2021-11-19 19:32:15 +03:00
bpf, docs: Better document the extended instruction format In addition to the normal 64-bit instruction encoding, eBPF also has a single instruction that uses a second 64-bit bits for a second immediate value. Instead of only documenting this format deep down in the document mention it in the instruction encoding section. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-5-hch@lst.de
2022-01-31 21:36:37 +03:00
64-bit immediate instructions
-----------------------------
bpf, docs: Add TOC and fix formatting. Add TOC and fix formatting. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-5-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:48 +03:00
Instructions with the ``BPF_IMM`` 'mode' modifier use the wide instruction
bpf, docs: Better document the extended instruction format In addition to the normal 64-bit instruction encoding, eBPF also has a single instruction that uses a second 64-bit bits for a second immediate value. Instead of only documenting this format deep down in the document mention it in the instruction encoding section. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-5-hch@lst.de
2022-01-31 21:36:37 +03:00
encoding for an extra imm64 value.
There is currently only one such instruction.
``BPF_LD | BPF_DW | BPF_IMM`` means::
dst_reg = imm64
bpf, docs: Generate nicer tables for instruction encodings Use RST tables that are nicely readable both in plain ascii as well as in html to render the instruction encodings, and add a few subheadings to better structure the text. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-4-hch@lst.de
2021-12-23 13:19:05 +03:00
bpf, docs: Move the packet access instructions last in instruction-set.rst The packet access instructions are a convoluted leftover from classic BPF. Move them last past the much more important atomic operations, and improve the rendering of the code example. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-5-hch@lst.de
2021-12-23 13:19:06 +03:00
bpf, docs: Better document the legacy packet access instruction Use consistent terminology and structured RST elements to better document these two oddball instructions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220131183638.3934982-4-hch@lst.de
2022-01-31 21:36:36 +03:00
Legacy BPF Packet access instructions
-------------------------------------
bpf, docs: Move the packet access instructions last in instruction-set.rst The packet access instructions are a convoluted leftover from classic BPF. Move them last past the much more important atomic operations, and improve the rendering of the code example. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211223101906.977624-5-hch@lst.de
2021-12-23 13:19:06 +03:00
bpf, docs: Move legacy packet instructions to a separate file Move legacy packet instructions to a separate file. Signed-off-by: Dave Thaler <dthaler@microsoft.com> Link: https://lore.kernel.org/r/20220927185958.14995-1-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-09-27 21:59:44 +03:00
eBPF previously introduced special instructions for access to packet data that were
carried over from classic BPF. However, these instructions are
deprecated and should no longer be used.
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