* event more eBPF instruction set documentation improvements
@ 2022-01-31 18:36 Christoph Hellwig
2022-01-31 18:36 ` [PATCH 1/5] bpf, docs: Document the byte swapping instructions Christoph Hellwig
` (4 more replies)
0 siblings, 5 replies; 10+ messages in thread
From: Christoph Hellwig @ 2022-01-31 18:36 UTC (permalink / raw)
To: Jonathan Corbet, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
Cc: Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, linux-doc, netdev, bpf
Hi all,
this series adds further improves the eBPF instruction set documentation.
It documents the byte swap instructions and polishes up the load and
store section.
Diffstat:
instruction-set.rst | 215 ++++++++++++++++++++++++++++++++++++----------------
1 file changed, 151 insertions(+), 64 deletions(-)
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH 1/5] bpf, docs: Document the byte swapping instructions
2022-01-31 18:36 event more eBPF instruction set documentation improvements Christoph Hellwig
@ 2022-01-31 18:36 ` Christoph Hellwig
2022-02-03 17:40 ` patchwork-bot+netdevbpf
2022-01-31 18:36 ` [PATCH 2/5] bpf, docs: Better document the regular load and store instructions Christoph Hellwig
` (3 subsequent siblings)
4 siblings, 1 reply; 10+ messages in thread
From: Christoph Hellwig @ 2022-01-31 18:36 UTC (permalink / raw)
To: Jonathan Corbet, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
Cc: Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, linux-doc, netdev, bpf
Add a section to document the byte swapping instructions.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
Documentation/bpf/instruction-set.rst | 44 ++++++++++++++++++++++++---
1 file changed, 40 insertions(+), 4 deletions(-)
diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst
index 3704836fe6df6..87f6ad62633a5 100644
--- a/Documentation/bpf/instruction-set.rst
+++ b/Documentation/bpf/instruction-set.rst
@@ -82,9 +82,9 @@ BPF_ALU uses 32-bit wide operands while BPF_ALU64 uses 64-bit wide operands for
otherwise identical operations.
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
@@ -98,8 +98,8 @@ The code field encodes the operation as below:
BPF_XOR 0xa0 dst ^= src
BPF_MOV 0xb0 dst = src
BPF_ARSH 0xc0 sign extending shift right
- BPF_END 0xd0 endianness conversion
- ======== ===== ==========================
+ BPF_END 0xd0 byte swap operations (see separate section below)
+ ======== ===== =================================================
BPF_ADD | BPF_X | BPF_ALU means::
@@ -118,6 +118,42 @@ BPF_XOR | BPF_K | BPF_ALU64 means::
src_reg = src_reg ^ imm32
+Byte swap instructions
+----------------------
+
+The byte swap instructions use an instruction class of ``BFP_ALU`` and a 4-bit
+code field of ``BPF_END``.
+
+The byte swap instructions instructions operate on the destination register
+only and do not use a separate source register or immediate value.
+
+The 1-bit source operand field in the opcode is used to to select what byte
+order the operation convert from or to:
+
+ ========= ===== =================================================
+ 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
+ ========= ===== =================================================
+
+The imm field encodes the width of the swap operations. The following widths
+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_FROM_LE`` and ``BPF_FROM_BE`` exist as aliases for ``BPF_TO_LE`` and
+``BPF_TO_LE`` respetively.
+
+
Jump instructions
-----------------
--
2.30.2
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH 2/5] bpf, docs: Better document the regular load and store instructions
2022-01-31 18:36 event more eBPF instruction set documentation improvements Christoph Hellwig
2022-01-31 18:36 ` [PATCH 1/5] bpf, docs: Document the byte swapping instructions Christoph Hellwig
@ 2022-01-31 18:36 ` Christoph Hellwig
2022-01-31 18:36 ` [PATCH 3/5] bpf, docs: Better document the legacy packet access instruction Christoph Hellwig
` (2 subsequent siblings)
4 siblings, 0 replies; 10+ messages in thread
From: Christoph Hellwig @ 2022-01-31 18:36 UTC (permalink / raw)
To: Jonathan Corbet, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
Cc: Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, linux-doc, netdev, bpf
Add a separate section and a little intro blurb for the regular load and
store instructions.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
Documentation/bpf/instruction-set.rst | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst
index 87f6ad62633a5..03da885301722 100644
--- a/Documentation/bpf/instruction-set.rst
+++ b/Documentation/bpf/instruction-set.rst
@@ -215,23 +215,30 @@ The mode modifier is one of:
BPF_IMM 0x00 used for 64-bit mov
BPF_ABS 0x20 legacy BPF packet access
BPF_IND 0x40 legacy BPF packet access
- BPF_MEM 0x60 all normal load and store operations
+ BPF_MEM 0x60 regular load and store operations
BPF_ATOMIC 0xc0 atomic operations
============= ===== ====================================
-BPF_MEM | <size> | BPF_STX means::
+
+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::
*(size *) (dst_reg + off) = src_reg
-BPF_MEM | <size> | BPF_ST means::
+``BPF_MEM | <size> | BPF_ST`` means::
*(size *) (dst_reg + off) = imm32
-BPF_MEM | <size> | BPF_LDX means::
+``BPF_MEM | <size> | BPF_LDX`` means::
dst_reg = *(size *) (src_reg + off)
-Where size is one of: BPF_B or BPF_H or BPF_W or BPF_DW.
+Where size is one of: ``BPF_B``, ``BPF_H``, ``BPF_W``, or ``BPF_DW``.
Atomic operations
-----------------
--
2.30.2
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH 3/5] bpf, docs: Better document the legacy packet access instruction
2022-01-31 18:36 event more eBPF instruction set documentation improvements Christoph Hellwig
2022-01-31 18:36 ` [PATCH 1/5] bpf, docs: Document the byte swapping instructions Christoph Hellwig
2022-01-31 18:36 ` [PATCH 2/5] bpf, docs: Better document the regular load and store instructions Christoph Hellwig
@ 2022-01-31 18:36 ` Christoph Hellwig
2022-02-03 17:32 ` Alexei Starovoitov
2022-01-31 18:36 ` [PATCH 4/5] bpf, docs: Better document the extended instruction format Christoph Hellwig
2022-01-31 18:36 ` [PATCH 5/5] bpf, docs: Better document the atomic instructions Christoph Hellwig
4 siblings, 1 reply; 10+ messages in thread
From: Christoph Hellwig @ 2022-01-31 18:36 UTC (permalink / raw)
To: Jonathan Corbet, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
Cc: Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, linux-doc, netdev, bpf
Use consistent terminology and structured RST elements to better document
these two oddball instructions.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
Documentation/bpf/instruction-set.rst | 54 ++++++++++++++++-----------
1 file changed, 32 insertions(+), 22 deletions(-)
diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst
index 03da885301722..b3c2621216c97 100644
--- a/Documentation/bpf/instruction-set.rst
+++ b/Documentation/bpf/instruction-set.rst
@@ -213,8 +213,8 @@ The mode modifier is one of:
mode modifier value description
============= ===== ====================================
BPF_IMM 0x00 used for 64-bit mov
- BPF_ABS 0x20 legacy BPF packet access
- BPF_IND 0x40 legacy BPF packet access
+ BPF_ABS 0x20 legacy BPF packet access (absolute)
+ BPF_IND 0x40 legacy BPF packet access (indirect)
BPF_MEM 0x60 regular load and store operations
BPF_ATOMIC 0xc0 atomic operations
============= ===== ====================================
@@ -294,29 +294,39 @@ eBPF has one 16-byte instruction: ``BPF_LD | BPF_DW | BPF_IMM`` which consists
of two consecutive ``struct bpf_insn`` 8-byte blocks and interpreted as single
instruction that loads 64-bit immediate value into a dst_reg.
-Packet access instructions
---------------------------
+Legacy BPF Packet access instructions
+-------------------------------------
-eBPF has two non-generic instructions: (BPF_ABS | <size> | BPF_LD) and
-(BPF_IND | <size> | BPF_LD) which are used to access packet data.
+eBPF has special instructions for access to packet data that have been
+carried over from classic BPF to retain the performance of legacy socket
+filters running in the eBPF interpreter.
-They had to be carried over from classic BPF to have strong performance of
-socket filters running in eBPF interpreter. These instructions can only
-be used when interpreter context is a pointer to ``struct sk_buff`` and
-have seven implicit operands. Register R6 is an implicit input that must
-contain pointer to sk_buff. Register R0 is an implicit output which contains
-the data fetched from the packet. Registers R1-R5 are scratch registers
-and must not be used to store the data across BPF_ABS | BPF_LD or
-BPF_IND | BPF_LD instructions.
+The instructions come in two forms: ``BPF_ABS | <size> | BPF_LD`` and
+``BPF_IND | <size> | BPF_LD``.
-These instructions have implicit program exit condition as well. When
-eBPF program is trying to access the data beyond the packet boundary,
-the interpreter will abort the execution of the program. JIT compilers
-therefore must preserve this property. src_reg and imm32 fields are
-explicit inputs to these instructions.
+These instructions are used to access packet data and can only be used when
+the interpreter context is a pointer to networking packet. ``BPF_ABS``
+accesses packet data at an absolute offset specified by the immediate data
+and ``BPF_IND`` access packet data at an offset that includes the value of
+a register in addition to the immediate data.
-For example, BPF_IND | BPF_W | BPF_LD means::
+These instructions have seven implicit operands:
- R0 = ntohl(*(u32 *) (((struct sk_buff *) R6)->data + src_reg + imm32))
+ * Register R6 is an implicit input that must contain pointer to a
+ struct sk_buff.
+ * Register R0 is an implicit output which contains the data fetched from
+ the packet.
+ * Registers R1-R5 are scratch registers that are clobbered after a call to
+ ``BPF_ABS | BPF_LD`` or ``BPF_IND`` | BPF_LD instructions.
+
+These instructions have an implicit program exit condition as well. When an
+eBPF program is trying to access the data beyond the packet boundary, the
+interpreter will abort the execution of the program.
+
+``BPF_ABS | BPF_W | BPF_LD`` means::
-and R1 - R5 are clobbered.
+ R0 = ntohl(*(u32 *) (((struct sk_buff *) R6)->data + imm32))
+
+``BPF_IND | BPF_W | BPF_LD`` means::
+
+ R0 = ntohl(*(u32 *) (((struct sk_buff *) R6)->data + src_reg + imm32))
--
2.30.2
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH 4/5] bpf, docs: Better document the extended instruction format
2022-01-31 18:36 event more eBPF instruction set documentation improvements Christoph Hellwig
` (2 preceding siblings ...)
2022-01-31 18:36 ` [PATCH 3/5] bpf, docs: Better document the legacy packet access instruction Christoph Hellwig
@ 2022-01-31 18:36 ` Christoph Hellwig
2022-01-31 18:36 ` [PATCH 5/5] bpf, docs: Better document the atomic instructions Christoph Hellwig
4 siblings, 0 replies; 10+ messages in thread
From: Christoph Hellwig @ 2022-01-31 18:36 UTC (permalink / raw)
To: Jonathan Corbet, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
Cc: Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, linux-doc, netdev, bpf
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>
---
Documentation/bpf/instruction-set.rst | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst
index b3c2621216c97..048aea0952a2e 100644
--- a/Documentation/bpf/instruction-set.rst
+++ b/Documentation/bpf/instruction-set.rst
@@ -22,7 +22,13 @@ necessary across calls.
Instruction encoding
====================
-eBPF uses 64-bit instructions with the following encoding:
+eBPF has two instruction encodings:
+
+ * 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.
+
+The basic instruction encoding looks as follows:
============= ======= =============== ==================== ============
32 bits (MSB) 16 bits 4 bits 4 bits 8 bits (LSB)
@@ -212,7 +218,7 @@ The mode modifier is one of:
============= ===== ====================================
mode modifier value description
============= ===== ====================================
- BPF_IMM 0x00 used for 64-bit mov
+ BPF_IMM 0x00 64-bit immediate instructions
BPF_ABS 0x20 legacy BPF packet access (absolute)
BPF_IND 0x40 legacy BPF packet access (indirect)
BPF_MEM 0x60 regular load and store operations
@@ -287,12 +293,18 @@ You may encounter ``BPF_XADD`` - this is a legacy name for ``BPF_ATOMIC``,
referring to the exclusive-add operation encoded when the immediate field is
zero.
-16-byte instructions
---------------------
+64-bit immediate instructions
+-----------------------------
+
+Instructions with the ``BPF_IMM`` mode modifier use the wide instruction
+encoding for an extra imm64 value.
+
+There is currently only one such instruction.
+
+``BPF_LD | BPF_DW | BPF_IMM`` means::
+
+ dst_reg = imm64
-eBPF has one 16-byte instruction: ``BPF_LD | BPF_DW | BPF_IMM`` which consists
-of two consecutive ``struct bpf_insn`` 8-byte blocks and interpreted as single
-instruction that loads 64-bit immediate value into a dst_reg.
Legacy BPF Packet access instructions
-------------------------------------
--
2.30.2
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH 5/5] bpf, docs: Better document the atomic instructions
2022-01-31 18:36 event more eBPF instruction set documentation improvements Christoph Hellwig
` (3 preceding siblings ...)
2022-01-31 18:36 ` [PATCH 4/5] bpf, docs: Better document the extended instruction format Christoph Hellwig
@ 2022-01-31 18:36 ` Christoph Hellwig
4 siblings, 0 replies; 10+ messages in thread
From: Christoph Hellwig @ 2022-01-31 18:36 UTC (permalink / raw)
To: Jonathan Corbet, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
Cc: Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, linux-doc, netdev, bpf
Use proper tables and RST markup to document the atomic instructions
in a structured way.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
Documentation/bpf/instruction-set.rst | 76 +++++++++++++++++----------
1 file changed, 49 insertions(+), 27 deletions(-)
diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst
index 048aea0952a2e..4e79a77febd43 100644
--- a/Documentation/bpf/instruction-set.rst
+++ b/Documentation/bpf/instruction-set.rst
@@ -249,39 +249,65 @@ Where size is one of: ``BPF_B``, ``BPF_H``, ``BPF_W``, or ``BPF_DW``.
Atomic operations
-----------------
-eBPF includes atomic operations, which use the immediate field for extra
-encoding::
+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.
- .imm = BPF_ADD, .code = BPF_ATOMIC | BPF_W | BPF_STX: lock xadd *(u32 *)(dst_reg + off16) += src_reg
- .imm = BPF_ADD, .code = BPF_ATOMIC | BPF_DW | BPF_STX: lock xadd *(u64 *)(dst_reg + off16) += src_reg
+All atomic operations supported by eBPF are encoded as store operations
+that use the ``BPF_ATOMIC`` mode modifier as follows:
-The basic atomic operations supported are::
+ * ``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_ADD
- BPF_AND
- BPF_OR
- BPF_XOR
+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:
-Each having equivalent semantics with the ``BPF_ADD`` example, that is: the
-memory location addresed by ``dst_reg + off`` is atomically modified, with
-``src_reg`` as the other operand. If the ``BPF_FETCH`` flag is set in the
-immediate, then these operations also overwrite ``src_reg`` with the
-value that was in memory before it was modified.
+ ======== ===== ===========
+ imm value description
+ ======== ===== ===========
+ BPF_ADD 0x00 atomic add
+ BPF_OR 0x40 atomic or
+ BPF_AND 0x50 atomic and
+ BPF_XOR 0xa0 atomic xor
+ ======== ===== ===========
-The more special operations are::
- BPF_XCHG
+``BPF_ATOMIC | BPF_W | BPF_STX`` with imm = BPF_ADD means::
-This atomically exchanges ``src_reg`` with the value addressed by ``dst_reg +
-off``. ::
+ *(u32 *)(dst_reg + off16) += src_reg
- BPF_CMPXCHG
+``BPF_ATOMIC | BPF_DW | BPF_STX`` with imm = BPF ADD means::
-This atomically compares the value addressed by ``dst_reg + off`` with
-``R0``. If they match it is replaced with ``src_reg``. In either case, the
-value that was there before is zero-extended and loaded back to ``R0``.
+ *(u64 *)(dst_reg + off16) += src_reg
-Note that 1 and 2 byte atomic operations are not supported.
+``BPF_XADD`` is a deprecated name for ``BPF_ATOMIC | BPF_ADD``.
+
+In addition to the simple atomic operations, there also is a modifier and
+two complex atomic operations:
+
+ =========== ================ ===========================
+ 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
+ =========== ================ ===========================
+
+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``.
Clang can generate atomic instructions by default when ``-mcpu=v3`` is
enabled. If a lower version for ``-mcpu`` is set, the only atomic instruction
@@ -289,10 +315,6 @@ Clang can generate is ``BPF_ADD`` *without* ``BPF_FETCH``. If you need to enable
the atomics features, while keeping a lower ``-mcpu`` version, you can use
``-Xclang -target-feature -Xclang +alu32``.
-You may encounter ``BPF_XADD`` - this is a legacy name for ``BPF_ATOMIC``,
-referring to the exclusive-add operation encoded when the immediate field is
-zero.
-
64-bit immediate instructions
-----------------------------
--
2.30.2
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH 3/5] bpf, docs: Better document the legacy packet access instruction
2022-01-31 18:36 ` [PATCH 3/5] bpf, docs: Better document the legacy packet access instruction Christoph Hellwig
@ 2022-02-03 17:32 ` Alexei Starovoitov
2022-02-03 17:40 ` Christoph Hellwig
0 siblings, 1 reply; 10+ messages in thread
From: Alexei Starovoitov @ 2022-02-03 17:32 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Jonathan Corbet, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, open list:DOCUMENTATION,
Network Development, bpf
On Mon, Jan 31, 2022 at 10:36 AM Christoph Hellwig <hch@lst.de> wrote:
> +These instructions are used to access packet data and can only be used when
> +the interpreter context is a pointer to networking packet. ``BPF_ABS``
...
> +These instructions have an implicit program exit condition as well. When an
> +eBPF program is trying to access the data beyond the packet boundary, the
> +interpreter will abort the execution of the program.
These two places make it sound like it's interpreter only behavior.
I've reworded it like:
-the interpreter context is a pointer to networking packet. ``BPF_ABS``
+the program context is a pointer to networking packet. ``BPF_ABS``
-interpreter will abort the execution of the program.
+program execution will be aborted.
and pushed to bpf-next with the rest of patches.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/5] bpf, docs: Document the byte swapping instructions
2022-01-31 18:36 ` [PATCH 1/5] bpf, docs: Document the byte swapping instructions Christoph Hellwig
@ 2022-02-03 17:40 ` patchwork-bot+netdevbpf
0 siblings, 0 replies; 10+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-02-03 17:40 UTC (permalink / raw)
To: Christoph Hellwig
Cc: corbet, ast, daniel, andrii, kafai, songliubraving, yhs,
john.fastabend, kpsingh, linux-doc, netdev, bpf
Hello:
This series was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:
On Mon, 31 Jan 2022 19:36:34 +0100 you wrote:
> Add a section to document the byte swapping instructions.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> Documentation/bpf/instruction-set.rst | 44 ++++++++++++++++++++++++---
> 1 file changed, 40 insertions(+), 4 deletions(-)
Here is the summary with links:
- [1/5] bpf, docs: Document the byte swapping instructions
https://git.kernel.org/bpf/bpf-next/c/dd33fb571f5c
- [2/5] bpf, docs: Better document the regular load and store instructions
https://git.kernel.org/bpf/bpf-next/c/63d8c242b9a5
- [3/5] bpf, docs: Better document the legacy packet access instruction
https://git.kernel.org/bpf/bpf-next/c/15175336270a
- [4/5] bpf, docs: Better document the extended instruction format
https://git.kernel.org/bpf/bpf-next/c/5ca15b8a939f
- [5/5] bpf, docs: Better document the atomic instructions
https://git.kernel.org/bpf/bpf-next/c/594d32348556
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 3/5] bpf, docs: Better document the legacy packet access instruction
2022-02-03 17:32 ` Alexei Starovoitov
@ 2022-02-03 17:40 ` Christoph Hellwig
2022-02-03 17:44 ` Alexei Starovoitov
0 siblings, 1 reply; 10+ messages in thread
From: Christoph Hellwig @ 2022-02-03 17:40 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Christoph Hellwig, Jonathan Corbet, Alexei Starovoitov,
Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu,
Yonghong Song, John Fastabend, KP Singh, open list:DOCUMENTATION,
Network Development, bpf
On Thu, Feb 03, 2022 at 09:32:38AM -0800, Alexei Starovoitov wrote:
> These two places make it sound like it's interpreter only behavior.
> I've reworded it like:
> -the interpreter context is a pointer to networking packet. ``BPF_ABS``
> +the program context is a pointer to networking packet. ``BPF_ABS``
>
> -interpreter will abort the execution of the program.
> +program execution will be aborted.
>
> and pushed to bpf-next with the rest of patches.
The interpreter thing is actually unchanged from the old text, but I
totally agree with your fixup. Thanks!
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 3/5] bpf, docs: Better document the legacy packet access instruction
2022-02-03 17:40 ` Christoph Hellwig
@ 2022-02-03 17:44 ` Alexei Starovoitov
0 siblings, 0 replies; 10+ messages in thread
From: Alexei Starovoitov @ 2022-02-03 17:44 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Jonathan Corbet, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, open list:DOCUMENTATION,
Network Development, bpf
On Thu, Feb 3, 2022 at 9:40 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Thu, Feb 03, 2022 at 09:32:38AM -0800, Alexei Starovoitov wrote:
> > These two places make it sound like it's interpreter only behavior.
> > I've reworded it like:
> > -the interpreter context is a pointer to networking packet. ``BPF_ABS``
> > +the program context is a pointer to networking packet. ``BPF_ABS``
> >
> > -interpreter will abort the execution of the program.
> > +program execution will be aborted.
> >
> > and pushed to bpf-next with the rest of patches.
>
> The interpreter thing is actually unchanged from the old text, but I
> totally agree with your fixup. Thanks!
The old doc had:
"the interpreter will abort the execution of the program. JIT compilers
therefore must preserve this property."
Since the latter sentence is now gone the former got ambiguous.
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2022-02-03 17:44 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-01-31 18:36 event more eBPF instruction set documentation improvements Christoph Hellwig
2022-01-31 18:36 ` [PATCH 1/5] bpf, docs: Document the byte swapping instructions Christoph Hellwig
2022-02-03 17:40 ` patchwork-bot+netdevbpf
2022-01-31 18:36 ` [PATCH 2/5] bpf, docs: Better document the regular load and store instructions Christoph Hellwig
2022-01-31 18:36 ` [PATCH 3/5] bpf, docs: Better document the legacy packet access instruction Christoph Hellwig
2022-02-03 17:32 ` Alexei Starovoitov
2022-02-03 17:40 ` Christoph Hellwig
2022-02-03 17:44 ` Alexei Starovoitov
2022-01-31 18:36 ` [PATCH 4/5] bpf, docs: Better document the extended instruction format Christoph Hellwig
2022-01-31 18:36 ` [PATCH 5/5] bpf, docs: Better document the atomic instructions Christoph Hellwig
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