From 63d8c242b9a502f1517b3e8c45d2125649dd5d7b Mon Sep 17 00:00:00 2001 From: Christoph Hellwig <hch@lst.de> Date: Mon, 31 Jan 2022 19:36:35 +0100 Subject: [PATCH] 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 --- 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