From: Dave Thaler <dthaler@xxxxxxxxxxxxx> Signed-off-by: Dave Thaler <dthaler@xxxxxxxxxxxxx> --- Documentation/bpf/instruction-set.rst | 14 ++++++++++---- Documentation/bpf/linux-notes.rst | 6 ++++++ 2 files changed, 16 insertions(+), 4 deletions(-) diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst index 4997d2088..a24bc5d53 100644 --- a/Documentation/bpf/instruction-set.rst +++ b/Documentation/bpf/instruction-set.rst @@ -7,6 +7,10 @@ eBPF Instruction Set Specification, v1.0 This document specifies version 1.0 of the eBPF instruction set. +Documentation conventions +========================= + +This specification uses the standard C types (uint32_t, etc.) in documentation. Registers and calling convention ================================ @@ -114,7 +118,9 @@ BPF_END 0xd0 byte swap operations (see `Byte swap instructions`_ below) ``BPF_ADD | BPF_X | BPF_ALU`` means:: - dst_reg = (u32) dst_reg + (u32) src_reg; + dst_reg = (uint32_t) dst_reg + (uint32_t) src_reg; + +where '(uint32_t)' indicates truncation to 32 bits. ``BPF_ADD | BPF_X | BPF_ALU64`` means:: @@ -122,7 +128,7 @@ BPF_END 0xd0 byte swap operations (see `Byte swap instructions`_ below) ``BPF_XOR | BPF_K | BPF_ALU`` means:: - src_reg = (u32) src_reg ^ (u32) imm32 + src_reg = (uint32_t) src_reg ^ (uint32_t) imm32 ``BPF_XOR | BPF_K | BPF_ALU64`` means:: @@ -276,11 +282,11 @@ BPF_XOR 0xa0 atomic xor ``BPF_ATOMIC | BPF_W | BPF_STX`` with 'imm' = BPF_ADD means:: - *(u32 *)(dst_reg + off16) += src_reg + *(uint32_t *)(dst_reg + off16) += src_reg ``BPF_ATOMIC | BPF_DW | BPF_STX`` with 'imm' = BPF ADD means:: - *(u64 *)(dst_reg + off16) += src_reg + *(uint32_t *)(dst_reg + off16) += src_reg In addition to the simple atomic operations, there also is a modifier and two complex atomic operations: diff --git a/Documentation/bpf/linux-notes.rst b/Documentation/bpf/linux-notes.rst index 1c31379b4..522ebe27d 100644 --- a/Documentation/bpf/linux-notes.rst +++ b/Documentation/bpf/linux-notes.rst @@ -7,6 +7,12 @@ Linux implementation notes This document provides more details specific to the Linux kernel implementation of the eBPF instruction set. +Arithmetic instructions +======================= + +While the eBPF instruction set document uses the standard C terminology as the cross-platform specification, +in the Linux kernel, uint32_t is expressed as u32, uint64_t is expressed as u64, etc. + Byte swap instructions ====================== -- 2.33.4
