From d00d5b82f0734205c718aa1acf7cc9b183fd6751 Mon Sep 17 00:00:00 2001 From: Dave Thaler Date: Fri, 27 Jan 2023 01:47:06 +0000 Subject: bpf, docs: Add note about type convention Add explanation about use of "u64", "u32", etc. as the type convention used in BPF documentation. Signed-off-by: Dave Thaler Acked-by: David Vernet Link: https://lore.kernel.org/r/20230127014706.1005-1-dthaler1968@googlemail.com Signed-off-by: Alexei Starovoitov --- Documentation/bpf/instruction-set.rst | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation/bpf') diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst index c1c17ee60ecb..af515de5fc38 100644 --- a/Documentation/bpf/instruction-set.rst +++ b/Documentation/bpf/instruction-set.rst @@ -7,6 +7,11 @@ eBPF Instruction Set Specification, v1.0 This document specifies version 1.0 of the eBPF instruction set. +Documentation conventions +========================= + +For brevity, this document uses the type notion "u64", "u32", etc. +to mean an unsigned integer whose width is the specified number of bits. Registers and calling convention ================================ @@ -164,6 +169,8 @@ the destination register is unchanged whereas for ``BPF_ALU`` the upper dst = (u32) ((u32) dst + (u32) src) +where '(u32)' indicates that the upper 32 bits are zeroed. + ``BPF_ADD | BPF_X | BPF_ALU64`` means:: dst = dst + src -- cgit v1.2.3