From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: [RFC bpf-next PATCH] bpf: add comments to BPF ld/ldx sizes Date: Wed, 17 Jan 2018 00:21:27 +0100 Message-ID: References: <151610226596.29962.4661213256715212454.stgit@firesoul> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Jesper Dangaard Brouer , Daniel Borkmann , Alexei Starovoitov Return-path: Received: from www62.your-server.de ([213.133.104.62]:40352 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750830AbeAPXV3 (ORCPT ); Tue, 16 Jan 2018 18:21:29 -0500 In-Reply-To: <151610226596.29962.4661213256715212454.stgit@firesoul> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 01/16/2018 12:31 PM, Jesper Dangaard Brouer wrote: > Doc BPF ld/ldx size defines, as it help me understand the code in filter.c. > > Signed-off-by: Jesper Dangaard Brouer > --- > 0 files changed > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index 395d261948de..4729d9a002d4 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -17,7 +17,7 @@ > #define BPF_ALU64 0x07 /* alu mode in double word width */ > > /* ld/ldx fields */ > -#define BPF_DW 0x18 /* double word */ > +#define BPF_DW 0x18 /* double word (64-bit) */ > #define BPF_XADD 0xc0 /* exclusive add */ > > /* alu/jmp fields */ > diff --git a/include/uapi/linux/bpf_common.h b/include/uapi/linux/bpf_common.h > index 18be90725ab0..ee97668bdadb 100644 > --- a/include/uapi/linux/bpf_common.h > +++ b/include/uapi/linux/bpf_common.h > @@ -15,9 +15,10 @@ > > /* ld/ldx fields */ > #define BPF_SIZE(code) ((code) & 0x18) > -#define BPF_W 0x00 > -#define BPF_H 0x08 > -#define BPF_B 0x10 > +#define BPF_W 0x00 /* 32-bit */ > +#define BPF_H 0x08 /* 16-bit */ > +#define BPF_B 0x10 /* 8-bit */ > +/* eBPF BPF_DW 0x18 64-bit */ Hmm, I don't really mind, but we do have it documented in: Documentation/networking/filter.txt +942 Feels like if we put a comment only on BPF_{B,H,W}, then we might also want to document all the others such as ALU ops, etc. > #define BPF_MODE(code) ((code) & 0xe0) > #define BPF_IMM 0x00 > #define BPF_ABS 0x20 >