Re: [RFC bpf-next PATCH] bpf: add comments to BPF ld/ldx sizes
From: Daniel Borkmann <daniel@iogearbox.net>
Date: 2018-01-16 23:21:29
On 01/16/2018 12:31 PM, Jesper Dangaard Brouer wrote:
quoted hunk ↗ jump to hunk
Doc BPF ld/ldx size defines, as it help me understand the code in filter.c. Signed-off-by: Jesper Dangaard Brouer <redacted> --- 0 files changeddiff --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