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libbpf: Make bpf_endian co-exist with vmlinux.h 

Make bpf_endian.h compatible with vmlinux.h. It is a frequent request from
users wanting to use bpf_endian.h in their BPF applications using CO-RE and
vmlinux.h.

To achieve that, re-implement byte swap macros and drop all the header
includes. This way it can be used both with linux header includes, as well as
with a vmlinux.h.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200630152125.3631920-2-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2020-06-30 08:21:24 -07:00 committed by Daniel Borkmann
parent ca4db6389d
commit 30ad688094
1 changed files with 35 additions and 8 deletions
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43
tools/lib/bpf/bpf_endian.h
View File

@ -2,8 +2,35 @@
#ifndef __BPF_ENDIAN__
#define __BPF_ENDIAN__
#include <linux/stddef.h>
#include <linux/swab.h>
/*
* Isolate byte #n and put it into byte #m, for __u##b type.
* E.g., moving byte #6 (nnnnnnnn) into byte #1 (mmmmmmmm) for __u64:
* 1) xxxxxxxx nnnnnnnn xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx mmmmmmmm xxxxxxxx
* 2) nnnnnnnn xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx mmmmmmmm xxxxxxxx 00000000
* 3) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 nnnnnnnn
* 4) 00000000 00000000 00000000 00000000 00000000 00000000 nnnnnnnn 00000000
*/
#define ___bpf_mvb(x, b, n, m) ((__u##b)(x) << (b-(n+1)*8) >> (b-8) << (m*8))
#define ___bpf_swab16(x) ((__u16)( \
___bpf_mvb(x, 16, 0, 1) | \
___bpf_mvb(x, 16, 1, 0)))
#define ___bpf_swab32(x) ((__u32)( \
___bpf_mvb(x, 32, 0, 3) | \
___bpf_mvb(x, 32, 1, 2) | \
___bpf_mvb(x, 32, 2, 1) | \
___bpf_mvb(x, 32, 3, 0)))
#define ___bpf_swab64(x) ((__u64)( \
___bpf_mvb(x, 64, 0, 7) | \
___bpf_mvb(x, 64, 1, 6) | \
___bpf_mvb(x, 64, 2, 5) | \
___bpf_mvb(x, 64, 3, 4) | \
___bpf_mvb(x, 64, 4, 3) | \
___bpf_mvb(x, 64, 5, 2) | \
___bpf_mvb(x, 64, 6, 1) | \
___bpf_mvb(x, 64, 7, 0)))
/* LLVM's BPF target selects the endianness of the CPU
* it compiles on, or the user specifies (bpfel/bpfeb),
@ -23,16 +50,16 @@
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
# define __bpf_ntohs(x) __builtin_bswap16(x)
# define __bpf_htons(x) __builtin_bswap16(x)
# define __bpf_constant_ntohs(x) ___constant_swab16(x)
# define __bpf_constant_htons(x) ___constant_swab16(x)
# define __bpf_constant_ntohs(x) ___bpf_swab16(x)
# define __bpf_constant_htons(x) ___bpf_swab16(x)
# define __bpf_ntohl(x) __builtin_bswap32(x)
# define __bpf_htonl(x) __builtin_bswap32(x)
# define __bpf_constant_ntohl(x) ___constant_swab32(x)
# define __bpf_constant_htonl(x) ___constant_swab32(x)
# define __bpf_constant_ntohl(x) ___bpf_swab32(x)
# define __bpf_constant_htonl(x) ___bpf_swab32(x)
# define __bpf_be64_to_cpu(x) __builtin_bswap64(x)
# define __bpf_cpu_to_be64(x) __builtin_bswap64(x)
# define __bpf_constant_be64_to_cpu(x) ___constant_swab64(x)
# define __bpf_constant_cpu_to_be64(x) ___constant_swab64(x)
# define __bpf_constant_be64_to_cpu(x) ___bpf_swab64(x)
# define __bpf_constant_cpu_to_be64(x) ___bpf_swab64(x)
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
# define __bpf_ntohs(x) (x)
# define __bpf_htons(x) (x)