Commit 30ad6880 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
Browse files

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: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200630152125.3631920-2-andriin@fb.com
parent ca4db638

tools/lib/bpf/bpf_endian.h

+35 −8
Original line number Diff line number Diff line
@@ -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)

CRA Git | Maintained and supported by SUSTech CRA and CCSE