github.com/yaling888/clash@v1.53.0/component/ebpf/bpf/bpf_endian.h (about)

     1  /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
     2  #ifndef __BPF_ENDIAN__
     3  #define __BPF_ENDIAN__
     4  
     5  /*
     6   * Isolate byte #n and put it into byte #m, for __u##b type.
     7   * E.g., moving byte #6 (nnnnnnnn) into byte #1 (mmmmmmmm) for __u64:
     8   * 1) xxxxxxxx nnnnnnnn xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx mmmmmmmm xxxxxxxx
     9   * 2) nnnnnnnn xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx mmmmmmmm xxxxxxxx 00000000
    10   * 3) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 nnnnnnnn
    11   * 4) 00000000 00000000 00000000 00000000 00000000 00000000 nnnnnnnn 00000000
    12   */
    13  #define ___bpf_mvb(x, b, n, m) ((__u##b)(x) << (b-(n+1)*8) >> (b-8) << (m*8))
    14  
    15  #define ___bpf_swab16(x) ((__u16)(			\
    16  			  ___bpf_mvb(x, 16, 0, 1) |	\
    17  			  ___bpf_mvb(x, 16, 1, 0)))
    18  
    19  #define ___bpf_swab32(x) ((__u32)(			\
    20  			  ___bpf_mvb(x, 32, 0, 3) |	\
    21  			  ___bpf_mvb(x, 32, 1, 2) |	\
    22  			  ___bpf_mvb(x, 32, 2, 1) |	\
    23  			  ___bpf_mvb(x, 32, 3, 0)))
    24  
    25  #define ___bpf_swab64(x) ((__u64)(			\
    26  			  ___bpf_mvb(x, 64, 0, 7) |	\
    27  			  ___bpf_mvb(x, 64, 1, 6) |	\
    28  			  ___bpf_mvb(x, 64, 2, 5) |	\
    29  			  ___bpf_mvb(x, 64, 3, 4) |	\
    30  			  ___bpf_mvb(x, 64, 4, 3) |	\
    31  			  ___bpf_mvb(x, 64, 5, 2) |	\
    32  			  ___bpf_mvb(x, 64, 6, 1) |	\
    33  			  ___bpf_mvb(x, 64, 7, 0)))
    34  
    35  /* LLVM's BPF target selects the endianness of the CPU
    36   * it compiles on, or the user specifies (bpfel/bpfeb),
    37   * respectively. The used __BYTE_ORDER__ is defined by
    38   * the compiler, we cannot rely on __BYTE_ORDER from
    39   * libc headers, since it doesn't reflect the actual
    40   * requested byte order.
    41   *
    42   * Note, LLVM's BPF target has different __builtin_bswapX()
    43   * semantics. It does map to BPF_ALU | BPF_END | BPF_TO_BE
    44   * in bpfel and bpfeb case, which means below, that we map
    45   * to cpu_to_be16(). We could use it unconditionally in BPF
    46   * case, but better not rely on it, so that this header here
    47   * can be used from application and BPF program side, which
    48   * use different targets.
    49   */
    50  #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
    51  # define __bpf_ntohs(x)			__builtin_bswap16(x)
    52  # define __bpf_htons(x)			__builtin_bswap16(x)
    53  # define __bpf_constant_ntohs(x)	___bpf_swab16(x)
    54  # define __bpf_constant_htons(x)	___bpf_swab16(x)
    55  # define __bpf_ntohl(x)			__builtin_bswap32(x)
    56  # define __bpf_htonl(x)			__builtin_bswap32(x)
    57  # define __bpf_constant_ntohl(x)	___bpf_swab32(x)
    58  # define __bpf_constant_htonl(x)	___bpf_swab32(x)
    59  # define __bpf_be64_to_cpu(x)		__builtin_bswap64(x)
    60  # define __bpf_cpu_to_be64(x)		__builtin_bswap64(x)
    61  # define __bpf_constant_be64_to_cpu(x)	___bpf_swab64(x)
    62  # define __bpf_constant_cpu_to_be64(x)	___bpf_swab64(x)
    63  #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
    64  # define __bpf_ntohs(x)			(x)
    65  # define __bpf_htons(x)			(x)
    66  # define __bpf_constant_ntohs(x)	(x)
    67  # define __bpf_constant_htons(x)	(x)
    68  # define __bpf_ntohl(x)			(x)
    69  # define __bpf_htonl(x)			(x)
    70  # define __bpf_constant_ntohl(x)	(x)
    71  # define __bpf_constant_htonl(x)	(x)
    72  # define __bpf_be64_to_cpu(x)		(x)
    73  # define __bpf_cpu_to_be64(x)		(x)
    74  # define __bpf_constant_be64_to_cpu(x)  (x)
    75  # define __bpf_constant_cpu_to_be64(x)  (x)
    76  #else
    77  # error "Fix your compiler's __BYTE_ORDER__?!"
    78  #endif
    79  
    80  #define bpf_htons(x)				\
    81  	(__builtin_constant_p(x) ?		\
    82  	 __bpf_constant_htons(x) : __bpf_htons(x))
    83  #define bpf_ntohs(x)				\
    84  	(__builtin_constant_p(x) ?		\
    85  	 __bpf_constant_ntohs(x) : __bpf_ntohs(x))
    86  #define bpf_htonl(x)				\
    87  	(__builtin_constant_p(x) ?		\
    88  	 __bpf_constant_htonl(x) : __bpf_htonl(x))
    89  #define bpf_ntohl(x)				\
    90  	(__builtin_constant_p(x) ?		\
    91  	 __bpf_constant_ntohl(x) : __bpf_ntohl(x))
    92  #define bpf_cpu_to_be64(x)			\
    93  	(__builtin_constant_p(x) ?		\
    94  	 __bpf_constant_cpu_to_be64(x) : __bpf_cpu_to_be64(x))
    95  #define bpf_be64_to_cpu(x)			\
    96  	(__builtin_constant_p(x) ?		\
    97  	 __bpf_constant_be64_to_cpu(x) : __bpf_be64_to_cpu(x))
    98  
    99  #endif /* __BPF_ENDIAN__ */