tools/testing/selftests/bpf/bpf_endian.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __BPF_ENDIAN__
   3 #define __BPF_ENDIAN__
   4
   5 #include <linux/stddef.h>
   6 #include <linux/swab.h>
   7
   8 /* LLVM's BPF target selects the endianness of the CPU
   9  * it compiles on, or the user specifies (bpfel/bpfeb),
  10  * respectively. The used __BYTE_ORDER__ is defined by
  11  * the compiler, we cannot rely on __BYTE_ORDER from
  12  * libc headers, since it doesn't reflect the actual
  13  * requested byte order.
  14  *
  15  * Note, LLVM's BPF target has different __builtin_bswapX()
  16  * semantics. It does map to BPF_ALU | BPF_END | BPF_TO_BE
  17  * in bpfel and bpfeb case, which means below, that we map
  18  * to cpu_to_be16(). We could use it unconditionally in BPF
  19  * case, but better not rely on it, so that this header here
  20  * can be used from application and BPF program side, which
  21  * use different targets.
  22  */
  23 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
  24 # define __bpf_ntohs(x)                 __builtin_bswap16(x)
  25 # define __bpf_htons(x)                 __builtin_bswap16(x)
  26 # define __bpf_constant_ntohs(x)        ___constant_swab16(x)
  27 # define __bpf_constant_htons(x)        ___constant_swab16(x)
  28 # define __bpf_ntohl(x)                 __builtin_bswap32(x)
  29 # define __bpf_htonl(x)                 __builtin_bswap32(x)
  30 # define __bpf_constant_ntohl(x)        ___constant_swab32(x)
  31 # define __bpf_constant_htonl(x)        ___constant_swab32(x)
  32 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
  33 # define __bpf_ntohs(x)                 (x)
  34 # define __bpf_htons(x)                 (x)
  35 # define __bpf_constant_ntohs(x)        (x)
  36 # define __bpf_constant_htons(x)        (x)
  37 # define __bpf_ntohl(x)                 (x)
  38 # define __bpf_htonl(x)                 (x)
  39 # define __bpf_constant_ntohl(x)        (x)
  40 # define __bpf_constant_htonl(x)        (x)
  41 #else
  42 # error "Fix your compiler's __BYTE_ORDER__?!"
  43 #endif
  44
  45 #define bpf_htons(x)                            \
  46         (__builtin_constant_p(x) ?              \
  47          __bpf_constant_htons(x) : __bpf_htons(x))
  48 #define bpf_ntohs(x)                            \
  49         (__builtin_constant_p(x) ?              \
  50          __bpf_constant_ntohs(x) : __bpf_ntohs(x))
  51 #define bpf_htonl(x)                            \
  52         (__builtin_constant_p(x) ?              \
  53          __bpf_constant_htonl(x) : __bpf_htonl(x))
  54 #define bpf_ntohl(x)                            \
  55         (__builtin_constant_p(x) ?              \
  56          __bpf_constant_ntohl(x) : __bpf_ntohl(x))
  57
  58 #endif /* __BPF_ENDIAN__ */