On Fri, Jul 19, 2019 at 7:35 AM Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> wrote:
>
> From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
>
> Using endian.h and its endianness macros makes this code build in a
> wider range of compilers, as some don't have those macros
> (__BYTE_ORDER__, __ORDER_LITTLE_ENDIAN__, __ORDER_BIG_ENDIAN__),
> so use instead endian.h's macros (__BYTE_ORDER, __LITTLE_ENDIAN,
> __BIG_ENDIAN) which makes this code even shorter :-)
gcc 4.6.0 starts to support __BYTE_ORDER__, __ORDER_LITTLE_ENDIAN__, etc.
I guess those platforms with failing compilation have gcc < 4.6.0.
Agree that for libbpf, which will be used outside kernel bpf selftest should
try to compile with lower versions of gcc.
>
> Acked-by: Andrii Nakryiko <andriin@xxxxxx>
> Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Fixes: 12ef5634a855 ("libbpf: simplify endianness check")
> Fixes: e6c64855fd7a ("libbpf: add btf__parse_elf API to load .BTF and .BTF.ext")
> Link: https://lkml.kernel.org/n/tip-eep5n8vgwcdphw3uc058k03u@xxxxxxxxxxxxxx
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> ---
> tools/lib/bpf/btf.c | 5 +++--
> tools/lib/bpf/libbpf.c | 5 +++--
> 2 files changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index 467224feb43b..d821107f55f9 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -1,6 +1,7 @@
> // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
> /* Copyright (c) 2018 Facebook */
>
> +#include <endian.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> @@ -419,9 +420,9 @@ struct btf *btf__new(__u8 *data, __u32 size)
>
> static bool btf_check_endianness(const GElf_Ehdr *ehdr)
> {
> -#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> +#if __BYTE_ORDER == __LITTLE_ENDIAN
> return ehdr->e_ident[EI_DATA] == ELFDATA2LSB;
> -#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
> +#elif __BYTE_ORDER == __BIG_ENDIAN
> return ehdr->e_ident[EI_DATA] == ELFDATA2MSB;
> #else
> # error "Unrecognized __BYTE_ORDER__"
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 794dd5064ae8..b1dec5b1de54 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -20,6 +20,7 @@
> #include <inttypes.h>
> #include <string.h>
> #include <unistd.h>
> +#include <endian.h>
> #include <fcntl.h>
> #include <errno.h>
> #include <asm/unistd.h>
> @@ -612,10 +613,10 @@ static int bpf_object__elf_init(struct bpf_object *obj)
>
> static int bpf_object__check_endianness(struct bpf_object *obj)
> {
> -#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> +#if __BYTE_ORDER == __LITTLE_ENDIAN
> if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
> return 0;
> -#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
> +#elif __BYTE_ORDER == __BIG_ENDIAN
> if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
> return 0;
> #else
> --
> 2.21.0
>
