| Message ID | 20190529011426.1328736-4-andriin@fb.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf-next,1/9] libbpf: fix detection of corrupted BPF instructions section | expand |
On Tue, May 28, 2019 at 6:14 PM Andrii Nakryiko <andriin@fb.com> wrote: > > Rewrite endianness check to use "more canonical" way, using > compiler-defined macros, similar to few other places in libbpf. It also > is more obvious and shorter. > > Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Song Liu <songliubraving@fb.com> > --- > tools/lib/bpf/libbpf.c | 37 ++++++++++++------------------------- > 1 file changed, 12 insertions(+), 25 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 7b80b9ae8a1f..c98f9942fba4 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -607,31 +607,18 @@ static int bpf_object__elf_init(struct bpf_object *obj) > return err; > } > > -static int > -bpf_object__check_endianness(struct bpf_object *obj) > -{ > - static unsigned int const endian = 1; > - > - switch (obj->efile.ehdr.e_ident[EI_DATA]) { > - case ELFDATA2LSB: > - /* We are big endian, BPF obj is little endian. */ > - if (*(unsigned char const *)&endian != 1) > - goto mismatch; > - break; > - > - case ELFDATA2MSB: > - /* We are little endian, BPF obj is big endian. */ > - if (*(unsigned char const *)&endian != 0) > - goto mismatch; > - break; > - default: > - return -LIBBPF_ERRNO__ENDIAN; > - } > - > - return 0; > - > -mismatch: > - pr_warning("Error: endianness mismatch.\n"); > +static int bpf_object__check_endianness(struct bpf_object *obj) > +{ > +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ > + if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB) > + return 0; > +#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ > + if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB) > + return 0; > +#else > +# error "Unrecognized __BYTE_ORDER__" > +#endif > + pr_warning("endianness mismatch.\n"); > return -LIBBPF_ERRNO__ENDIAN; > } > > -- > 2.17.1 >
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 7b80b9ae8a1f..c98f9942fba4 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -607,31 +607,18 @@ static int bpf_object__elf_init(struct bpf_object *obj) return err; } -static int -bpf_object__check_endianness(struct bpf_object *obj) -{ - static unsigned int const endian = 1; - - switch (obj->efile.ehdr.e_ident[EI_DATA]) { - case ELFDATA2LSB: - /* We are big endian, BPF obj is little endian. */ - if (*(unsigned char const *)&endian != 1) - goto mismatch; - break; - - case ELFDATA2MSB: - /* We are little endian, BPF obj is big endian. */ - if (*(unsigned char const *)&endian != 0) - goto mismatch; - break; - default: - return -LIBBPF_ERRNO__ENDIAN; - } - - return 0; - -mismatch: - pr_warning("Error: endianness mismatch.\n"); +static int bpf_object__check_endianness(struct bpf_object *obj) +{ +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ + if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB) + return 0; +#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ + if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB) + return 0; +#else +# error "Unrecognized __BYTE_ORDER__" +#endif + pr_warning("endianness mismatch.\n"); return -LIBBPF_ERRNO__ENDIAN; }
Rewrite endianness check to use "more canonical" way, using compiler-defined macros, similar to few other places in libbpf. It also is more obvious and shorter. Signed-off-by: Andrii Nakryiko <andriin@fb.com> --- tools/lib/bpf/libbpf.c | 37 ++++++++++++------------------------- 1 file changed, 12 insertions(+), 25 deletions(-)