From: Wang Nan <wangn...@huawei.com> Check endianness according to EHDR. Code is taken from tools/perf/util/symbol-elf.c.
Libbpf doesn't magically convert missmatched endianness. Even if we swap eBPF instructions to correct byte order, we are unable to deal with endianness in code logical generated by LLVM. Therefore, libbpf should simply reject missmatched ELF object, and let LLVM to create good code. Signed-off-by: Wang Nan <wangn...@huawei.com> Acked-by: Alexei Starovoitov <a...@plumgrid.com> Cc: Brendan Gregg <brendan.d.gr...@gmail.com> Cc: Daniel Borkmann <dan...@iogearbox.net> Cc: David Ahern <dsah...@gmail.com> Cc: He Kuang <heku...@huawei.com> Cc: Jiri Olsa <jo...@kernel.org> Cc: Kaixu Xia <xiaka...@huawei.com> Cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Peter Zijlstra <a.p.zijls...@chello.nl> Cc: Zefan Li <lize...@huawei.com> Cc: pi3or...@163.com Link: http://lkml.kernel.org/r/1435716878-189507-8-git-send-email-wangn...@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> --- tools/lib/bpf/libbpf.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 36dfbc1dfa77..15b3e82b22f6 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -192,6 +192,34 @@ errout: 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 -EINVAL; + } + + return 0; + +mismatch: + pr_warning("Error: endianness mismatch.\n"); + return -EINVAL; +} + static struct bpf_object * __bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz) { @@ -208,6 +236,8 @@ __bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz) if (bpf_object__elf_init(obj)) goto out; + if (bpf_object__check_endianness(obj)) + goto out; bpf_object__elf_finish(obj); return obj; -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
