From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932164AbbEQLE3 (ORCPT ); Sun, 17 May 2015 07:04:29 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:61094 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753225AbbEQK5q (ORCPT ); Sun, 17 May 2015 06:57:46 -0400 From: Wang Nan To: , , , , , , , , , , CC: , , Subject: [RFC PATCH v3 10/37] bpf tools: Check endianess and set swap flag according to EHDR Date: Sun, 17 May 2015 10:56:35 +0000 Message-ID: <1431860222-61636-11-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1431860222-61636-1-git-send-email-wangnan0@huawei.com> References: <1431860222-61636-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.197.200] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Check endianess according to EHDR to support loading eBPF objects into big endian machines. Code is taken from tools/perf/util/symbol-elf.c. Signed-off-by: Wang Nan --- tools/lib/bpf/libbpf.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 43c16bc..a4910a8 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -69,6 +69,7 @@ void libbpf_set_print(int (*warn)(const char *format, ...), struct bpf_object { char *path; + bool needs_swap; /* * Information when doing elf related work. Only valid if fd @@ -109,6 +110,7 @@ static struct bpf_object *bpf_obj_alloc(const char *path) if (!obj) goto out; + obj->needs_swap = false; obj->elf.fd = -1; return obj; out: @@ -179,6 +181,31 @@ errout: return err; } +static int +bpf_obj_swap_init(struct bpf_object *obj) +{ + static unsigned int const endian = 1; + + obj->needs_swap = false; + + switch (obj->elf.ehdr.e_ident[EI_DATA]) { + case ELFDATA2LSB: + /* We are big endian, BPF obj is little endian. */ + if (*(unsigned char const *)&endian != 1) + obj->needs_swap = true; + return 0; + + case ELFDATA2MSB: + /* We are little endian, BPF obj is big endian. */ + if (*(unsigned char const *)&endian != 0) + obj->needs_swap = true; + return 0; + + default: + return -EINVAL; + } +} + struct bpf_object *bpf_open_object(const char *path) { struct bpf_object *obj; @@ -200,6 +227,8 @@ struct bpf_object *bpf_open_object(const char *path) if (bpf_obj_elf_init(obj)) goto out; + if (bpf_obj_swap_init(obj)) + goto out; return obj; -- 1.8.3.4