Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934420AbbEOH7L (ORCPT ); Fri, 15 May 2015 03:59:11 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:62745 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934275AbbEOH7I (ORCPT ); Fri, 15 May 2015 03:59:08 -0400 From: Wang Nan To: , , , , , , , , , , , CC: , , , Subject: [RFC PATCH v2 21/37] tools lib bpf: relocation programs. Date: Fri, 15 May 2015 07:51:14 +0000 Message-ID: <1431676290-1230-22-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1431676290-1230-1-git-send-email-wangnan0@huawei.com> References: <1431676290-1230-1-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 Content-Length: 2203 Lines: 86 If an eBPF program access a map, LLVM generates a relocated load instruction. To enable the usage of that map, relocation must be done by replacing original instructions by map loading instructions. Based on relocation description collected during 'opening' phase, this patch replaces the instructions with map loading with correct map fd. Signed-off-by: Wang Nan --- tools/lib/bpf/libbpf.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 6ff4cb6..5e25ea7 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -676,6 +676,52 @@ bpf_obj_create_maps(struct bpf_object *obj) return 0; } +static int +bpf_program_relocate(struct bpf_object *obj, struct bpf_program *prog) +{ + int i; + + if (!prog || !prog->reloc_desc) + return 0; + + for (i = 0; i < prog->nr_reloc; i++) { + int insn_idx, map_idx; + struct bpf_insn *insns = prog->insns; + + insn_idx = prog->reloc_desc[i].insn_idx; + map_idx = prog->reloc_desc[i].map_idx; + + if (insn_idx >= (int)prog->insns_cnt) { + pr_warning("relocation out of range: '%s'\n", + prog->section_name); + return -ERANGE; + } + insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD; + insns[insn_idx].imm = obj->maps_fds[map_idx]; + } + + return 0; +} + +static int +bpf_obj_relocate(struct bpf_object *obj) +{ + struct bpf_program *prog; + size_t i; + int err; + + for (i = 0; i < obj->nr_programs; i++) { + prog = &obj->programs[i]; + + if ((err = bpf_program_relocate(obj, prog))) { + pr_warning("failed to relocate '%s'\n", + prog->section_name); + return err; + } + } + return 0; +} + static int bpf_obj_collect_reloc(struct bpf_object *obj) { int i, err; @@ -783,6 +829,8 @@ int bpf_load_object(struct bpf_object *obj) if (bpf_obj_create_maps(obj)) goto out; + if (bpf_obj_relocate(obj)) + goto out; return 0; out: -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/