linux-kernel - [RFC PATCH 13/22] perf bpf: collects relocation sections from object file.

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Message-ID: <1430391165-30267-14-git-send-email-wangnan0@huawei.com>
Date:	Thu, 30 Apr 2015 10:52:36 +0000
From:	Wang Nan <wangnan0@...wei.com>
To:	<ast@...mgrid.com>, <davem@...emloft.net>, <acme@...nel.org>,
	<mingo@...hat.com>, <a.p.zijlstra@...llo.nl>,
	<masami.hiramatsu.pt@...achi.com>, <jolsa@...nel.org>
CC:	<lizefan@...nel.org>, <linux-kernel@...r.kernel.org>,
	<pi3orama@....com>, <hekuang@...wei.com>
Subject: [RFC PATCH 13/22] perf bpf: collects relocation sections from object file.

This patch collects relocation sections into 'struct obj'. Such
sections are used for associating maps with bpf programs.

Signed-off-by: Wang Nan <wangnan0@...wei.com>
---
 tools/perf/util/bpf-loader.c | 17 +++++++++++++++++
 tools/perf/util/bpf-loader.h |  5 +++++
 2 files changed, 22 insertions(+)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index bbebaf1..66fbca2 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -46,6 +46,10 @@ static void bpf_obj_clear_elf(struct bpf_obj *obj)
 	if (!obj_elf_valid(obj))
 		return;
 
+	if (obj->elf.reloc) {
+		free(obj->elf.reloc);
+		obj->elf.reloc = NULL;
+	}
 	if (obj->elf.elf) {
 		elf_end(obj->elf.elf);
 		obj->elf.elf = NULL;
@@ -413,6 +417,19 @@ static int bpf_obj_elf_collect(struct bpf_obj *obj)
 						prog->name);
 				list_add(&prog->list, &obj->progs_list);
 			}
+		} else if (sh.sh_type == SHT_REL) {
+			obj->elf.reloc = realloc(obj->elf.reloc,
+						 sizeof(*obj->elf.reloc) *
+						  (++obj->elf.nr_reloc));
+			if (!obj->elf.reloc) {
+				pr_err("bpf: realloc reloc record failed\n");
+				err = -ENOMEM;
+			} else {
+				int n = obj->elf.nr_reloc - 1;
+
+				obj->elf.reloc[n].shdr = sh;
+				obj->elf.reloc[n].data = data;
+			}
 		}
 		if (err)
 			goto out;
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index f9cb46b..1417c0d 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -53,6 +53,11 @@ struct bpf_obj {
 		Elf *elf;
 		GElf_Ehdr ehdr;
 		Elf_Data *symbols;
+		struct {
+			GElf_Shdr shdr;
+			Elf_Data *data;
+		} *reloc;
+		int nr_reloc;
 	} elf;
 };
 #define obj_elf_valid(o)	((o)->elf.fd >= 0)
-- 
1.8.3.4

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