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authorWang Nan <wangnan0@huawei.com>2015-07-01 02:14:01 +0000
committerArnaldo Carvalho de Melo <acme@redhat.com>2015-08-07 10:16:57 -0300
commitb62f06e81bcf28d47fe736fe2beae40f15f496be (patch)
tree64d2cc088ee4c248d42b571cd37be9d622e100f2 /tools/lib
parenta5b8bd47dcc574cd3a71357b3a0f586969e4b887 (diff)
bpf tools: Collect relocation sections from SHT_REL sections
This patch collects relocation sections into 'struct object'. Such sections are used for connecting maps to bpf programs. 'reloc' field in 'struct bpf_object' is introduced for storing such information. This patch simply store the data into 'reloc' field. Following patch will parse them to know the exact instructions which are needed to be relocated. Note that the collected data will be invalid after ELF object file is closed. This is the second patch related to map relocation. The first one is 'bpf tools: Collect symbol table from SHT_SYMTAB section'. The principle of map relocation is described in its commit message. Signed-off-by: Wang Nan <wangnan0@huawei.com> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David Ahern <dsahern@gmail.com> Cc: He Kuang <hekuang@huawei.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Kaixu Xia <xiakaixu@huawei.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1435716878-189507-14-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/lib')
-rw-r--r--tools/lib/bpf/libbpf.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 102156f322b6..e8088f8214d1 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -110,6 +110,11 @@ struct bpf_object {
Elf *elf;
GElf_Ehdr ehdr;
Elf_Data *symbols;
+ struct {
+ GElf_Shdr shdr;
+ Elf_Data *data;
+ } *reloc;
+ int nr_reloc;
} efile;
char path[];
};
@@ -231,6 +236,9 @@ static void bpf_object__elf_finish(struct bpf_object *obj)
obj->efile.elf = NULL;
}
obj->efile.symbols = NULL;
+
+ zfree(&obj->efile.reloc);
+ obj->efile.nr_reloc = 0;
zclose(obj->efile.fd);
obj->efile.obj_buf = NULL;
obj->efile.obj_buf_sz = 0;
@@ -447,6 +455,24 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
pr_warning("failed to alloc program %s (%s): %s",
name, obj->path, errmsg);
}
+ } else if (sh.sh_type == SHT_REL) {
+ void *reloc = obj->efile.reloc;
+ int nr_reloc = obj->efile.nr_reloc + 1;
+
+ reloc = realloc(reloc,
+ sizeof(*obj->efile.reloc) * nr_reloc);
+ if (!reloc) {
+ pr_warning("realloc failed\n");
+ err = -ENOMEM;
+ } else {
+ int n = nr_reloc - 1;
+
+ obj->efile.reloc = reloc;
+ obj->efile.nr_reloc = nr_reloc;
+
+ obj->efile.reloc[n].shdr = sh;
+ obj->efile.reloc[n].data = data;
+ }
}
if (err)
goto out;