Messages in this thread Patch in this message | | | From | Wang Nan <> | Subject | [RFC PATCH v9 13/50] bpf tools: Collect relocation sections from SHT_REL sections | Date | Fri, 26 Jun 2015 14:15:18 +0000 |
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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.
Signed-off-by: Wang Nan <wangnan0@huawei.com> Acked-by: Alexei Starovoitov <ast@plumgrid.com> --- tools/lib/bpf/libbpf.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 9c01b55f..f3ace51 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[]; }; @@ -220,6 +225,9 @@ 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; @@ -440,6 +448,24 @@ static int bpf_object__elf_collect(struct bpf_object *obj) } else pr_debug("found program %s\n", prog->section_name); + } 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; -- 1.8.3.4
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