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Commit4708bbda5c("tools lib bpf: Fix maps resolution") attempted to fix map resolution by identifying the number of symbols that point to maps, and using this number to resolve each of the maps. However, during relocation the original definition of the map size was still in use. For up to two maps, the calculation was correct if there was a small difference in size between the map definition in libbpf and the one that the client library uses. However if the difference was large, particularly if more than two maps were used in the BPF program, the relocation would fail. For example, when using a map definition with size 28, with three maps, map relocation would count: (sym_offset / sizeof(struct bpf_map_def) => map_idx) (0 / 16 => 0), ie map_idx = 0 (28 / 16 => 1), ie map_idx = 1 (56 / 16 => 3), ie map_idx = 3 So, libbpf reports: libbpf: bpf relocation: map_idx 3 large than 2 Fix map relocation by checking the exact offset of maps when doing relocation. Signed-off-by: Joe Stringer <joe@ovn.org> [Allow different map size in an object] Signed-off-by: Wang Nan <wangnan0@huawei.com> Cc: Alexei Starovoitov <ast@fb.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: netdev@vger.kernel.org Fixes:4708bbda5c("tools lib bpf: Fix maps resolution") Link: http://lkml.kernel.org/r/20170123011128.26534-2-joe@ovn.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.