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Commit 077c066a authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by Daniel Borkmann
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tools/libbpf: improve the pr_debug statements to contain section numbers 



While debugging a bpf ELF loading issue, I needed to correlate the
ELF section number with the failed relocation section reference.
Thus, add section numbers/index to the pr_debug.

In debug mode, also print section that were skipped.  This helped
me identify that a section (.eh_frame) was skipped, and this was
the reason the relocation section (.rel.eh_frame) could not find
that section number.

The section numbers corresponds to the readelf tools Section Headers [Nr].

Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 8c88181e

tools/lib/bpf/libbpf.c

+13 −12
Original line number Diff line number Diff line
@@ -319,8 +319,8 @@ bpf_program__init(void *data, size_t size, char *section_name, int idx, 


	prog->section_name = strdup(section_name);

	if (!prog->section_name) {

		pr_warning("failed to alloc name for prog under section %s\n",

			   section_name);

		pr_warning("failed to alloc name for prog under section(%d) %s\n",

			   idx, section_name);

		goto errout;

	}
@@ -763,29 +763,29 @@ static int bpf_object__elf_collect(struct bpf_object *obj) 


		idx++;

		if (gelf_getshdr(scn, &sh) != &sh) {

			pr_warning("failed to get section header from %s\n",

				   obj->path);

			pr_warning("failed to get section(%d) header from %s\n",

				   idx, obj->path);

			err = -LIBBPF_ERRNO__FORMAT;

			goto out;

		}



		name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);

		if (!name) {

			pr_warning("failed to get section name from %s\n",

				   obj->path);

			pr_warning("failed to get section(%d) name from %s\n",

				   idx, obj->path);

			err = -LIBBPF_ERRNO__FORMAT;

			goto out;

		}



		data = elf_getdata(scn, 0);

		if (!data) {

			pr_warning("failed to get section data from %s(%s)\n",

				   name, obj->path);

			pr_warning("failed to get section(%d) data from %s(%s)\n",

				   idx, name, obj->path);

			err = -LIBBPF_ERRNO__FORMAT;

			goto out;

		}

		pr_debug("section %s, size %ld, link %d, flags %lx, type=%d\n",

			 name, (unsigned long)data->d_size,

		pr_debug("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",

			 idx, name, (unsigned long)data->d_size,

			 (int)sh.sh_link, (unsigned long)sh.sh_flags,

			 (int)sh.sh_type);
@@ -840,6 +840,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj) 
				obj->efile.reloc[n].shdr = sh;

				obj->efile.reloc[n].data = data;

			}

		} else {

			pr_debug("skip section(%d) %s\n", idx, name);

		}

		if (err)

			goto out;
@@ -1119,8 +1121,7 @@ static int bpf_object__collect_reloc(struct bpf_object *obj) 


		prog = bpf_object__find_prog_by_idx(obj, idx);

		if (!prog) {

			pr_warning("relocation failed: no %d section\n",

				   idx);

			pr_warning("relocation failed: no section(%d)\n", idx);

			return -LIBBPF_ERRNO__RELOC;

		}