From 5598e24ef8aef14727ff72eea71ec460200bc2e3 Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Fri, 17 Mar 2017 21:03:35 +0100 Subject: [PATCH 22/49] debugedit: Fix cross-endian build-id reading and updating section data. debugedit doesn't read raw mmap data any longer. Which made the complex way to read the build-id unnecessary (and it was broken for cross-endian). Just use gelf_getnote to read the notes. Also in some special cases when only the debug_info or build_id data was updated, but no section changed size and we had to preserve the allocated section headers we could hit a bug in elfutils that could trash some section data in case there were gaps between non-dirty and dirty sections. See https://sourceware.org/bugzilla/show_bug.cgi?id=21199 Add a workaround for that issue. This fixes the kompose package build on fedora ppc64. And makes it possible to replicate that issue on x86_64. Signed-off-by: Mark Wielaard (cherry picked from commit a6e767600309bdb1f8af33b44563a1187fb0dbc4) --- tools/debugedit.c | 63 +++++++++++++++++++++++++++---------------------------- 1 file changed, 31 insertions(+), 32 deletions(-) diff --git a/tools/debugedit.c b/tools/debugedit.c index 87a423fdb..0f373162d 100644 --- a/tools/debugedit.c +++ b/tools/debugedit.c @@ -2581,40 +2581,25 @@ main (int argc, char *argv[]) break; case SHT_NOTE: if (do_build_id - && build_id == NULL && (dso->shdr[i].sh_flags & SHF_ALLOC)) + && build_id == 0 && (dso->shdr[i].sh_flags & SHF_ALLOC)) { /* Look for a build-ID note here. */ + size_t off = 0; + GElf_Nhdr nhdr; + size_t name_off; + size_t desc_off; Elf_Data *data = elf_getdata (elf_getscn (dso->elf, i), NULL); - Elf32_Nhdr nh; - Elf_Data dst = - { - .d_version = EV_CURRENT, .d_type = ELF_T_NHDR, - .d_buf = &nh, .d_size = sizeof nh - }; - Elf_Data src = dst; - src.d_buf = data->d_buf; - assert (sizeof (Elf32_Nhdr) == sizeof (Elf64_Nhdr)); - while ((char *) data->d_buf + data->d_size - - (char *) src.d_buf > (int) sizeof nh - && elf32_xlatetom (&dst, &src, dso->ehdr.e_ident[EI_DATA])) - { - Elf32_Word len = sizeof nh + nh.n_namesz; - len = (len + 3) & ~3; - - if (nh.n_namesz == sizeof "GNU" && nh.n_type == 3 - && !memcmp ((char *) src.d_buf + sizeof nh, "GNU", sizeof "GNU")) - { - build_id = data; - build_id_offset = (char *) src.d_buf + len - - (char *) data->d_buf; - build_id_size = nh.n_descsz; - break; - } - - len += nh.n_descsz; - len = (len + 3) & ~3; - src.d_buf = (char *) src.d_buf + len; - } + while ((off = gelf_getnote (data, off, + &nhdr, &name_off, &desc_off)) > 0) + if (nhdr.n_type == NT_GNU_BUILD_ID + && nhdr.n_namesz == sizeof "GNU" + && (memcmp ((char *)data->d_buf + name_off, "GNU", + sizeof "GNU") == 0)) + { + build_id = data; + build_id_offset = desc_off; + build_id_size = nhdr.n_descsz; + } } break; default: @@ -2622,6 +2607,20 @@ main (int argc, char *argv[]) } } + /* Normally we only need to explicitly update the section headers + and data when any section data changed size. But because of a bug + in elfutils before 0.169 we will have to update and write out all + section data if any data has changed (when ELF_F_LAYOUT was + set). https://sourceware.org/bugzilla/show_bug.cgi?id=21199 */ + bool need_update = need_strp_update || need_stmt_update; + +#if !_ELFUTILS_PREREQ (0, 169) + /* string replacements or build_id updates don't change section size. */ + need_update = (need_update + || need_string_replacement + || (do_build_id && build_id != NULL)); +#endif + /* We might have changed the size of some debug sections. If so make sure the section headers are updated and the data offsets are correct. We set ELF_F_LAYOUT above because we don't want libelf @@ -2631,7 +2630,7 @@ main (int argc, char *argv[]) anything for the phdrs allocated sections. Keep the offset of allocated sections so they are at the same place in the file. Add unallocated ones after the allocated ones. */ - if (dso->phnum != 0 && (need_strp_update || need_stmt_update)) + if (dso->phnum != 0 && need_update) { Elf *elf = dso->elf; GElf_Off last_offset; -- 2.13.2