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debugedit: Fix cross-endian build-id reading and updating section data.

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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 <mark@klomp.org>
This commit is contained in:
Mark Wielaard 2017-03-17 21:03:35 +01:00 committed by Panu Matilainen
parent 2a38104411
commit 2da619aa8e
1 changed files with 31 additions and 32 deletions
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57
tools/debugedit.c
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@ -2581,39 +2581,24 @@ 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"))
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 = (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;
build_id_offset = desc_off;
build_id_size = nhdr.n_descsz;
}
}
break;
@ -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;