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libelf is overly strict about the type and alignment of Elf_Data

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objects inside one ELF section, which prevents the creation of a ELF
section with mixed data types. For example, gcc LTO use libelf to
create a .gnu_lto_XXX section that contains integers and a string
table, which doesn't work with our libelf implementation.

The changes made in this commit include:
* Allow Elf_Data type to be different than section type.
* Relax Elf_Data alignment check.
* Align each Elf_Data by their own alignment instead of section alignment.

MFC after:   1 month
This commit is contained in:
Kai Wang 2010-09-09 18:51:50 +00:00
parent b4fb1ba027
commit ea22f625a7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=212373
1 changed files with 6 additions and 11 deletions
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17
lib/libelf/elf_update.c
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@ -141,7 +141,7 @@ _libelf_compute_section_extents(Elf *e, Elf_Scn *s, off_t *rc)
/* Compute the section alignment. */
STAILQ_FOREACH(d, &s->s_data, d_next) {
if (d->d_type != elftype) {
if (d->d_type > ELF_T_LAST) {
LIBELF_SET_ERROR(DATA, 0);
return (0);
}
@ -149,11 +149,7 @@ _libelf_compute_section_extents(Elf *e, Elf_Scn *s, off_t *rc)
LIBELF_SET_ERROR(VERSION, 0);
return (0);
}
if ((d_align = d->d_align) % sh_align) {
LIBELF_SET_ERROR(LAYOUT, 0);
return (0);
}
if (d_align == 0 || (d_align & (d_align - 1))) {
if ((d_align = d->d_align) == 0 || (d_align & (d_align - 1))) {
LIBELF_SET_ERROR(DATA, 0);
return (0);
}
@ -168,7 +164,7 @@ _libelf_compute_section_extents(Elf *e, Elf_Scn *s, off_t *rc)
if ((uint64_t) d->d_off + d->d_size > scn_size)
scn_size = d->d_off + d->d_size;
} else {
scn_size = roundup2(scn_size, scn_alignment);
scn_size = roundup2(scn_size, d->d_align);
d->d_off = scn_size;
scn_size += d->d_size;
}
@ -560,8 +556,6 @@ _libelf_write_scn(Elf *e, char *nf, Elf_Scn *s, off_t rc)
elftype = _libelf_xlate_shtype(sh_type);
assert(elftype >= ELF_T_FIRST && elftype <= ELF_T_LAST);
msz = _libelf_msize(elftype, ec, e->e_version);
sh_off = s->s_offset;
assert(sh_off % _libelf_falign(elftype, ec) == 0);
@ -608,6 +602,8 @@ _libelf_write_scn(Elf *e, char *nf, Elf_Scn *s, off_t rc)
STAILQ_FOREACH(d, &s->s_data, d_next) {
msz = _libelf_msize(d->d_type, ec, e->e_version);
if ((uint64_t) rc < sh_off + d->d_off)
(void) memset(nf + rc,
LIBELF_PRIVATE(fillchar), sh_off + d->d_off - rc);
@ -615,13 +611,12 @@ _libelf_write_scn(Elf *e, char *nf, Elf_Scn *s, off_t rc)
rc = sh_off + d->d_off;
assert(d->d_buf != NULL);
assert(d->d_type == (Elf_Type) elftype);
assert(d->d_version == e->e_version);
assert(d->d_size % msz == 0);
nobjects = d->d_size / msz;
fsz = _libelf_fsize(elftype, ec, e->e_version, nobjects);
fsz = _libelf_fsize(d->d_type, ec, e->e_version, nobjects);
dst.d_buf = nf + rc;
dst.d_size = fsz;