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authorRoland McGrath <roland@gnu.org>2012-06-22 16:52:33 +0000
committerRoland McGrath <roland@gnu.org>2012-06-22 16:52:33 +0000
commit62655c7b8bfc33e6c12694f439ff8f7e8da3005a (patch)
tree2fc1a9e0c105bc25a22178c74a63c9ef710651a1 /bfd/elf.c
parentc24ccbcea9fbbd866f17e8934105830dae0810fc (diff)
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bfd/
* elf.c (assign_file_positions_for_non_load_sections): Define __ehdr_start symbol if it's referenced and there's a PT_LOAD segment that covers both the file and program headers. ld/ * NEWS: Mention __ehdr_start. ld/testsuite/ * ld-elf/ehdr_start.s: New file. * ld-elf/ehdr_start.d: New file.
Diffstat (limited to 'bfd/elf.c')
-rw-r--r--bfd/elf.c49
1 files changed, 49 insertions, 0 deletions
diff --git a/bfd/elf.c b/bfd/elf.c
index 0296ef5..1a53548 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -4826,6 +4826,7 @@ assign_file_positions_for_non_load_sections (bfd *abfd,
Elf_Internal_Phdr *phdrs;
Elf_Internal_Phdr *p;
struct elf_segment_map *m;
+ struct elf_segment_map *hdrs_segment;
bfd_vma filehdr_vaddr, filehdr_paddr;
bfd_vma phdrs_vaddr, phdrs_paddr;
file_ptr off;
@@ -4883,6 +4884,7 @@ assign_file_positions_for_non_load_sections (bfd *abfd,
filehdr_paddr = 0;
phdrs_vaddr = bed->maxpagesize + bed->s->sizeof_ehdr;
phdrs_paddr = 0;
+ hdrs_segment = NULL;
phdrs = elf_tdata (abfd)->phdr;
for (m = elf_tdata (abfd)->segment_map, p = phdrs;
m != NULL;
@@ -4903,12 +4905,59 @@ assign_file_positions_for_non_load_sections (bfd *abfd,
phdrs_paddr = p->p_paddr;
if (m->includes_filehdr)
{
+ hdrs_segment = m;
phdrs_vaddr += bed->s->sizeof_ehdr;
phdrs_paddr += bed->s->sizeof_ehdr;
}
}
}
+ if (hdrs_segment != NULL && link_info != NULL)
+ {
+ /* There is a segment that contains both the file headers and the
+ program headers, so provide a symbol __ehdr_start pointing there.
+ A program can use this to examine itself robustly. */
+
+ struct elf_link_hash_entry *hash
+ = elf_link_hash_lookup (elf_hash_table (link_info), "__ehdr_start",
+ FALSE, FALSE, TRUE);
+ /* If the symbol was referenced and not defined, define it. */
+ if (hash != NULL
+ && (hash->root.type == bfd_link_hash_new
+ || hash->root.type == bfd_link_hash_undefined
+ || hash->root.type == bfd_link_hash_undefweak
+ || hash->root.type == bfd_link_hash_common))
+ {
+ asection *s = NULL;
+ if (hdrs_segment->count != 0)
+ /* The segment contains sections, so use the first one. */
+ s = hdrs_segment->sections[0];
+ else
+ /* Use the first (i.e. lowest-addressed) section in any segment. */
+ for (m = elf_tdata (abfd)->segment_map; m != NULL; m = m->next)
+ if (m->count != 0)
+ {
+ s = m->sections[0];
+ break;
+ }
+
+ if (s != NULL)
+ {
+ hash->root.u.def.value = filehdr_vaddr - s->vma;
+ hash->root.u.def.section = s;
+ }
+ else
+ {
+ hash->root.u.def.value = filehdr_vaddr;
+ hash->root.u.def.section = bfd_abs_section_ptr;
+ }
+
+ hash->root.type = bfd_link_hash_defined;
+ hash->def_regular = 1;
+ hash->non_elf = 0;
+ }
+ }
+
for (m = elf_tdata (abfd)->segment_map, p = phdrs;
m != NULL;
m = m->next, p++)