[PATCH] Fix another eh_frame_hdr problem
Jakub Jelinek
jakub@redhat.com
Fri Dec 14 13:46:00 GMT 2001
On Sat, Dec 15, 2001 at 12:04:04AM +1030, Alan Modra wrote:
> Hi Jakub,
> I've run into another problem with your eh_frame_hdr patch.
>
> elf-eh-frame:_bfd_elf_discard_section_eh_frame_hdr calls
> _bfd_strip_section_from_output, but this is too late in the link
> process. In particular, the dynamic symbol table size, and
> dynamic symbol indices have been set up by that stage. Removing
> a section leave a "hole" in the table that is never written,
> resulting in junk in the symbols table.
>
> Would you please look at fixing this?
Sorry. This seems to work for me and make bootstrap passed.
Ok to commit?
2001-12-14 Jakub Jelinek <jakub@redhat.com>
* elf-bfd.h (_bfd_elf_maybe_strip_eh_frame_hdr): New prototype.
* elf-eh-frame.c (struct eh_frame_hdr_info): Add strip.
(_bfd_elf_discard_section_eh_frame): Don't create .eh_frame_hdr
sec_info here. Free ehbuf.
(_bfd_elf_discard_section_eh_frame_hdr): Don't size the section
if hdr_info->strip.
(_bfd_elf_maybe_strip_eh_frame_hdr): New.
* elflink.h (size_dynamic_sections): Call it.
--- bfd/elflink.h.jj Fri Dec 14 20:06:40 2001
+++ bfd/elflink.h Fri Dec 14 22:04:12 2001
@@ -3002,6 +3002,9 @@ NAME(bfd_elf,size_dynamic_sections) (out
if (dynobj == NULL)
return true;
+ if (! _bfd_elf_maybe_strip_eh_frame_hdr (info))
+ return false;
+
if (elf_hash_table (info)->dynamic_sections_created)
{
struct elf_info_failed eif;
--- bfd/elf-eh-frame.c.jj Thu Dec 13 13:22:35 2001
+++ bfd/elf-eh-frame.c Fri Dec 14 23:57:34 2001
@@ -86,6 +86,7 @@ struct eh_frame_hdr_info
We build it if we successfully read all .eh_frame input sections
and recognize them. */
boolean table;
+ boolean strip;
};
static bfd_vma read_unsigned_leb128
@@ -246,7 +247,7 @@ _bfd_elf_discard_section_eh_frame (abfd,
struct cie_header hdr;
struct cie cie;
struct eh_frame_hdr_info *hdr_info;
- struct eh_frame_sec_info *sec_info;
+ struct eh_frame_sec_info *sec_info = NULL;
unsigned int leb128_tmp;
unsigned int cie_usage_count, last_cie_ndx, i, offset, make_relative;
Elf_Internal_Rela *rel;
@@ -267,23 +268,20 @@ _bfd_elf_discard_section_eh_frame (abfd,
return false;
}
+ BFD_ASSERT (elf_section_data (ehdrsec)->sec_info_type
+ == ELF_INFO_TYPE_EH_FRAME_HDR);
+ hdr_info = (struct eh_frame_hdr_info *)
+ elf_section_data (ehdrsec)->sec_info;
+
/* Read the frame unwind information from abfd. */
ehbuf = (bfd_byte *) bfd_malloc (sec->_raw_size);
- if (ehbuf == NULL
- || ! bfd_get_section_contents (abfd, sec, ehbuf, (bfd_vma) 0,
- sec->_raw_size))
- {
- if (elf_section_data (ehdrsec)->sec_info_type
- != ELF_INFO_TYPE_EH_FRAME_HDR)
- {
- elf_section_data (ehdrsec)->sec_info
- = bfd_zmalloc (sizeof (struct eh_frame_hdr_info));
- elf_section_data (ehdrsec)->sec_info_type
- = ELF_INFO_TYPE_EH_FRAME_HDR;
- }
- return false;
- }
+ if (ehbuf == NULL)
+ goto free_no_table;
+
+ if (! bfd_get_section_contents (abfd, sec, ehbuf, (bfd_vma) 0,
+ sec->_raw_size))
+ goto free_no_table;
if (sec->_raw_size >= 4
&& bfd_get_32 (abfd, ehbuf) == 0
@@ -294,24 +292,10 @@ _bfd_elf_discard_section_eh_frame (abfd,
return false;
}
- if (elf_section_data (ehdrsec)->sec_info_type
- != ELF_INFO_TYPE_EH_FRAME_HDR)
- {
- hdr_info = (struct eh_frame_hdr_info *)
- bfd_zmalloc (sizeof (struct eh_frame_hdr_info));
- hdr_info->table = true;
- elf_section_data (ehdrsec)->sec_info = hdr_info;
- elf_section_data (ehdrsec)->sec_info_type
- = ELF_INFO_TYPE_EH_FRAME_HDR;
- }
- else
- hdr_info = (struct eh_frame_hdr_info *)
- elf_section_data (ehdrsec)->sec_info;
-
/* If .eh_frame section size doesn't fit into int, we cannot handle
it (it would need to use 64-bit .eh_frame format anyway). */
if (sec->_raw_size != (unsigned int) sec->_raw_size)
- return false;
+ goto free_no_table;
ptr_size = (elf_elfheader (abfd)->e_ident[EI_CLASS]
== ELFCLASS64) ? 8 : 4;
@@ -650,9 +634,12 @@ _bfd_elf_discard_section_eh_frame (abfd,
if (sec->_cooked_size == 0)
sec->flags |= SEC_EXCLUDE;
+ free (ehbuf);
return new_size != sec->_raw_size;
free_no_table:
+ if (ehbuf)
+ free (ehbuf);
if (sec_info)
free (sec_info);
hdr_info->table = false;
@@ -686,6 +673,8 @@ _bfd_elf_discard_section_eh_frame_hdr (a
hdr_info = (struct eh_frame_hdr_info *)
elf_section_data (sec)->sec_info;
+ if (hdr_info->strip)
+ return false;
sec->_cooked_size = EH_FRAME_HDR_SIZE;
if (hdr_info->table)
sec->_cooked_size += 4 + hdr_info->fde_count * 8;
@@ -696,6 +685,52 @@ _bfd_elf_discard_section_eh_frame_hdr (a
return true;
}
+/* This function is called from size_dynamic_sections.
+ It needs to decide whether .eh_frame_hdr should be output or not,
+ because later on it is too late for calling _bfd_strip_section_from_output,
+ since dynamic symbol table has been sized. */
+
+boolean
+_bfd_elf_maybe_strip_eh_frame_hdr (info)
+ struct bfd_link_info *info;
+{
+ asection *sec, *o;
+ bfd *abfd;
+ struct eh_frame_hdr_info *hdr_info;
+
+ sec = bfd_get_section_by_name (elf_hash_table (info)->dynobj, ".eh_frame_hdr");
+ if (sec == NULL)
+ return true;
+
+ hdr_info
+ = bfd_zmalloc (sizeof (struct eh_frame_hdr_info));
+ if (hdr_info == NULL)
+ return false;
+
+ elf_section_data (sec)->sec_info = hdr_info;
+ elf_section_data (sec)->sec_info_type = ELF_INFO_TYPE_EH_FRAME_HDR;
+
+ abfd = NULL;
+ if (info->eh_frame_hdr)
+ for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
+ {
+ /* Count only sections which have at least a single CIE or FDE.
+ There cannot be any CIE or FDE <= 8 bytes. */
+ o = bfd_get_section_by_name (abfd, ".eh_frame");
+ if (o && o->_raw_size > 8)
+ break;
+ }
+
+ if (abfd == NULL)
+ {
+ _bfd_strip_section_from_output (info, sec);
+ hdr_info->strip = true;
+ }
+ else
+ hdr_info->table = true;
+ return true;
+}
+
/* Adjust an address in the .eh_frame section. Given OFFSET within
SEC, this returns the new offset in the adjusted .eh_frame section,
or -1 if the address refers to a CIE/FDE which has been removed
--- bfd/elf-bfd.h.jj Thu Dec 13 13:22:35 2001
+++ bfd/elf-bfd.h Fri Dec 14 23:04:07 2001
@@ -1296,6 +1296,8 @@ extern boolean _bfd_elf_write_section_eh
PARAMS ((bfd *, asection *, asection *, bfd_byte *));
extern boolean _bfd_elf_write_section_eh_frame_hdr
PARAMS ((bfd *, asection *));
+extern boolean _bfd_elf_maybe_strip_eh_frame_hdr
+ PARAMS ((struct bfd_link_info *));
extern boolean _bfd_elf_link_record_dynamic_symbol
PARAMS ((struct bfd_link_info *, struct elf_link_hash_entry *));
Jakub
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