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.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 9f8fb8a23aa0b08c208ee2b4cea5dda14fdc4fc6..538864d3b9f5a7108bb599960ced3c733685db4b 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,9 @@
+2012-06-22  Roland McGrath  <mcgrathr@google.com>
+
+       * 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.
+
 2012-06-22  Andreas Schwab  <schwab@linux-m68k.org>
 
        * elf32-m68k.c (elf_m68k_finish_dynamic_symbol): Don't make

diff --git a/bfd/elf.c b/bfd/elf.c
index 0296ef567209caadbaa3049461b2d6c6342e9663..1a5354895d8b9809428df30cd9fa2fa1d2d1ff9b 100644 (file)
--- 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++)

diff --git a/ld/ChangeLog b/ld/ChangeLog
index f6e78f2feb88a5564e0c3053857a0b3d90348bda..91a4211b8931b275373672c30712b13c67f74cc9 100644 (file)
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,7 @@
+2012-06-22  Roland McGrath  <mcgrathr@google.com>
+
+       * NEWS: Mention __ehdr_start.
+
 2012-06-21  Alan Modra  <amodra@gmail.com>
 
        * ldlang.c (lang_insert_orphan): Don't make __start_<sec> symbol

diff --git a/ld/NEWS b/ld/NEWS
index cb2d428a28a85322a32b17028bff37a8dfa4898c..8701c5cd2ca8241995b9e5af4303889acb046672 100644 (file)
--- a/ld/NEWS
+++ b/ld/NEWS
@@ -1,5 +1,9 @@
 -*- text -*-
 
+* Add a linker-provided symbol when producing ELF output, '__ehdr_start'
+  to point to the ELF file header (and nearby program headers) in the
+  program's memory image.
+
 * Add support for S12X processor.
 
 * Add support for the VLE extension to the PowerPC architecture.
@@ -103,7 +107,7 @@ Changes in 2.20:
 
 * Add support for Lattice Mico32 (lm32) architecture.
 
-* Add CR16 ELF --embedded-relocs (used to embedded relocations into binaries 
+* Add CR16 ELF --embedded-relocs (used to embedded relocations into binaries
   for Embedded-PIC code) option.
 
 * Add to the PE/PE+ targets the support of two different kinds of

diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
index 57996a7ffed3a141b3085db134fc992aa143f402..d03c432d7d162345e9ee7c1d858d10f54e13576f 100644 (file)
--- a/ld/testsuite/ChangeLog
+++ b/ld/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2012-06-22  Roland McGrath  <mcgrathr@google.com>
+
+       * ld-elf/ehdr_start.s: New file.
+       * ld-elf/ehdr_start.d: New file.
+
 2012-06-21  Alan Modra  <amodra@gmail.com>
 
        * ld-gc/start.d: Update.

diff --git a/ld/testsuite/ld-elf/ehdr_start.d b/ld/testsuite/ld-elf/ehdr_start.d
new file mode 100644 (file)
index 0000000..3965eeb
--- /dev/null
+++ b/ld/testsuite/ld-elf/ehdr_start.d
@@ -0,0 +1,7 @@
+#source: ehdr_start.s
+#ld:
+#nm: -n
+
+#...
+[0-9a-f]*000 [ADRT] __ehdr_start
+#pass

diff --git a/ld/testsuite/ld-elf/ehdr_start.s b/ld/testsuite/ld-elf/ehdr_start.s
new file mode 100644 (file)
index 0000000..ab029dc
--- /dev/null
+++ b/ld/testsuite/ld-elf/ehdr_start.s
@@ -0,0 +1,10 @@
+       .text
+       .globl _start
+_start:
+       .space 16
+
+       .section .rodata,"a",%progbits
+       .globl foo
+foo:
+       .weak __ehdr_start
+       .dc.a __ehdr_start