Merge GDB 7.5.1

bfd/elf-nacl.c

+/* Native Client support for ELF
+   Copyright 2012 Free Software Foundation, Inc.
+
+   This file is part of BFD, the Binary File Descriptor library.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+   MA 02111-1307, USA.  */
+
+#include "sysdep.h"
+#include "bfd.h"
+#include "elf-bfd.h"
+#include "elf-nacl.h"
+#include "elf/common.h"
+#include "elf/internal.h"
+
+static bfd_boolean
+segment_executable (struct elf_segment_map *seg)
+{
+  if (seg->p_flags_valid)
+    return (seg->p_flags & PF_X) != 0;
+  else
+    {
+      /* The p_flags value has not been computed yet,
+         so we have to look through the sections.  */
+      unsigned int i;
+      for (i = 0; i < seg->count; ++i)
+        if (seg->sections[i]->flags & SEC_CODE)
+          return TRUE;
+    }
+  return FALSE;
+}
+
+static bfd_boolean
+segment_nonexecutable_and_has_contents (struct elf_segment_map *seg)
+{
+  bfd_boolean any_contents = FALSE;
+  unsigned int i;
+  for (i = 0; i < seg->count; ++i)
+    {
+      if (seg->sections[i]->flags & SEC_CODE)
+        return FALSE;
+      if (seg->sections[i]->flags & SEC_HAS_CONTENTS)
+        any_contents = TRUE;
+    }
+  return any_contents;
+}
+
+
+/* We permute the segment_map to get BFD to do the file layout we want:
+   The first non-executable PT_LOAD segment appears first in the file
+   and contains the ELF file header and phdrs.  */
+bfd_boolean
+nacl_modify_segment_map (bfd *abfd, struct bfd_link_info *info)
+{
+  struct elf_segment_map **m = &elf_tdata (abfd)->segment_map;
+  struct elf_segment_map **first_load = NULL;
+  struct elf_segment_map **last_load = NULL;
+  bfd_boolean moved_headers = FALSE;
+
+  if (info != NULL && info->user_phdrs)
+    /* The linker script used PHDRS explicitly, so don't change what the
+       user asked for.  */
+    return TRUE;
+
+  while (*m != NULL)
+    {
+      struct elf_segment_map *seg = *m;
+
+      if (seg->p_type == PT_LOAD)
+        {
+          /* First, we're just finding the earliest PT_LOAD.
+             By the normal rules, this will be the lowest-addressed one.
+             We only have anything interesting to do if it's executable.  */
+          last_load = m;
+          if (first_load == NULL)
+            {
+              if (!segment_executable (*m))
+                return TRUE;
+              first_load = m;
+            }
+          /* Now that we've noted the first PT_LOAD, we're looking for
+             the first non-executable PT_LOAD with a nonempty p_filesz.  */
+          else if (!moved_headers
+                   && segment_nonexecutable_and_has_contents (seg))
+            {
+              /* This is the one we were looking for!
+
+                 First, clear the flags on previous segments that
+                 say they include the file header and phdrs.  */
+              struct elf_segment_map *prevseg;
+              for (prevseg = *first_load;
+                   prevseg != seg;
+                   prevseg = prevseg->next)
+                if (prevseg->p_type == PT_LOAD)
+                  {
+                    prevseg->includes_filehdr = 0;
+                    prevseg->includes_phdrs = 0;
+                  }
+
+              /* This segment will include those headers instead.  */
+              seg->includes_filehdr = 1;
+              seg->includes_phdrs = 1;
+
+              moved_headers = TRUE;
+            }
+        }
+
+      m = &seg->next;
+    }
+
+  if (first_load != last_load && moved_headers)
+    {
+      /* Now swap the first and last PT_LOAD segments'
+         positions in segment_map.  */
+      struct elf_segment_map *first = *first_load;
+      struct elf_segment_map *last = *last_load;
+      *first_load = first->next;
+      first->next = last->next;
+      last->next = first;
+    }
+
+  return TRUE;
+}
+
+/* After nacl_modify_segment_map has done its work, the file layout has
+   been done as we wanted.  But the PT_LOAD phdrs are no longer in the
+   proper order for the ELF rule that they must appear in ascending address
+   order.  So find the two segments we swapped before, and swap them back.  */
+bfd_boolean
+nacl_modify_program_headers (bfd *abfd,
+                             struct bfd_link_info *info ATTRIBUTE_UNUSED)
+{
+  struct elf_segment_map **m = &elf_tdata (abfd)->segment_map;
+  Elf_Internal_Phdr *phdr = elf_tdata (abfd)->phdr;
+  Elf_Internal_Phdr *p = phdr;
+
+  if (info != NULL && info->user_phdrs)
+    /* The linker script used PHDRS explicitly, so don't change what the
+       user asked for.  */
+    return TRUE;
+
+  /* Find the PT_LOAD that contains the headers (should be the first).  */
+  while (*m != NULL)
+    {
+      if ((*m)->p_type == PT_LOAD && (*m)->includes_filehdr)
+        break;
+
+      m = &(*m)->next;
+      ++p;
+    }
+
+  if (*m != NULL)
+    {
+      struct elf_segment_map **first_load_seg = m;
+      Elf_Internal_Phdr *first_load_phdr = p;
+      struct elf_segment_map **next_load_seg = NULL;
+      Elf_Internal_Phdr *next_load_phdr = NULL;
+
+      /* Now move past that first one and find the PT_LOAD that should be
+         before it by address order.  */
+
+      m = &(*m)->next;
+      ++p;
+
+      while ((*m) != NULL)
+        {
+          if (p->p_type == PT_LOAD && p->p_vaddr < first_load_phdr->p_vaddr)
+            {
+              next_load_seg = m;
+              next_load_phdr = p;
+              break;
+            }
+
+          m = &(*m)->next;
+          ++p;
+        }
+
+      /* Swap their positions in the segment_map back to how they used to be.
+         The phdrs have already been set up by now, so we have to slide up
+         the earlier ones to insert the one that should be first.  */
+      if (next_load_seg != NULL)
+        {
+          Elf_Internal_Phdr move_phdr;
+          struct elf_segment_map *first_seg = *first_load_seg;
+          struct elf_segment_map *next_seg = *next_load_seg;
+          struct elf_segment_map *first_next = first_seg->next;
+          struct elf_segment_map *next_next = next_seg->next;
+
+          first_seg->next = next_next;
+          *first_load_seg = next_seg;
+
+          next_seg->next = first_next;
+          *next_load_seg = first_seg;
+
+          move_phdr = *next_load_phdr;
+          memmove (first_load_phdr + 1, first_load_phdr,
+                   (next_load_phdr - first_load_phdr) * sizeof move_phdr);
+          *first_load_phdr = move_phdr;
+        }
+    }
+
+  return TRUE;
+}