gdb/gdb-6.6-buildid-locate.patch

[base]

2007-10-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Port to GDB-6.7.

Index: gdb-6.7/gdb/Makefile.in
===================================================================
--- gdb-6.7.orig/gdb/Makefile.in	2007-10-16 16:19:18.000000000 +0200
+++ gdb-6.7/gdb/Makefile.in	2007-10-16 16:42:34.000000000 +0200
@@ -1932,7 +1932,8 @@ corelow.o: corelow.c $(defs_h) $(arch_ut
 	$(inferior_h) $(symtab_h) $(command_h) $(bfd_h) $(target_h) \
 	$(gdbcore_h) $(gdbthread_h) $(regcache_h) $(regset_h) $(symfile_h) \
 	$(exec_h) $(readline_h) $(gdb_assert_h) \
-	$(exceptions_h) $(solib_h)
+	$(exceptions_h) $(solib_h) $(auxv_h) $(elf_common_h) $(objfiles_h) \
+	$(gdbcmd_h)
 core-regset.o: core-regset.c $(defs_h) $(command_h) $(gdbcore_h) \
 	$(inferior_h) $(target_h) $(regcache_h) $(gdb_string_h) $(gregset_h)
 cp-abi.o: cp-abi.c $(defs_h) $(value_h) $(cp_abi_h) $(command_h) $(gdbcmd_h) \
@@ -2769,7 +2770,8 @@ symfile.o: symfile.c $(defs_h) $(bfdlink
 	$(gdb_stabs_h) $(gdb_obstack_h) $(completer_h) $(bcache_h) \
 	$(hashtab_h) $(readline_h) $(gdb_assert_h) $(block_h) \
 	$(gdb_string_h) $(gdb_stat_h) $(observer_h) $(exec_h) \
-	$(parser_defs_h) $(varobj_h) $(elf_bfd_h)
+	$(parser_defs_h) $(varobj_h) $(elf_bfd_h) $(gdb_stdint_h) $(libbfd_h) \
+	$(elf_bfd_h) $(elf_external_h)
 symfile-mem.o: symfile-mem.c $(defs_h) $(symtab_h) $(gdbcore_h) \
 	$(objfiles_h) $(exceptions_h) $(gdbcmd_h) $(target_h) $(value_h) \
 	$(symfile_h) $(observer_h) $(auxv_h) $(elf_common_h)
Index: gdb-6.7/gdb/corelow.c
===================================================================
--- gdb-6.7.orig/gdb/corelow.c	2007-09-04 01:06:35.000000000 +0200
+++ gdb-6.7/gdb/corelow.c	2007-10-16 16:41:50.000000000 +0200
@@ -44,6 +44,10 @@
 #include "gdb_assert.h"
 #include "exceptions.h"
 #include "solib.h"
+#include "auxv.h"
+#include "elf/common.h"
+#include "objfiles.h"
+#include "gdbcmd.h"
 
 
 #ifndef O_LARGEFILE
@@ -251,6 +255,66 @@ add_to_thread_list (bfd *abfd, asection 
     inferior_ptid = pid_to_ptid (thread_id);	/* Yes, make it current */
 }
 
+static int build_id_core_loads = 1;
+static void
+show_build_id_core_loads (struct ui_file *file, int from_tty,
+			  struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file, _("Automatic loading of the matching binaries "
+			    "for core files is %s.\n"), value);
+}
+
+static void 
+build_id_locate_exec (int from_tty)
+{
+  CORE_ADDR at_entry;
+  struct build_id *build_id;
+  char *exec_filename, *debug_filename;
+  char *build_id_filename;
+
+  if (exec_bfd != NULL)
+    return;
+
+  if (target_auxv_search (&current_target, AT_ENTRY, &at_entry) <= 0)
+    return;
+
+  build_id = build_id_addr_get (at_entry);
+  if (build_id == NULL)
+    return;
+
+  exec_filename = build_id_to_filename (build_id, &build_id_filename, 0);
+  if (exec_filename != NULL)
+    exec_file_attach (exec_filename, from_tty);
+  else
+    fprintf_unfiltered (gdb_stdlog,
+		     _("\nwarning: Missing the matching executable file: %s\n"),
+			build_id_filename);
+  xfree (build_id_filename);
+
+  /* `.note.gnu.build-id' section exists even for files without a separate
+     debuginfo.  */
+  debug_filename = build_id_to_filename (build_id, &build_id_filename, 1);
+  if (debug_filename != NULL)
+    {
+      symbol_file_add_main (debug_filename, from_tty);
+      xfree (debug_filename);
+    }
+  else
+    {
+      if (exec_filename != NULL)
+	symbol_file_add_main (exec_filename, from_tty);
+      if (symfile_objfile == NULL)
+	fprintf_unfiltered (gdb_stdlog,
+	_("\nwarning: Missing the matching executable's debug info file: %s\n"),
+			    build_id_filename);
+    }
+  xfree (build_id_filename);
+
+  xfree (exec_filename);
+
+  /* No automatic SOLIB_ADD as the libraries would get read twice.  */
+}
+
 /* This routine opens and sets up the core file bfd.  */
 
 static void
@@ -347,6 +411,15 @@ core_open (char *filename, int from_tty)
   ontop = !push_target (&core_ops);
   discard_cleanups (old_chain);
 
+  if (ontop)
+    {
+      /* Find the build_id identifiers.  If it gets executed after
+         POST_CREATE_INFERIOR we would clash with asking to discard the already
+         loaded VDSO symbols.  */
+      if (build_id_core_loads != 0)
+        build_id_locate_exec (from_tty);
+    }
+
   /* This is done first, before anything has a chance to query the
      inferior for information such as symbols.  */
   post_create_inferior (&core_ops, from_tty);
@@ -678,4 +751,13 @@ _initialize_corelow (void)
 
   if (!coreops_suppress_target)
     add_target (&core_ops);
+
+  add_setshow_zinteger_cmd ("build-id-core-loads", class_files,
+			    &build_id_core_loads, _("\
+Set debugging of the build-id locator."), _("\
+Show debugging of the build-id locator."), _("\
+Enables printf debugging output."),
+			    NULL,
+			    show_build_id_core_loads,
+			    &setlist, &showlist);
 }
Index: gdb-6.7/gdb/solib-svr4.c
===================================================================
--- gdb-6.7.orig/gdb/solib-svr4.c	2007-10-16 15:43:56.000000000 +0200
+++ gdb-6.7/gdb/solib-svr4.c	2007-10-16 16:44:44.000000000 +0200
@@ -957,9 +957,35 @@ svr4_current_sos (void)
 		free_so (new);
 	      else
 		{
-		  strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1);
-		  new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
-		  strcpy (new->so_original_name, new->so_name);
+		  struct build_id *build_id;
+
+		  strncpy (new->so_original_name, buffer, SO_NAME_MAX_PATH_SIZE - 1);
+		  new->so_original_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
+		  /* May get overwritten below.  */
+		  strcpy (new->so_name, new->so_original_name);
+
+		  build_id = build_id_addr_get (LM_DYNAMIC_FROM_LINK_MAP (new));
+		  if (build_id != NULL)
+		    {
+		      char *name, *build_id_filename;
+
+		      /* Missing the build-id matching separate debug info file
+			 would be handled while SO_NAME gets loaded.  */
+		      name = build_id_to_filename (build_id, &build_id_filename, 0);
+		      if (name != NULL)
+			{
+			  strncpy (new->so_name, name, SO_NAME_MAX_PATH_SIZE - 1);
+			  new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
+			  xfree (name);
+			}
+		      else
+			fprintf_unfiltered (gdb_stdlog,
+			_("\nwarning: Missing the matching library file: %s\n"),
+					    build_id_filename);
+		      xfree (build_id_filename);
+		      xfree (build_id);
+		    }
+
 		  if (debug_solib)
 		    {
 		      fprintf_unfiltered (gdb_stdlog, 
Index: gdb-6.7/gdb/symfile.c
===================================================================
--- gdb-6.7.orig/gdb/symfile.c	2007-10-15 21:42:26.000000000 +0200
+++ gdb-6.7/gdb/symfile.c	2007-10-16 16:46:30.000000000 +0200
@@ -53,6 +53,9 @@
 #include "parser-defs.h"
 #include "varobj.h"
 #include "elf-bfd.h"
+#include "gdb_stdint.h"
+#include "libbfd.h"
+#include "elf/external.h"
 
 #include <sys/types.h>
 #include <fcntl.h>
@@ -61,6 +64,7 @@
 #include <ctype.h>
 #include <time.h>
 #include <sys/time.h>
+#include <sys/param.h>
 
 
 int (*deprecated_ui_load_progress_hook) (const char *section, unsigned long num);
@@ -1238,16 +1242,62 @@ symbol_file_clear (int from_tty)
       printf_unfiltered (_("No symbol file now.\n"));
 }
 
+/* Locate NT_GNU_BUILD_ID and return its matching debug filename.
+   FIXME: NOTE decoding should be unified with the BFD core notes decoding.  */
+
+static int build_id_debug;
+static void
+show_build_id_debug (struct ui_file *file, int from_tty,
+		     struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file, _("Debugging of the build-id locator is %s.\n"),
+		    value);
+}
+
 struct build_id
   {
     size_t size;
     gdb_byte data[1];
   };
 
-/* Locate NT_GNU_BUILD_ID from ABFD and return its content.  */
+struct build_id *
+build_id_buf_get (bfd *templ, gdb_byte *buf, bfd_size_type size)
+{
+  bfd_byte *p;
+
+  p = buf;
+  while (p < buf + size)
+    {
+      /* FIXME: bad alignment assumption.  */
+      Elf_External_Note *xnp = (Elf_External_Note *) p;
+      size_t namesz = H_GET_32 (templ, xnp->namesz);
+      size_t descsz = H_GET_32 (templ, xnp->descsz);
+      bfd_byte *descdata = xnp->name + BFD_ALIGN (namesz, 4);
+
+      if (H_GET_32 (templ, xnp->type) == NT_GNU_BUILD_ID
+	  && namesz == sizeof "GNU"
+	  && memcmp (xnp->name, "GNU", sizeof "GNU") == 0)
+	{
+	  size_t size = descsz;
+	  gdb_byte *data = (void *) descdata;
+	  struct build_id *retval;
+
+	  retval = xmalloc (sizeof *retval - 1 + size);
+	  retval->size = size;
+	  memcpy (retval->data, data, size);
+
+	  return retval;
+	}
+      p = descdata + BFD_ALIGN (descsz, 4);
+    }
+  return NULL;
+}
+
+/* Separate debuginfo files have corrupted PHDR but SHDR is correct there.
+   Locate NT_GNU_BUILD_ID from ABFD and return its content.  */
 
 static struct build_id *
-build_id_bfd_get (bfd *abfd)
+build_id_bfd_shdr_get (bfd *abfd)
 {
   struct build_id *retval;
 
@@ -1263,6 +1313,348 @@ build_id_bfd_get (bfd *abfd)
   return retval;
 }
 
+/* Core files may have missing (corrupt) SHDR but PDHR is correct there.
+   bfd_elf_bfd_from_remote_memory () has too much overhead by
+   allocating/reading all the available ELF PT_LOADs.  */
+
+static struct build_id *
+build_id_phdr_get (bfd *templ, bfd_vma loadbase, unsigned e_phnum,
+		   Elf_Internal_Phdr *i_phdr)
+{
+  int i;
+  struct build_id *retval = NULL;
+
+  for (i = 0; i < e_phnum; i++)
+    if (i_phdr[i].p_type == PT_NOTE && i_phdr[i].p_filesz > 0)
+      {
+	Elf_Internal_Phdr *hdr = &i_phdr[i];
+	gdb_byte *buf;
+	int err;
+
+	buf = xmalloc (hdr->p_filesz);
+	err = target_read_memory (loadbase + i_phdr[i].p_vaddr, buf,
+				  hdr->p_filesz);
+	if (err == 0)
+	  retval = build_id_buf_get (templ, buf, hdr->p_filesz);
+	else
+	  retval = NULL;
+	xfree (buf);
+	if (retval != NULL)
+	  break;
+      }
+  return retval;
+}
+
+/* First we validate the file by reading in the ELF header and checking
+   the magic number.  */
+
+static inline bfd_boolean
+elf_file_p (Elf64_External_Ehdr *x_ehdrp64)
+{
+  gdb_assert (sizeof (Elf64_External_Ehdr) >= sizeof (Elf32_External_Ehdr));
+  gdb_assert (offsetof (Elf64_External_Ehdr, e_ident)
+	      == offsetof (Elf32_External_Ehdr, e_ident));
+  gdb_assert (sizeof (((Elf64_External_Ehdr *) 0)->e_ident)
+	      == sizeof (((Elf32_External_Ehdr *) 0)->e_ident));
+
+  return ((x_ehdrp64->e_ident[EI_MAG0] == ELFMAG0)
+	  && (x_ehdrp64->e_ident[EI_MAG1] == ELFMAG1)
+	  && (x_ehdrp64->e_ident[EI_MAG2] == ELFMAG2)
+	  && (x_ehdrp64->e_ident[EI_MAG3] == ELFMAG3));
+}
+
+/* Translate an ELF file header in external format into an ELF file header in
+   internal format.  */
+
+#define H_GET_WORD(bfd, ptr) (is64 ? H_GET_64 (bfd, (ptr))		\
+				   : H_GET_32 (bfd, (ptr)))
+#define H_GET_SIGNED_WORD(bfd, ptr) (is64 ? H_GET_S64 (bfd, (ptr))	\
+					  : H_GET_S32 (bfd, (ptr)))
+
+static void
+elf_swap_ehdr_in (bfd *abfd,
+		  const Elf64_External_Ehdr *src64,
+		  Elf_Internal_Ehdr *dst)
+{
+  int is64 = bfd_get_arch_size (abfd) == 64;
+#define SRC(field) (is64 ? src64->field \
+			 : ((const Elf32_External_Ehdr *) src64)->field)
+
+  int signed_vma = get_elf_backend_data (abfd)->sign_extend_vma;
+  memcpy (dst->e_ident, SRC (e_ident), EI_NIDENT);
+  dst->e_type = H_GET_16 (abfd, SRC (e_type));
+  dst->e_machine = H_GET_16 (abfd, SRC (e_machine));
+  dst->e_version = H_GET_32 (abfd, SRC (e_version));
+  if (signed_vma)
+    dst->e_entry = H_GET_SIGNED_WORD (abfd, SRC (e_entry));
+  else
+    dst->e_entry = H_GET_WORD (abfd, SRC (e_entry));
+  dst->e_phoff = H_GET_WORD (abfd, SRC (e_phoff));
+  dst->e_shoff = H_GET_WORD (abfd, SRC (e_shoff));
+  dst->e_flags = H_GET_32 (abfd, SRC (e_flags));
+  dst->e_ehsize = H_GET_16 (abfd, SRC (e_ehsize));
+  dst->e_phentsize = H_GET_16 (abfd, SRC (e_phentsize));
+  dst->e_phnum = H_GET_16 (abfd, SRC (e_phnum));
+  dst->e_shentsize = H_GET_16 (abfd, SRC (e_shentsize));
+  dst->e_shnum = H_GET_16 (abfd, SRC (e_shnum));
+  dst->e_shstrndx = H_GET_16 (abfd, SRC (e_shstrndx));
+
+#undef SRC
+}
+
+/* Translate an ELF program header table entry in external format into an
+   ELF program header table entry in internal format.  */
+
+void
+elf_swap_phdr_in (bfd *abfd,
+		  const Elf64_External_Phdr *src64,
+		  Elf_Internal_Phdr *dst)
+{
+  int is64 = bfd_get_arch_size (abfd) == 64;
+#define SRC(field) (is64 ? src64->field					\
+			 : ((const Elf32_External_Phdr *) src64)->field)
+
+  int signed_vma = get_elf_backend_data (abfd)->sign_extend_vma;
+
+  dst->p_type = H_GET_32 (abfd, SRC (p_type));
+  dst->p_flags = H_GET_32 (abfd, SRC (p_flags));
+  dst->p_offset = H_GET_WORD (abfd, SRC (p_offset));
+  if (signed_vma)
+    {
+      dst->p_vaddr = H_GET_SIGNED_WORD (abfd, SRC (p_vaddr));
+      dst->p_paddr = H_GET_SIGNED_WORD (abfd, SRC (p_paddr));
+    }
+  else
+    {
+      dst->p_vaddr = H_GET_WORD (abfd, SRC (p_vaddr));
+      dst->p_paddr = H_GET_WORD (abfd, SRC (p_paddr));
+    }
+  dst->p_filesz = H_GET_WORD (abfd, SRC (p_filesz));
+  dst->p_memsz = H_GET_WORD (abfd, SRC (p_memsz));
+  dst->p_align = H_GET_WORD (abfd, SRC (p_align));
+
+#undef SRC
+}
+
+#undef H_GET_SIGNED_WORD
+#undef H_GET_WORD
+
+static Elf_Internal_Phdr *
+elf_get_phdr (bfd *templ, bfd_vma ehdr_vma, unsigned *e_phnum_pointer,
+              bfd_vma *loadbase_pointer)
+{
+  /* sizeof (Elf64_External_Ehdr) >= sizeof (Elf32_External_Ehdr)  */
+  Elf64_External_Ehdr x_ehdr64;	/* Elf file header, external form */
+  Elf_Internal_Ehdr i_ehdr;	/* Elf file header, internal form */
+  bfd_size_type x_phdrs_size;
+  gdb_byte *x_phdrs_ptr;
+  Elf_Internal_Phdr *i_phdrs;
+  int err;
+  unsigned int i;
+  bfd_vma loadbase;
+  int loadbase_set;
+
+  gdb_assert (templ != NULL);
+  gdb_assert (sizeof (Elf64_External_Ehdr) >= sizeof (Elf32_External_Ehdr));
+
+  /* Read in the ELF header in external format.  */
+  err = target_read_memory (ehdr_vma, (bfd_byte *) &x_ehdr64, sizeof x_ehdr64);
+  if (err)
+    {
+      if (build_id_debug)
+        warning (_("build-id: Error reading ELF header at address 0x%lx"),
+		 (unsigned long) ehdr_vma);
+      return NULL;
+    }
+
+  /* Now check to see if we have a valid ELF file, and one that BFD can
+     make use of.  The magic number must match, the address size ('class')
+     and byte-swapping must match our XVEC entry.  */
+
+  if (! elf_file_p (&x_ehdr64)
+      || x_ehdr64.e_ident[EI_VERSION] != EV_CURRENT
+      || !((bfd_get_arch_size (templ) == 64
+            && x_ehdr64.e_ident[EI_CLASS] == ELFCLASS64)
+           || (bfd_get_arch_size (templ) == 32
+	       && x_ehdr64.e_ident[EI_CLASS] == ELFCLASS32)))
+    {
+      if (build_id_debug)
+        warning (_("build-id: Unrecognized ELF header at address 0x%lx"),
+		 (unsigned long) ehdr_vma);
+      return NULL;
+    }
+
+  /* Check that file's byte order matches xvec's */
+  switch (x_ehdr64.e_ident[EI_DATA])
+    {
+    case ELFDATA2MSB:		/* Big-endian */
+      if (! bfd_header_big_endian (templ))
+	{
+	  if (build_id_debug)
+	    warning (_("build-id: Unrecognized "
+		       "big-endian ELF header at address 0x%lx"),
+		     (unsigned long) ehdr_vma);
+	  return NULL;
+	}
+      break;
+    case ELFDATA2LSB:		/* Little-endian */
+      if (! bfd_header_little_endian (templ))
+	{
+	  if (build_id_debug)
+	    warning (_("build-id: Unrecognized "
+		       "little-endian ELF header at address 0x%lx"),
+		     (unsigned long) ehdr_vma);
+	  return NULL;
+	}
+      break;
+    case ELFDATANONE:		/* No data encoding specified */
+    default:			/* Unknown data encoding specified */
+      if (build_id_debug)
+	warning (_("build-id: Unrecognized "
+		   "ELF header endianity at address 0x%lx"),
+		 (unsigned long) ehdr_vma);
+      return NULL;
+    }
+
+  elf_swap_ehdr_in (templ, &x_ehdr64, &i_ehdr);
+
+  /* The file header tells where to find the program headers.
+     These are what we use to actually choose what to read.  */
+
+  if (i_ehdr.e_phentsize != (bfd_get_arch_size (templ) == 64
+                             ? sizeof (Elf64_External_Phdr)
+			     : sizeof (Elf32_External_Phdr))
+      || i_ehdr.e_phnum == 0)
+    {
+      if (build_id_debug)
+	warning (_("build-id: Invalid ELF program headers from the ELF header "
+		   "at address 0x%lx"), (unsigned long) ehdr_vma);
+      return NULL;
+    }
+
+  x_phdrs_size = (bfd_get_arch_size (templ) == 64 ? sizeof (Elf64_External_Phdr)
+						: sizeof (Elf32_External_Phdr));
+
+  i_phdrs = xmalloc (i_ehdr.e_phnum * (sizeof *i_phdrs + x_phdrs_size));
+  x_phdrs_ptr = (void *) &i_phdrs[i_ehdr.e_phnum];
+  err = target_read_memory (ehdr_vma + i_ehdr.e_phoff, (bfd_byte *) x_phdrs_ptr,
+			    i_ehdr.e_phnum * x_phdrs_size);
+  if (err)
+    {
+      free (i_phdrs);
+      if (build_id_debug)
+        warning (_("build-id: Error reading "
+		   "ELF program headers at address 0x%lx"),
+		 (unsigned long) (ehdr_vma + i_ehdr.e_phoff));
+      return NULL;
+    }
+
+  loadbase = ehdr_vma;
+  loadbase_set = 0;
+  for (i = 0; i < i_ehdr.e_phnum; ++i)
+    {
+      elf_swap_phdr_in (templ, (Elf64_External_Phdr *)
+			       (x_phdrs_ptr + i * x_phdrs_size), &i_phdrs[i]);
+      /* IA-64 vDSO may have two mappings for one segment, where one mapping
+	 is executable only, and one is read only.  We must not use the
+	 executable one (PF_R is the first one, PF_X the second one).  */
+      if (i_phdrs[i].p_type == PT_LOAD && (i_phdrs[i].p_flags & PF_R))
+	{
+	  /* Only the first PT_LOAD segment indicates the file bias.
+	     Next segments may have P_VADDR arbitrarily higher.
+	     If the first segment has P_VADDR zero any next segment must not
+	     confuse us, the first one sets LOADBASE certainly enough.  */
+	  if (!loadbase_set && i_phdrs[i].p_offset == 0)
+	    {
+	      loadbase = ehdr_vma - i_phdrs[i].p_vaddr;
+	      loadbase_set = 1;
+	    }
+	}
+    }
+
+  if (build_id_debug)
+    warning (_("build-id: Found ELF header at address 0x%lx, loadbase 0x%lx"),
+	     (unsigned long) ehdr_vma, (unsigned long) loadbase);
+
+  *e_phnum_pointer = i_ehdr.e_phnum;
+  *loadbase_pointer = loadbase;
+  return i_phdrs;
+}
+
+/* BUILD_ID_ADDR_GET gets ADDR located somewhere in the object.
+   Find the first section before ADDR containing an ELF header.
+   We rely on the fact the sections from multiple files do not mix.
+   FIXME: We should check ADDR is contained _inside_ the section with possibly
+   missing content (P_FILESZ < P_MEMSZ).  These omitted sections are currently
+   hidden by _BFD_ELF_MAKE_SECTION_FROM_PHDR.  */
+
+static CORE_ADDR build_id_addr;
+struct build_id_addr_sect
+  {
+    struct build_id_addr_sect *next;
+    asection *sect;
+  };
+static struct build_id_addr_sect *build_id_addr_sect;
+
+static void build_id_addr_candidate (bfd *abfd, asection *sect, void *obj)
+{
+  if (build_id_addr >= bfd_section_vma (abfd, sect))
+    {
+      struct build_id_addr_sect *candidate;
+
+      candidate = xmalloc (sizeof *candidate);
+      candidate->next = build_id_addr_sect;
+      build_id_addr_sect = candidate;
+      candidate->sect = sect;
+    }
+}
+
+struct build_id *
+build_id_addr_get (CORE_ADDR addr)
+{
+  struct build_id_addr_sect *candidate;
+  struct build_id *retval = NULL;
+  Elf_Internal_Phdr *i_phdr = NULL;
+  bfd_vma loadbase = 0;
+  unsigned e_phnum = 0;
+
+  if (core_bfd == NULL)
+    return NULL;
+
+  build_id_addr = addr;
+  gdb_assert (build_id_addr_sect == NULL);
+  bfd_map_over_sections (core_bfd, build_id_addr_candidate, NULL);
+
+  /* Sections are sorted in the high-to-low VMAs order.
+     Stop the search on the first ELF header we find.
+     Do not continue the search even if it does not contain NT_GNU_BUILD_ID.  */
+
+  for (candidate = build_id_addr_sect; candidate != NULL;
+       candidate = candidate->next)
+    {
+      i_phdr = elf_get_phdr (core_bfd,
+			     bfd_section_vma (core_bfd, candidate->sect),
+			     &e_phnum, &loadbase);
+      if (i_phdr != NULL)
+	break;
+    }
+
+  if (i_phdr != NULL)
+    {
+      retval = build_id_phdr_get (core_bfd, loadbase, e_phnum, i_phdr);
+      xfree (i_phdr);
+    }
+
+  while (build_id_addr_sect != NULL)
+    {
+      candidate = build_id_addr_sect;
+      build_id_addr_sect = candidate->next;
+      xfree (candidate);
+    }
+
+  return retval;
+}
+
 /* Return if FILENAME has NT_GNU_BUILD_ID matching the CHECK value.  */
 
 static int
@@ -1277,7 +1669,7 @@ build_id_verify (const char *filename, s
   if (abfd == NULL)
     return 0;
 
-  found = build_id_bfd_get (abfd);
+  found = build_id_bfd_shdr_get (abfd);
 
   if (found == NULL)
     warning (_("File \"%s\" has no build-id, file skipped"), filename);
@@ -1293,8 +1685,9 @@ build_id_verify (const char *filename, s
   return retval;
 }
 
-static char *
-build_id_to_debug_filename (struct build_id *build_id)
+char *
+build_id_to_filename (struct build_id *build_id, char **link_return,
+		      int add_debug_suffix)
 {
   char *link, *s, *retval = NULL;
   gdb_byte *data = build_id->data;
@@ -1302,7 +1695,9 @@ build_id_to_debug_filename (struct build
 
   /* DEBUG_FILE_DIRECTORY/.build-id/ab/cdef */
   link = xmalloc (strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1
-		  + 2 * size + (sizeof ".debug" - 1) + 1);
+		  + 2 * size
+		  + (add_debug_suffix ? sizeof ".debug" - 1 : 0)
+		  + 1);
   s = link + sprintf (link, "%s/.build-id/", debug_file_directory);
   if (size > 0)
     {
@@ -1313,12 +1708,14 @@ build_id_to_debug_filename (struct build
     *s++ = '/';
   while (size-- > 0)
     s += sprintf (s, "%02x", (unsigned) *data++);
-  strcpy (s, ".debug");
+  if (add_debug_suffix)
+    strcpy (s, ".debug");
+  else
+    *s = 0;
 
   /* lrealpath() is expensive even for the usually non-existent files.  */
   if (access (link, F_OK) == 0)
     retval = lrealpath (link);
-  xfree (link);
 
   if (retval != NULL && !build_id_verify (retval, build_id))
     {
@@ -1326,6 +1723,11 @@ build_id_to_debug_filename (struct build
       retval = NULL;
     }
 
+  if (link_return != NULL)
+    *link_return = link;
+  else
+    xfree (link);
+
   return retval;
 }
 
@@ -1423,23 +1825,27 @@ find_separate_debug_file (struct objfile
   unsigned long crc32;
   int i;
   struct build_id *build_id;
+  char *build_id_filename = NULL;
 
-  build_id = build_id_bfd_get (objfile->obfd);
+  build_id = build_id_bfd_shdr_get (objfile->obfd);
   if (build_id != NULL)
     {
       char *build_id_name;
 
-      build_id_name = build_id_to_debug_filename (build_id);
-      free (build_id);
+      build_id_name = build_id_to_filename (build_id, &build_id_filename, 1);
+      xfree (build_id);
       /* Prevent looping on a stripped .debug file.  */
       if (build_id_name != NULL && strcmp (build_id_name, objfile->name) == 0)
         {
-	  warning (_("\"%s\": separate debug info file has no debug info"),
+	  warning (_("\"%s\": The separate debug info file has no debug info"),
 		   build_id_name);
 	  xfree (build_id_name);
 	}
       else if (build_id_name != NULL)
-        return build_id_name;
+        {
+	  xfree (build_id_filename);
+	  return build_id_name;
+	}
     }
 
   basename = get_debug_link_info (objfile, &crc32);
@@ -1447,7 +1853,10 @@ find_separate_debug_file (struct objfile
   if (basename == NULL)
     /* There's no separate debug info, hence there's no way we could
        load it => no warning.  */
-    return NULL;
+    {
+      xfree (build_id_filename);
+      return NULL;
+    }
 
   dir = xstrdup (objfile->name);
 
@@ -1476,6 +1885,7 @@ find_separate_debug_file (struct objfile
 
   if (separate_debug_file_exists (debugfile, crc32, objfile->name))
     {
+      xfree (build_id_filename);
       xfree (basename);
       xfree (dir);
       return xstrdup (debugfile);
@@ -1489,6 +1899,7 @@ find_separate_debug_file (struct objfile
 
   if (separate_debug_file_exists (debugfile, crc32, objfile->name))
     {
+      xfree (build_id_filename);
       xfree (basename);
       xfree (dir);
       return xstrdup (debugfile);
@@ -1502,6 +1913,7 @@ find_separate_debug_file (struct objfile
 
   if (separate_debug_file_exists (debugfile, crc32, objfile->name))
     {
+      xfree (build_id_filename);
       xfree (basename);
       xfree (dir);
       return xstrdup (debugfile);
@@ -1521,6 +1933,7 @@ find_separate_debug_file (struct objfile
 
       if (separate_debug_file_exists (debugfile, crc32, objfile->name))
 	{
+	  xfree (build_id_filename);
 	  xfree (canon_name);
 	  xfree (basename);
 	  xfree (dir);
@@ -1528,6 +1941,14 @@ find_separate_debug_file (struct objfile
 	}
     }
   
+  if (build_id_filename != NULL)
+    {
+      fprintf_unfiltered (gdb_stdlog,
+		     _("\nwarning: Missing the separate debug info file: %s\n"),
+			  build_id_filename);
+      xfree (build_id_filename);
+    }
+
   if (canon_name)
     xfree (canon_name);
 
@@ -4223,4 +4644,12 @@ the global debug-file directory prepende
 				     NULL,
 				     show_debug_file_directory,
 				     &setlist, &showlist);
+
+  add_setshow_zinteger_cmd ("build-id", no_class, &build_id_debug, _("\
+Set debugging of the build-id locator."), _("\
+Show debugging of the build-id locator."), _("\
+Enables printf debugging output."),
+			    NULL,
+			    show_build_id_debug,
+			    &setdebuglist, &showdebuglist);
 }
Index: gdb-6.7/gdb/symfile.h
===================================================================
--- gdb-6.7.orig/gdb/symfile.h	2007-09-24 23:48:05.000000000 +0200
+++ gdb-6.7/gdb/symfile.h	2007-10-16 16:41:50.000000000 +0200
@@ -353,6 +353,12 @@ extern int symfile_map_offsets_to_segmen
 struct symfile_segment_data *get_symfile_segment_data (bfd *abfd);
 void free_symfile_segment_data (struct symfile_segment_data *data);
 
+/* build-id support.  */
+struct build_id;
+extern struct build_id *build_id_addr_get (CORE_ADDR addr);
+extern char *build_id_to_filename (struct build_id *build_id,
+				   char **link_return, int add_debug_suffix);
+
 /* From dwarf2read.c */
 
 extern int dwarf2_has_info (struct objfile *);