Blame SOURCES/gdb-6.6-buildid-locate.patch

689258
From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
689258
From: Fedora GDB patches <invalid@email.com>
689258
Date: Fri, 27 Oct 2017 21:07:50 +0200
689258
Subject: gdb-6.6-buildid-locate.patch
689258
689258
;; New locating of the matching binaries from the pure core file (build-id).
689258
;;=push+jan
689258
689258
diff --git a/gdb/build-id.c b/gdb/build-id.c
689258
--- a/gdb/build-id.c
689258
+++ b/gdb/build-id.c
689258
@@ -26,11 +26,67 @@
689258
 #include "objfiles.h"
689258
 #include "filenames.h"
689258
 #include "gdbcore.h"
689258
+#include "libbfd.h"
689258
+#include "gdbcore.h"
689258
+#include "gdbcmd.h"
689258
+#include "observable.h"
689258
+#include "elf/external.h"
689258
+#include "elf/internal.h"
689258
+#include "elf/common.h"
689258
+#include "elf-bfd.h"
689258
+#include <sys/stat.h>
689258
+
689258
+#define BUILD_ID_VERBOSE_NONE 0
689258
+#define BUILD_ID_VERBOSE_FILENAMES 1
689258
+#define BUILD_ID_VERBOSE_BINARY_PARSE 2
689258
+static int build_id_verbose = BUILD_ID_VERBOSE_FILENAMES;
689258
+static void
689258
+show_build_id_verbose (struct ui_file *file, int from_tty,
689258
+		       struct cmd_list_element *c, const char *value)
689258
+{
689258
+  fprintf_filtered (file, _("Verbosity level of the build-id locator is %s.\n"),
689258
+		    value);
689258
+}
689258
+/* Locate NT_GNU_BUILD_ID and return its matching debug filename.
689258
+   FIXME: NOTE decoding should be unified with the BFD core notes decoding.  */
689258
+
689258
+static struct bfd_build_id *
689258
+build_id_buf_get (bfd *templ, gdb_byte *buf, bfd_size_type size)
689258
+{
689258
+  bfd_byte *p;
689258
+
689258
+  p = buf;
689258
+  while (p < buf + size)
689258
+    {
689258
+      /* FIXME: bad alignment assumption.  */
689258
+      Elf_External_Note *xnp = (Elf_External_Note *) p;
689258
+      size_t namesz = H_GET_32 (templ, xnp->namesz);
689258
+      size_t descsz = H_GET_32 (templ, xnp->descsz);
689258
+      bfd_byte *descdata = (gdb_byte *) xnp->name + BFD_ALIGN (namesz, 4);
689258
+
689258
+      if (H_GET_32 (templ, xnp->type) == NT_GNU_BUILD_ID
689258
+	  && namesz == sizeof "GNU"
689258
+	  && memcmp (xnp->name, "GNU", sizeof "GNU") == 0)
689258
+	{
689258
+	  size_t size = descsz;
689258
+	  gdb_byte *data = (gdb_byte *) descdata;
689258
+	  struct bfd_build_id *retval;
689258
+
689258
+	  retval = (struct bfd_build_id *) xmalloc (sizeof *retval - 1 + size);
689258
+	  retval->size = size;
689258
+	  memcpy (retval->data, data, size);
689258
+
689258
+	  return retval;
689258
+	}
689258
+      p = descdata + BFD_ALIGN (descsz, 4);
689258
+    }
689258
+  return NULL;
689258
+}
689258
 
689258
 /* See build-id.h.  */
689258
 
689258
 const struct bfd_build_id *
689258
-build_id_bfd_get (bfd *abfd)
689258
+build_id_bfd_shdr_get (bfd *abfd)
689258
 {
689258
   if (!bfd_check_format (abfd, bfd_object))
689258
     return NULL;
689258
@@ -42,6 +98,348 @@ build_id_bfd_get (bfd *abfd)
689258
   return NULL;
689258
 }
689258
 
689258
+/* Core files may have missing (corrupt) SHDR but PDHR is correct there.
689258
+   bfd_elf_bfd_from_remote_memory () has too much overhead by
689258
+   allocating/reading all the available ELF PT_LOADs.  */
689258
+
689258
+static struct bfd_build_id *
689258
+build_id_phdr_get (bfd *templ, bfd_vma loadbase, unsigned e_phnum,
689258
+		   Elf_Internal_Phdr *i_phdr)
689258
+{
689258
+  int i;
689258
+  struct bfd_build_id *retval = NULL;
689258
+
689258
+  for (i = 0; i < e_phnum; i++)
689258
+    if (i_phdr[i].p_type == PT_NOTE && i_phdr[i].p_filesz > 0)
689258
+      {
689258
+	Elf_Internal_Phdr *hdr = &i_phdr[i];
689258
+	gdb_byte *buf;
689258
+	int err;
689258
+
689258
+	buf = (gdb_byte *) xmalloc (hdr->p_filesz);
689258
+	err = target_read_memory (loadbase + i_phdr[i].p_vaddr, buf,
689258
+				  hdr->p_filesz);
689258
+	if (err == 0)
689258
+	  retval = build_id_buf_get (templ, buf, hdr->p_filesz);
689258
+	else
689258
+	  retval = NULL;
689258
+	xfree (buf);
689258
+	if (retval != NULL)
689258
+	  break;
689258
+      }
689258
+  return retval;
689258
+}
689258
+
689258
+/* First we validate the file by reading in the ELF header and checking
689258
+   the magic number.  */
689258
+
689258
+static inline bfd_boolean
689258
+elf_file_p (Elf64_External_Ehdr *x_ehdrp64)
689258
+{
689258
+  gdb_assert (sizeof (Elf64_External_Ehdr) >= sizeof (Elf32_External_Ehdr));
689258
+  gdb_assert (offsetof (Elf64_External_Ehdr, e_ident)
689258
+	      == offsetof (Elf32_External_Ehdr, e_ident));
689258
+  gdb_assert (sizeof (((Elf64_External_Ehdr *) 0)->e_ident)
689258
+	      == sizeof (((Elf32_External_Ehdr *) 0)->e_ident));
689258
+
689258
+  return ((x_ehdrp64->e_ident[EI_MAG0] == ELFMAG0)
689258
+	  && (x_ehdrp64->e_ident[EI_MAG1] == ELFMAG1)
689258
+	  && (x_ehdrp64->e_ident[EI_MAG2] == ELFMAG2)
689258
+	  && (x_ehdrp64->e_ident[EI_MAG3] == ELFMAG3));
689258
+}
689258
+
689258
+/* Translate an ELF file header in external format into an ELF file header in
689258
+   internal format.  */
689258
+
689258
+#define H_GET_WORD(bfd, ptr) (is64 ? H_GET_64 (bfd, (ptr))		\
689258
+				   : H_GET_32 (bfd, (ptr)))
689258
+#define H_GET_SIGNED_WORD(bfd, ptr) (is64 ? H_GET_S64 (bfd, (ptr))	\
689258
+					  : H_GET_S32 (bfd, (ptr)))
689258
+
689258
+static void
689258
+elf_swap_ehdr_in (bfd *abfd,
689258
+		  const Elf64_External_Ehdr *src64,
689258
+		  Elf_Internal_Ehdr *dst)
689258
+{
689258
+  int is64 = bfd_get_arch_size (abfd) == 64;
689258
+#define SRC(field) (is64 ? src64->field \
689258
+			 : ((const Elf32_External_Ehdr *) src64)->field)
689258
+
689258
+  int signed_vma = get_elf_backend_data (abfd)->sign_extend_vma;
689258
+  memcpy (dst->e_ident, SRC (e_ident), EI_NIDENT);
689258
+  dst->e_type = H_GET_16 (abfd, SRC (e_type));
689258
+  dst->e_machine = H_GET_16 (abfd, SRC (e_machine));
689258
+  dst->e_version = H_GET_32 (abfd, SRC (e_version));
689258
+  if (signed_vma)
689258
+    dst->e_entry = H_GET_SIGNED_WORD (abfd, SRC (e_entry));
689258
+  else
689258
+    dst->e_entry = H_GET_WORD (abfd, SRC (e_entry));
689258
+  dst->e_phoff = H_GET_WORD (abfd, SRC (e_phoff));
689258
+  dst->e_shoff = H_GET_WORD (abfd, SRC (e_shoff));
689258
+  dst->e_flags = H_GET_32 (abfd, SRC (e_flags));
689258
+  dst->e_ehsize = H_GET_16 (abfd, SRC (e_ehsize));
689258
+  dst->e_phentsize = H_GET_16 (abfd, SRC (e_phentsize));
689258
+  dst->e_phnum = H_GET_16 (abfd, SRC (e_phnum));
689258
+  dst->e_shentsize = H_GET_16 (abfd, SRC (e_shentsize));
689258
+  dst->e_shnum = H_GET_16 (abfd, SRC (e_shnum));
689258
+  dst->e_shstrndx = H_GET_16 (abfd, SRC (e_shstrndx));
689258
+
689258
+#undef SRC
689258
+}
689258
+
689258
+/* Translate an ELF program header table entry in external format into an
689258
+   ELF program header table entry in internal format.  */
689258
+
689258
+static void
689258
+elf_swap_phdr_in (bfd *abfd,
689258
+		  const Elf64_External_Phdr *src64,
689258
+		  Elf_Internal_Phdr *dst)
689258
+{
689258
+  int is64 = bfd_get_arch_size (abfd) == 64;
689258
+#define SRC(field) (is64 ? src64->field					\
689258
+			 : ((const Elf32_External_Phdr *) src64)->field)
689258
+
689258
+  int signed_vma = get_elf_backend_data (abfd)->sign_extend_vma;
689258
+
689258
+  dst->p_type = H_GET_32 (abfd, SRC (p_type));
689258
+  dst->p_flags = H_GET_32 (abfd, SRC (p_flags));
689258
+  dst->p_offset = H_GET_WORD (abfd, SRC (p_offset));
689258
+  if (signed_vma)
689258
+    {
689258
+      dst->p_vaddr = H_GET_SIGNED_WORD (abfd, SRC (p_vaddr));
689258
+      dst->p_paddr = H_GET_SIGNED_WORD (abfd, SRC (p_paddr));
689258
+    }
689258
+  else
689258
+    {
689258
+      dst->p_vaddr = H_GET_WORD (abfd, SRC (p_vaddr));
689258
+      dst->p_paddr = H_GET_WORD (abfd, SRC (p_paddr));
689258
+    }
689258
+  dst->p_filesz = H_GET_WORD (abfd, SRC (p_filesz));
689258
+  dst->p_memsz = H_GET_WORD (abfd, SRC (p_memsz));
689258
+  dst->p_align = H_GET_WORD (abfd, SRC (p_align));
689258
+
689258
+#undef SRC
689258
+}
689258
+
689258
+#undef H_GET_SIGNED_WORD
689258
+#undef H_GET_WORD
689258
+
689258
+static Elf_Internal_Phdr *
689258
+elf_get_phdr (bfd *templ, bfd_vma ehdr_vma, unsigned *e_phnum_pointer,
689258
+              bfd_vma *loadbase_pointer)
689258
+{
689258
+  /* sizeof (Elf64_External_Ehdr) >= sizeof (Elf32_External_Ehdr)  */
689258
+  Elf64_External_Ehdr x_ehdr64;	/* Elf file header, external form */
689258
+  Elf_Internal_Ehdr i_ehdr;	/* Elf file header, internal form */
689258
+  bfd_size_type x_phdrs_size;
689258
+  gdb_byte *x_phdrs_ptr;
689258
+  Elf_Internal_Phdr *i_phdrs;
689258
+  int err;
689258
+  unsigned int i;
689258
+  bfd_vma loadbase;
689258
+  int loadbase_set;
689258
+
689258
+  gdb_assert (templ != NULL);
689258
+  gdb_assert (sizeof (Elf64_External_Ehdr) >= sizeof (Elf32_External_Ehdr));
689258
+
689258
+  /* Read in the ELF header in external format.  */
689258
+  err = target_read_memory (ehdr_vma, (bfd_byte *) &x_ehdr64, sizeof x_ehdr64);
689258
+  if (err)
689258
+    {
689258
+      if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
689258
+        warning (_("build-id: Error reading ELF header at address 0x%lx"),
689258
+		 (unsigned long) ehdr_vma);
689258
+      return NULL;
689258
+    }
689258
+
689258
+  /* Now check to see if we have a valid ELF file, and one that BFD can
689258
+     make use of.  The magic number must match, the address size ('class')
689258
+     and byte-swapping must match our XVEC entry.  */
689258
+
689258
+  if (! elf_file_p (&x_ehdr64)
689258
+      || x_ehdr64.e_ident[EI_VERSION] != EV_CURRENT
689258
+      || !((bfd_get_arch_size (templ) == 64
689258
+            && x_ehdr64.e_ident[EI_CLASS] == ELFCLASS64)
689258
+           || (bfd_get_arch_size (templ) == 32
689258
+	       && x_ehdr64.e_ident[EI_CLASS] == ELFCLASS32)))
689258
+    {
689258
+      if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
689258
+        warning (_("build-id: Unrecognized ELF header at address 0x%lx"),
689258
+		 (unsigned long) ehdr_vma);
689258
+      return NULL;
689258
+    }
689258
+
689258
+  /* Check that file's byte order matches xvec's */
689258
+  switch (x_ehdr64.e_ident[EI_DATA])
689258
+    {
689258
+    case ELFDATA2MSB:		/* Big-endian */
689258
+      if (! bfd_header_big_endian (templ))
689258
+	{
689258
+	  if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
689258
+	    warning (_("build-id: Unrecognized "
689258
+		       "big-endian ELF header at address 0x%lx"),
689258
+		     (unsigned long) ehdr_vma);
689258
+	  return NULL;
689258
+	}
689258
+      break;
689258
+    case ELFDATA2LSB:		/* Little-endian */
689258
+      if (! bfd_header_little_endian (templ))
689258
+	{
689258
+	  if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
689258
+	    warning (_("build-id: Unrecognized "
689258
+		       "little-endian ELF header at address 0x%lx"),
689258
+		     (unsigned long) ehdr_vma);
689258
+	  return NULL;
689258
+	}
689258
+      break;
689258
+    case ELFDATANONE:		/* No data encoding specified */
689258
+    default:			/* Unknown data encoding specified */
689258
+      if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
689258
+	warning (_("build-id: Unrecognized "
689258
+		   "ELF header endianity at address 0x%lx"),
689258
+		 (unsigned long) ehdr_vma);
689258
+      return NULL;
689258
+    }
689258
+
689258
+  elf_swap_ehdr_in (templ, &x_ehdr64, &i_ehdr);
689258
+
689258
+  /* The file header tells where to find the program headers.
689258
+     These are what we use to actually choose what to read.  */
689258
+
689258
+  if (i_ehdr.e_phentsize != (bfd_get_arch_size (templ) == 64
689258
+                             ? sizeof (Elf64_External_Phdr)
689258
+			     : sizeof (Elf32_External_Phdr))
689258
+      || i_ehdr.e_phnum == 0)
689258
+    {
689258
+      if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
689258
+	warning (_("build-id: Invalid ELF program headers from the ELF header "
689258
+		   "at address 0x%lx"), (unsigned long) ehdr_vma);
689258
+      return NULL;
689258
+    }
689258
+
689258
+  x_phdrs_size = (bfd_get_arch_size (templ) == 64 ? sizeof (Elf64_External_Phdr)
689258
+						: sizeof (Elf32_External_Phdr));
689258
+
689258
+  i_phdrs = (Elf_Internal_Phdr *) xmalloc (i_ehdr.e_phnum * (sizeof *i_phdrs + x_phdrs_size));
689258
+  x_phdrs_ptr = (gdb_byte *) &i_phdrs[i_ehdr.e_phnum];
689258
+  err = target_read_memory (ehdr_vma + i_ehdr.e_phoff, (bfd_byte *) x_phdrs_ptr,
689258
+			    i_ehdr.e_phnum * x_phdrs_size);
689258
+  if (err)
689258
+    {
689258
+      free (i_phdrs);
689258
+      if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
689258
+        warning (_("build-id: Error reading "
689258
+		   "ELF program headers at address 0x%lx"),
689258
+		 (unsigned long) (ehdr_vma + i_ehdr.e_phoff));
689258
+      return NULL;
689258
+    }
689258
+
689258
+  loadbase = ehdr_vma;
689258
+  loadbase_set = 0;
689258
+  for (i = 0; i < i_ehdr.e_phnum; ++i)
689258
+    {
689258
+      elf_swap_phdr_in (templ, (Elf64_External_Phdr *)
689258
+			       (x_phdrs_ptr + i * x_phdrs_size), &i_phdrs[i]);
689258
+      /* IA-64 vDSO may have two mappings for one segment, where one mapping
689258
+	 is executable only, and one is read only.  We must not use the
689258
+	 executable one (PF_R is the first one, PF_X the second one).  */
689258
+      if (i_phdrs[i].p_type == PT_LOAD && (i_phdrs[i].p_flags & PF_R))
689258
+	{
689258
+	  /* Only the first PT_LOAD segment indicates the file bias.
689258
+	     Next segments may have P_VADDR arbitrarily higher.
689258
+	     If the first segment has P_VADDR zero any next segment must not
689258
+	     confuse us, the first one sets LOADBASE certainly enough.  */
689258
+	  if (!loadbase_set && i_phdrs[i].p_offset == 0)
689258
+	    {
689258
+	      loadbase = ehdr_vma - i_phdrs[i].p_vaddr;
689258
+	      loadbase_set = 1;
689258
+	    }
689258
+	}
689258
+    }
689258
+
689258
+  if (build_id_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
689258
+    warning (_("build-id: Found ELF header at address 0x%lx, loadbase 0x%lx"),
689258
+	     (unsigned long) ehdr_vma, (unsigned long) loadbase);
689258
+
689258
+  *e_phnum_pointer = i_ehdr.e_phnum;
689258
+  *loadbase_pointer = loadbase;
689258
+  return i_phdrs;
689258
+}
689258
+
689258
+/* BUILD_ID_ADDR_GET gets ADDR located somewhere in the object.
689258
+   Find the first section before ADDR containing an ELF header.
689258
+   We rely on the fact the sections from multiple files do not mix.
689258
+   FIXME: We should check ADDR is contained _inside_ the section with possibly
689258
+   missing content (P_FILESZ < P_MEMSZ).  These omitted sections are currently
689258
+   hidden by _BFD_ELF_MAKE_SECTION_FROM_PHDR.  */
689258
+
689258
+static CORE_ADDR build_id_addr;
689258
+struct build_id_addr_sect
689258
+  {
689258
+    struct build_id_addr_sect *next;
689258
+    asection *sect;
689258
+  };
689258
+static struct build_id_addr_sect *build_id_addr_sect;
689258
+
689258
+static void build_id_addr_candidate (bfd *abfd, asection *sect, void *obj)
689258
+{
689258
+  if (build_id_addr >= bfd_section_vma (abfd, sect))
689258
+    {
689258
+      struct build_id_addr_sect *candidate;
689258
+
689258
+      candidate = (struct build_id_addr_sect *) xmalloc (sizeof *candidate);
689258
+      candidate->next = build_id_addr_sect;
689258
+      build_id_addr_sect = candidate;
689258
+      candidate->sect = sect;
689258
+    }
689258
+}
689258
+
689258
+struct bfd_build_id *
689258
+build_id_addr_get (CORE_ADDR addr)
689258
+{
689258
+  struct build_id_addr_sect *candidate;
689258
+  struct bfd_build_id *retval = NULL;
689258
+  Elf_Internal_Phdr *i_phdr = NULL;
689258
+  bfd_vma loadbase = 0;
689258
+  unsigned e_phnum = 0;
689258
+
689258
+  if (core_bfd == NULL)
689258
+    return NULL;
689258
+
689258
+  build_id_addr = addr;
689258
+  gdb_assert (build_id_addr_sect == NULL);
689258
+  bfd_map_over_sections (core_bfd, build_id_addr_candidate, NULL);
689258
+
689258
+  /* Sections are sorted in the high-to-low VMAs order.
689258
+     Stop the search on the first ELF header we find.
689258
+     Do not continue the search even if it does not contain NT_GNU_BUILD_ID.  */
689258
+
689258
+  for (candidate = build_id_addr_sect; candidate != NULL;
689258
+       candidate = candidate->next)
689258
+    {
689258
+      i_phdr = elf_get_phdr (core_bfd,
689258
+			     bfd_section_vma (core_bfd, candidate->sect),
689258
+			     &e_phnum, &loadbase);
689258
+      if (i_phdr != NULL)
689258
+	break;
689258
+    }
689258
+
689258
+  if (i_phdr != NULL)
689258
+    {
689258
+      retval = build_id_phdr_get (core_bfd, loadbase, e_phnum, i_phdr);
689258
+      xfree (i_phdr);
689258
+    }
689258
+
689258
+  while (build_id_addr_sect != NULL)
689258
+    {
689258
+      candidate = build_id_addr_sect;
689258
+      build_id_addr_sect = candidate->next;
689258
+      xfree (candidate);
689258
+    }
689258
+
689258
+  return retval;
689258
+}
689258
+
689258
 /* See build-id.h.  */
689258
 
689258
 int
689258
@@ -50,7 +448,7 @@ build_id_verify (bfd *abfd, size_t check_len, const bfd_byte *check)
689258
   const struct bfd_build_id *found;
689258
   int retval = 0;
689258
 
689258
-  found = build_id_bfd_get (abfd);
689258
+  found = build_id_bfd_shdr_get (abfd);
689258
 
689258
   if (found == NULL)
689258
     warning (_("File \"%s\" has no build-id, file skipped"),
689258
@@ -65,11 +463,50 @@ build_id_verify (bfd *abfd, size_t check_len, const bfd_byte *check)
689258
   return retval;
689258
 }
689258
 
689258
+static char *
689258
+link_resolve (const char *symlink, int level)
689258
+{
689258
+  char buf[PATH_MAX + 1], *target, *retval;
689258
+  ssize_t got;
689258
+
689258
+  if (level > 10)
689258
+    return xstrdup (symlink);
689258
+
689258
+  got = readlink (symlink, buf, sizeof (buf));
689258
+  if (got < 0 || got >= sizeof (buf))
689258
+    return xstrdup (symlink);
689258
+  buf[got] = '\0';
689258
+
689258
+  if (IS_ABSOLUTE_PATH (buf))
689258
+    target = xstrdup (buf);
689258
+  else
689258
+    {
689258
+      const std::string dir (ldirname (symlink));
689258
+
689258
+      target = xstrprintf ("%s"
689258
+#ifndef HAVE_DOS_BASED_FILE_SYSTEM
689258
+			   "/"
689258
+#else /* HAVE_DOS_BASED_FILE_SYSTEM */
689258
+			   "\\"
689258
+#endif /* HAVE_DOS_BASED_FILE_SYSTEM */
689258
+			   "%s", dir.c_str(), buf);
689258
+    }
689258
+
689258
+  retval = link_resolve (target, level + 1);
689258
+  xfree (target);
689258
+  return retval;
689258
+}
689258
+
689258
 /* See build-id.h.  */
689258
 
689258
 gdb_bfd_ref_ptr
689258
-build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id)
689258
+build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id,
689258
+		       char **link_return, int add_debug_suffix)
689258
 {
689258
+  char *debugdir;
689258
+  std::string link, link_all;
689258
+  struct cleanup *back_to;
689258
+  int ix;
689258
   gdb_bfd_ref_ptr abfd;
689258
 
689258
   /* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
689258
@@ -82,63 +519,296 @@ build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id)
689258
     {
689258
       const gdb_byte *data = build_id;
689258
       size_t size = build_id_len;
689258
+      char *filename = NULL;
689258
+      struct cleanup *inner;
689258
+      unsigned seqno;
689258
+      struct stat statbuf_trash;
689258
+      std::string link0;
689258
 
689258
-      std::string link = debugdir.get ();
689258
+      link = debugdir.get ();
689258
       link += "/.build-id/";
689258
 
689258
       if (size > 0)
689258
 	{
689258
 	  size--;
689258
-	  string_appendf (link, "%02x/", (unsigned) *data++);
689258
+	  string_appendf (link, "%02x", (unsigned) *data++);
689258
 	}
689258
-
689258
+      if (size > 0)
689258
+	link += "/";
689258
       while (size-- > 0)
689258
 	string_appendf (link, "%02x", (unsigned) *data++);
689258
 
689258
-      link += ".debug";
689258
-
689258
       if (separate_debug_file_debug)
689258
 	printf_unfiltered (_("  Trying %s\n"), link.c_str ());
689258
 
689258
-      /* lrealpath() is expensive even for the usually non-existent files.  */
689258
-      gdb::unique_xmalloc_ptr<char> filename;
689258
-      if (access (link.c_str (), F_OK) == 0)
689258
-	filename.reset (lrealpath (link.c_str ()));
689258
-
689258
-      if (filename == NULL)
689258
-	continue;
689258
+      for (seqno = 0;; seqno++)
689258
+	{
689258
+	  if (seqno)
689258
+	    {
689258
+	      /* There can be multiple build-id symlinks pointing to real files
689258
+		 with the same build-id (such as hard links).  Some of the real
689258
+		 files may not be installed.  */
689258
+
689258
+	      string_appendf (link, ".%u", seqno);
689258
+	    }
689258
+
689258
+	  if (add_debug_suffix)
689258
+	    link += ".debug";
689258
+
689258
+	  if (!seqno)
689258
+	    {
689258
+	      /* If none of the real files is found report as missing file
689258
+		 always the non-.%u-suffixed file.  */
689258
+	      link0 = link;
689258
+	    }
689258
+
689258
+	  /* `access' automatically dereferences LINK.  */
689258
+	  if (lstat (link.c_str (), &statbuf_trash) != 0)
689258
+	    {
689258
+	      /* Stop increasing SEQNO.  */
689258
+	      break;
689258
+	    }
689258
+
689258
+	  filename = lrealpath (link.c_str ());
689258
+	  if (filename == NULL)
689258
+	    continue;
689258
+
689258
+	  /* We expect to be silent on the non-existing files.  */
689258
+	  inner = make_cleanup (xfree, filename);
689258
+	  abfd = gdb_bfd_open (filename, gnutarget, -1);
689258
+	  do_cleanups (inner);
689258
+
689258
+	  if (abfd == NULL)
689258
+	    continue;
689258
+
689258
+	  if (build_id_verify (abfd.get(), build_id_len, build_id))
689258
+	    break;
689258
+
689258
+	  abfd.release ();
689258
+
689258
+	  filename = NULL;
689258
+	}
689258
 
689258
-      /* We expect to be silent on the non-existing files.  */
689258
-      abfd = gdb_bfd_open (filename.get (), gnutarget, -1);
689258
+      if (filename != NULL)
689258
+	{
689258
+	  /* LINK_ALL is not used below in this non-NULL FILENAME case.  */
689258
+	  break;
689258
+	}
689258
 
689258
-      if (abfd == NULL)
689258
-	continue;
689258
+      /* If the symlink has target request to install the target.
689258
+         BASE-debuginfo.rpm contains the symlink but BASE.rpm may be missing.
689258
+         https://bugzilla.redhat.com/show_bug.cgi?id=981154  */
689258
+      std::string link0_resolved (link_resolve (link0.c_str (), 0));
689258
 
689258
-      if (build_id_verify (abfd.get(), build_id_len, build_id))
689258
-	break;
689258
+      if (link_all.empty ())
689258
+	link_all = link0_resolved;
689258
+      else
689258
+	{
689258
+	  /* Use whitespace instead of DIRNAME_SEPARATOR to be compatible with
689258
+	     its possible use as an argument for installation command.  */
689258
+	  link_all += " " + link0_resolved;
689258
+	}
689258
+    }
689258
 
689258
-      abfd.release ();
689258
+  if (link_return != NULL)
689258
+    {
689258
+      if (abfd != NULL)
689258
+	{
689258
+	  *link_return = xstrdup (link.c_str ());
689258
+	}
689258
+      else
689258
+	{
689258
+	  *link_return = xstrdup (link_all.c_str ());
689258
+	}
689258
     }
689258
 
689258
   return abfd;
689258
 }
689258
 
689258
+char *
689258
+build_id_to_filename (const struct bfd_build_id *build_id, char **link_return)
689258
+{
689258
+  gdb_bfd_ref_ptr abfd;
689258
+  char *result;
689258
+  
689258
+  abfd = build_id_to_debug_bfd (build_id->size, build_id->data, link_return, 0);
689258
+  if (abfd == NULL)
689258
+    return NULL;
689258
+
689258
+  result = xstrdup (bfd_get_filename (abfd));
689258
+  abfd.release ();
689258
+  return result;
689258
+}
689258
+
689258
+/* This MISSING_FILEPAIR_HASH tracker is used only for the duplicite messages
689258
+     Try to install the hash file ...
689258
+   avoidance.  */
689258
+
689258
+struct missing_filepair
689258
+  {
689258
+    char *binary;
689258
+    char *debug;
689258
+    char data[1];
689258
+  };
689258
+
689258
+static struct htab *missing_filepair_hash;
689258
+static struct obstack missing_filepair_obstack;
689258
+
689258
+static void *
689258
+missing_filepair_xcalloc (size_t nmemb, size_t nmemb_size)
689258
+{
689258
+  void *retval;
689258
+  size_t size = nmemb * nmemb_size;
689258
+
689258
+  retval = obstack_alloc (&missing_filepair_obstack, size);
689258
+  memset (retval, 0, size);
689258
+  return retval;
689258
+}
689258
+
689258
+static hashval_t
689258
+missing_filepair_hash_func (const struct missing_filepair *elem)
689258
+{
689258
+  hashval_t retval = 0;
689258
+
689258
+  retval ^= htab_hash_string (elem->binary);
689258
+  if (elem->debug != NULL)
689258
+    retval ^= htab_hash_string (elem->debug);
689258
+
689258
+  return retval;
689258
+}
689258
+
689258
+static int
689258
+missing_filepair_eq (const struct missing_filepair *elem1,
689258
+		       const struct missing_filepair *elem2)
689258
+{
689258
+  return strcmp (elem1->binary, elem2->binary) == 0
689258
+         && ((elem1->debug == NULL) == (elem2->debug == NULL))
689258
+         && (elem1->debug == NULL || strcmp (elem1->debug, elem2->debug) == 0);
689258
+}
689258
+
689258
+static void
689258
+missing_filepair_change (void)
689258
+{
689258
+  if (missing_filepair_hash != NULL)
689258
+    {
689258
+      obstack_free (&missing_filepair_obstack, NULL);
689258
+      /* All their memory came just from missing_filepair_OBSTACK.  */
689258
+      missing_filepair_hash = NULL;
689258
+    }
689258
+}
689258
+
689258
+static void
689258
+debug_print_executable_changed (void)
689258
+{
689258
+  missing_filepair_change ();
689258
+}
689258
+
689258
+/* Notify user the file BINARY with (possibly NULL) associated separate debug
689258
+   information file DEBUG is missing.  DEBUG may or may not be the build-id
689258
+   file such as would be:
689258
+     /usr/lib/debug/.build-id/dd/b1d2ce632721c47bb9e8679f369e2295ce71be.debug
689258
+   */
689258
+
689258
+void
689258
+debug_print_missing (const char *binary, const char *debug)
689258
+{
689258
+  size_t binary_len0 = strlen (binary) + 1;
689258
+  size_t debug_len0 = debug ? strlen (debug) + 1 : 0;
689258
+  struct missing_filepair missing_filepair_find;
689258
+  struct missing_filepair *missing_filepair;
689258
+  struct missing_filepair **slot;
689258
+
689258
+  if (build_id_verbose < BUILD_ID_VERBOSE_FILENAMES)
689258
+    return;
689258
+
689258
+  if (missing_filepair_hash == NULL)
689258
+    {
689258
+      obstack_init (&missing_filepair_obstack);
689258
+      missing_filepair_hash = htab_create_alloc (64,
689258
+	(hashval_t (*) (const void *)) missing_filepair_hash_func,
689258
+	(int (*) (const void *, const void *)) missing_filepair_eq, NULL,
689258
+	missing_filepair_xcalloc, NULL);
689258
+    }
689258
+
689258
+  /* Use MISSING_FILEPAIR_FIND first instead of calling obstack_alloc with
689258
+     obstack_free in the case of a (rare) match.  The problem is ALLOC_F for
689258
+     MISSING_FILEPAIR_HASH allocates from MISSING_FILEPAIR_OBSTACK maintenance
689258
+     structures for MISSING_FILEPAIR_HASH.  Calling obstack_free would possibly
689258
+     not to free only MISSING_FILEPAIR but also some such structures (allocated
689258
+     during the htab_find_slot call).  */
689258
+
689258
+  missing_filepair_find.binary = (char *) binary;
689258
+  missing_filepair_find.debug = (char *) debug;
689258
+  slot = (struct missing_filepair **) htab_find_slot (missing_filepair_hash,
689258
+						      &missing_filepair_find,
689258
+						      INSERT);
689258
+
689258
+  /* While it may be still printed duplicitely with the missing debuginfo file
689258
+   * it is due to once printing about the binary file build-id link and once
689258
+   * about the .debug file build-id link as both the build-id symlinks are
689258
+   * located in the debuginfo package.  */
689258
+
689258
+  if (*slot != NULL)
689258
+    return;
689258
+
689258
+  missing_filepair = (struct missing_filepair *) obstack_alloc (&missing_filepair_obstack,
689258
+								sizeof (*missing_filepair) - 1
689258
+								+ binary_len0 + debug_len0);
689258
+  missing_filepair->binary = missing_filepair->data;
689258
+  memcpy (missing_filepair->binary, binary, binary_len0);
689258
+  if (debug != NULL)
689258
+    {
689258
+      missing_filepair->debug = missing_filepair->binary + binary_len0;
689258
+      memcpy (missing_filepair->debug, debug, debug_len0);
689258
+    }
689258
+  else
689258
+    missing_filepair->debug = NULL;
689258
+
689258
+  *slot = missing_filepair;
689258
+
689258
+  /* We do not collect and flush these messages as each such message
689258
+     already requires its own separate lines.  */
689258
+
689258
+  fprintf_unfiltered (gdb_stdlog,
689258
+		      _("Missing separate debuginfo for %s\n"), binary);
689258
+  if (debug != NULL)
689258
+    fprintf_unfiltered (gdb_stdlog, _("Try to install the hash file %s\n"),
689258
+			debug);
689258
+}
689258
+
689258
 /* See build-id.h.  */
689258
 
689258
 std::string
689258
-find_separate_debug_file_by_buildid (struct objfile *objfile)
689258
+find_separate_debug_file_by_buildid (struct objfile *objfile,
689258
+			gdb::unique_xmalloc_ptr<char> *build_id_filename_return)
689258
 {
689258
   const struct bfd_build_id *build_id;
689258
 
689258
-  build_id = build_id_bfd_get (objfile->obfd);
689258
+  if (build_id_filename_return)
689258
+    *build_id_filename_return = NULL;
689258
+
689258
+  build_id = build_id_bfd_shdr_get (objfile->obfd);
689258
   if (build_id != NULL)
689258
     {
689258
       if (separate_debug_file_debug)
689258
 	printf_unfiltered (_("\nLooking for separate debug info (build-id) for "
689258
 			     "%s\n"), objfile_name (objfile));
689258
 
689258
+      char *build_id_filename_cstr = NULL;
689258
       gdb_bfd_ref_ptr abfd (build_id_to_debug_bfd (build_id->size,
689258
-						   build_id->data));
689258
+						    build_id->data,
689258
+	      (!build_id_filename_return ? NULL : &build_id_filename_cstr), 1));
689258
+      if (build_id_filename_return)
689258
+	{
689258
+	  if (!build_id_filename_cstr)
689258
+	    gdb_assert (!*build_id_filename_return);
689258
+	  else
689258
+	    {
689258
+	      *build_id_filename_return = gdb::unique_xmalloc_ptr<char> (build_id_filename_cstr);
689258
+	      build_id_filename_cstr = NULL;
689258
+	    }
689258
+	}
689258
+
689258
       /* Prevent looping on a stripped .debug file.  */
689258
       if (abfd != NULL
689258
 	  && filename_cmp (bfd_get_filename (abfd.get ()),
689258
@@ -151,3 +821,21 @@ find_separate_debug_file_by_buildid (struct objfile *objfile)
689258
 
689258
   return std::string ();
689258
 }
689258
+
689258
+extern void _initialize_build_id (void);
689258
+
689258
+void
689258
+_initialize_build_id (void)
689258
+{
689258
+  add_setshow_zinteger_cmd ("build-id-verbose", no_class, &build_id_verbose,
689258
+			    _("\
689258
+Set debugging level of the build-id locator."), _("\
689258
+Show debugging level of the build-id locator."), _("\
689258
+Level 1 (default) enables printing the missing debug filenames,\n\
689258
+level 2 also prints the parsing of binaries to find the identificators."),
689258
+			    NULL,
689258
+			    show_build_id_verbose,
689258
+			    &setlist, &showlist);
689258
+
689258
+  gdb::observers::executable_changed.attach (debug_print_executable_changed);
689258
+}
689258
diff --git a/gdb/build-id.h b/gdb/build-id.h
689258
--- a/gdb/build-id.h
689258
+++ b/gdb/build-id.h
689258
@@ -22,9 +22,10 @@
689258
 
689258
 #include "gdb_bfd.h"
689258
 
689258
-/* Locate NT_GNU_BUILD_ID from ABFD and return its content.  */
689258
+/* Separate debuginfo files have corrupted PHDR but SHDR is correct there.
689258
+   Locate NT_GNU_BUILD_ID from ABFD and return its content.  */
689258
 
689258
-extern const struct bfd_build_id *build_id_bfd_get (bfd *abfd);
689258
+extern const struct bfd_build_id *build_id_bfd_shdr_get (bfd *abfd);
689258
 
689258
 /* Return true if ABFD has NT_GNU_BUILD_ID matching the CHECK value.
689258
    Otherwise, issue a warning and return false.  */
689258
@@ -38,13 +39,18 @@ extern int build_id_verify (bfd *abfd,
689258
    the caller.  */
689258
 
689258
 extern gdb_bfd_ref_ptr build_id_to_debug_bfd (size_t build_id_len,
689258
-					      const bfd_byte *build_id);
689258
+					      const bfd_byte *build_id,
689258
+					      char **link_return,
689258
+					      int add_debug_suffix);
689258
+
689258
+extern char *build_id_to_filename (const struct bfd_build_id *build_id,
689258
+				   char **link_return);
689258
 
689258
 /* Find the separate debug file for OBJFILE, by using the build-id
689258
    associated with OBJFILE's BFD.  If successful, returns the file name for the
689258
    separate debug file, otherwise, return an empty string.  */
689258
 
689258
-extern std::string find_separate_debug_file_by_buildid
689258
-  (struct objfile *objfile);
689258
+extern std::string find_separate_debug_file_by_buildid (struct objfile *objfile,
689258
+		       gdb::unique_xmalloc_ptr<char> *build_id_filename_return);
689258
 
689258
 #endif /* BUILD_ID_H */
689258
diff --git a/gdb/coffread.c b/gdb/coffread.c
689258
--- a/gdb/coffread.c
689258
+++ b/gdb/coffread.c
689258
@@ -733,7 +733,8 @@ coff_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags)
689258
   /* Try to add separate debug file if no symbols table found.   */
689258
   if (!objfile_has_partial_symbols (objfile))
689258
     {
689258
-      std::string debugfile = find_separate_debug_file_by_buildid (objfile);
689258
+      std::string debugfile = find_separate_debug_file_by_buildid (objfile,
689258
+								   NULL);
689258
 
689258
       if (debugfile.empty ())
689258
 	debugfile = find_separate_debug_file_by_debuglink (objfile);
689258
diff --git a/gdb/corelow.c b/gdb/corelow.c
689258
--- a/gdb/corelow.c
689258
+++ b/gdb/corelow.c
689258
@@ -45,6 +45,10 @@
689258
 #include "gdb_bfd.h"
689258
 #include "completer.h"
689258
 #include "filestuff.h"
689258
+#include "auxv.h"
689258
+#include "elf/common.h"
689258
+#include "gdbcmd.h"
689258
+#include "build-id.h"
689258
 
689258
 #ifndef O_LARGEFILE
689258
 #define O_LARGEFILE 0
689258
@@ -321,6 +325,54 @@ add_to_thread_list (bfd *abfd, asection *asect, void *reg_sect_arg)
689258
     inferior_ptid = ptid;			/* Yes, make it current.  */
689258
 }
689258
 
689258
+static int build_id_core_loads = 1;
689258
+
689258
+static void
689258
+build_id_locate_exec (int from_tty)
689258
+{
689258
+  CORE_ADDR at_entry;
689258
+  struct bfd_build_id *build_id;
689258
+  char *execfilename, *debug_filename;
689258
+  char *build_id_filename;
689258
+  struct cleanup *back_to;
689258
+
689258
+  if (exec_bfd != NULL || symfile_objfile != NULL)
689258
+    return;
689258
+
689258
+  if (target_auxv_search (current_top_target (), AT_ENTRY, &at_entry) <= 0)
689258
+    return;
689258
+
689258
+  build_id = build_id_addr_get (at_entry);
689258
+  if (build_id == NULL)
689258
+    return;
689258
+  back_to = make_cleanup (xfree, build_id);
689258
+
689258
+  /* SYMFILE_OBJFILE should refer to the main executable (not only to its
689258
+     separate debug info file).  gcc44+ keeps .eh_frame only in the main
689258
+     executable without its duplicate .debug_frame in the separate debug info
689258
+     file - such .eh_frame would not be found if SYMFILE_OBJFILE would refer
689258
+     directly to the separate debug info file.  */
689258
+
689258
+  execfilename = build_id_to_filename (build_id, &build_id_filename);
689258
+  make_cleanup (xfree, build_id_filename);
689258
+
689258
+  if (execfilename != NULL)
689258
+    {
689258
+      make_cleanup (xfree, execfilename);
689258
+      exec_file_attach (execfilename, from_tty);
689258
+      symbol_file_add_main (execfilename,
689258
+			    symfile_add_flag (!from_tty ? 0 : SYMFILE_VERBOSE));
689258
+      if (symfile_objfile != NULL)
689258
+        symfile_objfile->flags |= OBJF_BUILD_ID_CORE_LOADED;
689258
+    }
689258
+  else
689258
+    debug_print_missing (_("the main executable file"), build_id_filename);
689258
+
689258
+  do_cleanups (back_to);
689258
+
689258
+  /* No automatic SOLIB_ADD as the libraries would get read twice.  */
689258
+}
689258
+
689258
 /* Issue a message saying we have no core to debug, if FROM_TTY.  */
689258
 
689258
 static void
689258
@@ -464,6 +516,14 @@ core_target_open (const char *arg, int from_tty)
689258
 	switch_to_thread (thread);
689258
     }
689258
 
689258
+  /* Find the build_id identifiers.  If it gets executed after
689258
+     POST_CREATE_INFERIOR we would clash with asking to discard the already
689258
+     loaded VDSO symbols.  If it gets executed before bfd_map_over_sections
689258
+     INFERIOR_PTID is still not set and libthread_db initialization crashes on
689258
+     PID == 0 in ps_pglobal_lookup.  */
689258
+  if (build_id_core_loads != 0)
689258
+    build_id_locate_exec (from_tty);
689258
+
689258
   post_create_inferior (target, from_tty);
689258
 
689258
   /* Now go through the target stack looking for threads since there
689258
@@ -1072,4 +1132,11 @@ void
689258
 _initialize_corelow (void)
689258
 {
689258
   add_target (core_target_info, core_target_open, filename_completer);
689258
+
689258
+  add_setshow_boolean_cmd ("build-id-core-loads", class_files,
689258
+			   &build_id_core_loads, _("\
689258
+Set whether CORE-FILE loads the build-id associated files automatically."), _("\
689258
+Show whether CORE-FILE loads the build-id associated files automatically."),
689258
+			   NULL, NULL, NULL,
689258
+			   &setlist, &showlist);
689258
 }
689258
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
689258
--- a/gdb/doc/gdb.texinfo
689258
+++ b/gdb/doc/gdb.texinfo
689258
@@ -19570,6 +19570,27 @@ information files.
689258
 
689258
 @end table
689258
 
689258
+You can also adjust the current verbosity of the @dfn{build id} locating.
689258
+
689258
+@table @code
689258
+
689258
+@kindex set build-id-verbose
689258
+@item set build-id-verbose 0
689258
+No additional messages are printed.
689258
+
689258
+@item set build-id-verbose 1
689258
+Missing separate debug filenames are printed.
689258
+
689258
+@item set build-id-verbose 2
689258
+Missing separate debug filenames are printed and also all the parsing of the
689258
+binaries to find their @dfn{build id} content is printed.
689258
+
689258
+@kindex show build-id-verbose
689258
+@item show build-id-verbose
689258
+Show the current verbosity value for the @dfn{build id} content locating.
689258
+
689258
+@end table
689258
+
689258
 @cindex @code{.gnu_debuglink} sections
689258
 @cindex debug link sections
689258
 A debug link is a special section of the executable file named
689258
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
689258
--- a/gdb/dwarf2read.c
689258
+++ b/gdb/dwarf2read.c
689258
@@ -2683,7 +2683,7 @@ dwarf2_get_dwz_file (struct dwarf2_per_objfile *dwarf2_per_objfile)
689258
     }
689258
 
689258
   if (dwz_bfd == NULL)
689258
-    dwz_bfd = build_id_to_debug_bfd (buildid_len, buildid);
689258
+    dwz_bfd = build_id_to_debug_bfd (buildid_len, buildid, NULL, 1);
689258
 
689258
   if (dwz_bfd == NULL)
689258
     error (_("could not find '.gnu_debugaltlink' file for %s"),
689258
diff --git a/gdb/elfread.c b/gdb/elfread.c
689258
--- a/gdb/elfread.c
689258
+++ b/gdb/elfread.c
689258
@@ -1290,7 +1290,9 @@ elf_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags)
689258
 	   && objfile->separate_debug_objfile == NULL
689258
 	   && objfile->separate_debug_objfile_backlink == NULL)
689258
     {
689258
-      std::string debugfile = find_separate_debug_file_by_buildid (objfile);
689258
+      gdb::unique_xmalloc_ptr<char> build_id_filename;
689258
+      std::string debugfile
689258
+	= find_separate_debug_file_by_buildid (objfile, &build_id_filename);
689258
 
689258
       if (debugfile.empty ())
689258
 	debugfile = find_separate_debug_file_by_debuglink (objfile);
689258
@@ -1302,6 +1304,10 @@ elf_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags)
689258
 	  symbol_file_add_separate (abfd.get (), debugfile.c_str (),
689258
 				    symfile_flags, objfile);
689258
 	}
689258
+      /* Check if any separate debug info has been extracted out.  */
689258
+      else if (bfd_get_section_by_name (objfile->obfd, ".gnu_debuglink")
689258
+	       != NULL)
689258
+	debug_print_missing (objfile_name (objfile), build_id_filename.get ());
689258
     }
689258
 }
689258
 
689258
diff --git a/gdb/objfiles.h b/gdb/objfiles.h
689258
--- a/gdb/objfiles.h
689258
+++ b/gdb/objfiles.h
689258
@@ -470,6 +470,10 @@ struct objfile
689258
   htab_t static_links {};
689258
 };
689258
 
689258
+/* This file was loaded according to the BUILD_ID_CORE_LOADS rules.  */
689258
+
689258
+#define OBJF_BUILD_ID_CORE_LOADED static_cast<enum objfile_flag>(1 << 12)
689258
+
689258
 /* Declarations for functions defined in objfiles.c */
689258
 
689258
 extern struct gdbarch *get_objfile_arch (const struct objfile *);
689258
diff --git a/gdb/python/py-objfile.c b/gdb/python/py-objfile.c
689258
--- a/gdb/python/py-objfile.c
689258
+++ b/gdb/python/py-objfile.c
689258
@@ -137,7 +137,7 @@ objfpy_get_build_id (PyObject *self, void *closure)
689258
 
689258
   TRY
689258
     {
689258
-      build_id = build_id_bfd_get (objfile->obfd);
689258
+      build_id = build_id_bfd_shdr_get (objfile->obfd);
689258
     }
689258
   CATCH (except, RETURN_MASK_ALL)
689258
     {
689258
@@ -544,7 +544,7 @@ objfpy_lookup_objfile_by_build_id (const char *build_id)
689258
       /* Don't return separate debug files.  */
689258
       if (objfile->separate_debug_objfile_backlink != NULL)
689258
 	continue;
689258
-      obfd_build_id = build_id_bfd_get (objfile->obfd);
689258
+      obfd_build_id = build_id_bfd_shdr_get (objfile->obfd);
689258
       if (obfd_build_id == NULL)
689258
 	continue;
689258
       if (objfpy_build_id_matches (obfd_build_id, build_id))
689258
diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
689258
--- a/gdb/solib-svr4.c
689258
+++ b/gdb/solib-svr4.c
689258
@@ -45,6 +45,7 @@
689258
 #include "auxv.h"
689258
 #include "gdb_bfd.h"
689258
 #include "probe.h"
689258
+#include "build-id.h"
689258
 
689258
 static struct link_map_offsets *svr4_fetch_link_map_offsets (void);
689258
 static int svr4_have_link_map_offsets (void);
689258
@@ -1356,9 +1357,51 @@ svr4_read_so_list (CORE_ADDR lm, CORE_ADDR prev_lm,
689258
 	  continue;
689258
 	}
689258
 
689258
-      strncpy (newobj->so_name, buffer.get (), SO_NAME_MAX_PATH_SIZE - 1);
689258
-      newobj->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
689258
-      strcpy (newobj->so_original_name, newobj->so_name);
689258
+      {
689258
+	struct bfd_build_id *build_id;
689258
+
689258
+	strncpy (newobj->so_original_name, buffer.get (), SO_NAME_MAX_PATH_SIZE - 1);
689258
+	newobj->so_original_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
689258
+	/* May get overwritten below.  */
689258
+	strcpy (newobj->so_name, newobj->so_original_name);
689258
+
689258
+	build_id = build_id_addr_get (((lm_info_svr4 *) newobj->lm_info)->l_ld);
689258
+	if (build_id != NULL)
689258
+	  {
689258
+	    char *name, *build_id_filename;
689258
+
689258
+	    /* Missing the build-id matching separate debug info file
689258
+	       would be handled while SO_NAME gets loaded.  */
689258
+	    name = build_id_to_filename (build_id, &build_id_filename);
689258
+	    if (name != NULL)
689258
+	      {
689258
+		strncpy (newobj->so_name, name, SO_NAME_MAX_PATH_SIZE - 1);
689258
+		newobj->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
689258
+		xfree (name);
689258
+	      }
689258
+	    else
689258
+	      {
689258
+		debug_print_missing (newobj->so_name, build_id_filename);
689258
+
689258
+		/* In the case the main executable was found according to
689258
+		   its build-id (from a core file) prevent loading
689258
+		   a different build of a library with accidentally the
689258
+		   same SO_NAME.
689258
+
689258
+		   It suppresses bogus backtraces (and prints "??" there
689258
+		   instead) if the on-disk files no longer match the
689258
+		   running program version.  */
689258
+
689258
+		if (symfile_objfile != NULL
689258
+		    && (symfile_objfile->flags
689258
+			& OBJF_BUILD_ID_CORE_LOADED) != 0)
689258
+		  newobj->so_name[0] = 0;
689258
+	      }
689258
+
689258
+	    xfree (build_id_filename);
689258
+	    xfree (build_id);
689258
+	  }
689258
+      }
689258
 
689258
       /* If this entry has no name, or its name matches the name
689258
 	 for the main executable, don't include it in the list.  */
689258
diff --git a/gdb/symfile.h b/gdb/symfile.h
689258
--- a/gdb/symfile.h
689258
+++ b/gdb/symfile.h
689258
@@ -537,6 +537,10 @@ void expand_symtabs_matching
689258
 void map_symbol_filenames (symbol_filename_ftype *fun, void *data,
689258
 			   int need_fullname);
689258
 
689258
+/* build-id support.  */
689258
+extern struct bfd_build_id *build_id_addr_get (CORE_ADDR addr);
689258
+extern void debug_print_missing (const char *binary, const char *debug);
689258
+
689258
 /* From dwarf2read.c */
689258
 
689258
 /* Names for a dwarf2 debugging section.  The field NORMAL is the normal
689258
diff --git a/gdb/testsuite/gdb.base/corefile.exp b/gdb/testsuite/gdb.base/corefile.exp
689258
--- a/gdb/testsuite/gdb.base/corefile.exp
689258
+++ b/gdb/testsuite/gdb.base/corefile.exp
689258
@@ -311,3 +311,33 @@ gdb_test_multiple "core-file $corefile" $test {
689258
 	pass $test
689258
     }
689258
 }
689258
+
689258
+
689258
+# Test auto-loading of binary files through build-id from the core file.
689258
+set buildid [build_id_debug_filename_get $binfile]
689258
+set wholetest "binfile found by build-id"
689258
+if {$buildid == ""} {
689258
+    untested "$wholetest (binary has no build-id)"
689258
+} else {
689258
+    gdb_exit
689258
+    gdb_start
689258
+
689258
+    regsub {\.debug$} $buildid {} buildid
689258
+    set debugdir [standard_output_file ${testfile}-debugdir]
689258
+    file delete -force -- $debugdir
689258
+    file mkdir $debugdir/[file dirname $buildid]
689258
+    file copy $binfile $debugdir/$buildid
689258
+
689258
+    set test "show debug-file-directory"
689258
+    gdb_test_multiple $test $test {
689258
+	-re "The directory where separate debug symbols are searched for is \"(.*)\"\\.\r\n$gdb_prompt $" {
689258
+	    set debugdir_orig $expect_out(1,string)
689258
+	    pass $test
689258
+	}
689258
+    }
689258
+    gdb_test_no_output "set debug-file-directory $debugdir:$debugdir_orig" "set debug-file-directory"
689258
+    gdb_test "show build-id-core-loads" {Whether CORE-FILE loads the build-id associated files automatically is on\.}
689258
+    gdb_test "core-file $corefile" "\r\nProgram terminated with .*" "core-file without executable"
689258
+    gdb_test "info files" "Local exec file:\r\n\[ \t\]*`[string_to_regexp $debugdir/$buildid]', file type .*"
689258
+    pass $wholetest
689258
+}
689258
diff --git a/gdb/testsuite/gdb.base/new-ui-pending-input.exp b/gdb/testsuite/gdb.base/new-ui-pending-input.exp
689258
--- a/gdb/testsuite/gdb.base/new-ui-pending-input.exp
689258
+++ b/gdb/testsuite/gdb.base/new-ui-pending-input.exp
689258
@@ -62,6 +62,7 @@ proc test_command_line_new_ui_pending_input {} {
689258
     set options ""
689258
     append options " -iex \"set height 0\""
689258
     append options " -iex \"set width 0\""
689258
+    append options " -iex \"set build-id-verbose 0\""
689258
     append options " -iex \"new-ui console $extra_tty_name\""
689258
     append options " -ex \"b $bpline\""
689258
     append options " -ex \"run\""
689258
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
689258
--- a/gdb/testsuite/lib/gdb.exp
689258
+++ b/gdb/testsuite/lib/gdb.exp
689258
@@ -1695,6 +1695,16 @@ proc default_gdb_start { } {
689258
 	    warning "Couldn't set the width to 0."
689258
 	}
689258
     }
689258
+    # Turn off the missing warnings as the testsuite does not expect it.
689258
+    send_gdb "set build-id-verbose 0\n"
689258
+    gdb_expect 10 {
689258
+	-re "$gdb_prompt $" {
689258
+	    verbose "Disabled the missing debug infos warnings." 2
689258
+	}
689258
+	timeout {
689258
+	    warning "Could not disable the missing debug infos warnings.."
689258
+	}
689258
+    }
689258
     return 0
689258
 }
689258
 
689258
diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
689258
--- a/gdb/testsuite/lib/mi-support.exp
689258
+++ b/gdb/testsuite/lib/mi-support.exp
689258
@@ -309,6 +309,16 @@ proc default_mi_gdb_start { args } {
689258
 	    warning "Couldn't set the width to 0."
689258
 	}
689258
     }
689258
+    # Turn off the missing warnings as the testsuite does not expect it.
689258
+    send_gdb "190-gdb-set build-id-verbose 0\n"
689258
+    gdb_expect 10 {
689258
+	-re ".*190-gdb-set build-id-verbose 0\r\n190\\\^done\r\n$mi_gdb_prompt$" {
689258
+	    verbose "Disabled the missing debug infos warnings." 2
689258
+	}
689258
+	timeout {
689258
+	    warning "Could not disable the missing debug infos warnings.."
689258
+	}
689258
+    }
689258
 
689258
     if { $separate_inferior_pty } {
689258
 	mi_create_inferior_pty