Re: [patch 1/2] build id

sami wagiaalla
2010-11-29T21:49:26Z

[-- Attachment #1: Type: text/plain, Size: 630 bytes --]

On 11/23/2010 02:11 PM, Eli Zaretskii wrote:
>> Date: Tue, 23 Nov 2010 11:27:36 -0500
>> From: sami wagiaalla<swagiaal@redhat.com>
>>
>> This patch comes from the Fedora rpm and supports the use of build id
>> for locating and loading core file executables, and printing information
>> about missing debug info files.
>
> Thanks.
>

Thanks for the review :) The attached patch combines the two patches as
Joel preferred and address the issues Eli brought up. Except for the
FIXME's. I could not figure out what was meant by the FIXME's so I have
asked Tromey and Jan for help. Or if anyone else is interested.

Patch Attached.

[-- Attachment #2: build-id-locate.patch --]
[-- Type: text/x-patch, Size: 35904 bytes --]

Use build id to locate debuginfo and executable files.

2010-11-22 Sami Wagiaalla <swagiaal@redhat.com>

* solib-svr4.c (svr4_current_sos): Use buildid to set soname.
* corelow.c (build_id_locate_exec): New function.
(core_open): Use build id to find executable file.
(_initialize_corelow): Add build-id-core-loads to show/set list.
* elfread.c (build_id_addr_get): New function.
(show_build_id_verbose): New funciton.
(build_id_buf_get): New function.
(build_id_phdr_get): New function.
(build_id_bfd_get): Rename this...
(build_id_bfd_shdr_get): ...to this.
(elf_file_p): New function.
(build_id_verify): Updated
(find_separate_debug_file_by_buildid): Update.
(H_GET_WORD): New.
(H_GET_SIGNED_WORD): New.
(build_id_to_debug_filename): Rename this to...
(build_id_to_filename): ... this.
Add and handel add_debug_suffix boolean.
(struct missing_filepair): New.
(missing_filepair_xcalloc): New.
(missing_filepair_hash_func): New.
(missing_filepair_eq): New.
(missing_filepair_changed): New.
(debug_print_executable_changed): New.
(debug_print_missing): New.
(find_separate_debug_file_by_buildid): Add parameter
'char **build_id_filename_return'
(_initialize_elfread): Add build-id-verbose to sho/set list.

2010-11-22 Sami Wagiaalla <swagiaal@redhat.com>

* gdb.texinfo: Document build-id-verbose.
Document build-id-core-loads.

2010-11-22 Sami Wagiaalla <swagiaal@redhat.com>

* lib/gdb.exp: Test set/show build-id-verbose.
* lib/mi-support.exp: Ditto.

diff --git a/gdb/corelow.c b/gdb/corelow.c
index e138ff2..c82dd13 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -47,6 +47,9 @@
#include "filenames.h"
#include "progspace.h"
#include "objfiles.h"
+#include "auxv.h"
+#include "elf/common.h"
+#include "gdbcmd.h"

#ifndef O_LARGEFILE
@@ -275,6 +278,57 @@ add_to_thread_list (bfd *abfd, asection *asect, void *reg_sect_arg)
inferior_ptid = ptid; /* Yes, make it current */
}

+/* Boolean which indicates whether files associated through build id
+ with the current core file should be loaded. */
+static int build_id_core_loads = 1;
+
+/* Using build_id of the current target find the corresponding executable file,
+ and set it as the current executable file. */
+
+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;
+ struct cleanup *back_to;
+
+ if (exec_bfd != NULL || symfile_objfile != 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;
+
+ /* SYMFILE_OBJFILE should refer to the main executable (not only to its
+ separate debug info file). gcc44+ keeps .eh_frame only in the main
+ executable without its duplicate .debug_frame in the separate debug info
+ file - such .eh_frame would not be found if SYMFILE_OBJFILE would refer
+ directly to the separate debug info file. */
+
+ exec_filename = build_id_to_filename (build_id, &build_id_filename, 0);
+ back_to = make_cleanup (xfree, build_id_filename);
+
+ if (exec_filename != NULL)
+ {
+ make_cleanup (xfree, exec_filename);
+ exec_file_attach (exec_filename, from_tty);
+ symbol_file_add_main (exec_filename, from_tty);
+ if (symfile_objfile != NULL)
+ symfile_objfile->flags |= OBJF_BUILD_ID_CORE_LOADED;
+ }
+ else
+ debug_print_missing (_("the main executable file"), build_id_filename);
+
+ do_cleanups (back_to);
+
+ /* No automatic SOLIB_ADD as the libraries would get read twice. */
+}
+
/* This routine opens and sets up the core file bfd. */

static void
@@ -372,6 +426,12 @@ core_open (char *filename, int from_tty)
push_target (&core_ops);
discard_cleanups (old_chain);

+ /* 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);
+
/* Do this before acknowledging the inferior, so if
post_create_inferior throws (can happen easilly if you're loading
a core file with the wrong exec), we aren't left with threads
@@ -913,4 +973,11 @@ _initialize_corelow (void)
init_core_ops ();

add_target (&core_ops);
+
+ add_setshow_boolean_cmd ("build-id-core-loads", class_files,
+ &build_id_core_loads, _("\
+Set whether CORE-FILE loads the build-id associated files automatically."), _("\
+Show whether CORE-FILE loads the build-id associated files automatically.."),
+ NULL, NULL, NULL,
+ &setlist, &showlist);
}
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index ddc711b..9c05e39 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -15237,6 +15237,48 @@ information files.

@end table

+You can also adjust the current verbosity of the @dfn{build id} locating.
+
+@table @code
+
+@kindex set build-id-verbose
+@item set build-id-verbose 0
+No additional messages are printed.
+
+@item set build-id-verbose 1
+Missing separate debug filenames are printed.
+
+@item set build-id-verbose 2
+Missing separate debug filenames are printed and also all the parsing of the
+binaries to find their @dfn{build id} content is printed.
+
+@kindex show build-id-verbose
+@item show build-id-verbose
+Show the current verbosity value for the @dfn{build id} content locating.
+
+@end table
+
+For corefiles the @dfn{build id} can be used to load the corresponding
+executable. This feature can be turned on or off through the following
+options:
+
+@table @code
+
+@kindex set build-id-core-loads on
+@item set build-id-core-loads on
+Automatically load files associated with a corefile's build id.
+
+@kindex set build-id-core-loads off
+@item set build-id-core-loads off
+Do not load files associated with a corefile's build id.
+
+@kindex show build-id-core-loads
+@item show build-id-core-loads
+Show whether @dfn{build id} will be used to load files asscociated with the
+corefile being inspected.
+
+@end table
+
@cindex @code{.gnu_debuglink} sections
@cindex debug link sections
A debug link is a special section of the executable file named
diff --git a/gdb/elfread.c b/gdb/elfread.c
index 270f93f..db217dd 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -37,6 +37,10 @@
#include "complaints.h"
#include "demangle.h"
#include "psympriv.h"
+#include "libbfd.h"
+#include "gdbcore.h"
+#include "gdbcmd.h"
+#include "observer.h"

extern void _initialize_elfread (void);

@@ -572,16 +576,68 @@ elf_symtab_read (struct objfile *objfile, int type,
}
}

+/* Locate NT_GNU_BUILD_ID and return its matching debug filename.
+ FIXME: NOTE decoding should be unified with the BFD core notes decoding. */
+
+#define BUILD_ID_VERBOSE_NONE 0
+#define BUILD_ID_VERBOSE_FILENAMES 1
+#define BUILD_ID_VERBOSE_BINARY_PARSE 2
+static int build_id_verbose = BUILD_ID_VERBOSE_FILENAMES;
+static void
+show_build_id_verbose (struct ui_file *file, int from_tty,
+ struct cmd_list_element *c, const char *value)
+{
+ fprintf_filtered (file, _("Verbosity level 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. */
+/* Scan the given buffer for NT_GNU_BUILD_ID return it its content if found
+ otherwise return NULL. */
+
+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;

@@ -597,6 +653,361 @@ build_id_bfd_get (bfd *abfd)
return retval;
}

+/* Starting at program header I_PHDR search each program header for
+ the one containing build-id. Return it if found otherwise return
+ NULL.
+ 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;
+}
+
+/* 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)))
+
+/* Translate an ELF header table entry in external format into an ELF header
+ table entry in internal format. */
+
+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
+
+/* Get an array of program file headers of TEMPL. Store the number of
+ headers in address pointed to by E_PHNUM_POINTER. */
+
+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_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
+ 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_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
+ 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_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
+ 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_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
+ 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_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
+ 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_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
+ 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_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
+ 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_verbose >= BUILD_ID_VERBOSE_BINARY_PARSE)
+ 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;
+
+/* Construct a list of candidate sections which can contain build-id. */
+
+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;
+ }
+}
+
+/* Find and return the build_id for the object file containing ADDR. */
+
+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
@@ -611,7 +1022,7 @@ build_id_verify (const char *filename, struct build_id *check)
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);
@@ -628,14 +1039,19 @@ build_id_verify (const char *filename, struct build_id *check)
return retval;
}

-static char *
-build_id_to_debug_filename (struct build_id *build_id)
+/* Return the file name of the debug info file or executable associated with
+ BUILD_ID. If ADD_DEBUG_SUFFIX is false do not append the .debug suffix. */
+
+char *
+build_id_to_filename (struct build_id *build_id, char **link_return,
+ int add_debug_suffix)
{
char *link, *debugdir, *retval = NULL;
+ char *link_all = NULL;

/* DEBUG_FILE_DIRECTORY/.build-id/ab/cdef */
- link = alloca (strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1
- + 2 * build_id->size + (sizeof ".debug" - 1) + 1);
+ link = xmalloc (strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1
+ + 2 * build_id->size + (sizeof ".debug" - 1) + 1);

/* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
cause "/.build-id/..." lookups. */
@@ -666,7 +1082,10 @@ build_id_to_debug_filename (struct build_id *build_id)
*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)
@@ -679,26 +1098,211 @@ build_id_to_debug_filename (struct build_id *build_id)
}

if (retval != NULL)
- break;
+ {
+ /* LINK_ALL is not used below in this non-NULL RETVAL case. */
+ break;
+ }
+
+ if (link_all == NULL)
+ link_all = xstrdup (link);
+ else
+ {
+ size_t len_orig = strlen (link_all);
+
+ link_all = xrealloc (link_all, len_orig + 1 + strlen (link) + 1);
+
+ /* Use whitespace instead of DIRNAME_SEPARATOR to be compatible with
+ its possible use as an argument for installation command. */
+ link_all[len_orig] = ' ';
+
+ strcpy (&link_all[len_orig + 1], link);
+ }

debugdir = debugdir_end;
}
while (*debugdir != 0);

+ if (link_return != NULL)
+ {
+ if (retval != NULL)
+ {
+ *link_return = link;
+ link = NULL;
+ }
+ else
+ {
+ *link_return = link_all;
+ link_all = NULL;
+ }
+ }
+ xfree (link);
+ xfree (link_all);
+
return retval;
}

+/* This MISSING_FILEPAIR_HASH tracker is used only for the duplicite messages
+ Try to install the hash file ...
+ avoidance. */
+
+struct missing_filepair
+ {
+ char *binary;
+ char *debug;
+ char data[1];
+ };
+
+static struct htab *missing_filepair_hash;
+static struct obstack missing_filepair_obstack;
+
+/* Allocate a missing_filepair entry. */
+
+static void *
+missing_filepair_xcalloc (size_t nmemb, size_t nmemb_size)
+{
+ void *retval;
+ size_t size = nmemb * nmemb_size;
+
+ retval = obstack_alloc (&missing_filepair_obstack, size);
+ memset (retval, 0, size);
+ return retval;
+}
+
+/* Hash function for missing_filepair. */
+
+static hashval_t
+missing_filepair_hash_func (const struct missing_filepair *elem)
+{
+ hashval_t retval = 0;
+
+ retval ^= htab_hash_string (elem->binary);
+ if (elem->debug != NULL)
+ retval ^= htab_hash_string (elem->debug);
+
+ return retval;
+}
+
+/* Comparison function for missing_filepair. */
+
+static int
+missing_filepair_eq (const struct missing_filepair *elem1,
+ const struct missing_filepair *elem2)
+{
+ return strcmp (elem1->binary, elem2->binary) == 0
+ && ((elem1->debug == NULL) == (elem2->debug == NULL))
+ && (elem1->debug == NULL || strcmp (elem1->debug, elem2->debug) == 0);
+}
+
+/* Free missing_filepair obstack. */
+
+static void
+missing_filepair_changed (void)
+{
+ if (missing_filepair_hash != NULL)
+ {
+ obstack_free (&missing_filepair_obstack, NULL);
+ /* All their memory came just from missing_filepair_OBSTACK. */
+ missing_filepair_hash = NULL;
+ }
+}
+
+static void
+debug_print_executable_changed (void)
+{
+ missing_filepair_changed ();
+}
+
+/* Notify user the file BINARY with (possibly NULL) associated separate debug
+ information file DEBUG is missing. DEBUG may or may not be the build-id
+ file such as would be:
+ /usr/lib/debug/.build-id/dd/b1d2ce632721c47bb9e8679f369e2295ce71be.debug
+ */
+
+void
+debug_print_missing (const char *binary, const char *debug)
+{
+ size_t binary_len0 = strlen (binary) + 1;
+ size_t debug_len0 = debug ? strlen (debug) + 1 : 0;
+ struct missing_filepair missing_filepair_find;
+ struct missing_filepair *missing_filepair;
+ struct missing_filepair **slot;
+
+ if (build_id_verbose < BUILD_ID_VERBOSE_FILENAMES)
+ return;
+
+ if (missing_filepair_hash == NULL)
+ {
+ obstack_init (&missing_filepair_obstack);
+ missing_filepair_hash = htab_create_alloc (64,
+ (hashval_t (*) (const void *)) missing_filepair_hash_func,
+ (int (*) (const void *, const void *)) missing_filepair_eq, NULL,
+ missing_filepair_xcalloc, NULL);
+ }
+
+ /* Use MISSING_FILEPAIR_FIND first instead of calling obstack_alloc with
+ obstack_free in the case of a (rare) match. The problem is ALLOC_F for
+ MISSING_FILEPAIR_HASH allocates from MISSING_FILEPAIR_OBSTACK maintenance
+ structures for MISSING_FILEPAIR_HASH. Calling obstack_free would possibly
+ not to free only MISSING_FILEPAIR but also some such structures (allocated
+ during the htab_find_slot call). */
+
+ missing_filepair_find.binary = (char *) binary;
+ missing_filepair_find.debug = (char *) debug;
+ slot = (struct missing_filepair **) htab_find_slot (missing_filepair_hash,
+ &missing_filepair_find,
+ INSERT);
+
+ /* While it may be still printed duplicitely with the missing debuginfo file
+ * it is due to once printing about the binary file build-id link and once
+ * about the .debug file build-id link as both the build-id symlinks are
+ * located in the debuginfo package. */
+
+ if (*slot != NULL)
+ return;
+
+ missing_filepair = obstack_alloc (&missing_filepair_obstack,
+ sizeof (*missing_filepair) - 1
+ + binary_len0 + debug_len0);
+ missing_filepair->binary = missing_filepair->data;
+ memcpy (missing_filepair->binary, binary, binary_len0);
+ if (debug != NULL)
+ {
+ missing_filepair->debug = missing_filepair->binary + binary_len0;
+ memcpy (missing_filepair->debug, debug, debug_len0);
+ }
+ else
+ missing_filepair->debug = NULL;
+
+ *slot = missing_filepair;
+
+ /* We do not collect and flush these messages as each such message
+ already requires its own separate lines. */
+
+ fprintf_unfiltered (gdb_stdlog,
+ _("Missing separate debuginfo for %s\n"), binary);
+ if (debug != NULL)
+ fprintf_unfiltered (gdb_stdlog, _("Try to install the hash file %s\n"),
+ debug);
+}
+
+/* Using the build id of OBJFILE find its separate debug info file. */
+
static char *
-find_separate_debug_file_by_buildid (struct objfile *objfile)
+find_separate_debug_file_by_buildid (struct objfile *objfile,
+ char **build_id_filename_return)
{
struct build_id *build_id;

- build_id = build_id_bfd_get (objfile->obfd);
+ if (build_id_filename_return)
+ *build_id_filename_return = NULL;
+
+ 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);
+ build_id_name = build_id_to_filename (build_id, build_id_filename_return,
+ 1);
xfree (build_id);
/* Prevent looping on a stripped .debug file. */
if (build_id_name != NULL && strcmp (build_id_name, objfile->name) == 0)
@@ -708,7 +1312,7 @@ find_separate_debug_file_by_buildid (struct objfile *objfile)
xfree (build_id_name);
}
else if (build_id_name != NULL)
- return build_id_name;
+ return build_id_name;
}
return NULL;
}
@@ -881,9 +1485,10 @@ elf_symfile_read (struct objfile *objfile, int symfile_flags)
`.gnu_debuglink' may no longer be present with `.note.gnu.build-id'. */
if (!objfile_has_partial_symbols (objfile))
{
- char *debugfile;
+ char *debugfile, *build_id_filename;

- debugfile = find_separate_debug_file_by_buildid (objfile);
+ debugfile = find_separate_debug_file_by_buildid (objfile,
+ &build_id_filename);

if (debugfile == NULL)
debugfile = find_separate_debug_file_by_debuglink (objfile);
@@ -895,6 +1500,12 @@ elf_symfile_read (struct objfile *objfile, int symfile_flags)
symbol_file_add_separate (abfd, symfile_flags, objfile);
xfree (debugfile);
}
+ /* Check if any separate debug info has been extracted out. */
+ else if (bfd_get_section_by_name (objfile->obfd, ".gnu_debuglink")
+ != NULL)
+ debug_print_missing (objfile->name, build_id_filename);
+
+ xfree (build_id_filename);
}
}

@@ -1070,4 +1681,16 @@ void
_initialize_elfread (void)
{
add_symtab_fns (&elf_sym_fns);
+
+ add_setshow_zinteger_cmd ("build-id-verbose", no_class, &build_id_verbose,
+ _("\
+Set debugging level of the build-id locator."), _("\
+Show debugging level of the build-id locator."), _("\
+Level 1 (default) enables printing the missing debug filenames,\n\
+level 2 also prints the parsing of binaries to find the identificators."),
+ NULL,
+ show_build_id_verbose,
+ &setlist, &showlist);
+
+ observer_attach_executable_changed (debug_print_executable_changed);
}
diff --git a/gdb/exec.c b/gdb/exec.c
index de0c459..1dfa253 100644
--- a/gdb/exec.c
+++ b/gdb/exec.c
@@ -177,15 +177,16 @@ exec_file_clear (int from_tty)
printf_unfiltered (_("No executable file now.\n"));
}

-/* Set FILENAME as the new exec file.
+/* Set FILENAME as the new exec file. Open and process the give
+ executable file.

- This function is intended to be behave essentially the same
+ This function is intended to behave essentially the same
as exec_file_command, except that the latter will detect when
a target is being debugged, and will ask the user whether it
should be shut down first. (If the answer is "no", then the
new file is ignored.)

- This file is used by exec_file_command, to do the work of opening
+ This function is used by exec_file_command, to do the work of opening
and processing the exec file after any prompting has happened.

And, it is used by child_attach, when the attach command was
diff --git a/gdb/objfiles.h b/gdb/objfiles.h
index 130ae26..f004ff1 100644
--- a/gdb/objfiles.h
+++ b/gdb/objfiles.h
@@ -432,6 +432,10 @@ struct objfile

#define OBJF_USERLOADED (1 << 3) /* User loaded */

+/* This file was loaded according to the BUILD_ID_CORE_LOADS rules. */
+
+#define OBJF_BUILD_ID_CORE_LOADED (1 << 12)
+
/* The object file that contains the runtime common minimal symbols
for SunOS4. Note that this objfile has no associated BFD. */

diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index db21360..df60943 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -1179,9 +1179,51 @@ svr4_current_sos (void)
safe_strerror (errcode));
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);
+ /* Set so_name using build_id. */
+
+ 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
+ {
+ debug_print_missing (new->so_name, build_id_filename);
+
+ /* In the case the main executable was found according to
+ its build-id (from a core file) prevent loading
+ a different build of a library with accidentally the
+ same SO_NAME.
+
+ It suppresses bogus backtraces (and prints "??" there
+ instead) if the on-disk files no longer match the
+ running program version. */
+
+ if (symfile_objfile != NULL
+ && (symfile_objfile->flags
+ & OBJF_BUILD_ID_CORE_LOADED) != 0)
+ new->so_name[0] = 0;
+ }
+
+ xfree (build_id_filename);
+ xfree (build_id);
+ }
}
xfree (buffer);

diff --git a/gdb/symfile.h b/gdb/symfile.h
index c9f4e65..0df6883 100644
--- a/gdb/symfile.h
+++ b/gdb/symfile.h
@@ -546,6 +546,13 @@ void free_symfile_segment_data (struct symfile_segment_data *data);

extern struct cleanup *increment_reading_symtab (void);

+/* 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);
+extern void debug_print_missing (const char *binary, const char *debug);
+
/* From dwarf2read.c */

extern int dwarf2_has_info (struct objfile *);
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 63e68d3..6ff682a 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -1349,6 +1349,16 @@ proc default_gdb_start { } {
warning "Couldn't set the width to 0."
}
}
+ # Turn off the missing warnings as the testsuite does not expect it.
+ send_gdb "set build-id-verbose 0\n"
+ gdb_expect 10 {
+ -re "$gdb_prompt $" {
+ verbose "Disabled the missing debug infos warnings." 2
+ }
+ timeout {
+ warning "Could not disable the missing debug infos warnings.."
+ }
+ }
return 0;
}

diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
index 5de3183..2c046f7 100644
--- a/gdb/testsuite/lib/mi-support.exp
+++ b/gdb/testsuite/lib/mi-support.exp
@@ -221,6 +221,16 @@ proc default_mi_gdb_start { args } {
}
}
}
+ # Turn off the missing warnings as the testsuite does not expect it.
+ send_gdb "190-gdb-set build-id-verbose 0\n"
+ gdb_expect 10 {
+ -re ".*190-gdb-set build-id-verbose 0\r\n190\\\^done\r\n$mi_gdb_prompt$" {
+ verbose "Disabled the missing debug infos warnings." 2
+ }
+ timeout {
+ warning "Could not disable the missing debug infos warnings.."
+ }
+ }

detect_async