gdb/solib-spu.c

   1 /* Cell SPU GNU/Linux support -- shared library handling.
   2    Copyright (C) 2009, 2010 Free Software Foundation, Inc.
   3
   4    Contributed by Ulrich Weigand <uweigand@de.ibm.com>.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "gdbcore.h"
  23 #include "gdb_string.h"
  24 #include "gdb_assert.h"
  25 #include "gdb_stat.h"
  26 #include "arch-utils.h"
  27 #include "bfd.h"
  28 #include "symtab.h"
  29 #include "solib.h"
  30 #include "solib-svr4.h"
  31 #include "solist.h"
  32 #include "inferior.h"
  33 #include "objfiles.h"
  34 #include "observer.h"
  35 #include "breakpoint.h"
  36 #include "gdbthread.h"
  37
  38 #include "spu-tdep.h"
  39
  40 /* Highest SPE id (file handle) the inferior may have.  */
  41 #define MAX_SPE_FD 1024
  42
  43 /* Stand-alone SPE executable?  */
  44 #define spu_standalone_p() \
  45   (symfile_objfile && symfile_objfile->obfd \
  46    && bfd_get_arch (symfile_objfile->obfd) == bfd_arch_spu)
  47
  48
  49 /* Relocate main SPE executable.  */
  50 static void
  51 spu_relocate_main_executable (int spufs_fd)
  52 {
  53   struct section_offsets *new_offsets;
  54   int i;
  55
  56   if (symfile_objfile == NULL)
  57     return;
  58
  59   new_offsets = alloca (symfile_objfile->num_sections
  60                         * sizeof (struct section_offsets));
  61
  62   for (i = 0; i < symfile_objfile->num_sections; i++)
  63     new_offsets->offsets[i] = SPUADDR (spufs_fd, 0);
  64
  65   objfile_relocate (symfile_objfile, new_offsets);
  66 }
  67
  68 /* When running a stand-alone SPE executable, we may need to skip one more
  69    exec event on startup, to get past the binfmt_misc loader.  */
  70 static void
  71 spu_skip_standalone_loader (void)
  72 {
  73   if (target_has_execution && !current_inferior ()->attach_flag)
  74     {
  75       struct target_waitstatus ws;
  76
  77       /* Only some kernels report an extra SIGTRAP with the binfmt_misc
  78          loader; others do not.  In addition, if we have attached to an
  79          already running inferior instead of starting a new one, we will
  80          not see the extra SIGTRAP -- and we cannot readily distinguish
  81          the two cases, in particular with the extended-remote target.
  82
  83          Thus we issue a single-step here.  If no extra SIGTRAP was pending,
  84          this will step past the first instruction of the stand-alone SPE
  85          executable loader, but we don't care about that.  */
  86
  87       inferior_thread ()->in_infcall = 1;   /* Suppress MI messages.  */
  88
  89       target_resume (inferior_ptid, 1, TARGET_SIGNAL_0);
  90       target_wait (minus_one_ptid, &ws, 0);
  91       set_executing (minus_one_ptid, 0);
  92
  93       inferior_thread ()->in_infcall = 0;
  94     }
  95 }
  96
  97 /* Build a list of `struct so_list' objects describing the shared
  98    objects currently loaded in the inferior.  */
  99 static struct so_list *
 100 spu_current_sos (void)
 101 {
 102   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch);
 103   struct so_list *head;
 104   struct so_list **link_ptr;
 105
 106   char buf[MAX_SPE_FD * 4];
 107   int i, size;
 108
 109   /* First, retrieve the SVR4 shared library list.  */
 110   head = svr4_so_ops.current_sos ();
 111
 112   /* Append our libraries to the end of the list.  */
 113   for (link_ptr = &head; *link_ptr; link_ptr = &(*link_ptr)->next)
 114     ;
 115
 116   /* Determine list of SPU ids.  */
 117   size = target_read (&current_target, TARGET_OBJECT_SPU, NULL,
 118                       buf, 0, sizeof buf);
 119
 120   /* Do not add stand-alone SPE executable context as shared library,
 121      but relocate main SPE executable objfile.  */
 122   if (spu_standalone_p ())
 123     {
 124       if (size == 4)
 125         {
 126           int fd = extract_unsigned_integer (buf, 4, byte_order);
 127           spu_relocate_main_executable (fd);
 128
 129           /* Re-enable breakpoints after main SPU context was established;
 130              see also comments in spu_solib_create_inferior_hook.  */
 131           enable_breakpoints_after_startup ();
 132         }
 133
 134       return head;
 135     }
 136
 137   /* Create an so_list entry for each SPU id.  */
 138   for (i = 0; i < size; i += 4)
 139     {
 140       int fd = extract_unsigned_integer (buf + i, 4, byte_order);
 141       struct so_list *new;
 142
 143       unsigned long long addr;
 144       char annex[32], id[100];
 145       int len;
 146
 147       /* Read object ID.  There's a race window where the inferior may have
 148          already created the SPE context, but not installed the object-id
 149          yet.  Skip such entries; we'll be back for them later.  */
 150       xsnprintf (annex, sizeof annex, "%d/object-id", fd);
 151       len = target_read (&current_target, TARGET_OBJECT_SPU, annex,
 152                          id, 0, sizeof id);
 153       if (len <= 0 || len >= sizeof id)
 154         continue;
 155       id[len] = 0;
 156       if (sscanf (id, "0x%llx", &addr) != 1 || !addr)
 157         continue;
 158
 159       /* Allocate so_list structure.  */
 160       new = XZALLOC (struct so_list);
 161
 162       /* Encode FD and object ID in path name.  Choose the name so as not
 163          to conflict with any (normal) SVR4 library path name.  */
 164       xsnprintf (new->so_name, sizeof new->so_name, "@%s <%d>",
 165                  hex_string (addr), fd);
 166       strcpy (new->so_original_name, new->so_name);
 167
 168       *link_ptr = new;
 169       link_ptr = &new->next;
 170     }
 171
 172   return head;
 173 }
 174
 175 /* Free so_list information.  */
 176 static void
 177 spu_free_so (struct so_list *so)
 178 {
 179   if (so->so_original_name[0] != '@')
 180     svr4_so_ops.free_so (so);
 181 }
 182
 183 /* Relocate section addresses.  */
 184 static void
 185 spu_relocate_section_addresses (struct so_list *so,
 186                                 struct target_section *sec)
 187 {
 188   if (so->so_original_name[0] != '@')
 189     svr4_so_ops.relocate_section_addresses (so, sec);
 190   else
 191     {
 192       unsigned long long addr;
 193       int fd;
 194
 195       /* Set addr_low/high to just LS offset for display.  */
 196       if (so->addr_low == 0 && so->addr_high == 0
 197           && strcmp (sec->the_bfd_section->name, ".text") == 0)
 198         {
 199           so->addr_low = sec->addr;
 200           so->addr_high = sec->endaddr;
 201         }
 202
 203       /* Decode object ID.  */
 204       if (sscanf (so->so_original_name, "@0x%llx <%d>", &addr, &fd) != 2)
 205         internal_error (__FILE__, __LINE__, "bad object ID");
 206
 207       sec->addr = SPUADDR (fd, sec->addr);
 208       sec->endaddr = SPUADDR (fd, sec->endaddr);
 209     }
 210 }
 211
 212
 213 /* Inferior memory should contain an SPE executable image at location ADDR.
 214    Allocate a BFD representing that executable.  Return NULL on error.  */
 215
 216 static void *
 217 spu_bfd_iovec_open (bfd *nbfd, void *open_closure)
 218 {
 219   return open_closure;
 220 }
 221
 222 static int
 223 spu_bfd_iovec_close (bfd *nbfd, void *stream)
 224 {
 225   xfree (stream);
 226   return 1;
 227 }
 228
 229 static file_ptr
 230 spu_bfd_iovec_pread (bfd *abfd, void *stream, void *buf,
 231                      file_ptr nbytes, file_ptr offset)
 232 {
 233   CORE_ADDR addr = *(CORE_ADDR *)stream;
 234   int ret;
 235
 236   ret = target_read_memory (addr + offset, buf, nbytes);
 237   if (ret != 0)
 238     {
 239       bfd_set_error (bfd_error_invalid_operation);
 240       return -1;
 241     }
 242
 243   return nbytes;
 244 }
 245
 246 static int
 247 spu_bfd_iovec_stat (bfd *abfd, void *stream, struct stat *sb)
 248 {
 249   /* We don't have an easy way of finding the size of embedded spu
 250      images.  We could parse the in-memory ELF header and section
 251      table to find the extent of the last section but that seems
 252      pointless when the size is needed only for checks of other
 253      parsed values in dbxread.c.  */
 254   sb->st_size = INT_MAX;
 255   return 0;
 256 }
 257
 258 static bfd *
 259 spu_bfd_fopen (char *name, CORE_ADDR addr)
 260 {
 261   bfd *nbfd;
 262
 263   CORE_ADDR *open_closure = xmalloc (sizeof (CORE_ADDR));
 264   *open_closure = addr;
 265
 266   nbfd = bfd_openr_iovec (xstrdup (name), "elf32-spu",
 267                           spu_bfd_iovec_open, open_closure,
 268                           spu_bfd_iovec_pread, spu_bfd_iovec_close,
 269                           spu_bfd_iovec_stat);
 270   if (!nbfd)
 271     return NULL;
 272
 273   if (!bfd_check_format (nbfd, bfd_object))
 274     {
 275       bfd_close (nbfd);
 276       return NULL;
 277     }
 278
 279   return nbfd;
 280 }
 281
 282 /* Open shared library BFD.  */
 283 static bfd *
 284 spu_bfd_open (char *pathname)
 285 {
 286   char *original_name = strrchr (pathname, '@');
 287   bfd *abfd;
 288   asection *spu_name;
 289   unsigned long long addr;
 290   int fd;
 291
 292   /* Handle regular SVR4 libraries.  */
 293   if (!original_name)
 294     return svr4_so_ops.bfd_open (pathname);
 295
 296   /* Decode object ID.  */
 297   if (sscanf (original_name, "@0x%llx <%d>", &addr, &fd) != 2)
 298     internal_error (__FILE__, __LINE__, "bad object ID");
 299
 300   /* Open BFD representing SPE executable.  */
 301   abfd = spu_bfd_fopen (original_name, (CORE_ADDR) addr);
 302   if (!abfd)
 303     error (_("Cannot read SPE executable at %s"), original_name);
 304
 305   /* Retrieve SPU name note.  */
 306   spu_name = bfd_get_section_by_name (abfd, ".note.spu_name");
 307   if (spu_name)
 308     {
 309       int sect_size = bfd_section_size (abfd, spu_name);
 310       if (sect_size > 20)
 311         {
 312           char *buf = alloca (sect_size - 20 + strlen (original_name) + 1);
 313           bfd_get_section_contents (abfd, spu_name, buf, 20, sect_size - 20);
 314           buf[sect_size - 20] = '\0';
 315
 316           strcat (buf, original_name);
 317
 318           xfree ((char *)abfd->filename);
 319           abfd->filename = xstrdup (buf);
 320         }
 321     }
 322
 323   return abfd;
 324 }
 325
 326 /* Lookup global symbol in a SPE executable.  */
 327 static struct symbol *
 328 spu_lookup_lib_symbol (const struct objfile *objfile,
 329                        const char *name,
 330                        const domain_enum domain)
 331 {
 332   if (bfd_get_arch (objfile->obfd) == bfd_arch_spu)
 333     return lookup_global_symbol_from_objfile (objfile, name, domain);
 334
 335   if (svr4_so_ops.lookup_lib_global_symbol != NULL)
 336     return svr4_so_ops.lookup_lib_global_symbol (objfile, name, domain);
 337   return NULL;
 338 }
 339
 340 /* Enable shared library breakpoint.  */
 341 static int
 342 spu_enable_break (struct objfile *objfile)
 343 {
 344   struct minimal_symbol *spe_event_sym = NULL;
 345
 346   /* The libspe library will call __spe_context_update_event whenever any
 347      SPE context is allocated or destroyed.  */
 348   spe_event_sym = lookup_minimal_symbol ("__spe_context_update_event",
 349                                          NULL, objfile);
 350
 351   /* Place a solib_event breakpoint on the symbol.  */
 352   if (spe_event_sym)
 353     {
 354       CORE_ADDR addr = SYMBOL_VALUE_ADDRESS (spe_event_sym);
 355       addr = gdbarch_convert_from_func_ptr_addr (target_gdbarch, addr,
 356                                                  &current_target);
 357       create_solib_event_breakpoint (target_gdbarch, addr);
 358       return 1;
 359     }
 360
 361   return 0;
 362 }
 363
 364 /* Create inferior hook.  */
 365 static void
 366 spu_solib_create_inferior_hook (int from_tty)
 367 {
 368   /* Handle SPE stand-alone executables.  */
 369   if (spu_standalone_p ())
 370     {
 371       /* After an SPE stand-alone executable was loaded, we'll receive
 372          an additional trap due to the binfmt_misc handler.  Make sure
 373          to skip that trap.  */
 374       spu_skip_standalone_loader ();
 375
 376       /* If the user established breakpoints before starting the inferior, GDB
 377          would attempt to insert those now.  This would fail because the SPU
 378          context has not yet been created and the SPU executable has not yet
 379          been loaded.  To prevent such failures, we disable all user-created
 380          breakpoints now; they will be re-enabled in spu_current_sos once the
 381          main SPU context has been detected.  */
 382       disable_breakpoints_before_startup ();
 383
 384       /* A special case arises when re-starting an executable, because at
 385          this point it still resides at the relocated address range that was
 386          determined during its last execution.  We need to undo the relocation
 387          so that that multi-architecture target recognizes the stand-alone
 388          initialization special case.  */
 389       spu_relocate_main_executable (-1);
 390     }
 391
 392   /* Call SVR4 hook -- this will re-insert the SVR4 solib breakpoints.  */
 393   svr4_so_ops.solib_create_inferior_hook (from_tty);
 394
 395   /* If the inferior is statically linked against libspe, we need to install
 396      our own solib breakpoint right now.  Otherwise, it will be installed by
 397      the solib_loaded observer below as soon as libspe is loaded.  */
 398   spu_enable_break (NULL);
 399 }
 400
 401 /* Install SPE "shared library" handling.  This is called by -tdep code
 402    that wants to support SPU as a secondary architecture.  */
 403 void
 404 set_spu_solib_ops (struct gdbarch *gdbarch)
 405 {
 406   static struct target_so_ops spu_so_ops;
 407
 408   /* Initialize this lazily, to avoid an initialization order
 409      dependency on solib-svr4.c's _initialize routine.  */
 410   if (spu_so_ops.current_sos == NULL)
 411     {
 412       spu_so_ops = svr4_so_ops;
 413       spu_so_ops.solib_create_inferior_hook = spu_solib_create_inferior_hook;
 414       spu_so_ops.relocate_section_addresses = spu_relocate_section_addresses;
 415       spu_so_ops.free_so = spu_free_so;
 416       spu_so_ops.current_sos = spu_current_sos;
 417       spu_so_ops.bfd_open = spu_bfd_open;
 418       spu_so_ops.lookup_lib_global_symbol = spu_lookup_lib_symbol;
 419     }
 420
 421   set_solib_ops (gdbarch, &spu_so_ops);
 422 }
 423
 424 /* Observer for the solib_loaded event.  Used to install our breakpoint
 425    if libspe is a shared library.  */
 426 static void
 427 spu_solib_loaded (struct so_list *so)
 428 {
 429   if (strstr (so->so_original_name, "/libspe") != NULL)
 430     {
 431       solib_read_symbols (so, so->from_tty ? SYMFILE_VERBOSE : 0);
 432       spu_enable_break (so->objfile);
 433     }
 434 }
 435
 436 void
 437 _initialize_spu_solib (void)
 438 {
 439   observer_attach_solib_loaded (spu_solib_loaded);
 440 }
 441