gdb/frv-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux running on the Fujitsu FR-V,
   2    for GDB.
   3
   4    Copyright (C) 2004-2020 Free Software Foundation, Inc.
   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 "target.h"
  24 #include "frame.h"
  25 #include "osabi.h"
  26 #include "regcache.h"
  27 #include "elf-bfd.h"
  28 #include "elf/frv.h"
  29 #include "frv-tdep.h"
  30 #include "trad-frame.h"
  31 #include "frame-unwind.h"
  32 #include "regset.h"
  33 #include "linux-tdep.h"
  34 #include "gdbarch.h"
  35
  36 /* Define the size (in bytes) of an FR-V instruction.  */
  37 static const int frv_instr_size = 4;
  38
  39 enum {
  40   NORMAL_SIGTRAMP = 1,
  41   RT_SIGTRAMP = 2
  42 };
  43
  44 static int
  45 frv_linux_pc_in_sigtramp (struct gdbarch *gdbarch, CORE_ADDR pc,
  46                           const char *name)
  47 {
  48   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  49   gdb_byte buf[frv_instr_size];
  50   LONGEST instr;
  51   int retval = 0;
  52
  53   if (target_read_memory (pc, buf, sizeof buf) != 0)
  54     return 0;
  55
  56   instr = extract_unsigned_integer (buf, sizeof buf, byte_order);
  57
  58   if (instr == 0x8efc0077)      /* setlos #__NR_sigreturn, gr7 */
  59     retval = NORMAL_SIGTRAMP;
  60   else if (instr == 0x8efc00ad) /* setlos #__NR_rt_sigreturn, gr7 */
  61     retval = RT_SIGTRAMP;
  62   else
  63     return 0;
  64
  65   if (target_read_memory (pc + frv_instr_size, buf, sizeof buf) != 0)
  66     return 0;
  67   instr = extract_unsigned_integer (buf, sizeof buf, byte_order);
  68   if (instr != 0xc0700000)      /* tira gr0, 0 */
  69     return 0;
  70
  71   /* If we get this far, we'll return a non-zero value, either
  72      NORMAL_SIGTRAMP (1) or RT_SIGTRAMP (2).  */
  73   return retval;
  74 }
  75
  76 /* Given NEXT_FRAME, the "callee" frame of the sigtramp frame that we
  77    wish to decode, and REGNO, one of the frv register numbers defined
  78    in frv-tdep.h, return the address of the saved register (corresponding
  79    to REGNO) in the sigtramp frame.  Return -1 if the register is not
  80    found in the sigtramp frame.  The magic numbers in the code below
  81    were computed by examining the following kernel structs:
  82
  83    From arch/frv/kernel/signal.c:
  84
  85       struct sigframe
  86       {
  87               void (*pretcode)(void);
  88               int sig;
  89               struct sigcontext sc;
  90               unsigned long extramask[_NSIG_WORDS-1];
  91               uint32_t retcode[2];
  92       };
  93
  94       struct rt_sigframe
  95       {
  96               void (*pretcode)(void);
  97               int sig;
  98               struct siginfo *pinfo;
  99               void *puc;
 100               struct siginfo info;
 101               struct ucontext uc;
 102               uint32_t retcode[2];
 103       };
 104
 105    From include/asm-frv/ucontext.h:
 106
 107       struct ucontext {
 108               unsigned long             uc_flags;
 109               struct ucontext           *uc_link;
 110               stack_t                   uc_stack;
 111               struct sigcontext uc_mcontext;
 112               sigset_t          uc_sigmask;
 113       };
 114
 115    From include/asm-frv/signal.h:
 116
 117       typedef struct sigaltstack {
 118               void *ss_sp;
 119               int ss_flags;
 120               size_t ss_size;
 121       } stack_t;
 122
 123    From include/asm-frv/sigcontext.h:
 124
 125       struct sigcontext {
 126               struct user_context       sc_context;
 127               unsigned long             sc_oldmask;
 128       } __attribute__((aligned(8)));
 129
 130    From include/asm-frv/registers.h:
 131       struct user_int_regs
 132       {
 133               unsigned long             psr;
 134               unsigned long             isr;
 135               unsigned long             ccr;
 136               unsigned long             cccr;
 137               unsigned long             lr;
 138               unsigned long             lcr;
 139               unsigned long             pc;
 140               unsigned long             __status;
 141               unsigned long             syscallno;
 142               unsigned long             orig_gr8;
 143               unsigned long             gner[2];
 144               unsigned long long        iacc[1];
 145
 146               union {
 147                       unsigned long     tbr;
 148                       unsigned long     gr[64];
 149               };
 150       };
 151
 152       struct user_fpmedia_regs
 153       {
 154               unsigned long     fr[64];
 155               unsigned long     fner[2];
 156               unsigned long     msr[2];
 157               unsigned long     acc[8];
 158               unsigned char     accg[8];
 159               unsigned long     fsr[1];
 160       };
 161
 162       struct user_context
 163       {
 164               struct user_int_regs              i;
 165               struct user_fpmedia_regs  f;
 166
 167               void *extension;
 168       } __attribute__((aligned(8)));  */
 169
 170 static LONGEST
 171 frv_linux_sigcontext_reg_addr (struct frame_info *this_frame, int regno,
 172                                CORE_ADDR *sc_addr_cache_ptr)
 173 {
 174   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 175   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 176   CORE_ADDR sc_addr;
 177
 178   if (sc_addr_cache_ptr && *sc_addr_cache_ptr)
 179     {
 180       sc_addr = *sc_addr_cache_ptr;
 181     }
 182   else
 183     {
 184       CORE_ADDR pc, sp;
 185       gdb_byte buf[4];
 186       int tramp_type;
 187
 188       pc = get_frame_pc (this_frame);
 189       tramp_type = frv_linux_pc_in_sigtramp (gdbarch, pc, 0);
 190
 191       get_frame_register (this_frame, sp_regnum, buf);
 192       sp = extract_unsigned_integer (buf, sizeof buf, byte_order);
 193
 194       if (tramp_type == NORMAL_SIGTRAMP)
 195         {
 196           /* For a normal sigtramp frame, the sigcontext struct starts
 197              at SP + 8.  */
 198           sc_addr = sp + 8;
 199         }
 200       else if (tramp_type == RT_SIGTRAMP)
 201         {
 202           /* For a realtime sigtramp frame, SP + 12 contains a pointer
 203              to a ucontext struct.  The ucontext struct contains a
 204              sigcontext struct starting 24 bytes in.  (The offset of
 205              uc_mcontext within struct ucontext is derived as follows:
 206              stack_t is a 12-byte struct and struct sigcontext is
 207              8-byte aligned.  This gives an offset of 8 + 12 + 4 (for
 208              padding) = 24.)  */
 209           if (target_read_memory (sp + 12, buf, sizeof buf) != 0)
 210             {
 211               warning (_("Can't read realtime sigtramp frame."));
 212               return 0;
 213             }
 214           sc_addr = extract_unsigned_integer (buf, sizeof buf, byte_order);
 215           sc_addr += 24;
 216         }
 217       else
 218         internal_error (__FILE__, __LINE__, _("not a signal trampoline"));
 219
 220       if (sc_addr_cache_ptr)
 221         *sc_addr_cache_ptr = sc_addr;
 222     }
 223
 224   switch (regno)
 225     {
 226     case psr_regnum :
 227       return sc_addr + 0;
 228     /* sc_addr + 4 has "isr", the Integer Status Register.  */
 229     case ccr_regnum :
 230       return sc_addr + 8;
 231     case cccr_regnum :
 232       return sc_addr + 12;
 233     case lr_regnum :
 234       return sc_addr + 16;
 235     case lcr_regnum :
 236       return sc_addr + 20;
 237     case pc_regnum :
 238       return sc_addr + 24;
 239     /* sc_addr + 28 is __status, the exception status.
 240        sc_addr + 32 is syscallno, the syscall number or -1.
 241        sc_addr + 36 is orig_gr8, the original syscall arg #1.
 242        sc_addr + 40 is gner[0].
 243        sc_addr + 44 is gner[1].  */
 244     case iacc0h_regnum :
 245       return sc_addr + 48;
 246     case iacc0l_regnum :
 247       return sc_addr + 52;
 248     default :
 249       if (first_gpr_regnum <= regno && regno <= last_gpr_regnum)
 250         return sc_addr + 56 + 4 * (regno - first_gpr_regnum);
 251       else if (first_fpr_regnum <= regno && regno <= last_fpr_regnum)
 252         return sc_addr + 312 + 4 * (regno - first_fpr_regnum);
 253       else
 254         return -1;  /* not saved.  */
 255     }
 256 }
 257
 258 /* Signal trampolines.  */
 259
 260 static struct trad_frame_cache *
 261 frv_linux_sigtramp_frame_cache (struct frame_info *this_frame,
 262                                 void **this_cache)
 263 {
 264   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 265   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 266   struct trad_frame_cache *cache;
 267   CORE_ADDR addr;
 268   gdb_byte buf[4];
 269   int regnum;
 270   CORE_ADDR sc_addr_cache_val = 0;
 271   struct frame_id this_id;
 272
 273   if (*this_cache)
 274     return (struct trad_frame_cache *) *this_cache;
 275
 276   cache = trad_frame_cache_zalloc (this_frame);
 277
 278   /* FIXME: cagney/2004-05-01: This is is long standing broken code.
 279      The frame ID's code address should be the start-address of the
 280      signal trampoline and not the current PC within that
 281      trampoline.  */
 282   get_frame_register (this_frame, sp_regnum, buf);
 283   addr = extract_unsigned_integer (buf, sizeof buf, byte_order);
 284   this_id = frame_id_build (addr, get_frame_pc (this_frame));
 285   trad_frame_set_id (cache, this_id);
 286
 287   for (regnum = 0; regnum < frv_num_regs; regnum++)
 288     {
 289       LONGEST reg_addr = frv_linux_sigcontext_reg_addr (this_frame, regnum,
 290                                                         &sc_addr_cache_val);
 291       if (reg_addr != -1)
 292         trad_frame_set_reg_addr (cache, regnum, reg_addr);
 293     }
 294
 295   *this_cache = cache;
 296   return cache;
 297 }
 298
 299 static void
 300 frv_linux_sigtramp_frame_this_id (struct frame_info *this_frame,
 301                                   void **this_cache,
 302                                   struct frame_id *this_id)
 303 {
 304   struct trad_frame_cache *cache
 305     = frv_linux_sigtramp_frame_cache (this_frame, this_cache);
 306   trad_frame_get_id (cache, this_id);
 307 }
 308
 309 static struct value *
 310 frv_linux_sigtramp_frame_prev_register (struct frame_info *this_frame,
 311                                         void **this_cache, int regnum)
 312 {
 313   /* Make sure we've initialized the cache.  */
 314   struct trad_frame_cache *cache
 315     = frv_linux_sigtramp_frame_cache (this_frame, this_cache);
 316   return trad_frame_get_register (cache, this_frame, regnum);
 317 }
 318
 319 static int
 320 frv_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
 321                                   struct frame_info *this_frame,
 322                                   void **this_cache)
 323 {
 324   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 325   CORE_ADDR pc = get_frame_pc (this_frame);
 326   const char *name;
 327
 328   find_pc_partial_function (pc, &name, NULL, NULL);
 329   if (frv_linux_pc_in_sigtramp (gdbarch, pc, name))
 330     return 1;
 331
 332   return 0;
 333 }
 334
 335 static const struct frame_unwind frv_linux_sigtramp_frame_unwind =
 336 {
 337   SIGTRAMP_FRAME,
 338   default_frame_unwind_stop_reason,
 339   frv_linux_sigtramp_frame_this_id,
 340   frv_linux_sigtramp_frame_prev_register,
 341   NULL,
 342   frv_linux_sigtramp_frame_sniffer
 343 };
 344 \f
 345 /* The FRV kernel defines ELF_NGREG as 46.  We add 2 in order to include
 346    the loadmap addresses in the register set.  (See below for more info.)  */
 347 #define FRV_ELF_NGREG (46 + 2)
 348 typedef unsigned char frv_elf_greg_t[4];
 349 typedef struct { frv_elf_greg_t reg[FRV_ELF_NGREG]; } frv_elf_gregset_t;
 350
 351 typedef unsigned char frv_elf_fpreg_t[4];
 352 typedef struct
 353 {
 354   frv_elf_fpreg_t fr[64];
 355   frv_elf_fpreg_t fner[2];
 356   frv_elf_fpreg_t msr[2];
 357   frv_elf_fpreg_t acc[8];
 358   unsigned char accg[8];
 359   frv_elf_fpreg_t fsr[1];
 360 } frv_elf_fpregset_t;
 361
 362 /* Register maps.  */
 363
 364 static const struct regcache_map_entry frv_linux_gregmap[] =
 365   {
 366     { 1, psr_regnum, 4 },
 367     { 1, REGCACHE_MAP_SKIP, 4 }, /* isr */
 368     { 1, ccr_regnum, 4 },
 369     { 1, cccr_regnum, 4 },
 370     { 1, lr_regnum, 4 },
 371     { 1, lcr_regnum, 4 },
 372     { 1, pc_regnum, 4 },
 373     { 1, REGCACHE_MAP_SKIP, 4 }, /* __status */
 374     { 1, REGCACHE_MAP_SKIP, 4 }, /* syscallno */
 375     { 1, REGCACHE_MAP_SKIP, 4 }, /* orig_gr8 */
 376     { 1, gner0_regnum, 4 },
 377     { 1, gner1_regnum, 4 },
 378     { 1, REGCACHE_MAP_SKIP, 8 }, /* iacc0 */
 379     { 1, tbr_regnum, 4 },
 380     { 31, first_gpr_regnum + 1, 4 }, /* gr1 ... gr31 */
 381
 382     /* Technically, the loadmap addresses are not part of `pr_reg' as
 383        found in the elf_prstatus struct.  The fields which communicate
 384        the loadmap address appear (by design) immediately after
 385        `pr_reg' though, and the BFD function elf32_frv_grok_prstatus()
 386        has been implemented to include these fields in the register
 387        section that it extracts from the core file.  So, for our
 388        purposes, they may be viewed as registers.  */
 389
 390     { 1, fdpic_loadmap_exec_regnum, 4 },
 391     { 1, fdpic_loadmap_interp_regnum, 4 },
 392     { 0 }
 393   };
 394
 395 static const struct regcache_map_entry frv_linux_fpregmap[] =
 396   {
 397     { 64, first_fpr_regnum, 4 }, /* fr0 ... fr63 */
 398     { 1, fner0_regnum, 4 },
 399     { 1, fner1_regnum, 4 },
 400     { 1, msr0_regnum, 4 },
 401     { 1, msr1_regnum, 4 },
 402     { 8, acc0_regnum, 4 },      /* acc0 ... acc7 */
 403     { 1, accg0123_regnum, 4 },
 404     { 1, accg4567_regnum, 4 },
 405     { 1, fsr0_regnum, 4 },
 406     { 0 }
 407   };
 408
 409 /* Unpack an frv_elf_gregset_t into GDB's register cache.  */
 410
 411 static void
 412 frv_linux_supply_gregset (const struct regset *regset,
 413                           struct regcache *regcache,
 414                           int regnum, const void *gregs, size_t len)
 415 {
 416   int regi;
 417
 418   /* gr0 always contains 0.  Also, the kernel passes the TBR value in
 419      this slot.  */
 420   regcache->raw_supply_zeroed (first_gpr_regnum);
 421
 422   /* Fill gr32, ..., gr63 with zeros. */
 423   for (regi = first_gpr_regnum + 32; regi <= last_gpr_regnum; regi++)
 424     regcache->raw_supply_zeroed (regi);
 425
 426   regcache_supply_regset (regset, regcache, regnum, gregs, len);
 427 }
 428
 429 /* FRV Linux kernel register sets.  */
 430
 431 static const struct regset frv_linux_gregset =
 432 {
 433   frv_linux_gregmap,
 434   frv_linux_supply_gregset, regcache_collect_regset
 435 };
 436
 437 static const struct regset frv_linux_fpregset =
 438 {
 439   frv_linux_fpregmap,
 440   regcache_supply_regset, regcache_collect_regset
 441 };
 442
 443 static void
 444 frv_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
 445                                         iterate_over_regset_sections_cb *cb,
 446                                         void *cb_data,
 447                                         const struct regcache *regcache)
 448 {
 449   cb (".reg", sizeof (frv_elf_gregset_t), sizeof (frv_elf_gregset_t),
 450       &frv_linux_gregset, NULL, cb_data);
 451   cb (".reg2", sizeof (frv_elf_fpregset_t), sizeof (frv_elf_fpregset_t),
 452       &frv_linux_fpregset, NULL, cb_data);
 453 }
 454
 455 \f
 456 static void
 457 frv_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 458 {
 459   linux_init_abi (info, gdbarch);
 460
 461   /* Set the sigtramp frame sniffer.  */
 462   frame_unwind_append_unwinder (gdbarch, &frv_linux_sigtramp_frame_unwind);
 463
 464   set_gdbarch_iterate_over_regset_sections
 465     (gdbarch, frv_linux_iterate_over_regset_sections);
 466 }
 467
 468 static enum gdb_osabi
 469 frv_linux_elf_osabi_sniffer (bfd *abfd)
 470 {
 471   int elf_flags;
 472
 473   elf_flags = elf_elfheader (abfd)->e_flags;
 474
 475   /* Assume GNU/Linux if using the FDPIC ABI.  If/when another OS shows
 476      up that uses this ABI, we'll need to start using .note sections
 477      or some such.  */
 478   if (elf_flags & EF_FRV_FDPIC)
 479     return GDB_OSABI_LINUX;
 480   else
 481     return GDB_OSABI_UNKNOWN;
 482 }
 483
 484 void
 485 _initialize_frv_linux_tdep (void)
 486 {
 487   gdbarch_register_osabi (bfd_arch_frv, 0, GDB_OSABI_LINUX,
 488                           frv_linux_init_abi);
 489   gdbarch_register_osabi_sniffer (bfd_arch_frv,
 490                                   bfd_target_elf_flavour,
 491                                   frv_linux_elf_osabi_sniffer);
 492 }