gdb/frv-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux running on the Fujitsu FR-V,
   2    for GDB.
   3    Copyright 2004 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "target.h"
  24 #include "frame.h"
  25 #include "osabi.h"
  26 #include "elf-bfd.h"
  27 #include "elf/frv.h"
  28 #include "frv-tdep.h"
  29 #include "trad-frame.h"
  30 #include "frame-unwind.h"
  31
  32 /* Define the size (in bytes) of an FR-V instruction.  */
  33 static const int frv_instr_size = 4;
  34
  35 enum {
  36   NORMAL_SIGTRAMP = 1,
  37   RT_SIGTRAMP = 2
  38 };
  39
  40 static int
  41 frv_linux_pc_in_sigtramp (CORE_ADDR pc, char *name)
  42 {
  43   char buf[frv_instr_size];
  44   LONGEST instr;
  45   int retval = 0;
  46
  47   if (target_read_memory (pc, buf, sizeof buf) != 0)
  48     return 0;
  49
  50   instr = extract_unsigned_integer (buf, sizeof buf);
  51
  52   if (instr == 0x8efc0077)      /* setlos #__NR_sigreturn, gr7 */
  53     retval = NORMAL_SIGTRAMP;
  54   else if (instr -= 0x8efc00ad) /* setlos #__NR_rt_sigreturn, gr7 */
  55     retval = RT_SIGTRAMP;
  56   else
  57     return 0;
  58
  59   if (target_read_memory (pc + frv_instr_size, buf, sizeof buf) != 0)
  60     return 0;
  61   instr = extract_unsigned_integer (buf, sizeof buf);
  62   if (instr != 0xc0700000)      /* tira gr0, 0 */
  63     return 0;
  64
  65   /* If we get this far, we'll return a non-zero value, either
  66      NORMAL_SIGTRAMP (1) or RT_SIGTRAMP (2).  */
  67   return retval;
  68 }
  69
  70 /* Given NEXT_FRAME, the "callee" frame of the sigtramp frame that we
  71    wish to decode, and REGNO, one of the frv register numbers defined
  72    in frv-tdep.h, return the address of the saved register (corresponding
  73    to REGNO) in the sigtramp frame.  Return -1 if the register is not
  74    found in the sigtramp frame.  The magic numbers in the code below
  75    were computed by examining the following kernel structs:
  76
  77    From arch/frv/kernel/signal.c:
  78
  79       struct sigframe
  80       {
  81               void (*pretcode)(void);
  82               int sig;
  83               struct sigcontext sc;
  84               unsigned long extramask[_NSIG_WORDS-1];
  85               uint32_t retcode[2];
  86       };
  87
  88       struct rt_sigframe
  89       {
  90               void (*pretcode)(void);
  91               int sig;
  92               struct siginfo *pinfo;
  93               void *puc;
  94               struct siginfo info;
  95               struct ucontext uc;
  96               uint32_t retcode[2];
  97       };
  98
  99    From include/asm-frv/ucontext.h:
 100
 101       struct ucontext {
 102               unsigned long             uc_flags;
 103               struct ucontext           *uc_link;
 104               stack_t                   uc_stack;
 105               struct sigcontext uc_mcontext;
 106               sigset_t          uc_sigmask;
 107       };
 108
 109    From include/asm-frv/signal.h:
 110
 111       typedef struct sigaltstack {
 112               void *ss_sp;
 113               int ss_flags;
 114               size_t ss_size;
 115       } stack_t;
 116
 117    From include/asm-frv/sigcontext.h:
 118
 119       struct sigcontext {
 120               struct user_context       sc_context;
 121               unsigned long             sc_oldmask;
 122       } __attribute__((aligned(8)));
 123
 124    From include/asm-frv/registers.h:
 125       struct user_int_regs
 126       {
 127               unsigned long             psr;
 128               unsigned long             isr;
 129               unsigned long             ccr;
 130               unsigned long             cccr;
 131               unsigned long             lr;
 132               unsigned long             lcr;
 133               unsigned long             pc;
 134               unsigned long             __status;
 135               unsigned long             syscallno;
 136               unsigned long             orig_gr8;
 137               unsigned long             gner[2];
 138               unsigned long long        iacc[1];
 139
 140               union {
 141                       unsigned long     tbr;
 142                       unsigned long     gr[64];
 143               };
 144       };
 145
 146       struct user_fpmedia_regs
 147       {
 148               unsigned long     fr[64];
 149               unsigned long     fner[2];
 150               unsigned long     msr[2];
 151               unsigned long     acc[8];
 152               unsigned char     accg[8];
 153               unsigned long     fsr[1];
 154       };
 155
 156       struct user_context
 157       {
 158               struct user_int_regs              i;
 159               struct user_fpmedia_regs  f;
 160
 161               void *extension;
 162       } __attribute__((aligned(8)));  */
 163
 164 static LONGEST
 165 frv_linux_sigcontext_reg_addr (struct frame_info *next_frame, int regno,
 166                                CORE_ADDR *sc_addr_cache_ptr)
 167 {
 168   CORE_ADDR sc_addr;
 169
 170   if (sc_addr_cache_ptr && *sc_addr_cache_ptr)
 171     {
 172       sc_addr = *sc_addr_cache_ptr;
 173     }
 174   else
 175     {
 176       CORE_ADDR pc, sp;
 177       char buf[4];
 178       int tramp_type;
 179
 180       pc = frame_pc_unwind (next_frame);
 181       tramp_type = frv_linux_pc_in_sigtramp (pc, 0);
 182
 183       frame_unwind_register (next_frame, sp_regnum, buf);
 184       sp = extract_unsigned_integer (buf, sizeof buf);
 185
 186       if (tramp_type == NORMAL_SIGTRAMP)
 187         {
 188           /* For a normal sigtramp frame, the sigcontext struct starts
 189              at SP + 8.  */
 190           sc_addr = sp + 8;
 191         }
 192       else if (tramp_type == RT_SIGTRAMP)
 193         {
 194           /* For a realtime sigtramp frame, SP + 12 contains a pointer
 195              to a ucontext struct.  The ucontext struct contains a
 196              sigcontext struct starting 24 bytes in.  (The offset of
 197              uc_mcontext within struct ucontext is derived as follows:
 198              stack_t is a 12-byte struct and struct sigcontext is
 199              8-byte aligned.  This gives an offset of 8 + 12 + 4 (for
 200              padding) = 24.) */
 201           if (target_read_memory (sp + 12, buf, sizeof buf) != 0)
 202             {
 203               warning (_("Can't read realtime sigtramp frame."));
 204               return 0;
 205             }
 206           sc_addr = extract_unsigned_integer (buf, sizeof buf);
 207           sc_addr += 24;
 208         }
 209       else
 210         internal_error (__FILE__, __LINE__, _("not a signal trampoline"));
 211
 212       if (sc_addr_cache_ptr)
 213         *sc_addr_cache_ptr = sc_addr;
 214     }
 215
 216   switch (regno)
 217     {
 218     case psr_regnum :
 219       return sc_addr + 0;
 220     /* sc_addr + 4 has "isr", the Integer Status Register.  */
 221     case ccr_regnum :
 222       return sc_addr + 8;
 223     case cccr_regnum :
 224       return sc_addr + 12;
 225     case lr_regnum :
 226       return sc_addr + 16;
 227     case lcr_regnum :
 228       return sc_addr + 20;
 229     case pc_regnum :
 230       return sc_addr + 24;
 231     /* sc_addr + 28 is __status, the exception status.
 232        sc_addr + 32 is syscallno, the syscall number or -1.
 233        sc_addr + 36 is orig_gr8, the original syscall arg #1.
 234        sc_addr + 40 is gner[0].
 235        sc_addr + 44 is gner[1]. */
 236     case iacc0h_regnum :
 237       return sc_addr + 48;
 238     case iacc0l_regnum :
 239       return sc_addr + 52;
 240     default :
 241       if (first_gpr_regnum <= regno && regno <= last_gpr_regnum)
 242         return sc_addr + 56 + 4 * (regno - first_gpr_regnum);
 243       else if (first_fpr_regnum <= regno && regno <= last_fpr_regnum)
 244         return sc_addr + 312 + 4 * (regno - first_fpr_regnum);
 245       else
 246         return -1;  /* not saved. */
 247     }
 248 }
 249
 250 /* Signal trampolines.  */
 251
 252 static struct trad_frame_cache *
 253 frv_linux_sigtramp_frame_cache (struct frame_info *next_frame, void **this_cache)
 254 {
 255   struct trad_frame_cache *cache;
 256   struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
 257   CORE_ADDR addr;
 258   char buf[4];
 259   int regnum;
 260   CORE_ADDR sc_addr_cache_val = 0;
 261   struct frame_id this_id;
 262
 263   if (*this_cache)
 264     return *this_cache;
 265
 266   cache = trad_frame_cache_zalloc (next_frame);
 267
 268   /* FIXME: cagney/2004-05-01: This is is long standing broken code.
 269      The frame ID's code address should be the start-address of the
 270      signal trampoline and not the current PC within that
 271      trampoline.  */
 272   frame_unwind_register (next_frame, sp_regnum, buf);
 273   this_id = frame_id_build (extract_unsigned_integer (buf, sizeof buf),
 274                             frame_pc_unwind (next_frame));
 275   trad_frame_set_id (cache, this_id);
 276
 277   for (regnum = 0; regnum < frv_num_regs; regnum++)
 278     {
 279       LONGEST reg_addr = frv_linux_sigcontext_reg_addr (next_frame, regnum,
 280                                                         &sc_addr_cache_val);
 281       if (reg_addr != -1)
 282         trad_frame_set_reg_addr (cache, regnum, reg_addr);
 283     }
 284
 285   *this_cache = cache;
 286   return cache;
 287 }
 288
 289 static void
 290 frv_linux_sigtramp_frame_this_id (struct frame_info *next_frame, void **this_cache,
 291                              struct frame_id *this_id)
 292 {
 293   struct trad_frame_cache *cache =
 294     frv_linux_sigtramp_frame_cache (next_frame, this_cache);
 295   trad_frame_get_id (cache, this_id);
 296 }
 297
 298 static void
 299 frv_linux_sigtramp_frame_prev_register (struct frame_info *next_frame,
 300                                    void **this_cache,
 301                                    int regnum, int *optimizedp,
 302                                    enum lval_type *lvalp, CORE_ADDR *addrp,
 303                                    int *realnump, void *valuep)
 304 {
 305   /* Make sure we've initialized the cache.  */
 306   struct trad_frame_cache *cache =
 307     frv_linux_sigtramp_frame_cache (next_frame, this_cache);
 308   trad_frame_get_register (cache, next_frame, regnum, optimizedp, lvalp,
 309                            addrp, realnump, valuep);
 310 }
 311
 312 static const struct frame_unwind frv_linux_sigtramp_frame_unwind =
 313 {
 314   SIGTRAMP_FRAME,
 315   frv_linux_sigtramp_frame_this_id,
 316   frv_linux_sigtramp_frame_prev_register
 317 };
 318
 319 static const struct frame_unwind *
 320 frv_linux_sigtramp_frame_sniffer (struct frame_info *next_frame)
 321 {
 322   CORE_ADDR pc = frame_pc_unwind (next_frame);
 323   char *name;
 324
 325   find_pc_partial_function (pc, &name, NULL, NULL);
 326   if (frv_linux_pc_in_sigtramp (pc, name))
 327     return &frv_linux_sigtramp_frame_unwind;
 328
 329   return NULL;
 330 }
 331
 332 static void
 333 frv_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 334 {
 335   /* Set the sigtramp frame sniffer.  */
 336   frame_unwind_append_sniffer (gdbarch, frv_linux_sigtramp_frame_sniffer);
 337 }
 338
 339 static enum gdb_osabi
 340 frv_linux_elf_osabi_sniffer (bfd *abfd)
 341 {
 342   int elf_flags;
 343
 344   elf_flags = elf_elfheader (abfd)->e_flags;
 345
 346   /* Assume GNU/Linux if using the FDPIC ABI.  If/when another OS shows
 347      up that uses this ABI, we'll need to start using .note sections
 348      or some such.  */
 349   if (elf_flags & EF_FRV_FDPIC)
 350     return GDB_OSABI_LINUX;
 351   else
 352     return GDB_OSABI_UNKNOWN;
 353 }
 354
 355 /* Provide a prototype to silence -Wmissing-prototypes.  */
 356 void _initialize_frv_linux_tdep (void);
 357
 358 void
 359 _initialize_frv_linux_tdep (void)
 360 {
 361   gdbarch_register_osabi (bfd_arch_frv, 0, GDB_OSABI_LINUX, frv_linux_init_abi);
 362   gdbarch_register_osabi_sniffer (bfd_arch_frv,
 363                                   bfd_target_elf_flavour,
 364                                   frv_linux_elf_osabi_sniffer);
 365 }