gdb/mips-irix-tdep.c

   1 /* Target-dependent code for the MIPS architecture running on IRIX,
   2    for GDB, the GNU Debugger.
   3
   4    Copyright (C) 2002-2014 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 "osabi.h"
  23 #include "solib.h"
  24 #include "solib-irix.h"
  25 #include "elf-bfd.h"
  26 #include "mips-tdep.h"
  27 #include "trad-frame.h"
  28 #include "tramp-frame.h"
  29
  30 static void
  31 mips_irix_elf_osabi_sniff_abi_tag_sections (bfd *abfd, asection *sect,
  32                                             void *obj)
  33 {
  34   enum gdb_osabi *os_ident_ptr = obj;
  35   const char *name;
  36   unsigned int sectsize;
  37
  38   name = bfd_get_section_name (abfd, sect);
  39   sectsize = bfd_section_size (abfd, sect);
  40
  41   if (strncmp (name, ".MIPS.", 6) == 0 && sectsize > 0)
  42     {
  43       /* The presence of a section named with a ".MIPS." prefix is
  44          indicative of an IRIX binary.  */
  45       *os_ident_ptr = GDB_OSABI_IRIX;
  46     }
  47 }
  48
  49 static enum gdb_osabi
  50 mips_irix_elf_osabi_sniffer (bfd *abfd)
  51 {
  52   unsigned int elfosabi;
  53   enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
  54
  55   /* If the generic sniffer gets a hit, return and let other sniffers
  56      get a crack at it.  */
  57   bfd_map_over_sections (abfd,
  58                          generic_elf_osabi_sniff_abi_tag_sections,
  59                          &osabi);
  60   if (osabi != GDB_OSABI_UNKNOWN)
  61     return GDB_OSABI_UNKNOWN;
  62
  63   elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
  64
  65   if (elfosabi == ELFOSABI_NONE)
  66     {
  67       /* When elfosabi is ELFOSABI_NONE (0), then the ELF structures in the
  68          file are conforming to the base specification for that machine
  69          (there are no OS-specific extensions).  In order to determine the
  70          real OS in use we must look for OS notes that have been added.
  71
  72          For IRIX, we simply look for sections named with .MIPS. as
  73          prefixes.  */
  74       bfd_map_over_sections (abfd,
  75                              mips_irix_elf_osabi_sniff_abi_tag_sections,
  76                              &osabi);
  77     }
  78   return osabi;
  79 }
  80
  81 /* Unwinding past the signal handler on mips-irix.
  82
  83    Note: The following has only been tested with N32, but can probably
  84          be made to work with a small number of adjustments.
  85
  86    On mips-irix, the sigcontext_t structure is stored at the base
  87    of the frame established by the _sigtramp function.  The definition
  88    of this structure can be found in <sys/signal.h> (comments have been
  89    C++'ified to avoid a collision with the C-style comment delimiters
  90    used by this comment):
  91
  92       typedef struct sigcontext {
  93         __uint32_t      sc_regmask;     // regs to restore in sigcleanup
  94         __uint32_t      sc_status;      // cp0 status register
  95         __uint64_t      sc_pc;          // pc at time of signal
  96         // General purpose registers
  97         __uint64_t      sc_regs[32];    // processor regs 0 to 31
  98         // Floating point coprocessor state
  99         __uint64_t      sc_fpregs[32];  // fp regs 0 to 31
 100         __uint32_t      sc_ownedfp;     // fp has been used
 101         __uint32_t      sc_fpc_csr;     // fpu control and status reg
 102         __uint32_t      sc_fpc_eir;     // fpu exception instruction reg
 103                                         // implementation/revision
 104         __uint32_t      sc_ssflags;     // signal stack state to restore
 105         __uint64_t      sc_mdhi;        // Multiplier hi and low regs
 106         __uint64_t      sc_mdlo;
 107         // System coprocessor registers at time of signal
 108         __uint64_t      sc_cause;       // cp0 cause register
 109         __uint64_t      sc_badvaddr;    // cp0 bad virtual address
 110         __uint64_t      sc_triggersave; // state of graphics trigger (SGI)
 111         sigset_t        sc_sigset;      // signal mask to restore
 112         __uint64_t      sc_fp_rounded_result;   // for Ieee 754 support
 113         __uint64_t      sc_pad[31];
 114       } sigcontext_t;
 115
 116    The following macros provide the offset of some of the fields
 117    used to retrieve the value of the registers before the signal
 118    was raised.  */
 119
 120 /* The size of the sigtramp frame.  The sigtramp frame base can then
 121    be computed by adding this size to the SP.  */
 122 #define SIGTRAMP_FRAME_SIZE 48
 123 /* The offset in sigcontext_t where the PC is saved.  */
 124 #define SIGCONTEXT_PC_OFF 8
 125 /* The offset in sigcontext_t where the GP registers are saved.  */
 126 #define SIGCONTEXT_REGS_OFF (SIGCONTEXT_PC_OFF + 8)
 127 /* The offset in sigcontext_t where the FP regsiters are saved.  */
 128 #define SIGCONTEXT_FPREGS_OFF (SIGCONTEXT_REGS_OFF + 32 * 8)
 129 /* The offset in sigcontext_t where the FP CSR register is saved.  */
 130 #define SIGCONTEXT_FPCSR_OFF (SIGCONTEXT_FPREGS_OFF + 32 * 8 + 4)
 131 /* The offset in sigcontext_t where the multiplier hi register is saved.  */
 132 #define SIGCONTEXT_HI_OFF (SIGCONTEXT_FPCSR_OFF + 2 * 4)
 133 /* The offset in sigcontext_t where the multiplier lo register is saved.  */
 134 #define SIGCONTEXT_LO_OFF (SIGCONTEXT_HI_OFF + 4)
 135
 136 /* Implement the "init" routine in struct tramp_frame for the N32 ABI
 137    on mips-irix.  */
 138 static void
 139 mips_irix_n32_tramp_frame_init (const struct tramp_frame *self,
 140                                 struct frame_info *this_frame,
 141                                 struct trad_frame_cache *this_cache,
 142                                 CORE_ADDR func)
 143 {
 144   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 145   const int num_regs = gdbarch_num_regs (gdbarch);
 146   int sp_cooked_regno = num_regs + MIPS_SP_REGNUM;
 147   const CORE_ADDR sp = get_frame_register_signed (this_frame, sp_cooked_regno);
 148   const CORE_ADDR sigcontext_base = sp + 48;
 149   const struct mips_regnum *regs = mips_regnum (gdbarch);
 150   int ireg;
 151
 152   trad_frame_set_reg_addr (this_cache, regs->pc + gdbarch_num_regs (gdbarch),
 153                            sigcontext_base + SIGCONTEXT_PC_OFF);
 154
 155   for (ireg = 1; ireg < 32; ireg++)
 156     trad_frame_set_reg_addr (this_cache, ireg + MIPS_ZERO_REGNUM + num_regs,
 157                              sigcontext_base + SIGCONTEXT_REGS_OFF + ireg * 8);
 158
 159   for (ireg = 0; ireg < 32; ireg++)
 160     trad_frame_set_reg_addr (this_cache, ireg + regs->fp0 + num_regs,
 161                              sigcontext_base + SIGCONTEXT_FPREGS_OFF
 162                                + ireg * 8);
 163
 164   trad_frame_set_reg_addr (this_cache, regs->fp_control_status + num_regs,
 165                            sigcontext_base + SIGCONTEXT_FPCSR_OFF);
 166
 167   trad_frame_set_reg_addr (this_cache, regs->hi + num_regs,
 168                            sigcontext_base + SIGCONTEXT_HI_OFF);
 169
 170   trad_frame_set_reg_addr (this_cache, regs->lo + num_regs,
 171                            sigcontext_base + SIGCONTEXT_LO_OFF);
 172
 173   trad_frame_set_id (this_cache, frame_id_build (sigcontext_base, func));
 174 }
 175
 176 /* The tramp_frame structure describing sigtramp frames on mips-irix N32.
 177
 178    Note that the list of instructions below is pretty much a pure dump
 179    of function _sigtramp on mips-irix.  A few instructions are actually
 180    not tested (mask set to 0), because a portion of these instructions
 181    contain an address which changes due to relocation.  We could use
 182    a smarter mask that checks the instrutction code alone, but given
 183    the number of instructions already being checked, this seemed
 184    unnecessary.  */
 185
 186 static const struct tramp_frame mips_irix_n32_tramp_frame =
 187 {
 188   SIGTRAMP_FRAME,
 189   4,
 190   {
 191    { 0x3c0c8000, -1 }, /*    lui     t0,0x8000 */
 192    { 0x27bdffd0, -1 }, /*    addiu   sp,sp,-48 */
 193    { 0x008c6024, -1 }, /*    and     t0,a0,t0 */
 194    { 0xffa40018, -1 }, /*    sd      a0,24(sp) */
 195    { 0x00000000,  0 }, /*    beqz    t0,0xfaefcb8 <_sigtramp+40> */
 196    { 0xffa60028, -1 }, /*    sd      a2,40(sp) */
 197    { 0x01806027, -1 }, /*    nor     t0,t0,zero */
 198    { 0xffa00020, -1 }, /*    sd      zero,32(sp) */
 199    { 0x00000000,  0 }, /*    b       0xfaefcbc <_sigtramp+44> */
 200    { 0x008c2024, -1 }, /*    and     a0,a0,t0 */
 201    { 0xffa60020, -1 }, /*    sd      a2,32(sp) */
 202    { 0x03e0c025, -1 }, /*    move    t8,ra */
 203    { 0x00000000,  0 }, /*    bal     0xfaefcc8 <_sigtramp+56> */
 204    { 0x00000000, -1 }, /*    nop */
 205    { 0x3c0c0007, -1 }, /*    lui     t0,0x7 */
 206    { 0x00e0c825, -1 }, /*    move    t9,a3 */
 207    { 0x658c80fc, -1 }, /*    daddiu  t0,t0,-32516 */
 208    { 0x019f602d, -1 }, /*    daddu   t0,t0,ra */
 209    { 0x0300f825, -1 }, /*    move    ra,t8 */
 210    { 0x8d8c9880, -1 }, /*    lw      t0,-26496(t0) */
 211    { 0x8d8c0000, -1 }, /*    lw      t0,0(t0) */
 212    { 0x8d8d0000, -1 }, /*    lw      t1,0(t0) */
 213    { 0xffac0008, -1 }, /*    sd      t0,8(sp) */
 214    { 0x0320f809, -1 }, /*    jalr    t9 */
 215    { 0xffad0010, -1 }, /*    sd      t1,16(sp) */
 216    { 0xdfad0010, -1 }, /*    ld      t1,16(sp) */
 217    { 0xdfac0008, -1 }, /*    ld      t0,8(sp) */
 218    { 0xad8d0000, -1 }, /*    sw      t1,0(t0) */
 219    { 0xdfa40020, -1 }, /*    ld      a0,32(sp) */
 220    { 0xdfa50028, -1 }, /*    ld      a1,40(sp) */
 221    { 0xdfa60018, -1 }, /*    ld      a2,24(sp) */
 222    { 0x24020440, -1 }, /*    li      v0,1088 */
 223    { 0x0000000c, -1 }, /*    syscall */
 224    { TRAMP_SENTINEL_INSN, -1 }
 225   },
 226   mips_irix_n32_tramp_frame_init
 227 };
 228
 229 /* Implement the "init" routine in struct tramp_frame for the stack-based
 230    trampolines used on mips-irix.  */
 231
 232 static void
 233 mips_irix_n32_stack_tramp_frame_init (const struct tramp_frame *self,
 234                                       struct frame_info *this_frame,
 235                                       struct trad_frame_cache *this_cache,
 236                                       CORE_ADDR func)
 237 {
 238   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 239   const int num_regs = gdbarch_num_regs (gdbarch);
 240   int sp_cooked_regno = num_regs + MIPS_SP_REGNUM;
 241   const CORE_ADDR sp = get_frame_register_signed (this_frame, sp_cooked_regno);
 242
 243   /* The previous frame's PC is stored in RA.  */
 244   trad_frame_set_reg_realreg (this_cache, gdbarch_pc_regnum (gdbarch),
 245                               num_regs + MIPS_RA_REGNUM);
 246
 247   trad_frame_set_id (this_cache, frame_id_build (sp, func));
 248 }
 249
 250 /* A tramp_frame structure describing the stack-based trampoline
 251    used on mips-irix.  These trampolines are created on the stack
 252    before being called.  */
 253
 254 static const struct tramp_frame mips_irix_n32_stack_tramp_frame =
 255 {
 256   SIGTRAMP_FRAME,
 257   4,
 258   {
 259    { 0x8f210000, 0xffff0000 },  /* lw     at, N(t9) */
 260    { 0x8f2f0000, 0xffff0000 },  /* lw     t3, M(t9) */
 261    { 0x00200008, 0xffffffff },  /* jr     at        */
 262    { 0x0020c82d, 0xffffffff },  /* move   t9, at    */
 263    { TRAMP_SENTINEL_INSN, -1 }
 264   },
 265   mips_irix_n32_stack_tramp_frame_init
 266 };
 267
 268 static void
 269 mips_irix_init_abi (struct gdbarch_info info,
 270                     struct gdbarch *gdbarch)
 271 {
 272   set_solib_ops (gdbarch, &irix_so_ops);
 273   tramp_frame_prepend_unwinder (gdbarch, &mips_irix_n32_stack_tramp_frame);
 274   tramp_frame_prepend_unwinder (gdbarch, &mips_irix_n32_tramp_frame);
 275 }
 276
 277 /* Provide a prototype to silence -Wmissing-prototypes.  */
 278 extern initialize_file_ftype _initialize_mips_irix_tdep;
 279
 280 void
 281 _initialize_mips_irix_tdep (void)
 282 {
 283   /* Register an ELF OS ABI sniffer for IRIX binaries.  */
 284   gdbarch_register_osabi_sniffer (bfd_arch_mips,
 285                                   bfd_target_elf_flavour,
 286                                   mips_irix_elf_osabi_sniffer);
 287
 288   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_IRIX,
 289                           mips_irix_init_abi);
 290 }