gdb/vax-tdep.c - gdb

Global variables defined

Data types defined

Functions defined

Source code

  1. /* Target-dependent code for the VAX.

  3.    Copyright (C) 1986-2015 Free Software Foundation, Inc.

  5.    This file is part of GDB.

  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 3 of the License, or
  10.    (at your option) any later version.

  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.

  17.    You should have received a copy of the GNU General Public License
  18.    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

  20. #include "defs.h"
  21. #include "arch-utils.h"
  22. #include "dis-asm.h"
  23. #include "floatformat.h"
  24. #include "frame.h"
  25. #include "frame-base.h"
  26. #include "frame-unwind.h"
  27. #include "gdbcore.h"
  28. #include "gdbtypes.h"
  29. #include "osabi.h"
  30. #include "regcache.h"
  31. #include "regset.h"
  32. #include "trad-frame.h"
  33. #include "value.h"

  35. #include "vax-tdep.h"

  37. /* Return the name of register REGNUM.  */

  39. static const char *
  40. ‌vax_register_name (struct gdbarch *gdbarch, int regnum)
  41. {
  42.   static char *register_names[] =
  43.   {
  44.     "r0", "r1", "r2",  "r3",  "r4", "r5", "r6", "r7",
  45.     "r8", "r9", "r10", "r11", "ap", "fp", "sp", "pc",
  46.     "ps",
  47.   };

  49.   if (regnum >= 0 && regnum < ARRAY_SIZE (register_names))
  50.     return register_names[regnum];

  52.   return NULL;
  53. }

  55. /* Return the GDB type object for the "standard" data type of data in
  56.    register REGNUM.  */

  58. static struct type *
  59. ‌vax_register_type (struct gdbarch *gdbarch, int regnum)
  60. {
  61.   return builtin_type (gdbarch)->builtin_int;
  62. }

  64. /* Core file support.  */

  66. /* Supply register REGNUM from the buffer specified by GREGS and LEN
  67.    in the general-purpose register set REGSET to register cache
  68.    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */

  70. static void
  71. ‌vax_supply_gregset (const struct regset *regset, struct regcache *regcache,
  72.                     int regnum, const void *gregs, size_t len)
  73. {
  74.   const gdb_byte *regs = gregs;
  75.   int i;

  77.   for (i = 0; i < VAX_NUM_REGS; i++)
  78.     {
  79.       if (regnum == i || regnum == -1)
  80.         regcache_raw_supply (regcache, i, regs + i * 4);
  81.     }
  82. }

  84. /* VAX register set.  */

  86. ‌static const struct regset vax_gregset =
  87. {
  88.   NULL,
  89.   vax_supply_gregset
  90. };

  92. /* Iterate over core file register note sections.  */

  94. static void
  95. ‌vax_iterate_over_regset_sections (struct gdbarch *gdbarch,
  96.                                   iterate_over_regset_sections_cb *cb,
  97.                                   void *cb_data,
  98.                                   const struct regcache *regcache)
  99. {
  100.   cb (".reg", VAX_NUM_REGS * 4, &vax_gregset, NULL, cb_data);
  101. }

  103. /* The VAX UNIX calling convention uses R1 to pass a structure return
  104.    value address instead of passing it as a first (hidden) argument as
  105.    the VMS calling convention suggests.  */

  107. static CORE_ADDR
  108. ‌vax_store_arguments (struct regcache *regcache, int nargs,
  109.                      struct value **args, CORE_ADDR sp)
  110. {
  111.   struct gdbarch *gdbarch = get_regcache_arch (regcache);
  112.   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  113.   gdb_byte buf[4];
  114.   int count = 0;
  115.   int i;

  117.   /* We create an argument list on the stack, and make the argument
  118.      pointer to it.  */

  120.   /* Push arguments in reverse order.  */
  121.   for (i = nargs - 1; i >= 0; i--)
  122.     {
  123.       int len = TYPE_LENGTH (value_enclosing_type (args[i]));

  125.       sp -= (len + 3) & ~3;
  126.       count += (len + 3) / 4;
  127.       write_memory (sp, value_contents_all (args[i]), len);
  128.     }

  130.   /* Push argument count.  */
  131.   sp -= 4;
  132.   store_unsigned_integer (buf, 4, byte_order, count);
  133.   write_memory (sp, buf, 4);

  135.   /* Update the argument pointer.  */
  136.   store_unsigned_integer (buf, 4, byte_order, sp);
  137.   regcache_cooked_write (regcache, VAX_AP_REGNUM, buf);

  139.   return sp;
  140. }

  142. static CORE_ADDR
  143. ‌vax_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
  144.                      struct regcache *regcache, CORE_ADDR bp_addr, int nargs,
  145.                      struct value **args, CORE_ADDR sp, int struct_return,
  146.                      CORE_ADDR struct_addr)
  147. {
  148.   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  149.   CORE_ADDR fp = sp;
  150.   gdb_byte buf[4];

  152.   /* Set up the function arguments.  */
  153.   sp = vax_store_arguments (regcache, nargs, args, sp);

  155.   /* Store return value address.  */
  156.   if (struct_return)
  157.     regcache_cooked_write_unsigned (regcache, VAX_R1_REGNUM, struct_addr);

  159.   /* Store return address in the PC slot.  */
  160.   sp -= 4;
  161.   store_unsigned_integer (buf, 4, byte_order, bp_addr);
  162.   write_memory (sp, buf, 4);

  164.   /* Store the (fake) frame pointer in the FP slot.  */
  165.   sp -= 4;
  166.   store_unsigned_integer (buf, 4, byte_order, fp);
  167.   write_memory (sp, buf, 4);

  169.   /* Skip the AP slot.  */
  170.   sp -= 4;

  172.   /* Store register save mask and control bits.  */
  173.   sp -= 4;
  174.   store_unsigned_integer (buf, 4, byte_order, 0);
  175.   write_memory (sp, buf, 4);

  177.   /* Store condition handler.  */
  178.   sp -= 4;
  179.   store_unsigned_integer (buf, 4, byte_order, 0);
  180.   write_memory (sp, buf, 4);

  182.   /* Update the stack pointer and frame pointer.  */
  183.   store_unsigned_integer (buf, 4, byte_order, sp);
  184.   regcache_cooked_write (regcache, VAX_SP_REGNUM, buf);
  185.   regcache_cooked_write (regcache, VAX_FP_REGNUM, buf);

  187.   /* Return the saved (fake) frame pointer.  */
  188.   return fp;
  189. }

  191. static struct frame_id
  192. ‌vax_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
  193. {
  194.   CORE_ADDR fp;

  196.   fp = get_frame_register_unsigned (this_frame, VAX_FP_REGNUM);
  197.   return frame_id_build (fp, get_frame_pc (this_frame));
  198. }


  201. static enum return_value_convention
  202. ‌vax_return_value (struct gdbarch *gdbarch, struct value *function,
  203.                   struct type *type, struct regcache *regcache,
  204.                   gdb_byte *readbuf, const gdb_byte *writebuf)
  205. {
  206.   int len = TYPE_LENGTH (type);
  207.   gdb_byte buf[8];

  209.   if (TYPE_CODE (type) == TYPE_CODE_STRUCT
  210.       || TYPE_CODE (type) == TYPE_CODE_UNION
  211.       || TYPE_CODE (type) == TYPE_CODE_ARRAY)
  212.     {
  213.       /* The default on VAX is to return structures in static memory.
  214.          Consequently a function must return the address where we can
  215.          find the return value.  */

  217.       if (readbuf)
  218.         {
  219.           ULONGEST addr;

  221.           regcache_raw_read_unsigned (regcache, VAX_R0_REGNUM, &addr);
  222.           read_memory (addr, readbuf, len);
  223.         }

  225.       return RETURN_VALUE_ABI_RETURNS_ADDRESS;
  226.     }

  228.   if (readbuf)
  229.     {
  230.       /* Read the contents of R0 and (if necessary) R1.  */
  231.       regcache_cooked_read (regcache, VAX_R0_REGNUM, buf);
  232.       if (len > 4)
  233.         regcache_cooked_read (regcache, VAX_R1_REGNUM, buf + 4);
  234.       memcpy (readbuf, buf, len);
  235.     }
  236.   if (writebuf)
  237.     {
  238.       /* Read the contents to R0 and (if necessary) R1.  */
  239.       memcpy (buf, writebuf, len);
  240.       regcache_cooked_write (regcache, VAX_R0_REGNUM, buf);
  241.       if (len > 4)
  242.         regcache_cooked_write (regcache, VAX_R1_REGNUM, buf + 4);
  243.     }

  245.   return RETURN_VALUE_REGISTER_CONVENTION;
  246. }


  249. /* Use the program counter to determine the contents and size of a
  250.    breakpoint instruction.  Return a pointer to a string of bytes that
  251.    encode a breakpoint instruction, store the length of the string in
  252.    *LEN and optionally adjust *PC to point to the correct memory
  253.    location for inserting the breakpoint.  */

  255. static const gdb_byte *
  256. ‌vax_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pc, int *len)
  257. {
  258.   static gdb_byte break_insn[] = { 3 };

  260.   *len = sizeof (break_insn);
  261.   return break_insn;
  262. }

  264. /* Advance PC across any function entry prologue instructions
  265.    to reach some "real" code.  */

  267. static CORE_ADDR
  268. ‌vax_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
  269. {
  270.   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  271.   gdb_byte op = read_memory_unsigned_integer (pc, 1, byte_order);

  273.   if (op == 0x11)
  274.     pc += 2;                        /* skip brb */
  275.   if (op == 0x31)
  276.     pc += 3;                        /* skip brw */
  277.   if (op == 0xC2
  278.       && read_memory_unsigned_integer (pc + 2, 1, byte_order) == 0x5E)
  279.     pc += 3;                        /* skip subl2 */
  280.   if (op == 0x9E
  281.       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xAE
  282.       && read_memory_unsigned_integer (pc + 3, 1, byte_order) == 0x5E)
  283.     pc += 4;                        /* skip movab */
  284.   if (op == 0x9E
  285.       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xCE
  286.       && read_memory_unsigned_integer (pc + 4, 1, byte_order) == 0x5E)
  287.     pc += 5;                        /* skip movab */
  288.   if (op == 0x9E
  289.       && read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xEE
  290.       && read_memory_unsigned_integer (pc + 6, 1, byte_order) == 0x5E)
  291.     pc += 7;                        /* skip movab */

  293.   return pc;
  294. }


  297. /* Unwinding the stack is relatively easy since the VAX has a
  298.    dedicated frame pointer, and frames are set up automatically as the
  299.    result of a function call.  Most of the relevant information can be
  300.    inferred from the documentation of the Procedure Call Instructions
  301.    in the VAX MACRO and Instruction Set Reference Manual.  */

  303. ‌struct vax_frame_cache
  304. {
  305.   /* Base address.  */
  306.   CORE_ADDR base;

  308.   /* Table of saved registers.  */
  309.   struct trad_frame_saved_reg *saved_regs;
  310. };

  312. static struct vax_frame_cache *
  313. ‌vax_frame_cache (struct frame_info *this_frame, void **this_cache)
  314. {
  315.   struct vax_frame_cache *cache;
  316.   CORE_ADDR addr;
  317.   ULONGEST mask;
  318.   int regnum;

  320.   if (*this_cache)
  321.     return *this_cache;

  323.   /* Allocate a new cache.  */
  324.   cache = FRAME_OBSTACK_ZALLOC (struct vax_frame_cache);
  325.   cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);

  327.   /* The frame pointer is used as the base for the frame.  */
  328.   cache->base = get_frame_register_unsigned (this_frame, VAX_FP_REGNUM);
  329.   if (cache->base == 0)
  330.     return cache;

  332.   /* The register save mask and control bits determine the layout of
  333.      the stack frame.  */
  334.   mask = get_frame_memory_unsigned (this_frame, cache->base + 4, 4) >> 16;

  336.   /* These are always saved.  */
  337.   cache->saved_regs[VAX_PC_REGNUM].addr = cache->base + 16;
  338.   cache->saved_regs[VAX_FP_REGNUM].addr = cache->base + 12;
  339.   cache->saved_regs[VAX_AP_REGNUM].addr = cache->base + 8;
  340.   cache->saved_regs[VAX_PS_REGNUM].addr = cache->base + 4;

  342.   /* Scan the register save mask and record the location of the saved
  343.      registers.  */
  344.   addr = cache->base + 20;
  345.   for (regnum = 0; regnum < VAX_AP_REGNUM; regnum++)
  346.     {
  347.       if (mask & (1 << regnum))
  348.         {
  349.           cache->saved_regs[regnum].addr = addr;
  350.           addr += 4;
  351.         }
  352.     }

  354.   /* The CALLS/CALLG flag determines whether this frame has a General
  355.      Argument List or a Stack Argument List.  */
  356.   if (mask & (1 << 13))
  357.     {
  358.       ULONGEST numarg;

  360.       /* This is a procedure with Stack Argument List.  Adjust the
  361.          stack address for the arguments that were pushed onto the
  362.          stack.  The return instruction will automatically pop the
  363.          arguments from the stack.  */
  364.       numarg = get_frame_memory_unsigned (this_frame, addr, 1);
  365.       addr += 4 + numarg * 4;
  366.     }

  368.   /* Bits 1:0 of the stack pointer were saved in the control bits.  */
  369.   trad_frame_set_value (cache->saved_regs, VAX_SP_REGNUM, addr + (mask >> 14));

  371.   return cache;
  372. }

  374. static void
  375. ‌vax_frame_this_id (struct frame_info *this_frame, void **this_cache,
  376.                    struct frame_id *this_id)
  377. {
  378.   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);

  380.   /* This marks the outermost frame.  */
  381.   if (cache->base == 0)
  382.     return;

  384.   (*this_id) = frame_id_build (cache->base, get_frame_func (this_frame));
  385. }

  387. static struct value *
  388. ‌vax_frame_prev_register (struct frame_info *this_frame,
  389.                          void **this_cache, int regnum)
  390. {
  391.   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);

  393.   return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
  394. }

  396. ‌static const struct frame_unwind vax_frame_unwind =
  397. {
  398.   NORMAL_FRAME,
  399.   default_frame_unwind_stop_reason,
  400.   vax_frame_this_id,
  401.   vax_frame_prev_register,
  402.   NULL,
  403.   default_frame_sniffer
  404. };


  407. static CORE_ADDR
  408. ‌vax_frame_base_address (struct frame_info *this_frame, void **this_cache)
  409. {
  410.   struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);

  412.   return cache->base;
  413. }

  415. static CORE_ADDR
  416. ‌vax_frame_args_address (struct frame_info *this_frame, void **this_cache)
  417. {
  418.   return get_frame_register_unsigned (this_frame, VAX_AP_REGNUM);
  419. }

  421. ‌static const struct frame_base vax_frame_base =
  422. {
  423.   &vax_frame_unwind,
  424.   vax_frame_base_address,
  425.   vax_frame_base_address,
  426.   vax_frame_args_address
  427. };

  429. /* Return number of arguments for FRAME.  */

  431. static int
  432. ‌vax_frame_num_args (struct frame_info *frame)
  433. {
  434.   CORE_ADDR args;

  436.   /* Assume that the argument pointer for the outermost frame is
  437.      hosed, as is the case on NetBSD/vax ELF.  */
  438.   if (get_frame_base_address (frame) == 0)
  439.     return 0;

  441.   args = get_frame_register_unsigned (frame, VAX_AP_REGNUM);
  442.   return get_frame_memory_unsigned (frame, args, 1);
  443. }

  445. static CORE_ADDR
  446. ‌vax_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
  447. {
  448.   return frame_unwind_register_unsigned (next_frame, VAX_PC_REGNUM);
  449. }


  452. /* Initialize the current architecture based on INFO.  If possible, re-use an
  453.    architecture from ARCHES, which is a list of architectures already created
  454.    during this debugging session.

  456.    Called e.g. at program startup, when reading a core file, and when reading
  457.    a binary file.  */

  459. static struct gdbarch *
  460. ‌vax_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
  461. {
  462.   struct gdbarch *gdbarch;

  464.   /* If there is already a candidate, use it.  */
  465.   arches = gdbarch_list_lookup_by_info (arches, &info);
  466.   if (arches != NULL)
  467.     return arches->gdbarch;

  469.   gdbarch = gdbarch_alloc (&info, NULL);

  471.   set_gdbarch_float_format (gdbarch, floatformats_vax_f);
  472.   set_gdbarch_double_format (gdbarch, floatformats_vax_d);
  473.   set_gdbarch_long_double_format (gdbarch, floatformats_vax_d);
  474.   set_gdbarch_long_double_bit (gdbarch, 64);

  476.   /* Register info */
  477.   set_gdbarch_num_regs (gdbarch, VAX_NUM_REGS);
  478.   set_gdbarch_register_name (gdbarch, vax_register_name);
  479.   set_gdbarch_register_type (gdbarch, vax_register_type);
  480.   set_gdbarch_sp_regnum (gdbarch, VAX_SP_REGNUM);
  481.   set_gdbarch_pc_regnum (gdbarch, VAX_PC_REGNUM);
  482.   set_gdbarch_ps_regnum (gdbarch, VAX_PS_REGNUM);

  484.   set_gdbarch_iterate_over_regset_sections
  485.     (gdbarch, vax_iterate_over_regset_sections);

  487.   /* Frame and stack info */
  488.   set_gdbarch_skip_prologue (gdbarch, vax_skip_prologue);
  489.   set_gdbarch_frame_num_args (gdbarch, vax_frame_num_args);
  490.   set_gdbarch_frame_args_skip (gdbarch, 4);

  492.   /* Stack grows downward.  */
  493.   set_gdbarch_inner_than (gdbarch, core_addr_lessthan);

  495.   /* Return value info */
  496.   set_gdbarch_return_value (gdbarch, vax_return_value);

  498.   /* Call dummy code.  */
  499.   set_gdbarch_push_dummy_call (gdbarch, vax_push_dummy_call);
  500.   set_gdbarch_dummy_id (gdbarch, vax_dummy_id);

  502.   /* Breakpoint info */
  503.   set_gdbarch_breakpoint_from_pc (gdbarch, vax_breakpoint_from_pc);

  505.   /* Misc info */
  506.   set_gdbarch_deprecated_function_start_offset (gdbarch, 2);
  507.   set_gdbarch_believe_pcc_promotion (gdbarch, 1);

  509.   set_gdbarch_print_insn (gdbarch, print_insn_vax);

  511.   set_gdbarch_unwind_pc (gdbarch, vax_unwind_pc);

  513.   frame_base_set_default (gdbarch, &vax_frame_base);

  515.   /* Hook in ABI-specific overrides, if they have been registered.  */
  516.   gdbarch_init_osabi (info, gdbarch);

  518.   frame_unwind_append_unwinder (gdbarch, &vax_frame_unwind);

  520.   return (gdbarch);
  521. }

  523. /* Provide a prototype to silence -Wmissing-prototypes.  */
  524. void _initialize_vax_tdep (void);

  526. void
  527. ‌_initialize_vax_tdep (void)
  528. {
  529.   gdbarch_register (bfd_arch_vax, vax_gdbarch_init, NULL);
  530. }