rs6000-tdep.c

早期freebsd实现

saved SP register!  There should *not* be a separate stack in the
GDB process that keeps track of these dummy frames!  -- [e-mail] Aug92
 */
   
pop_dummy_frame ()
{
  CORE_ADDR sp, pc;
  int ii;
  sp = dummy_frame_addr [--dummy_frame_count];

  /* restore all fpr's. */
  for (ii = 1; ii <= 32; ++ii)
    read_memory (sp-(ii*8), &registers[REGISTER_BYTE (32-ii+FP0_REGNUM)], 8);

  /* restore all gpr's */
  for (ii=1; ii <= 32; ++ii) {
    read_memory (sp-256-(ii*4), &registers[REGISTER_BYTE (32-ii)], 4);
  }

  /* restore the rest of the registers. */
  for (ii=1; ii <=(LAST_SP_REGNUM-FIRST_SP_REGNUM+1); ++ii)
    read_memory (sp-384-(ii*4),
    		&registers[REGISTER_BYTE (FPLAST_REGNUM + ii)], 4);

  read_memory (sp-(DUMMY_FRAME_SIZE-8), 
  				&registers [REGISTER_BYTE(PC_REGNUM)], 4);

  /* when a dummy frame was being pushed, we had to decrement %sp first, in 
     order to secure astack space. Thus, saved %sp (or %r1) value, is not the
     one we should restore. Change it with the one we need. */

  *(int*)&registers [REGISTER_BYTE(FP_REGNUM)] = sp;

  /* Now we can restore all registers. */

  target_store_registers (-1);
  pc = read_pc ();
  flush_cached_frames ();
  set_current_frame (create_new_frame (sp, pc));
}


/* pop the innermost frame, go back to the caller. */

void
pop_frame ()
{
  int pc, lr, sp, prev_sp;		/* %pc, %lr, %sp */
  struct aix_framedata fdata;
  FRAME fr = get_current_frame ();
  int addr, ii;

  pc = read_pc ();
  sp = FRAME_FP (fr);

  if (stop_stack_dummy && dummy_frame_count) {
    pop_dummy_frame ();
    return;
  }

  /* figure out previous %pc value. If the function is frameless, it is 
     still in the link register, otherwise walk the frames and retrieve the
     saved %pc value in the previous frame. */

  addr = get_pc_function_start (fr->pc) + FUNCTION_START_OFFSET;
  function_frame_info (addr, &fdata);

  read_memory (sp, &prev_sp, 4);
  if (fdata.frameless)
    lr = read_register (LR_REGNUM);
  else
    read_memory (prev_sp+8, &lr, 4);

  /* reset %pc value. */
  write_register (PC_REGNUM, lr);

  /* reset register values if any was saved earlier. */
  addr = prev_sp - fdata.offset;

  if (fdata.saved_gpr != -1)
    for (ii=fdata.saved_gpr; ii <= 31; ++ii) {
      read_memory (addr, &registers [REGISTER_BYTE (ii)], 4);
      addr += sizeof (int);
    }

  if (fdata.saved_fpr != -1)
    for (ii=fdata.saved_fpr; ii <= 31; ++ii) {
      read_memory (addr, &registers [REGISTER_BYTE (ii+FP0_REGNUM)], 8);
      addr += 8;
  }

  write_register (SP_REGNUM, prev_sp);
  target_store_registers (-1);
  flush_cached_frames ();
  set_current_frame (create_new_frame (prev_sp, lr));
}


/* fixup the call sequence of a dummy function, with the real function address.
   its argumets will be passed by gdb. */

void
fix_call_dummy(dummyname, pc, fun, nargs, type)
  char *dummyname;
  CORE_ADDR pc;
  CORE_ADDR fun;
  int nargs;					/* not used */
  int type;					/* not used */
{
#define	TOC_ADDR_OFFSET		20
#define	TARGET_ADDR_OFFSET	28

  int ii;
  CORE_ADDR target_addr;
  CORE_ADDR tocvalue;

  target_addr = fun;
  tocvalue = find_toc_address (target_addr);

  ii  = *(int*)((char*)dummyname + TOC_ADDR_OFFSET);
  ii = (ii & 0xffff0000) | (tocvalue >> 16);
  *(int*)((char*)dummyname + TOC_ADDR_OFFSET) = ii;

  ii  = *(int*)((char*)dummyname + TOC_ADDR_OFFSET+4);
  ii = (ii & 0xffff0000) | (tocvalue & 0x0000ffff);
  *(int*)((char*)dummyname + TOC_ADDR_OFFSET+4) = ii;

  ii  = *(int*)((char*)dummyname + TARGET_ADDR_OFFSET);
  ii = (ii & 0xffff0000) | (target_addr >> 16);
  *(int*)((char*)dummyname + TARGET_ADDR_OFFSET) = ii;

  ii  = *(int*)((char*)dummyname + TARGET_ADDR_OFFSET+4);
  ii = (ii & 0xffff0000) | (target_addr & 0x0000ffff);
  *(int*)((char*)dummyname + TARGET_ADDR_OFFSET+4) = ii;
}


/* return information about a function frame.
   in struct aix_frameinfo fdata:
    - frameless is TRUE, if function does not save %pc value in its frame.
    - offset is the number of bytes used in the frame to save registers.
    - saved_gpr is the number of the first saved gpr.
    - saved_fpr is the number of the first saved fpr.
    - alloca_reg is the number of the register used for alloca() handling.
      Otherwise -1.
 */
void
function_frame_info (pc, fdata)
  CORE_ADDR pc;
  struct aix_framedata *fdata;
{
  unsigned int tmp;
  register unsigned int op;

  fdata->offset = 0;
  fdata->saved_gpr = fdata->saved_fpr = fdata->alloca_reg = -1;

  op  = read_memory_integer (pc, 4);
  if (op == 0x7c0802a6) {		/* mflr r0 */
    pc += 4;
    op = read_memory_integer (pc, 4);
    fdata->frameless = 0;
  }
  else				/* else, this is a frameless invocation */
    fdata->frameless = 1;


  if ((op & 0xfc00003e) == 0x7c000026) { /* mfcr Rx */
    pc += 4;
    op = read_memory_integer (pc, 4);
  }

  if ((op & 0xfc000000) == 0x48000000) { /* bl foo, to save fprs??? */
    pc += 4;
    op = read_memory_integer (pc, 4);
    /* At this point, make sure this is not a trampoline function
       (a function that simply calls another functions, and nothing else).
       If the next is not a nop, this branch was part of the function
       prologue. */

    if (op == 0x4def7b82 ||		/* crorc 15, 15, 15 */
	op == 0x0)
      return;				/* prologue is over */
  }

  if ((op & 0xfc1f0000) == 0xd8010000) { /* stfd Rx,NUM(r1) */
    pc += 4;				 /* store floating register double */
    op = read_memory_integer (pc, 4);
  }

  if ((op & 0xfc1f0000) == 0xbc010000) { /* stm Rx, NUM(r1) */
    int tmp2;
    fdata->saved_gpr = (op >> 21) & 0x1f;
    tmp2 = op & 0xffff;
    if (tmp2 > 0x7fff)
      tmp2 = 0xffff0000 | tmp2;

    if (tmp2 < 0) {
      tmp2 = tmp2 * -1;
      fdata->saved_fpr = (tmp2 - ((32 - fdata->saved_gpr) * 4)) / 8;
      if ( fdata->saved_fpr > 0)
        fdata->saved_fpr = 32 - fdata->saved_fpr;
      else
        fdata->saved_fpr = -1;
    }
    fdata->offset = tmp2;
    pc += 4;
    op = read_memory_integer (pc, 4);
  }

  while (((tmp = op >> 16) == 0x9001) ||	/* st   r0, NUM(r1) */
	 (tmp == 0x9421) ||			/* stu  r1, NUM(r1) */
	 (op == 0x93e1fffc)) 			/* st   r31,-4(r1) */
  {
    /* gcc takes a short cut and uses this instruction to save r31 only. */

    if (op == 0x93e1fffc) {
      if (fdata->offset)
/*        fatal ("Unrecognized prolog."); */
        printf ("Unrecognized prolog!\n");

      fdata->saved_gpr = 31;
      fdata->offset = 4;
    }
    pc += 4;
    op = read_memory_integer (pc, 4);
  }

  while ((tmp = (op >> 22)) == 0x20f) {	/* l	r31, ... or */
    pc += 4;				/* l	r30, ...    */
    op = read_memory_integer (pc, 4);
  }

  /* store parameters into stack */
  while(
	(op & 0xfc1f0000) == 0xd8010000 || 	/* stfd Rx,NUM(r1) */
	(op & 0xfc1f0000) == 0x90010000 ||	/* st r?, NUM(r1)  */
	(op & 0xfc000000) == 0xfc000000 ||	/* frsp, fp?, .. */
	(op & 0xd0000000) == 0xd0000000)	/* stfs, fp?, .. */
    {
      pc += 4;					/* store fpr double */
      op = read_memory_integer (pc, 4);
    }

  if (op == 0x603f0000)				/* oril r31, r1, 0x0 */
    fdata->alloca_reg = 31;
}


/* Pass the arguments in either registers, or in the stack. In RS6000, the first
   eight words of the argument list (that might be less than eight parameters if
   some parameters occupy more than one word) are passed in r3..r11 registers.
   float and double parameters are passed in fpr's, in addition to that. Rest of
   the parameters if any are passed in user stack. There might be cases in which
   half of the parameter is copied into registers, the other half is pushed into
   stack.

   If the function is returning a structure, then the return address is passed
   in r3, then the first 7 words of the parametes can be passed in registers,
   starting from r4. */

CORE_ADDR
push_arguments (nargs, args, sp, struct_return, struct_addr)
  int nargs;
  value *args;
  CORE_ADDR sp;
  int struct_return;
  CORE_ADDR struct_addr;
{
  int ii, len;
  int argno;					/* current argument number */
  int argbytes;					/* current argument byte */
  char tmp_buffer [50];
  value arg;
  int f_argno = 0;				/* current floating point argno */

  CORE_ADDR saved_sp, pc;

  if ( dummy_frame_count <= 0)
    printf ("FATAL ERROR -push_arguments()! frame not found!!\n");

  /* The first eight words of ther arguments are passed in registers. Copy
     them appropriately.

     If the function is returning a `struct', then the first word (which 
     will be passed in r3) is used for struct return address. In that
     case we should advance one word and start from r4 register to copy 
     parameters. */

  ii =  struct_return ? 1 : 0;

  for (argno=0, argbytes=0; argno < nargs && ii<8; ++ii) {

    arg = value_arg_coerce (args[argno]);
    len = TYPE_LENGTH (VALUE_TYPE (arg));

    if (TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_FLT) {

      /* floating point arguments are passed in fpr's, as well as gpr's.
         There are 13 fpr's reserved for passing parameters. At this point
         there is no way we would run out of them. */

      if (len > 8)
        printf (
"Fatal Error: a floating point parameter #%d with a size > 8 is found!\n", argno);

      bcopy (VALUE_CONTENTS (arg), 
         &registers[REGISTER_BYTE(FP0_REGNUM + 1 + f_argno)], len);
      ++f_argno;
    }

    if (len > 4) {

      /* Argument takes more than one register. */
      while (argbytes < len) {

	*(int*)&registers[REGISTER_BYTE(ii+3)] = 0;
	bcopy ( ((char*)VALUE_CONTENTS (arg))+argbytes, 
			&registers[REGISTER_BYTE(ii+3)], 
			(len - argbytes) > 4 ? 4 : len - argbytes);
	++ii, argbytes += 4;

	if (ii >= 8)
	  goto ran_out_of_registers_for_arguments;
      }
      argbytes = 0;
      --ii;
    }
    else {        /* Argument can fit in one register. No problem. */
      *(int*)&registers[REGISTER_BYTE(ii+3)] = 0;
      bcopy (VALUE_CONTENTS (arg), &registers[REGISTER_BYTE(ii+3)], len);
    }
    ++argno;
  }

ran_out_of_registers_for_arguments:

  /* location for 8 parameters are always reserved. */
  sp -= 4 * 8;

  /* another six words for back chain, TOC register, link register, etc. */
  sp -= 24;

  /* if there are more arguments, allocate space for them in 
     the stack, then push them starting from the ninth one. */

  if ((argno < nargs) || argbytes) {
    int space = 0, jj;
    value val;

    if (argbytes) {
      space += ((len - argbytes + 3) & -4);
      jj = argno + 1;
    }
    else
      jj = argno;

    for (; jj < nargs; ++jj) {
      val = value_arg_coerce (args[jj]);
      space += ((TYPE_LENGTH (VALUE_TYPE (val))) + 3) & -4;
    }

    /* add location required for the rest of the parameters */
    space = (space + 7) & -8;
    sp -= space;

    /* This is another instance we need to be concerned about securing our
	stack space. If we write anything underneath %sp (r1), we might conflict
	with the kernel who thinks he is free to use this area. So, update %sp
	first before doing anything else. */

    write_register (SP_REGNUM, sp);

    /* if the last argument copied into the registers didn't fit there 
       completely, push the rest of it into stack. */

    if (argbytes) {
      write_memory (
        sp+24+(ii*4), ((char*)VALUE_CONTENTS (arg))+argbytes, len - argbytes);
      ++argno;
      ii += ((len - argbytes + 3) & -4) / 4;
    }

    /* push the rest of the arguments into stack. */
    for (; argno < nargs; ++argno) {

      arg = value_arg_coerce (args[argno]);
      len = TYPE_LENGTH (VALUE_TYPE (arg));


      /* float types should be passed in fpr's, as well as in the stack. */
      if (TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_FLT && f_argno < 13) {

        if (len > 8)
          printf (
"Fatal Error: a floating point parameter #%d with a size > 8 is found!\n", argno);