1 /* Target-machine dependent code for Motorola 88000 series, for GDB.
2 Copyright 1988, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 2000,
3 2001 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 2 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, write to the Free Software
19 Foundation, Inc., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
32 /* Size of an instruction */
33 #define BYTES_PER_88K_INSN 4
35 void frame_find_saved_regs ();
37 /* Is this target an m88110? Otherwise assume m88100. This has
38 relevance for the ways in which we screw with instruction pointers. */
40 int target_is_m88110 = 0;
42 /* The m88k kernel aligns all instructions on 4-byte boundaries. The
43 kernel also uses the least significant two bits for its own hocus
44 pocus. When gdb receives an address from the kernel, it needs to
45 preserve those right-most two bits, but gdb also needs to be careful
46 to realize that those two bits are not really a part of the address
47 of an instruction. Shrug. */
50 m88k_addr_bits_remove (CORE_ADDR addr)
56 /* Given a GDB frame, determine the address of the calling function's frame.
57 This will be used to create a new GDB frame struct, and then
58 INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC will be called for the new frame.
60 For us, the frame address is its stack pointer value, so we look up
61 the function prologue to determine the caller's sp value, and return it. */
64 frame_chain (struct frame_info *thisframe)
67 frame_find_saved_regs (thisframe, (struct frame_saved_regs *) 0);
68 /* NOTE: this depends on frame_find_saved_regs returning the VALUE, not
69 the ADDRESS, of SP_REGNUM. It also depends on the cache of
70 frame_find_saved_regs results. */
71 if (thisframe->fsr->regs[SP_REGNUM])
72 return thisframe->fsr->regs[SP_REGNUM];
74 return thisframe->frame; /* Leaf fn -- next frame up has same SP. */
78 frameless_function_invocation (struct frame_info *frame)
81 frame_find_saved_regs (frame, (struct frame_saved_regs *) 0);
82 /* NOTE: this depends on frame_find_saved_regs returning the VALUE, not
83 the ADDRESS, of SP_REGNUM. It also depends on the cache of
84 frame_find_saved_regs results. */
85 if (frame->fsr->regs[SP_REGNUM])
86 return 0; /* Frameful -- return addr saved somewhere */
88 return 1; /* Frameless -- no saved return address */
92 init_extra_frame_info (int fromleaf, struct frame_info *frame)
94 frame->fsr = 0; /* Not yet allocated */
95 frame->args_pointer = 0; /* Unknown */
96 frame->locals_pointer = 0; /* Unknown */
99 /* Examine an m88k function prologue, recording the addresses at which
100 registers are saved explicitly by the prologue code, and returning
101 the address of the first instruction after the prologue (but not
102 after the instruction at address LIMIT, as explained below).
104 LIMIT places an upper bound on addresses of the instructions to be
105 examined. If the prologue code scan reaches LIMIT, the scan is
106 aborted and LIMIT is returned. This is used, when examining the
107 prologue for the current frame, to keep examine_prologue () from
108 claiming that a given register has been saved when in fact the
109 instruction that saves it has not yet been executed. LIMIT is used
110 at other times to stop the scan when we hit code after the true
111 function prologue (e.g. for the first source line) which might
112 otherwise be mistaken for function prologue.
114 The format of the function prologue matched by this routine is
115 derived from examination of the source to gcc 1.95, particularly
116 the routine output_prologue () in config/out-m88k.c.
118 subu r31,r31,n # stack pointer update
120 (st rn,r31,offset)? # save incoming regs
121 (st.d rn,r31,offset)?
123 (addu r30,r31,n)? # frame pointer update
125 (pic sequence)? # PIC code prologue
127 (or rn,rm,0)? # Move parameters to other regs
130 /* Macros for extracting fields from instructions. */
132 #define BITMASK(pos, width) (((0x1 << (width)) - 1) << (pos))
133 #define EXTRACT_FIELD(val, pos, width) ((val) >> (pos) & BITMASK (0, width))
134 #define SUBU_OFFSET(x) ((unsigned)(x & 0xFFFF))
135 #define ST_OFFSET(x) ((unsigned)((x) & 0xFFFF))
136 #define ST_SRC(x) EXTRACT_FIELD ((x), 21, 5)
137 #define ADDU_OFFSET(x) ((unsigned)(x & 0xFFFF))
140 * prologue_insn_tbl is a table of instructions which may comprise a
141 * function prologue. Associated with each table entry (corresponding
142 * to a single instruction or group of instructions), is an action.
143 * This action is used by examine_prologue (below) to determine
144 * the state of certain machine registers and where the stack frame lives.
147 enum prologue_insn_action
149 PIA_SKIP, /* don't care what the instruction does */
150 PIA_NOTE_ST, /* note register stored and where */
151 PIA_NOTE_STD, /* note pair of registers stored and where */
152 PIA_NOTE_SP_ADJUSTMENT, /* note stack pointer adjustment */
153 PIA_NOTE_FP_ASSIGNMENT, /* note frame pointer assignment */
154 PIA_NOTE_PROLOGUE_END, /* no more prologue */
157 struct prologue_insns
161 enum prologue_insn_action action;
164 struct prologue_insns prologue_insn_tbl[] =
166 /* Various register move instructions */
167 {0x58000000, 0xf800ffff, PIA_SKIP}, /* or/or.u with immed of 0 */
168 {0xf4005800, 0xfc1fffe0, PIA_SKIP}, /* or rd, r0, rs */
169 {0xf4005800, 0xfc00ffff, PIA_SKIP}, /* or rd, rs, r0 */
171 /* Stack pointer setup: "subu sp, sp, n" where n is a multiple of 8 */
172 {0x67ff0000, 0xffff0007, PIA_NOTE_SP_ADJUSTMENT},
174 /* Frame pointer assignment: "addu r30, r31, n" */
175 {0x63df0000, 0xffff0000, PIA_NOTE_FP_ASSIGNMENT},
177 /* Store to stack instructions; either "st rx, sp, n" or "st.d rx, sp, n" */
178 {0x241f0000, 0xfc1f0000, PIA_NOTE_ST}, /* st rx, sp, n */
179 {0x201f0000, 0xfc1f0000, PIA_NOTE_STD}, /* st.d rs, sp, n */
181 /* Instructions needed for setting up r25 for pic code. */
182 {0x5f200000, 0xffff0000, PIA_SKIP}, /* or.u r25, r0, offset_high */
183 {0xcc000002, 0xffffffff, PIA_SKIP}, /* bsr.n Lab */
184 {0x5b390000, 0xffff0000, PIA_SKIP}, /* or r25, r25, offset_low */
185 {0xf7396001, 0xffffffff, PIA_SKIP}, /* Lab: addu r25, r25, r1 */
187 /* Various branch or jump instructions which have a delay slot -- these
188 do not form part of the prologue, but the instruction in the delay
189 slot might be a store instruction which should be noted. */
190 {0xc4000000, 0xe4000000, PIA_NOTE_PROLOGUE_END},
191 /* br.n, bsr.n, bb0.n, or bb1.n */
192 {0xec000000, 0xfc000000, PIA_NOTE_PROLOGUE_END}, /* bcnd.n */
193 {0xf400c400, 0xfffff7e0, PIA_NOTE_PROLOGUE_END} /* jmp.n or jsr.n */
198 /* Fetch the instruction at ADDR, returning 0 if ADDR is beyond LIM or
199 is not the address of a valid instruction, the address of the next
200 instruction beyond ADDR otherwise. *PWORD1 receives the first word
201 of the instruction. */
203 #define NEXT_PROLOGUE_INSN(addr, lim, pword1) \
204 (((addr) < (lim)) ? next_insn (addr, pword1) : 0)
206 /* Read the m88k instruction at 'memaddr' and return the address of
207 the next instruction after that, or 0 if 'memaddr' is not the
208 address of a valid instruction. The instruction
209 is stored at 'pword1'. */
212 next_insn (CORE_ADDR memaddr, unsigned long *pword1)
214 *pword1 = read_memory_integer (memaddr, BYTES_PER_88K_INSN);
215 return memaddr + BYTES_PER_88K_INSN;
218 /* Read a register from frames called by us (or from the hardware regs). */
221 read_next_frame_reg (struct frame_info *frame, int regno)
223 for (; frame; frame = frame->next)
225 if (regno == SP_REGNUM)
226 return FRAME_FP (frame);
227 else if (frame->fsr->regs[regno])
228 return read_memory_integer (frame->fsr->regs[regno], 4);
230 return read_register (regno);
233 /* Examine the prologue of a function. `ip' points to the first instruction.
234 `limit' is the limit of the prologue (e.g. the addr of the first
235 linenumber, or perhaps the program counter if we're stepping through).
236 `frame_sp' is the stack pointer value in use in this frame.
237 `fsr' is a pointer to a frame_saved_regs structure into which we put
238 info about the registers saved by this frame.
239 `fi' is a struct frame_info pointer; we fill in various fields in it
240 to reflect the offsets of the arg pointer and the locals pointer. */
243 examine_prologue (register CORE_ADDR ip, register CORE_ADDR limit,
244 CORE_ADDR frame_sp, struct frame_saved_regs *fsr,
245 struct frame_info *fi)
247 register CORE_ADDR next_ip;
251 char must_adjust[32]; /* If set, must adjust offsets in fsr */
252 int sp_offset = -1; /* -1 means not set (valid must be mult of 8) */
253 int fp_offset = -1; /* -1 means not set */
255 CORE_ADDR prologue_end = 0;
257 memset (must_adjust, '\0', sizeof (must_adjust));
258 next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn);
262 struct prologue_insns *pip;
264 for (pip = prologue_insn_tbl; (insn & pip->mask) != pip->insn;)
265 if (++pip >= prologue_insn_tbl + sizeof prologue_insn_tbl)
266 goto end_of_prologue_found; /* not a prologue insn */
275 offset = ST_OFFSET (insn);
276 must_adjust[src] = 1;
277 fsr->regs[src++] = offset; /* Will be adjusted later */
278 if (pip->action == PIA_NOTE_STD && src < 32)
281 must_adjust[src] = 1;
282 fsr->regs[src++] = offset;
286 goto end_of_prologue_found;
288 case PIA_NOTE_SP_ADJUSTMENT:
290 sp_offset = -SUBU_OFFSET (insn);
292 goto end_of_prologue_found;
294 case PIA_NOTE_FP_ASSIGNMENT:
296 fp_offset = ADDU_OFFSET (insn);
298 goto end_of_prologue_found;
300 case PIA_NOTE_PROLOGUE_END:
311 next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn);
314 end_of_prologue_found:
319 /* We're done with the prologue. If we don't care about the stack
320 frame itself, just return. (Note that fsr->regs has been trashed,
321 but the one caller who calls with fi==0 passes a dummy there.) */
329 sp_offset original (before any alloca calls) displacement of SP
332 fp_offset displacement from original SP to the FP for this frame
335 fsr->regs[0..31] displacement from original SP to the stack
336 location where reg[0..31] is stored.
338 must_adjust[0..31] set if corresponding offset was set.
340 If alloca has been called between the function prologue and the current
341 IP, then the current SP (frame_sp) will not be the original SP as set by
342 the function prologue. If the current SP is not the original SP, then the
343 compiler will have allocated an FP for this frame, fp_offset will be set,
344 and we can use it to calculate the original SP.
346 Then, we figure out where the arguments and locals are, and relocate the
347 offsets in fsr->regs to absolute addresses. */
351 /* We have a frame pointer, so get it, and base our calc's on it. */
352 frame_fp = (CORE_ADDR) read_next_frame_reg (fi->next, ACTUAL_FP_REGNUM);
353 frame_sp = frame_fp - fp_offset;
357 /* We have no frame pointer, therefore frame_sp is still the same value
358 as set by prologue. But where is the frame itself? */
359 if (must_adjust[SRP_REGNUM])
361 /* Function header saved SRP (r1), the return address. Frame starts
362 4 bytes down from where it was saved. */
363 frame_fp = frame_sp + fsr->regs[SRP_REGNUM] - 4;
364 fi->locals_pointer = frame_fp;
368 /* Function header didn't save SRP (r1), so we are in a leaf fn or
369 are otherwise confused. */
374 /* The locals are relative to the FP (whether it exists as an allocated
375 register, or just as an assumed offset from the SP) */
376 fi->locals_pointer = frame_fp;
378 /* The arguments are just above the SP as it was before we adjusted it
380 fi->args_pointer = frame_sp - sp_offset;
382 /* Now that we know the SP value used by the prologue, we know where
383 it saved all the registers. */
384 for (src = 0; src < 32; src++)
385 if (must_adjust[src])
386 fsr->regs[src] += frame_sp;
388 /* The saved value of the SP is always known. */
390 if (fsr->regs[SP_REGNUM] != 0
391 && fsr->regs[SP_REGNUM] != frame_sp - sp_offset)
392 fprintf_unfiltered (gdb_stderr, "Bad saved SP value %x != %x, offset %x!\n",
393 fsr->regs[SP_REGNUM],
394 frame_sp - sp_offset, sp_offset);
396 fsr->regs[SP_REGNUM] = frame_sp - sp_offset;
401 /* Given an ip value corresponding to the start of a function,
402 return the ip of the first instruction after the function
406 m88k_skip_prologue (CORE_ADDR ip)
408 struct frame_saved_regs saved_regs_dummy;
409 struct symtab_and_line sal;
412 sal = find_pc_line (ip, 0);
413 limit = (sal.end) ? sal.end : 0xffffffff;
415 return (examine_prologue (ip, limit, (CORE_ADDR) 0, &saved_regs_dummy,
416 (struct frame_info *) 0));
419 /* Put here the code to store, into a struct frame_saved_regs,
420 the addresses of the saved registers of frame described by FRAME_INFO.
421 This includes special registers such as pc and fp saved in special
422 ways in the stack frame. sp is even more special:
423 the address we return for it IS the sp for the next frame.
425 We cache the result of doing this in the frame_obstack, since it is
429 frame_find_saved_regs (struct frame_info *fi, struct frame_saved_regs *fsr)
431 register struct frame_saved_regs *cache_fsr;
433 struct symtab_and_line sal;
438 cache_fsr = (struct frame_saved_regs *)
439 frame_obstack_alloc (sizeof (struct frame_saved_regs));
440 memset (cache_fsr, '\0', sizeof (struct frame_saved_regs));
443 /* Find the start and end of the function prologue. If the PC
444 is in the function prologue, we only consider the part that
445 has executed already. In the case where the PC is not in
446 the function prologue, we set limit to two instructions beyond
447 where the prologue ends in case if any of the prologue instructions
448 were moved into a delay slot of a branch instruction. */
450 ip = get_pc_function_start (fi->pc);
451 sal = find_pc_line (ip, 0);
452 limit = (sal.end && sal.end < fi->pc) ? sal.end + 2 * BYTES_PER_88K_INSN
455 /* This will fill in fields in *fi as well as in cache_fsr. */
456 #ifdef SIGTRAMP_FRAME_FIXUP
457 if (fi->signal_handler_caller)
458 SIGTRAMP_FRAME_FIXUP (fi->frame);
460 examine_prologue (ip, limit, fi->frame, cache_fsr, fi);
461 #ifdef SIGTRAMP_SP_FIXUP
462 if (fi->signal_handler_caller && fi->fsr->regs[SP_REGNUM])
463 SIGTRAMP_SP_FIXUP (fi->fsr->regs[SP_REGNUM]);
471 /* Return the address of the locals block for the frame
472 described by FI. Returns 0 if the address is unknown.
473 NOTE! Frame locals are referred to by negative offsets from the
474 argument pointer, so this is the same as frame_args_address(). */
477 frame_locals_address (struct frame_info *fi)
479 struct frame_saved_regs fsr;
481 if (fi->args_pointer) /* Cached value is likely there. */
482 return fi->args_pointer;
484 /* Nope, generate it. */
486 get_frame_saved_regs (fi, &fsr);
488 return fi->args_pointer;
491 /* Return the address of the argument block for the frame
492 described by FI. Returns 0 if the address is unknown. */
495 frame_args_address (struct frame_info *fi)
497 struct frame_saved_regs fsr;
499 if (fi->args_pointer) /* Cached value is likely there. */
500 return fi->args_pointer;
502 /* Nope, generate it. */
504 get_frame_saved_regs (fi, &fsr);
506 return fi->args_pointer;
509 /* Return the saved PC from this frame.
511 If the frame has a memory copy of SRP_REGNUM, use that. If not,
512 just use the register SRP_REGNUM itself. */
515 frame_saved_pc (struct frame_info *frame)
517 return read_next_frame_reg (frame, SRP_REGNUM);
521 #define DUMMY_FRAME_SIZE 192
524 write_word (CORE_ADDR sp, ULONGEST word)
526 register int len = REGISTER_SIZE;
527 char buffer[MAX_REGISTER_RAW_SIZE];
529 store_unsigned_integer (buffer, len, word);
530 write_memory (sp, buffer, len);
534 m88k_push_dummy_frame (void)
536 register CORE_ADDR sp = read_register (SP_REGNUM);
540 sp -= DUMMY_FRAME_SIZE; /* allocate a bunch of space */
542 for (rn = 0, offset = 0; rn <= SP_REGNUM; rn++, offset += 4)
543 write_word (sp + offset, read_register (rn));
545 write_word (sp + offset, read_register (SXIP_REGNUM));
548 write_word (sp + offset, read_register (SNIP_REGNUM));
551 write_word (sp + offset, read_register (SFIP_REGNUM));
554 write_word (sp + offset, read_register (PSR_REGNUM));
557 write_word (sp + offset, read_register (FPSR_REGNUM));
560 write_word (sp + offset, read_register (FPCR_REGNUM));
563 write_register (SP_REGNUM, sp);
564 write_register (ACTUAL_FP_REGNUM, sp);
570 register struct frame_info *frame = get_current_frame ();
571 register CORE_ADDR fp;
573 struct frame_saved_regs fsr;
575 fp = FRAME_FP (frame);
576 get_frame_saved_regs (frame, &fsr);
578 if (PC_IN_CALL_DUMMY (read_pc (), read_register (SP_REGNUM), FRAME_FP (fi)))
580 /* FIXME: I think get_frame_saved_regs should be handling this so
581 that we can deal with the saved registers properly (e.g. frame
582 1 is a call dummy, the user types "frame 2" and then "print $ps"). */
583 register CORE_ADDR sp = read_register (ACTUAL_FP_REGNUM);
586 for (regnum = 0, offset = 0; regnum <= SP_REGNUM; regnum++, offset += 4)
587 (void) write_register (regnum, read_memory_integer (sp + offset, 4));
589 write_register (SXIP_REGNUM, read_memory_integer (sp + offset, 4));
592 write_register (SNIP_REGNUM, read_memory_integer (sp + offset, 4));
595 write_register (SFIP_REGNUM, read_memory_integer (sp + offset, 4));
598 write_register (PSR_REGNUM, read_memory_integer (sp + offset, 4));
601 write_register (FPSR_REGNUM, read_memory_integer (sp + offset, 4));
604 write_register (FPCR_REGNUM, read_memory_integer (sp + offset, 4));
610 for (regnum = FP_REGNUM; regnum > 0; regnum--)
611 if (fsr.regs[regnum])
612 write_register (regnum,
613 read_memory_integer (fsr.regs[regnum], 4));
614 write_pc (frame_saved_pc (frame));
616 reinit_frame_cache ();
620 _initialize_m88k_tdep (void)
622 tm_print_insn = print_insn_m88k;