1 /* Target-dependent code for Atmel AVR, for GDB.
3 Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
4 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
6 This file is part of GDB.
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.
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.
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/>. */
21 /* Contributed by Theodore A. Roth, troth@openavr.org */
23 /* Portions of this file were taken from the original gdb-4.18 patch developed
24 by Denis Chertykov, denisc@overta.ru */
28 #include "frame-unwind.h"
29 #include "frame-base.h"
30 #include "trad-frame.h"
36 #include "arch-utils.h"
38 #include "gdb_string.h"
43 (AVR micros are pure Harvard Architecture processors.)
45 The AVR family of microcontrollers have three distinctly different memory
46 spaces: flash, sram and eeprom. The flash is 16 bits wide and is used for
47 the most part to store program instructions. The sram is 8 bits wide and is
48 used for the stack and the heap. Some devices lack sram and some can have
49 an additional external sram added on as a peripheral.
51 The eeprom is 8 bits wide and is used to store data when the device is
52 powered down. Eeprom is not directly accessible, it can only be accessed
53 via io-registers using a special algorithm. Accessing eeprom via gdb's
54 remote serial protocol ('m' or 'M' packets) looks difficult to do and is
55 not included at this time.
57 [The eeprom could be read manually via ``x/b <eaddr + AVR_EMEM_START>'' or
58 written using ``set {unsigned char}<eaddr + AVR_EMEM_START>''. For this to
59 work, the remote target must be able to handle eeprom accesses and perform
60 the address translation.]
62 All three memory spaces have physical addresses beginning at 0x0. In
63 addition, the flash is addressed by gcc/binutils/gdb with respect to 8 bit
64 bytes instead of the 16 bit wide words used by the real device for the
67 In order for remote targets to work correctly, extra bits must be added to
68 addresses before they are send to the target or received from the target
69 via the remote serial protocol. The extra bits are the MSBs and are used to
70 decode which memory space the address is referring to. */
73 #define XMALLOC(TYPE) ((TYPE*) xmalloc (sizeof (TYPE)))
75 /* Constants: prefixed with AVR_ to avoid name space clashes */
89 AVR_NUM_REGS = 32 + 1 /*SREG*/ + 1 /*SP*/ + 1 /*PC*/,
90 AVR_NUM_REG_BYTES = 32 + 1 /*SREG*/ + 2 /*SP*/ + 4 /*PC*/,
92 AVR_PC_REG_INDEX = 35, /* index into array of registers */
94 AVR_MAX_PROLOGUE_SIZE = 64, /* bytes */
96 /* Count of pushed registers. From r2 to r17 (inclusively), r28, r29 */
99 /* Number of the last pushed register. r17 for current avr-gcc */
100 AVR_LAST_PUSHED_REGNUM = 17,
102 AVR_ARG1_REGNUM = 24, /* Single byte argument */
103 AVR_ARGN_REGNUM = 25, /* Multi byte argments */
105 AVR_RET1_REGNUM = 24, /* Single byte return value */
106 AVR_RETN_REGNUM = 25, /* Multi byte return value */
108 /* FIXME: TRoth/2002-01-??: Can we shift all these memory masks left 8
109 bits? Do these have to match the bfd vma values?. It sure would make
110 things easier in the future if they didn't need to match.
112 Note: I chose these values so as to be consistent with bfd vma
115 TRoth/2002-04-08: There is already a conflict with very large programs
116 in the mega128. The mega128 has 128K instruction bytes (64K words),
117 thus the Most Significant Bit is 0x10000 which gets masked off my
120 The problem manifests itself when trying to set a breakpoint in a
121 function which resides in the upper half of the instruction space and
122 thus requires a 17-bit address.
124 For now, I've just removed the EEPROM mask and changed AVR_MEM_MASK
125 from 0x00ff0000 to 0x00f00000. Eeprom is not accessible from gdb yet,
126 but could be for some remote targets by just adding the correct offset
127 to the address and letting the remote target handle the low-level
128 details of actually accessing the eeprom. */
130 AVR_IMEM_START = 0x00000000, /* INSN memory */
131 AVR_SMEM_START = 0x00800000, /* SRAM memory */
133 /* No eeprom mask defined */
134 AVR_MEM_MASK = 0x00f00000, /* mask to determine memory space */
136 AVR_EMEM_START = 0x00810000, /* EEPROM memory */
137 AVR_MEM_MASK = 0x00ff0000, /* mask to determine memory space */
143 NORMAL and CALL are the typical types (the -mcall-prologues gcc option
144 causes the generation of the CALL type prologues). */
147 AVR_PROLOGUE_NONE, /* No prologue */
149 AVR_PROLOGUE_CALL, /* -mcall-prologues */
151 AVR_PROLOGUE_INTR, /* interrupt handler */
152 AVR_PROLOGUE_SIG, /* signal handler */
155 /* Any function with a frame looks like this
156 ....... <-SP POINTS HERE
157 LOCALS1 <-FP POINTS HERE
166 struct avr_unwind_cache
168 /* The previous frame's inner most stack address. Used as this
169 frame ID's stack_addr. */
171 /* The frame's base, optionally used by the high-level debug info. */
175 /* Table indicating the location of each and every register. */
176 struct trad_frame_saved_reg *saved_regs;
181 /* Number of bytes stored to the stack by call instructions.
182 2 bytes for avr1-5, 3 bytes for avr6. */
186 /* Lookup the name of a register given it's number. */
189 avr_register_name (struct gdbarch *gdbarch, int regnum)
191 static const char * const register_names[] = {
192 "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
193 "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
194 "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
195 "r24", "r25", "r26", "r27", "r28", "r29", "r30", "r31",
200 if (regnum >= (sizeof (register_names) / sizeof (*register_names)))
202 return register_names[regnum];
205 /* Return the GDB type object for the "standard" data type
206 of data in register N. */
209 avr_register_type (struct gdbarch *gdbarch, int reg_nr)
211 if (reg_nr == AVR_PC_REGNUM)
212 return builtin_type (gdbarch)->builtin_uint32;
213 if (reg_nr == AVR_SP_REGNUM)
214 return builtin_type (gdbarch)->builtin_data_ptr;
216 return builtin_type (gdbarch)->builtin_uint8;
219 /* Instruction address checks and convertions. */
222 avr_make_iaddr (CORE_ADDR x)
224 return ((x) | AVR_IMEM_START);
227 /* FIXME: TRoth: Really need to use a larger mask for instructions. Some
228 devices are already up to 128KBytes of flash space.
230 TRoth/2002-04-8: See comment above where AVR_IMEM_START is defined. */
233 avr_convert_iaddr_to_raw (CORE_ADDR x)
235 return ((x) & 0xffffffff);
238 /* SRAM address checks and convertions. */
241 avr_make_saddr (CORE_ADDR x)
243 return ((x) | AVR_SMEM_START);
247 avr_convert_saddr_to_raw (CORE_ADDR x)
249 return ((x) & 0xffffffff);
252 /* EEPROM address checks and convertions. I don't know if these will ever
253 actually be used, but I've added them just the same. TRoth */
255 /* TRoth/2002-04-08: Commented out for now to allow fix for problem with large
256 programs in the mega128. */
258 /* static CORE_ADDR */
259 /* avr_make_eaddr (CORE_ADDR x) */
261 /* return ((x) | AVR_EMEM_START); */
265 /* avr_eaddr_p (CORE_ADDR x) */
267 /* return (((x) & AVR_MEM_MASK) == AVR_EMEM_START); */
270 /* static CORE_ADDR */
271 /* avr_convert_eaddr_to_raw (CORE_ADDR x) */
273 /* return ((x) & 0xffffffff); */
276 /* Convert from address to pointer and vice-versa. */
279 avr_address_to_pointer (struct gdbarch *gdbarch,
280 struct type *type, gdb_byte *buf, CORE_ADDR addr)
282 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
284 /* Is it a code address? */
285 if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_FUNC
286 || TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_METHOD)
288 store_unsigned_integer (buf, TYPE_LENGTH (type), byte_order,
289 avr_convert_iaddr_to_raw (addr >> 1));
293 /* Strip off any upper segment bits. */
294 store_unsigned_integer (buf, TYPE_LENGTH (type), byte_order,
295 avr_convert_saddr_to_raw (addr));
300 avr_pointer_to_address (struct gdbarch *gdbarch,
301 struct type *type, const gdb_byte *buf)
303 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
305 = extract_unsigned_integer (buf, TYPE_LENGTH (type), byte_order);
307 /* Is it a code address? */
308 if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_FUNC
309 || TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_METHOD
310 || TYPE_CODE_SPACE (TYPE_TARGET_TYPE (type)))
311 return avr_make_iaddr (addr << 1);
313 return avr_make_saddr (addr);
317 avr_read_pc (struct regcache *regcache)
320 regcache_cooked_read_unsigned (regcache, AVR_PC_REGNUM, &pc);
321 return avr_make_iaddr (pc);
325 avr_write_pc (struct regcache *regcache, CORE_ADDR val)
327 regcache_cooked_write_unsigned (regcache, AVR_PC_REGNUM,
328 avr_convert_iaddr_to_raw (val));
331 /* Function: avr_scan_prologue
333 This function decodes an AVR function prologue to determine:
334 1) the size of the stack frame
335 2) which registers are saved on it
336 3) the offsets of saved regs
337 This information is stored in the avr_unwind_cache structure.
339 Some devices lack the sbiw instruction, so on those replace this:
345 A typical AVR function prologue with a frame pointer might look like this:
346 push rXX ; saved regs
352 sbiw r28,<LOCALS_SIZE>
353 in __tmp_reg__,__SREG__
356 out __SREG__,__tmp_reg__
359 A typical AVR function prologue without a frame pointer might look like
361 push rXX ; saved regs
364 A main function prologue looks like this:
365 ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>)
366 ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>)
370 A signal handler prologue looks like this:
373 in __tmp_reg__, __SREG__
376 push rXX ; save registers r18:r27, r30:r31
378 push r28 ; save frame pointer
382 sbiw r28, <LOCALS_SIZE>
386 A interrupt handler prologue looks like this:
390 in __tmp_reg__, __SREG__
393 push rXX ; save registers r18:r27, r30:r31
395 push r28 ; save frame pointer
399 sbiw r28, <LOCALS_SIZE>
405 A `-mcall-prologues' prologue looks like this (Note that the megas use a
406 jmp instead of a rjmp, thus the prologue is one word larger since jmp is a
407 32 bit insn and rjmp is a 16 bit insn):
408 ldi r26,lo8(<LOCALS_SIZE>)
409 ldi r27,hi8(<LOCALS_SIZE>)
410 ldi r30,pm_lo8(.L_foo_body)
411 ldi r31,pm_hi8(.L_foo_body)
412 rjmp __prologue_saves__+RRR
415 /* Not really part of a prologue, but still need to scan for it, is when a
416 function prologue moves values passed via registers as arguments to new
417 registers. In this case, all local variables live in registers, so there
418 may be some register saves. This is what it looks like:
422 There could be multiple movw's. If the target doesn't have a movw insn, it
423 will use two mov insns. This could be done after any of the above prologue
427 avr_scan_prologue (struct gdbarch *gdbarch, CORE_ADDR pc_beg, CORE_ADDR pc_end,
428 struct avr_unwind_cache *info)
430 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
434 struct minimal_symbol *msymbol;
435 unsigned char prologue[AVR_MAX_PROLOGUE_SIZE];
439 len = pc_end - pc_beg;
440 if (len > AVR_MAX_PROLOGUE_SIZE)
441 len = AVR_MAX_PROLOGUE_SIZE;
443 /* FIXME: TRoth/2003-06-11: This could be made more efficient by only
444 reading in the bytes of the prologue. The problem is that the figuring
445 out where the end of the prologue is is a bit difficult. The old code
446 tried to do that, but failed quite often. */
447 read_memory (pc_beg, prologue, len);
449 /* Scanning main()'s prologue
450 ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>)
451 ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>)
458 static const unsigned char img[] = {
459 0xde, 0xbf, /* out __SP_H__,r29 */
460 0xcd, 0xbf /* out __SP_L__,r28 */
463 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
464 /* ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>) */
465 if ((insn & 0xf0f0) == 0xe0c0)
467 locals = (insn & 0xf) | ((insn & 0x0f00) >> 4);
468 insn = extract_unsigned_integer (&prologue[vpc + 2], 2, byte_order);
469 /* ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>) */
470 if ((insn & 0xf0f0) == 0xe0d0)
472 locals |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
473 if (vpc + 4 + sizeof (img) < len
474 && memcmp (prologue + vpc + 4, img, sizeof (img)) == 0)
476 info->prologue_type = AVR_PROLOGUE_MAIN;
484 /* Scanning `-mcall-prologues' prologue
485 Classic prologue is 10 bytes, mega prologue is a 12 bytes long */
487 while (1) /* Using a while to avoid many goto's */
494 /* At least the fifth instruction must have been executed to
495 modify frame shape. */
499 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
500 /* ldi r26,<LOCALS_SIZE> */
501 if ((insn & 0xf0f0) != 0xe0a0)
503 loc_size = (insn & 0xf) | ((insn & 0x0f00) >> 4);
506 insn = extract_unsigned_integer (&prologue[vpc + 2], 2, byte_order);
507 /* ldi r27,<LOCALS_SIZE> / 256 */
508 if ((insn & 0xf0f0) != 0xe0b0)
510 loc_size |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
513 insn = extract_unsigned_integer (&prologue[vpc + 4], 2, byte_order);
514 /* ldi r30,pm_lo8(.L_foo_body) */
515 if ((insn & 0xf0f0) != 0xe0e0)
517 body_addr = (insn & 0xf) | ((insn & 0x0f00) >> 4);
520 insn = extract_unsigned_integer (&prologue[vpc + 6], 2, byte_order);
521 /* ldi r31,pm_hi8(.L_foo_body) */
522 if ((insn & 0xf0f0) != 0xe0f0)
524 body_addr |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
527 msymbol = lookup_minimal_symbol ("__prologue_saves__", NULL, NULL);
531 insn = extract_unsigned_integer (&prologue[vpc + 8], 2, byte_order);
532 /* rjmp __prologue_saves__+RRR */
533 if ((insn & 0xf000) == 0xc000)
535 /* Extract PC relative offset from RJMP */
536 i = (insn & 0xfff) | (insn & 0x800 ? (-1 ^ 0xfff) : 0);
537 /* Convert offset to byte addressable mode */
539 /* Destination address */
542 if (body_addr != (pc_beg + 10)/2)
547 else if ((insn & 0xfe0e) == 0x940c)
549 /* Extract absolute PC address from JMP */
550 i = (((insn & 0x1) | ((insn & 0x1f0) >> 3) << 16)
551 | (extract_unsigned_integer (&prologue[vpc + 10], 2, byte_order)
553 /* Convert address to byte addressable mode */
556 if (body_addr != (pc_beg + 12)/2)
564 /* Resolve offset (in words) from __prologue_saves__ symbol.
565 Which is a pushes count in `-mcall-prologues' mode */
566 num_pushes = AVR_MAX_PUSHES - (i - SYMBOL_VALUE_ADDRESS (msymbol)) / 2;
568 if (num_pushes > AVR_MAX_PUSHES)
570 fprintf_unfiltered (gdb_stderr, _("Num pushes too large: %d\n"),
579 info->saved_regs[AVR_FP_REGNUM + 1].addr = num_pushes;
581 info->saved_regs[AVR_FP_REGNUM].addr = num_pushes - 1;
584 for (from = AVR_LAST_PUSHED_REGNUM + 1 - (num_pushes - 2);
585 from <= AVR_LAST_PUSHED_REGNUM; ++from)
586 info->saved_regs [from].addr = ++i;
588 info->size = loc_size + num_pushes;
589 info->prologue_type = AVR_PROLOGUE_CALL;
591 return pc_beg + pc_offset;
594 /* Scan for the beginning of the prologue for an interrupt or signal
595 function. Note that we have to set the prologue type here since the
596 third stage of the prologue may not be present (e.g. no saved registered
597 or changing of the SP register). */
601 static const unsigned char img[] = {
602 0x78, 0x94, /* sei */
603 0x1f, 0x92, /* push r1 */
604 0x0f, 0x92, /* push r0 */
605 0x0f, 0xb6, /* in r0,0x3f SREG */
606 0x0f, 0x92, /* push r0 */
607 0x11, 0x24 /* clr r1 */
609 if (len >= sizeof (img)
610 && memcmp (prologue, img, sizeof (img)) == 0)
612 info->prologue_type = AVR_PROLOGUE_INTR;
614 info->saved_regs[AVR_SREG_REGNUM].addr = 3;
615 info->saved_regs[0].addr = 2;
616 info->saved_regs[1].addr = 1;
619 else if (len >= sizeof (img) - 2
620 && memcmp (img + 2, prologue, sizeof (img) - 2) == 0)
622 info->prologue_type = AVR_PROLOGUE_SIG;
623 vpc += sizeof (img) - 2;
624 info->saved_regs[AVR_SREG_REGNUM].addr = 3;
625 info->saved_regs[0].addr = 2;
626 info->saved_regs[1].addr = 1;
631 /* First stage of the prologue scanning.
632 Scan pushes (saved registers) */
634 for (; vpc < len; vpc += 2)
636 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
637 if ((insn & 0xfe0f) == 0x920f) /* push rXX */
639 /* Bits 4-9 contain a mask for registers R0-R32. */
640 int regno = (insn & 0x1f0) >> 4;
642 info->saved_regs[regno].addr = info->size;
649 if (vpc >= AVR_MAX_PROLOGUE_SIZE)
650 fprintf_unfiltered (gdb_stderr,
651 _("Hit end of prologue while scanning pushes\n"));
653 /* Second stage of the prologue scanning.
658 if (scan_stage == 1 && vpc < len)
660 static const unsigned char img[] = {
661 0xcd, 0xb7, /* in r28,__SP_L__ */
662 0xde, 0xb7 /* in r29,__SP_H__ */
664 unsigned short insn1;
666 if (vpc + sizeof (img) < len
667 && memcmp (prologue + vpc, img, sizeof (img)) == 0)
674 /* Third stage of the prologue scanning. (Really two stages)
676 sbiw r28,XX or subi r28,lo8(XX)
678 in __tmp_reg__,__SREG__
681 out __SREG__,__tmp_reg__
684 if (scan_stage == 2 && vpc < len)
687 static const unsigned char img[] = {
688 0x0f, 0xb6, /* in r0,0x3f */
689 0xf8, 0x94, /* cli */
690 0xde, 0xbf, /* out 0x3e,r29 ; SPH */
691 0x0f, 0xbe, /* out 0x3f,r0 ; SREG */
692 0xcd, 0xbf /* out 0x3d,r28 ; SPL */
694 static const unsigned char img_sig[] = {
695 0xde, 0xbf, /* out 0x3e,r29 ; SPH */
696 0xcd, 0xbf /* out 0x3d,r28 ; SPL */
698 static const unsigned char img_int[] = {
699 0xf8, 0x94, /* cli */
700 0xde, 0xbf, /* out 0x3e,r29 ; SPH */
701 0x78, 0x94, /* sei */
702 0xcd, 0xbf /* out 0x3d,r28 ; SPL */
705 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
707 if ((insn & 0xff30) == 0x9720) /* sbiw r28,XXX */
708 locals_size = (insn & 0xf) | ((insn & 0xc0) >> 2);
709 else if ((insn & 0xf0f0) == 0x50c0) /* subi r28,lo8(XX) */
711 locals_size = (insn & 0xf) | ((insn & 0xf00) >> 4);
712 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
714 locals_size += ((insn & 0xf) | ((insn & 0xf00) >> 4) << 8);
719 /* Scan the last part of the prologue. May not be present for interrupt
720 or signal handler functions, which is why we set the prologue type
721 when we saw the beginning of the prologue previously. */
723 if (vpc + sizeof (img_sig) < len
724 && memcmp (prologue + vpc, img_sig, sizeof (img_sig)) == 0)
726 vpc += sizeof (img_sig);
728 else if (vpc + sizeof (img_int) < len
729 && memcmp (prologue + vpc, img_int, sizeof (img_int)) == 0)
731 vpc += sizeof (img_int);
733 if (vpc + sizeof (img) < len
734 && memcmp (prologue + vpc, img, sizeof (img)) == 0)
736 info->prologue_type = AVR_PROLOGUE_NORMAL;
740 info->size += locals_size;
745 /* If we got this far, we could not scan the prologue, so just return the pc
746 of the frame plus an adjustment for argument move insns. */
748 for (; vpc < len; vpc += 2)
750 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
751 if ((insn & 0xff00) == 0x0100) /* movw rXX, rYY */
753 else if ((insn & 0xfc00) == 0x2c00) /* mov rXX, rYY */
763 avr_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
765 CORE_ADDR func_addr, func_end;
766 CORE_ADDR prologue_end = pc;
768 /* See what the symbol table says */
770 if (find_pc_partial_function (pc, NULL, &func_addr, &func_end))
772 struct symtab_and_line sal;
773 struct avr_unwind_cache info = {0};
774 struct trad_frame_saved_reg saved_regs[AVR_NUM_REGS];
776 info.saved_regs = saved_regs;
778 /* Need to run the prologue scanner to figure out if the function has a
779 prologue and possibly skip over moving arguments passed via registers
780 to other registers. */
782 prologue_end = avr_scan_prologue (gdbarch, func_addr, func_end, &info);
784 if (info.prologue_type == AVR_PROLOGUE_NONE)
788 sal = find_pc_line (func_addr, 0);
790 if (sal.line != 0 && sal.end < func_end)
795 /* Either we didn't find the start of this function (nothing we can do),
796 or there's no line info, or the line after the prologue is after
797 the end of the function (there probably isn't a prologue). */
802 /* Not all avr devices support the BREAK insn. Those that don't should treat
803 it as a NOP. Thus, it should be ok. Since the avr is currently a remote
804 only target, this shouldn't be a problem (I hope). TRoth/2003-05-14 */
806 static const unsigned char *
807 avr_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR * pcptr, int *lenptr)
809 static const unsigned char avr_break_insn [] = { 0x98, 0x95 };
810 *lenptr = sizeof (avr_break_insn);
811 return avr_break_insn;
814 /* Given a return value in `regcache' with a type `type',
815 extract and copy its value into `valbuf'.
817 Return values are always passed via registers r25:r24:... */
820 avr_extract_return_value (struct type *type, struct regcache *regcache,
823 struct gdbarch *gdbarch = get_regcache_arch (regcache);
824 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
828 if (TYPE_LENGTH (type) == 1)
830 regcache_cooked_read_unsigned (regcache, 24, &c);
831 store_unsigned_integer (valbuf, 1, byte_order, c);
836 /* The MSB of the return value is always in r25, calculate which
837 register holds the LSB. */
838 int lsb_reg = 25 - TYPE_LENGTH (type) + 1;
840 for (i=0; i< TYPE_LENGTH (type); i++)
842 regcache_cooked_read (regcache, lsb_reg + i,
843 (bfd_byte *) valbuf + i);
848 /* Determine, for architecture GDBARCH, how a return value of TYPE
849 should be returned. If it is supposed to be returned in registers,
850 and READBUF is non-zero, read the appropriate value from REGCACHE,
851 and copy it into READBUF. If WRITEBUF is non-zero, write the value
852 from WRITEBUF into REGCACHE. */
854 static enum return_value_convention
855 avr_return_value (struct gdbarch *gdbarch, struct type *func_type,
856 struct type *valtype, struct regcache *regcache,
857 gdb_byte *readbuf, const gdb_byte *writebuf)
859 int struct_return = ((TYPE_CODE (valtype) == TYPE_CODE_STRUCT
860 || TYPE_CODE (valtype) == TYPE_CODE_UNION
861 || TYPE_CODE (valtype) == TYPE_CODE_ARRAY)
862 && !(TYPE_LENGTH (valtype) == 1
863 || TYPE_LENGTH (valtype) == 2
864 || TYPE_LENGTH (valtype) == 4
865 || TYPE_LENGTH (valtype) == 8));
867 if (writebuf != NULL)
869 gdb_assert (!struct_return);
870 error (_("Cannot store return value."));
875 gdb_assert (!struct_return);
876 avr_extract_return_value (valtype, regcache, readbuf);
880 return RETURN_VALUE_STRUCT_CONVENTION;
882 return RETURN_VALUE_REGISTER_CONVENTION;
886 /* Put here the code to store, into fi->saved_regs, the addresses of
887 the saved registers of frame described by FRAME_INFO. This
888 includes special registers such as pc and fp saved in special ways
889 in the stack frame. sp is even more special: the address we return
890 for it IS the sp for the next frame. */
892 static struct avr_unwind_cache *
893 avr_frame_unwind_cache (struct frame_info *this_frame,
894 void **this_prologue_cache)
896 CORE_ADDR start_pc, current_pc;
899 struct avr_unwind_cache *info;
900 struct gdbarch *gdbarch;
901 struct gdbarch_tdep *tdep;
904 if (*this_prologue_cache)
905 return *this_prologue_cache;
907 info = FRAME_OBSTACK_ZALLOC (struct avr_unwind_cache);
908 *this_prologue_cache = info;
909 info->saved_regs = trad_frame_alloc_saved_regs (this_frame);
912 info->prologue_type = AVR_PROLOGUE_NONE;
914 start_pc = get_frame_func (this_frame);
915 current_pc = get_frame_pc (this_frame);
916 if ((start_pc > 0) && (start_pc <= current_pc))
917 avr_scan_prologue (get_frame_arch (this_frame),
918 start_pc, current_pc, info);
920 if ((info->prologue_type != AVR_PROLOGUE_NONE)
921 && (info->prologue_type != AVR_PROLOGUE_MAIN))
923 ULONGEST high_base; /* High byte of FP */
925 /* The SP was moved to the FP. This indicates that a new frame
926 was created. Get THIS frame's FP value by unwinding it from
928 this_base = get_frame_register_unsigned (this_frame, AVR_FP_REGNUM);
929 high_base = get_frame_register_unsigned (this_frame, AVR_FP_REGNUM + 1);
930 this_base += (high_base << 8);
932 /* The FP points at the last saved register. Adjust the FP back
933 to before the first saved register giving the SP. */
934 prev_sp = this_base + info->size;
938 /* Assume that the FP is this frame's SP but with that pushed
939 stack space added back. */
940 this_base = get_frame_register_unsigned (this_frame, AVR_SP_REGNUM);
941 prev_sp = this_base + info->size;
944 /* Add 1 here to adjust for the post-decrement nature of the push
946 info->prev_sp = avr_make_saddr (prev_sp + 1);
947 info->base = avr_make_saddr (this_base);
949 gdbarch = get_frame_arch (this_frame);
951 /* Adjust all the saved registers so that they contain addresses and not
953 for (i = 0; i < gdbarch_num_regs (gdbarch) - 1; i++)
954 if (info->saved_regs[i].addr > 0)
955 info->saved_regs[i].addr = info->prev_sp - info->saved_regs[i].addr;
957 /* Except for the main and startup code, the return PC is always saved on
958 the stack and is at the base of the frame. */
960 if (info->prologue_type != AVR_PROLOGUE_MAIN)
961 info->saved_regs[AVR_PC_REGNUM].addr = info->prev_sp;
963 /* The previous frame's SP needed to be computed. Save the computed
965 tdep = gdbarch_tdep (gdbarch);
966 trad_frame_set_value (info->saved_regs, AVR_SP_REGNUM,
967 info->prev_sp - 1 + tdep->call_length);
973 avr_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
977 pc = frame_unwind_register_unsigned (next_frame, AVR_PC_REGNUM);
979 return avr_make_iaddr (pc);
983 avr_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame)
987 sp = frame_unwind_register_unsigned (next_frame, AVR_SP_REGNUM);
989 return avr_make_saddr (sp);
992 /* Given a GDB frame, determine the address of the calling function's
993 frame. This will be used to create a new GDB frame struct. */
996 avr_frame_this_id (struct frame_info *this_frame,
997 void **this_prologue_cache,
998 struct frame_id *this_id)
1000 struct avr_unwind_cache *info
1001 = avr_frame_unwind_cache (this_frame, this_prologue_cache);
1006 /* The FUNC is easy. */
1007 func = get_frame_func (this_frame);
1009 /* Hopefully the prologue analysis either correctly determined the
1010 frame's base (which is the SP from the previous frame), or set
1011 that base to "NULL". */
1012 base = info->prev_sp;
1016 id = frame_id_build (base, func);
1020 static struct value *
1021 avr_frame_prev_register (struct frame_info *this_frame,
1022 void **this_prologue_cache, int regnum)
1024 struct gdbarch *gdbarch = get_frame_arch (this_frame);
1025 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
1026 struct avr_unwind_cache *info
1027 = avr_frame_unwind_cache (this_frame, this_prologue_cache);
1029 if (regnum == AVR_PC_REGNUM)
1031 if (trad_frame_addr_p (info->saved_regs, regnum))
1033 /* Reading the return PC from the PC register is slightly
1034 abnormal. register_size(AVR_PC_REGNUM) says it is 4 bytes,
1035 but in reality, only two bytes (3 in upcoming mega256) are
1036 stored on the stack.
1038 Also, note that the value on the stack is an addr to a word
1039 not a byte, so we will need to multiply it by two at some
1042 And to confuse matters even more, the return address stored
1043 on the stack is in big endian byte order, even though most
1044 everything else about the avr is little endian. Ick! */
1047 unsigned char buf[3];
1048 struct gdbarch *gdbarch = get_frame_arch (this_frame);
1049 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
1051 read_memory (info->saved_regs[regnum].addr, buf, tdep->call_length);
1053 /* Extract the PC read from memory as a big-endian. */
1055 for (i = 0; i < tdep->call_length; i++)
1056 pc = (pc << 8) | buf[i];
1058 return frame_unwind_got_constant (this_frame, regnum, pc << 1);
1061 return frame_unwind_got_optimized (this_frame, regnum);
1064 return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
1067 static const struct frame_unwind avr_frame_unwind = {
1070 avr_frame_prev_register,
1072 default_frame_sniffer
1076 avr_frame_base_address (struct frame_info *this_frame, void **this_cache)
1078 struct avr_unwind_cache *info
1079 = avr_frame_unwind_cache (this_frame, this_cache);
1084 static const struct frame_base avr_frame_base = {
1086 avr_frame_base_address,
1087 avr_frame_base_address,
1088 avr_frame_base_address
1091 /* Assuming THIS_FRAME is a dummy, return the frame ID of that dummy
1092 frame. The frame ID's base needs to match the TOS value saved by
1093 save_dummy_frame_tos(), and the PC match the dummy frame's breakpoint. */
1095 static struct frame_id
1096 avr_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
1100 base = get_frame_register_unsigned (this_frame, AVR_SP_REGNUM);
1101 return frame_id_build (avr_make_saddr (base), get_frame_pc (this_frame));
1104 /* When arguments must be pushed onto the stack, they go on in reverse
1105 order. The below implements a FILO (stack) to do this. */
1110 struct stack_item *prev;
1114 static struct stack_item *
1115 push_stack_item (struct stack_item *prev, const bfd_byte *contents, int len)
1117 struct stack_item *si;
1118 si = xmalloc (sizeof (struct stack_item));
1119 si->data = xmalloc (len);
1122 memcpy (si->data, contents, len);
1126 static struct stack_item *pop_stack_item (struct stack_item *si);
1127 static struct stack_item *
1128 pop_stack_item (struct stack_item *si)
1130 struct stack_item *dead = si;
1137 /* Setup the function arguments for calling a function in the inferior.
1139 On the AVR architecture, there are 18 registers (R25 to R8) which are
1140 dedicated for passing function arguments. Up to the first 18 arguments
1141 (depending on size) may go into these registers. The rest go on the stack.
1143 All arguments are aligned to start in even-numbered registers (odd-sized
1144 arguments, including char, have one free register above them). For example,
1145 an int in arg1 and a char in arg2 would be passed as such:
1150 Arguments that are larger than 2 bytes will be split between two or more
1151 registers as available, but will NOT be split between a register and the
1152 stack. Arguments that go onto the stack are pushed last arg first (this is
1153 similar to the d10v). */
1155 /* NOTE: TRoth/2003-06-17: The rest of this comment is old looks to be
1158 An exceptional case exists for struct arguments (and possibly other
1159 aggregates such as arrays) -- if the size is larger than WORDSIZE bytes but
1160 not a multiple of WORDSIZE bytes. In this case the argument is never split
1161 between the registers and the stack, but instead is copied in its entirety
1162 onto the stack, AND also copied into as many registers as there is room
1163 for. In other words, space in registers permitting, two copies of the same
1164 argument are passed in. As far as I can tell, only the one on the stack is
1165 used, although that may be a function of the level of compiler
1166 optimization. I suspect this is a compiler bug. Arguments of these odd
1167 sizes are left-justified within the word (as opposed to arguments smaller
1168 than WORDSIZE bytes, which are right-justified).
1170 If the function is to return an aggregate type such as a struct, the caller
1171 must allocate space into which the callee will copy the return value. In
1172 this case, a pointer to the return value location is passed into the callee
1173 in register R0, which displaces one of the other arguments passed in via
1174 registers R0 to R2. */
1177 avr_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
1178 struct regcache *regcache, CORE_ADDR bp_addr,
1179 int nargs, struct value **args, CORE_ADDR sp,
1180 int struct_return, CORE_ADDR struct_addr)
1182 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
1184 unsigned char buf[3];
1185 int call_length = gdbarch_tdep (gdbarch)->call_length;
1186 CORE_ADDR return_pc = avr_convert_iaddr_to_raw (bp_addr);
1187 int regnum = AVR_ARGN_REGNUM;
1188 struct stack_item *si = NULL;
1191 /* FIXME: TRoth/2003-06-18: Not sure what to do when returning a struct. */
1194 fprintf_unfiltered (gdb_stderr, "struct_return: 0x%lx\n", struct_addr);
1195 regcache_cooked_write_unsigned (regcache, argreg--, struct_addr & 0xff);
1196 regcache_cooked_write_unsigned (regcache, argreg--, (struct_addr >>8) & 0xff);
1200 for (i = 0; i < nargs; i++)
1204 struct value *arg = args[i];
1205 struct type *type = check_typedef (value_type (arg));
1206 const bfd_byte *contents = value_contents (arg);
1207 int len = TYPE_LENGTH (type);
1209 /* Calculate the potential last register needed. */
1210 last_regnum = regnum - (len + (len & 1));
1212 /* If there are registers available, use them. Once we start putting
1213 stuff on the stack, all subsequent args go on stack. */
1214 if ((si == NULL) && (last_regnum >= 8))
1218 /* Skip a register for odd length args. */
1222 val = extract_unsigned_integer (contents, len, byte_order);
1223 for (j = 0; j < len; j++)
1224 regcache_cooked_write_unsigned
1225 (regcache, regnum--, val >> (8 * (len - j - 1)));
1227 /* No registers available, push the args onto the stack. */
1230 /* From here on, we don't care about regnum. */
1231 si = push_stack_item (si, contents, len);
1235 /* Push args onto the stack. */
1239 /* Add 1 to sp here to account for post decr nature of pushes. */
1240 write_memory (sp + 1, si->data, si->len);
1241 si = pop_stack_item (si);
1244 /* Set the return address. For the avr, the return address is the BP_ADDR.
1245 Need to push the return address onto the stack noting that it needs to be
1246 in big-endian order on the stack. */
1247 for (i = 1; i <= call_length; i++)
1249 buf[call_length - i] = return_pc & 0xff;
1254 /* Use 'sp + 1' since pushes are post decr ops. */
1255 write_memory (sp + 1, buf, call_length);
1257 /* Finally, update the SP register. */
1258 regcache_cooked_write_unsigned (regcache, AVR_SP_REGNUM,
1259 avr_convert_saddr_to_raw (sp));
1261 /* Return SP value for the dummy frame, where the return address hasn't been
1263 return sp + call_length;
1266 /* Initialize the gdbarch structure for the AVR's. */
1268 static struct gdbarch *
1269 avr_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
1271 struct gdbarch *gdbarch;
1272 struct gdbarch_tdep *tdep;
1273 struct gdbarch_list *best_arch;
1276 /* Avr-6 call instructions save 3 bytes. */
1277 switch (info.bfd_arch_info->mach)
1292 /* If there is already a candidate, use it. */
1293 for (best_arch = gdbarch_list_lookup_by_info (arches, &info);
1295 best_arch = gdbarch_list_lookup_by_info (best_arch->next, &info))
1297 if (gdbarch_tdep (best_arch->gdbarch)->call_length == call_length)
1298 return best_arch->gdbarch;
1301 /* None found, create a new architecture from the information provided. */
1302 tdep = XMALLOC (struct gdbarch_tdep);
1303 gdbarch = gdbarch_alloc (&info, tdep);
1305 tdep->call_length = call_length;
1307 set_gdbarch_short_bit (gdbarch, 2 * TARGET_CHAR_BIT);
1308 set_gdbarch_int_bit (gdbarch, 2 * TARGET_CHAR_BIT);
1309 set_gdbarch_long_bit (gdbarch, 4 * TARGET_CHAR_BIT);
1310 set_gdbarch_long_long_bit (gdbarch, 8 * TARGET_CHAR_BIT);
1311 set_gdbarch_ptr_bit (gdbarch, 2 * TARGET_CHAR_BIT);
1312 set_gdbarch_addr_bit (gdbarch, 32);
1314 set_gdbarch_float_bit (gdbarch, 4 * TARGET_CHAR_BIT);
1315 set_gdbarch_double_bit (gdbarch, 4 * TARGET_CHAR_BIT);
1316 set_gdbarch_long_double_bit (gdbarch, 4 * TARGET_CHAR_BIT);
1318 set_gdbarch_float_format (gdbarch, floatformats_ieee_single);
1319 set_gdbarch_double_format (gdbarch, floatformats_ieee_single);
1320 set_gdbarch_long_double_format (gdbarch, floatformats_ieee_single);
1322 set_gdbarch_read_pc (gdbarch, avr_read_pc);
1323 set_gdbarch_write_pc (gdbarch, avr_write_pc);
1325 set_gdbarch_num_regs (gdbarch, AVR_NUM_REGS);
1327 set_gdbarch_sp_regnum (gdbarch, AVR_SP_REGNUM);
1328 set_gdbarch_pc_regnum (gdbarch, AVR_PC_REGNUM);
1330 set_gdbarch_register_name (gdbarch, avr_register_name);
1331 set_gdbarch_register_type (gdbarch, avr_register_type);
1333 set_gdbarch_return_value (gdbarch, avr_return_value);
1334 set_gdbarch_print_insn (gdbarch, print_insn_avr);
1336 set_gdbarch_push_dummy_call (gdbarch, avr_push_dummy_call);
1338 set_gdbarch_address_to_pointer (gdbarch, avr_address_to_pointer);
1339 set_gdbarch_pointer_to_address (gdbarch, avr_pointer_to_address);
1341 set_gdbarch_skip_prologue (gdbarch, avr_skip_prologue);
1342 set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
1344 set_gdbarch_breakpoint_from_pc (gdbarch, avr_breakpoint_from_pc);
1346 frame_unwind_append_unwinder (gdbarch, &avr_frame_unwind);
1347 frame_base_set_default (gdbarch, &avr_frame_base);
1349 set_gdbarch_dummy_id (gdbarch, avr_dummy_id);
1351 set_gdbarch_unwind_pc (gdbarch, avr_unwind_pc);
1352 set_gdbarch_unwind_sp (gdbarch, avr_unwind_sp);
1357 /* Send a query request to the avr remote target asking for values of the io
1358 registers. If args parameter is not NULL, then the user has requested info
1359 on a specific io register [This still needs implemented and is ignored for
1360 now]. The query string should be one of these forms:
1362 "Ravr.io_reg" -> reply is "NN" number of io registers
1364 "Ravr.io_reg:addr,len" where addr is first register and len is number of
1365 registers to be read. The reply should be "<NAME>,VV;" for each io register
1366 where, <NAME> is a string, and VV is the hex value of the register.
1368 All io registers are 8-bit. */
1371 avr_io_reg_read_command (char *args, int from_tty)
1377 unsigned int nreg = 0;
1381 /* Find out how many io registers the target has. */
1382 bufsiz = target_read_alloc (¤t_target, TARGET_OBJECT_AVR,
1383 "avr.io_reg", &buf);
1387 fprintf_unfiltered (gdb_stderr,
1388 _("ERR: info io_registers NOT supported "
1389 "by current target\n"));
1393 if (sscanf (buf, "%x", &nreg) != 1)
1395 fprintf_unfiltered (gdb_stderr,
1396 _("Error fetching number of io registers\n"));
1403 reinitialize_more_filter ();
1405 printf_unfiltered (_("Target has %u io registers:\n\n"), nreg);
1407 /* only fetch up to 8 registers at a time to keep the buffer small */
1410 for (i = 0; i < nreg; i += step)
1412 /* how many registers this round? */
1415 j = nreg - i; /* last block is less than 8 registers */
1417 snprintf (query, sizeof (query) - 1, "avr.io_reg:%x,%x", i, j);
1418 bufsiz = target_read_alloc (¤t_target, TARGET_OBJECT_AVR,
1422 for (k = i; k < (i + j); k++)
1424 if (sscanf (p, "%[^,],%x;", query, &val) == 2)
1426 printf_filtered ("[%02x] %-15s : %02x\n", k, query, val);
1427 while ((*p != ';') && (*p != '\0'))
1429 p++; /* skip over ';' */
1439 extern initialize_file_ftype _initialize_avr_tdep; /* -Wmissing-prototypes */
1442 _initialize_avr_tdep (void)
1444 register_gdbarch_init (bfd_arch_avr, avr_gdbarch_init);
1446 /* Add a new command to allow the user to query the avr remote target for
1447 the values of the io space registers in a saner way than just using
1450 /* FIXME: TRoth/2002-02-18: This should probably be changed to 'info avr
1451 io_registers' to signify it is not available on other platforms. */
1453 add_cmd ("io_registers", class_info, avr_io_reg_read_command,
1454 _("query remote avr target for io space register values"),