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 0 for NULL. */
247 return ((x) | AVR_SMEM_START);
251 avr_convert_saddr_to_raw (CORE_ADDR x)
253 return ((x) & 0xffffffff);
256 /* EEPROM address checks and convertions. I don't know if these will ever
257 actually be used, but I've added them just the same. TRoth */
259 /* TRoth/2002-04-08: Commented out for now to allow fix for problem with large
260 programs in the mega128. */
262 /* static CORE_ADDR */
263 /* avr_make_eaddr (CORE_ADDR x) */
265 /* return ((x) | AVR_EMEM_START); */
269 /* avr_eaddr_p (CORE_ADDR x) */
271 /* return (((x) & AVR_MEM_MASK) == AVR_EMEM_START); */
274 /* static CORE_ADDR */
275 /* avr_convert_eaddr_to_raw (CORE_ADDR x) */
277 /* return ((x) & 0xffffffff); */
280 /* Convert from address to pointer and vice-versa. */
283 avr_address_to_pointer (struct gdbarch *gdbarch,
284 struct type *type, gdb_byte *buf, CORE_ADDR addr)
286 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
288 /* Is it a code address? */
289 if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_FUNC
290 || TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_METHOD)
292 store_unsigned_integer (buf, TYPE_LENGTH (type), byte_order,
293 avr_convert_iaddr_to_raw (addr >> 1));
297 /* Strip off any upper segment bits. */
298 store_unsigned_integer (buf, TYPE_LENGTH (type), byte_order,
299 avr_convert_saddr_to_raw (addr));
304 avr_pointer_to_address (struct gdbarch *gdbarch,
305 struct type *type, const gdb_byte *buf)
307 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
309 = extract_unsigned_integer (buf, TYPE_LENGTH (type), byte_order);
311 /* Is it a code address? */
312 if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_FUNC
313 || TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_METHOD
314 || TYPE_CODE_SPACE (TYPE_TARGET_TYPE (type)))
315 return avr_make_iaddr (addr << 1);
317 return avr_make_saddr (addr);
321 avr_integer_to_address (struct gdbarch *gdbarch,
322 struct type *type, const gdb_byte *buf)
324 ULONGEST addr = unpack_long (type, buf);
326 return avr_make_saddr (addr);
330 avr_read_pc (struct regcache *regcache)
333 regcache_cooked_read_unsigned (regcache, AVR_PC_REGNUM, &pc);
334 return avr_make_iaddr (pc);
338 avr_write_pc (struct regcache *regcache, CORE_ADDR val)
340 regcache_cooked_write_unsigned (regcache, AVR_PC_REGNUM,
341 avr_convert_iaddr_to_raw (val));
344 /* Function: avr_scan_prologue
346 This function decodes an AVR function prologue to determine:
347 1) the size of the stack frame
348 2) which registers are saved on it
349 3) the offsets of saved regs
350 This information is stored in the avr_unwind_cache structure.
352 Some devices lack the sbiw instruction, so on those replace this:
358 A typical AVR function prologue with a frame pointer might look like this:
359 push rXX ; saved regs
365 sbiw r28,<LOCALS_SIZE>
366 in __tmp_reg__,__SREG__
369 out __SREG__,__tmp_reg__
372 A typical AVR function prologue without a frame pointer might look like
374 push rXX ; saved regs
377 A main function prologue looks like this:
378 ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>)
379 ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>)
383 A signal handler prologue looks like this:
386 in __tmp_reg__, __SREG__
389 push rXX ; save registers r18:r27, r30:r31
391 push r28 ; save frame pointer
395 sbiw r28, <LOCALS_SIZE>
399 A interrupt handler prologue looks like this:
403 in __tmp_reg__, __SREG__
406 push rXX ; save registers r18:r27, r30:r31
408 push r28 ; save frame pointer
412 sbiw r28, <LOCALS_SIZE>
418 A `-mcall-prologues' prologue looks like this (Note that the megas use a
419 jmp instead of a rjmp, thus the prologue is one word larger since jmp is a
420 32 bit insn and rjmp is a 16 bit insn):
421 ldi r26,lo8(<LOCALS_SIZE>)
422 ldi r27,hi8(<LOCALS_SIZE>)
423 ldi r30,pm_lo8(.L_foo_body)
424 ldi r31,pm_hi8(.L_foo_body)
425 rjmp __prologue_saves__+RRR
428 /* Not really part of a prologue, but still need to scan for it, is when a
429 function prologue moves values passed via registers as arguments to new
430 registers. In this case, all local variables live in registers, so there
431 may be some register saves. This is what it looks like:
435 There could be multiple movw's. If the target doesn't have a movw insn, it
436 will use two mov insns. This could be done after any of the above prologue
440 avr_scan_prologue (struct gdbarch *gdbarch, CORE_ADDR pc_beg, CORE_ADDR pc_end,
441 struct avr_unwind_cache *info)
443 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
447 struct minimal_symbol *msymbol;
448 unsigned char prologue[AVR_MAX_PROLOGUE_SIZE];
452 len = pc_end - pc_beg;
453 if (len > AVR_MAX_PROLOGUE_SIZE)
454 len = AVR_MAX_PROLOGUE_SIZE;
456 /* FIXME: TRoth/2003-06-11: This could be made more efficient by only
457 reading in the bytes of the prologue. The problem is that the figuring
458 out where the end of the prologue is is a bit difficult. The old code
459 tried to do that, but failed quite often. */
460 read_memory (pc_beg, prologue, len);
462 /* Scanning main()'s prologue
463 ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>)
464 ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>)
471 static const unsigned char img[] = {
472 0xde, 0xbf, /* out __SP_H__,r29 */
473 0xcd, 0xbf /* out __SP_L__,r28 */
476 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
477 /* ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>) */
478 if ((insn & 0xf0f0) == 0xe0c0)
480 locals = (insn & 0xf) | ((insn & 0x0f00) >> 4);
481 insn = extract_unsigned_integer (&prologue[vpc + 2], 2, byte_order);
482 /* ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>) */
483 if ((insn & 0xf0f0) == 0xe0d0)
485 locals |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
486 if (vpc + 4 + sizeof (img) < len
487 && memcmp (prologue + vpc + 4, img, sizeof (img)) == 0)
489 info->prologue_type = AVR_PROLOGUE_MAIN;
497 /* Scanning `-mcall-prologues' prologue
498 Classic prologue is 10 bytes, mega prologue is a 12 bytes long */
500 while (1) /* Using a while to avoid many goto's */
507 /* At least the fifth instruction must have been executed to
508 modify frame shape. */
512 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
513 /* ldi r26,<LOCALS_SIZE> */
514 if ((insn & 0xf0f0) != 0xe0a0)
516 loc_size = (insn & 0xf) | ((insn & 0x0f00) >> 4);
519 insn = extract_unsigned_integer (&prologue[vpc + 2], 2, byte_order);
520 /* ldi r27,<LOCALS_SIZE> / 256 */
521 if ((insn & 0xf0f0) != 0xe0b0)
523 loc_size |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
526 insn = extract_unsigned_integer (&prologue[vpc + 4], 2, byte_order);
527 /* ldi r30,pm_lo8(.L_foo_body) */
528 if ((insn & 0xf0f0) != 0xe0e0)
530 body_addr = (insn & 0xf) | ((insn & 0x0f00) >> 4);
533 insn = extract_unsigned_integer (&prologue[vpc + 6], 2, byte_order);
534 /* ldi r31,pm_hi8(.L_foo_body) */
535 if ((insn & 0xf0f0) != 0xe0f0)
537 body_addr |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
540 msymbol = lookup_minimal_symbol ("__prologue_saves__", NULL, NULL);
544 insn = extract_unsigned_integer (&prologue[vpc + 8], 2, byte_order);
545 /* rjmp __prologue_saves__+RRR */
546 if ((insn & 0xf000) == 0xc000)
548 /* Extract PC relative offset from RJMP */
549 i = (insn & 0xfff) | (insn & 0x800 ? (-1 ^ 0xfff) : 0);
550 /* Convert offset to byte addressable mode */
552 /* Destination address */
555 if (body_addr != (pc_beg + 10)/2)
560 else if ((insn & 0xfe0e) == 0x940c)
562 /* Extract absolute PC address from JMP */
563 i = (((insn & 0x1) | ((insn & 0x1f0) >> 3) << 16)
564 | (extract_unsigned_integer (&prologue[vpc + 10], 2, byte_order)
566 /* Convert address to byte addressable mode */
569 if (body_addr != (pc_beg + 12)/2)
577 /* Resolve offset (in words) from __prologue_saves__ symbol.
578 Which is a pushes count in `-mcall-prologues' mode */
579 num_pushes = AVR_MAX_PUSHES - (i - SYMBOL_VALUE_ADDRESS (msymbol)) / 2;
581 if (num_pushes > AVR_MAX_PUSHES)
583 fprintf_unfiltered (gdb_stderr, _("Num pushes too large: %d\n"),
592 info->saved_regs[AVR_FP_REGNUM + 1].addr = num_pushes;
594 info->saved_regs[AVR_FP_REGNUM].addr = num_pushes - 1;
597 for (from = AVR_LAST_PUSHED_REGNUM + 1 - (num_pushes - 2);
598 from <= AVR_LAST_PUSHED_REGNUM; ++from)
599 info->saved_regs [from].addr = ++i;
601 info->size = loc_size + num_pushes;
602 info->prologue_type = AVR_PROLOGUE_CALL;
604 return pc_beg + pc_offset;
607 /* Scan for the beginning of the prologue for an interrupt or signal
608 function. Note that we have to set the prologue type here since the
609 third stage of the prologue may not be present (e.g. no saved registered
610 or changing of the SP register). */
614 static const unsigned char img[] = {
615 0x78, 0x94, /* sei */
616 0x1f, 0x92, /* push r1 */
617 0x0f, 0x92, /* push r0 */
618 0x0f, 0xb6, /* in r0,0x3f SREG */
619 0x0f, 0x92, /* push r0 */
620 0x11, 0x24 /* clr r1 */
622 if (len >= sizeof (img)
623 && memcmp (prologue, img, sizeof (img)) == 0)
625 info->prologue_type = AVR_PROLOGUE_INTR;
627 info->saved_regs[AVR_SREG_REGNUM].addr = 3;
628 info->saved_regs[0].addr = 2;
629 info->saved_regs[1].addr = 1;
632 else if (len >= sizeof (img) - 2
633 && memcmp (img + 2, prologue, sizeof (img) - 2) == 0)
635 info->prologue_type = AVR_PROLOGUE_SIG;
636 vpc += sizeof (img) - 2;
637 info->saved_regs[AVR_SREG_REGNUM].addr = 3;
638 info->saved_regs[0].addr = 2;
639 info->saved_regs[1].addr = 1;
644 /* First stage of the prologue scanning.
645 Scan pushes (saved registers) */
647 for (; vpc < len; vpc += 2)
649 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
650 if ((insn & 0xfe0f) == 0x920f) /* push rXX */
652 /* Bits 4-9 contain a mask for registers R0-R32. */
653 int regno = (insn & 0x1f0) >> 4;
655 info->saved_regs[regno].addr = info->size;
662 if (vpc >= AVR_MAX_PROLOGUE_SIZE)
663 fprintf_unfiltered (gdb_stderr,
664 _("Hit end of prologue while scanning pushes\n"));
666 /* Handle static small stack allocation using rcall or push. */
668 while (scan_stage == 1 && vpc < len)
670 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
671 if (insn == 0xd000) /* rcall .+0 */
673 info->size += gdbarch_tdep (gdbarch)->call_length;
676 else if (insn == 0x920f) /* push r0 */
685 /* Second stage of the prologue scanning.
690 if (scan_stage == 1 && vpc < len)
692 static const unsigned char img[] = {
693 0xcd, 0xb7, /* in r28,__SP_L__ */
694 0xde, 0xb7 /* in r29,__SP_H__ */
696 unsigned short insn1;
698 if (vpc + sizeof (img) < len
699 && memcmp (prologue + vpc, img, sizeof (img)) == 0)
706 /* Third stage of the prologue scanning. (Really two stages)
708 sbiw r28,XX or subi r28,lo8(XX)
710 in __tmp_reg__,__SREG__
713 out __SREG__,__tmp_reg__
716 if (scan_stage == 2 && vpc < len)
719 static const unsigned char img[] = {
720 0x0f, 0xb6, /* in r0,0x3f */
721 0xf8, 0x94, /* cli */
722 0xde, 0xbf, /* out 0x3e,r29 ; SPH */
723 0x0f, 0xbe, /* out 0x3f,r0 ; SREG */
724 0xcd, 0xbf /* out 0x3d,r28 ; SPL */
726 static const unsigned char img_sig[] = {
727 0xde, 0xbf, /* out 0x3e,r29 ; SPH */
728 0xcd, 0xbf /* out 0x3d,r28 ; SPL */
730 static const unsigned char img_int[] = {
731 0xf8, 0x94, /* cli */
732 0xde, 0xbf, /* out 0x3e,r29 ; SPH */
733 0x78, 0x94, /* sei */
734 0xcd, 0xbf /* out 0x3d,r28 ; SPL */
737 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
738 if ((insn & 0xff30) == 0x9720) /* sbiw r28,XXX */
740 locals_size = (insn & 0xf) | ((insn & 0xc0) >> 2);
743 else if ((insn & 0xf0f0) == 0x50c0) /* subi r28,lo8(XX) */
745 locals_size = (insn & 0xf) | ((insn & 0xf00) >> 4);
747 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
749 locals_size += ((insn & 0xf) | ((insn & 0xf00) >> 4)) << 8;
754 /* Scan the last part of the prologue. May not be present for interrupt
755 or signal handler functions, which is why we set the prologue type
756 when we saw the beginning of the prologue previously. */
758 if (vpc + sizeof (img_sig) < len
759 && memcmp (prologue + vpc, img_sig, sizeof (img_sig)) == 0)
761 vpc += sizeof (img_sig);
763 else if (vpc + sizeof (img_int) < len
764 && memcmp (prologue + vpc, img_int, sizeof (img_int)) == 0)
766 vpc += sizeof (img_int);
768 if (vpc + sizeof (img) < len
769 && memcmp (prologue + vpc, img, sizeof (img)) == 0)
771 info->prologue_type = AVR_PROLOGUE_NORMAL;
775 info->size += locals_size;
780 /* If we got this far, we could not scan the prologue, so just return the pc
781 of the frame plus an adjustment for argument move insns. */
783 for (; vpc < len; vpc += 2)
785 insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
786 if ((insn & 0xff00) == 0x0100) /* movw rXX, rYY */
788 else if ((insn & 0xfc00) == 0x2c00) /* mov rXX, rYY */
798 avr_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
800 CORE_ADDR func_addr, func_end;
801 CORE_ADDR post_prologue_pc;
803 /* See what the symbol table says */
805 if (!find_pc_partial_function (pc, NULL, &func_addr, &func_end))
808 post_prologue_pc = skip_prologue_using_sal (gdbarch, func_addr);
809 if (post_prologue_pc != 0)
810 return max (pc, post_prologue_pc);
813 CORE_ADDR prologue_end = pc;
814 struct avr_unwind_cache info = {0};
815 struct trad_frame_saved_reg saved_regs[AVR_NUM_REGS];
817 info.saved_regs = saved_regs;
819 /* Need to run the prologue scanner to figure out if the function has a
820 prologue and possibly skip over moving arguments passed via registers
821 to other registers. */
823 prologue_end = avr_scan_prologue (gdbarch, func_addr, func_end, &info);
825 if (info.prologue_type != AVR_PROLOGUE_NONE)
829 /* Either we didn't find the start of this function (nothing we can do),
830 or there's no line info, or the line after the prologue is after
831 the end of the function (there probably isn't a prologue). */
836 /* Not all avr devices support the BREAK insn. Those that don't should treat
837 it as a NOP. Thus, it should be ok. Since the avr is currently a remote
838 only target, this shouldn't be a problem (I hope). TRoth/2003-05-14 */
840 static const unsigned char *
841 avr_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR * pcptr, int *lenptr)
843 static const unsigned char avr_break_insn [] = { 0x98, 0x95 };
844 *lenptr = sizeof (avr_break_insn);
845 return avr_break_insn;
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)
860 /* Single byte are returned in r24.
861 Otherwise, the MSB of the return value is always in r25, calculate which
862 register holds the LSB. */
865 if ((TYPE_CODE (valtype) == TYPE_CODE_STRUCT
866 || TYPE_CODE (valtype) == TYPE_CODE_UNION
867 || TYPE_CODE (valtype) == TYPE_CODE_ARRAY)
868 && TYPE_LENGTH (valtype) > 8)
869 return RETURN_VALUE_STRUCT_CONVENTION;
871 if (TYPE_LENGTH (valtype) <= 2)
873 else if (TYPE_LENGTH (valtype) <= 4)
875 else if (TYPE_LENGTH (valtype) <= 8)
880 if (writebuf != NULL)
882 for (i = 0; i < TYPE_LENGTH (valtype); i++)
883 regcache_cooked_write (regcache, lsb_reg + i, writebuf + i);
888 for (i = 0; i < TYPE_LENGTH (valtype); i++)
889 regcache_cooked_read (regcache, lsb_reg + i, readbuf + i);
892 return RETURN_VALUE_REGISTER_CONVENTION;
896 /* Put here the code to store, into fi->saved_regs, the addresses of
897 the saved registers of frame described by FRAME_INFO. This
898 includes special registers such as pc and fp saved in special ways
899 in the stack frame. sp is even more special: the address we return
900 for it IS the sp for the next frame. */
902 static struct avr_unwind_cache *
903 avr_frame_unwind_cache (struct frame_info *this_frame,
904 void **this_prologue_cache)
906 CORE_ADDR start_pc, current_pc;
909 struct avr_unwind_cache *info;
910 struct gdbarch *gdbarch;
911 struct gdbarch_tdep *tdep;
914 if (*this_prologue_cache)
915 return *this_prologue_cache;
917 info = FRAME_OBSTACK_ZALLOC (struct avr_unwind_cache);
918 *this_prologue_cache = info;
919 info->saved_regs = trad_frame_alloc_saved_regs (this_frame);
922 info->prologue_type = AVR_PROLOGUE_NONE;
924 start_pc = get_frame_func (this_frame);
925 current_pc = get_frame_pc (this_frame);
926 if ((start_pc > 0) && (start_pc <= current_pc))
927 avr_scan_prologue (get_frame_arch (this_frame),
928 start_pc, current_pc, info);
930 if ((info->prologue_type != AVR_PROLOGUE_NONE)
931 && (info->prologue_type != AVR_PROLOGUE_MAIN))
933 ULONGEST high_base; /* High byte of FP */
935 /* The SP was moved to the FP. This indicates that a new frame
936 was created. Get THIS frame's FP value by unwinding it from
938 this_base = get_frame_register_unsigned (this_frame, AVR_FP_REGNUM);
939 high_base = get_frame_register_unsigned (this_frame, AVR_FP_REGNUM + 1);
940 this_base += (high_base << 8);
942 /* The FP points at the last saved register. Adjust the FP back
943 to before the first saved register giving the SP. */
944 prev_sp = this_base + info->size;
948 /* Assume that the FP is this frame's SP but with that pushed
949 stack space added back. */
950 this_base = get_frame_register_unsigned (this_frame, AVR_SP_REGNUM);
951 prev_sp = this_base + info->size;
954 /* Add 1 here to adjust for the post-decrement nature of the push
956 info->prev_sp = avr_make_saddr (prev_sp + 1);
957 info->base = avr_make_saddr (this_base);
959 gdbarch = get_frame_arch (this_frame);
961 /* Adjust all the saved registers so that they contain addresses and not
963 for (i = 0; i < gdbarch_num_regs (gdbarch) - 1; i++)
964 if (info->saved_regs[i].addr > 0)
965 info->saved_regs[i].addr = info->prev_sp - info->saved_regs[i].addr;
967 /* Except for the main and startup code, the return PC is always saved on
968 the stack and is at the base of the frame. */
970 if (info->prologue_type != AVR_PROLOGUE_MAIN)
971 info->saved_regs[AVR_PC_REGNUM].addr = info->prev_sp;
973 /* The previous frame's SP needed to be computed. Save the computed
975 tdep = gdbarch_tdep (gdbarch);
976 trad_frame_set_value (info->saved_regs, AVR_SP_REGNUM,
977 info->prev_sp - 1 + tdep->call_length);
983 avr_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
987 pc = frame_unwind_register_unsigned (next_frame, AVR_PC_REGNUM);
989 return avr_make_iaddr (pc);
993 avr_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame)
997 sp = frame_unwind_register_unsigned (next_frame, AVR_SP_REGNUM);
999 return avr_make_saddr (sp);
1002 /* Given a GDB frame, determine the address of the calling function's
1003 frame. This will be used to create a new GDB frame struct. */
1006 avr_frame_this_id (struct frame_info *this_frame,
1007 void **this_prologue_cache,
1008 struct frame_id *this_id)
1010 struct avr_unwind_cache *info
1011 = avr_frame_unwind_cache (this_frame, this_prologue_cache);
1016 /* The FUNC is easy. */
1017 func = get_frame_func (this_frame);
1019 /* Hopefully the prologue analysis either correctly determined the
1020 frame's base (which is the SP from the previous frame), or set
1021 that base to "NULL". */
1022 base = info->prev_sp;
1026 id = frame_id_build (base, func);
1030 static struct value *
1031 avr_frame_prev_register (struct frame_info *this_frame,
1032 void **this_prologue_cache, int regnum)
1034 struct gdbarch *gdbarch = get_frame_arch (this_frame);
1035 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
1036 struct avr_unwind_cache *info
1037 = avr_frame_unwind_cache (this_frame, this_prologue_cache);
1039 if (regnum == AVR_PC_REGNUM)
1041 if (trad_frame_addr_p (info->saved_regs, regnum))
1043 /* Reading the return PC from the PC register is slightly
1044 abnormal. register_size(AVR_PC_REGNUM) says it is 4 bytes,
1045 but in reality, only two bytes (3 in upcoming mega256) are
1046 stored on the stack.
1048 Also, note that the value on the stack is an addr to a word
1049 not a byte, so we will need to multiply it by two at some
1052 And to confuse matters even more, the return address stored
1053 on the stack is in big endian byte order, even though most
1054 everything else about the avr is little endian. Ick! */
1057 unsigned char buf[3];
1058 struct gdbarch *gdbarch = get_frame_arch (this_frame);
1059 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
1061 read_memory (info->saved_regs[regnum].addr, buf, tdep->call_length);
1063 /* Extract the PC read from memory as a big-endian. */
1065 for (i = 0; i < tdep->call_length; i++)
1066 pc = (pc << 8) | buf[i];
1068 return frame_unwind_got_constant (this_frame, regnum, pc << 1);
1071 return frame_unwind_got_optimized (this_frame, regnum);
1074 return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
1077 static const struct frame_unwind avr_frame_unwind = {
1080 avr_frame_prev_register,
1082 default_frame_sniffer
1086 avr_frame_base_address (struct frame_info *this_frame, void **this_cache)
1088 struct avr_unwind_cache *info
1089 = avr_frame_unwind_cache (this_frame, this_cache);
1094 static const struct frame_base avr_frame_base = {
1096 avr_frame_base_address,
1097 avr_frame_base_address,
1098 avr_frame_base_address
1101 /* Assuming THIS_FRAME is a dummy, return the frame ID of that dummy
1102 frame. The frame ID's base needs to match the TOS value saved by
1103 save_dummy_frame_tos(), and the PC match the dummy frame's breakpoint. */
1105 static struct frame_id
1106 avr_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
1110 base = get_frame_register_unsigned (this_frame, AVR_SP_REGNUM);
1111 return frame_id_build (avr_make_saddr (base), get_frame_pc (this_frame));
1114 /* When arguments must be pushed onto the stack, they go on in reverse
1115 order. The below implements a FILO (stack) to do this. */
1120 struct stack_item *prev;
1124 static struct stack_item *
1125 push_stack_item (struct stack_item *prev, const bfd_byte *contents, int len)
1127 struct stack_item *si;
1128 si = xmalloc (sizeof (struct stack_item));
1129 si->data = xmalloc (len);
1132 memcpy (si->data, contents, len);
1136 static struct stack_item *pop_stack_item (struct stack_item *si);
1137 static struct stack_item *
1138 pop_stack_item (struct stack_item *si)
1140 struct stack_item *dead = si;
1147 /* Setup the function arguments for calling a function in the inferior.
1149 On the AVR architecture, there are 18 registers (R25 to R8) which are
1150 dedicated for passing function arguments. Up to the first 18 arguments
1151 (depending on size) may go into these registers. The rest go on the stack.
1153 All arguments are aligned to start in even-numbered registers (odd-sized
1154 arguments, including char, have one free register above them). For example,
1155 an int in arg1 and a char in arg2 would be passed as such:
1160 Arguments that are larger than 2 bytes will be split between two or more
1161 registers as available, but will NOT be split between a register and the
1162 stack. Arguments that go onto the stack are pushed last arg first (this is
1163 similar to the d10v). */
1165 /* NOTE: TRoth/2003-06-17: The rest of this comment is old looks to be
1168 An exceptional case exists for struct arguments (and possibly other
1169 aggregates such as arrays) -- if the size is larger than WORDSIZE bytes but
1170 not a multiple of WORDSIZE bytes. In this case the argument is never split
1171 between the registers and the stack, but instead is copied in its entirety
1172 onto the stack, AND also copied into as many registers as there is room
1173 for. In other words, space in registers permitting, two copies of the same
1174 argument are passed in. As far as I can tell, only the one on the stack is
1175 used, although that may be a function of the level of compiler
1176 optimization. I suspect this is a compiler bug. Arguments of these odd
1177 sizes are left-justified within the word (as opposed to arguments smaller
1178 than WORDSIZE bytes, which are right-justified).
1180 If the function is to return an aggregate type such as a struct, the caller
1181 must allocate space into which the callee will copy the return value. In
1182 this case, a pointer to the return value location is passed into the callee
1183 in register R0, which displaces one of the other arguments passed in via
1184 registers R0 to R2. */
1187 avr_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
1188 struct regcache *regcache, CORE_ADDR bp_addr,
1189 int nargs, struct value **args, CORE_ADDR sp,
1190 int struct_return, CORE_ADDR struct_addr)
1192 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
1194 unsigned char buf[3];
1195 int call_length = gdbarch_tdep (gdbarch)->call_length;
1196 CORE_ADDR return_pc = avr_convert_iaddr_to_raw (bp_addr);
1197 int regnum = AVR_ARGN_REGNUM;
1198 struct stack_item *si = NULL;
1202 regcache_cooked_write_unsigned (regcache, regnum--,
1203 struct_addr & 0xff);
1204 regcache_cooked_write_unsigned (regcache, regnum--,
1205 (struct_addr >> 8) & 0xff);
1208 for (i = 0; i < nargs; i++)
1212 struct value *arg = args[i];
1213 struct type *type = check_typedef (value_type (arg));
1214 const bfd_byte *contents = value_contents (arg);
1215 int len = TYPE_LENGTH (type);
1217 /* Calculate the potential last register needed. */
1218 last_regnum = regnum - (len + (len & 1));
1220 /* If there are registers available, use them. Once we start putting
1221 stuff on the stack, all subsequent args go on stack. */
1222 if ((si == NULL) && (last_regnum >= 8))
1226 /* Skip a register for odd length args. */
1230 val = extract_unsigned_integer (contents, len, byte_order);
1231 for (j = 0; j < len; j++)
1232 regcache_cooked_write_unsigned
1233 (regcache, regnum--, val >> (8 * (len - j - 1)));
1235 /* No registers available, push the args onto the stack. */
1238 /* From here on, we don't care about regnum. */
1239 si = push_stack_item (si, contents, len);
1243 /* Push args onto the stack. */
1247 /* Add 1 to sp here to account for post decr nature of pushes. */
1248 write_memory (sp + 1, si->data, si->len);
1249 si = pop_stack_item (si);
1252 /* Set the return address. For the avr, the return address is the BP_ADDR.
1253 Need to push the return address onto the stack noting that it needs to be
1254 in big-endian order on the stack. */
1255 for (i = 1; i <= call_length; i++)
1257 buf[call_length - i] = return_pc & 0xff;
1262 /* Use 'sp + 1' since pushes are post decr ops. */
1263 write_memory (sp + 1, buf, call_length);
1265 /* Finally, update the SP register. */
1266 regcache_cooked_write_unsigned (regcache, AVR_SP_REGNUM,
1267 avr_convert_saddr_to_raw (sp));
1269 /* Return SP value for the dummy frame, where the return address hasn't been
1271 return sp + call_length;
1274 /* Unfortunately dwarf2 register for SP is 32. */
1277 avr_dwarf_reg_to_regnum (struct gdbarch *gdbarch, int reg)
1279 if (reg >= 0 && reg < 32)
1282 return AVR_SP_REGNUM;
1284 warning (_("Unmapped DWARF Register #%d encountered."), reg);
1289 /* Initialize the gdbarch structure for the AVR's. */
1291 static struct gdbarch *
1292 avr_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
1294 struct gdbarch *gdbarch;
1295 struct gdbarch_tdep *tdep;
1296 struct gdbarch_list *best_arch;
1299 /* Avr-6 call instructions save 3 bytes. */
1300 switch (info.bfd_arch_info->mach)
1315 /* If there is already a candidate, use it. */
1316 for (best_arch = gdbarch_list_lookup_by_info (arches, &info);
1318 best_arch = gdbarch_list_lookup_by_info (best_arch->next, &info))
1320 if (gdbarch_tdep (best_arch->gdbarch)->call_length == call_length)
1321 return best_arch->gdbarch;
1324 /* None found, create a new architecture from the information provided. */
1325 tdep = XMALLOC (struct gdbarch_tdep);
1326 gdbarch = gdbarch_alloc (&info, tdep);
1328 tdep->call_length = call_length;
1330 set_gdbarch_short_bit (gdbarch, 2 * TARGET_CHAR_BIT);
1331 set_gdbarch_int_bit (gdbarch, 2 * TARGET_CHAR_BIT);
1332 set_gdbarch_long_bit (gdbarch, 4 * TARGET_CHAR_BIT);
1333 set_gdbarch_long_long_bit (gdbarch, 8 * TARGET_CHAR_BIT);
1334 set_gdbarch_ptr_bit (gdbarch, 2 * TARGET_CHAR_BIT);
1335 set_gdbarch_addr_bit (gdbarch, 32);
1337 set_gdbarch_float_bit (gdbarch, 4 * TARGET_CHAR_BIT);
1338 set_gdbarch_double_bit (gdbarch, 4 * TARGET_CHAR_BIT);
1339 set_gdbarch_long_double_bit (gdbarch, 4 * TARGET_CHAR_BIT);
1341 set_gdbarch_float_format (gdbarch, floatformats_ieee_single);
1342 set_gdbarch_double_format (gdbarch, floatformats_ieee_single);
1343 set_gdbarch_long_double_format (gdbarch, floatformats_ieee_single);
1345 set_gdbarch_read_pc (gdbarch, avr_read_pc);
1346 set_gdbarch_write_pc (gdbarch, avr_write_pc);
1348 set_gdbarch_num_regs (gdbarch, AVR_NUM_REGS);
1350 set_gdbarch_sp_regnum (gdbarch, AVR_SP_REGNUM);
1351 set_gdbarch_pc_regnum (gdbarch, AVR_PC_REGNUM);
1353 set_gdbarch_register_name (gdbarch, avr_register_name);
1354 set_gdbarch_register_type (gdbarch, avr_register_type);
1356 set_gdbarch_return_value (gdbarch, avr_return_value);
1357 set_gdbarch_print_insn (gdbarch, print_insn_avr);
1359 set_gdbarch_push_dummy_call (gdbarch, avr_push_dummy_call);
1361 set_gdbarch_dwarf2_reg_to_regnum (gdbarch, avr_dwarf_reg_to_regnum);
1363 set_gdbarch_address_to_pointer (gdbarch, avr_address_to_pointer);
1364 set_gdbarch_pointer_to_address (gdbarch, avr_pointer_to_address);
1365 set_gdbarch_integer_to_address (gdbarch, avr_integer_to_address);
1367 set_gdbarch_skip_prologue (gdbarch, avr_skip_prologue);
1368 set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
1370 set_gdbarch_breakpoint_from_pc (gdbarch, avr_breakpoint_from_pc);
1372 frame_unwind_append_unwinder (gdbarch, &avr_frame_unwind);
1373 frame_base_set_default (gdbarch, &avr_frame_base);
1375 set_gdbarch_dummy_id (gdbarch, avr_dummy_id);
1377 set_gdbarch_unwind_pc (gdbarch, avr_unwind_pc);
1378 set_gdbarch_unwind_sp (gdbarch, avr_unwind_sp);
1383 /* Send a query request to the avr remote target asking for values of the io
1384 registers. If args parameter is not NULL, then the user has requested info
1385 on a specific io register [This still needs implemented and is ignored for
1386 now]. The query string should be one of these forms:
1388 "Ravr.io_reg" -> reply is "NN" number of io registers
1390 "Ravr.io_reg:addr,len" where addr is first register and len is number of
1391 registers to be read. The reply should be "<NAME>,VV;" for each io register
1392 where, <NAME> is a string, and VV is the hex value of the register.
1394 All io registers are 8-bit. */
1397 avr_io_reg_read_command (char *args, int from_tty)
1403 unsigned int nreg = 0;
1407 /* Find out how many io registers the target has. */
1408 bufsiz = target_read_alloc (¤t_target, TARGET_OBJECT_AVR,
1409 "avr.io_reg", &buf);
1413 fprintf_unfiltered (gdb_stderr,
1414 _("ERR: info io_registers NOT supported "
1415 "by current target\n"));
1419 if (sscanf (buf, "%x", &nreg) != 1)
1421 fprintf_unfiltered (gdb_stderr,
1422 _("Error fetching number of io registers\n"));
1429 reinitialize_more_filter ();
1431 printf_unfiltered (_("Target has %u io registers:\n\n"), nreg);
1433 /* only fetch up to 8 registers at a time to keep the buffer small */
1436 for (i = 0; i < nreg; i += step)
1438 /* how many registers this round? */
1441 j = nreg - i; /* last block is less than 8 registers */
1443 snprintf (query, sizeof (query) - 1, "avr.io_reg:%x,%x", i, j);
1444 bufsiz = target_read_alloc (¤t_target, TARGET_OBJECT_AVR,
1448 for (k = i; k < (i + j); k++)
1450 if (sscanf (p, "%[^,],%x;", query, &val) == 2)
1452 printf_filtered ("[%02x] %-15s : %02x\n", k, query, val);
1453 while ((*p != ';') && (*p != '\0'))
1455 p++; /* skip over ';' */
1465 extern initialize_file_ftype _initialize_avr_tdep; /* -Wmissing-prototypes */
1468 _initialize_avr_tdep (void)
1470 register_gdbarch_init (bfd_arch_avr, avr_gdbarch_init);
1472 /* Add a new command to allow the user to query the avr remote target for
1473 the values of the io space registers in a saner way than just using
1476 /* FIXME: TRoth/2002-02-18: This should probably be changed to 'info avr
1477 io_registers' to signify it is not available on other platforms. */
1479 add_cmd ("io_registers", class_info, avr_io_reg_read_command,
1480 _("query remote avr target for io space register values"),