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binutils-gdb/gdb/avr-tdep.c

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/* Target-dependent code for Atmel AVR, for GDB.
Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
2006, 2007 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA. */
/* Contributed by Theodore A. Roth, troth@openavr.org */
/* Portions of this file were taken from the original gdb-4.18 patch developed
by Denis Chertykov, denisc@overta.ru */
#include "defs.h"
#include "frame.h"
#include "frame-unwind.h"
#include "frame-base.h"
#include "trad-frame.h"
#include "gdbcmd.h"
#include "gdbcore.h"
#include "gdbtypes.h"
#include "inferior.h"
#include "symfile.h"
#include "arch-utils.h"
#include "regcache.h"
#include "gdb_string.h"
#include "dis-asm.h"
/* AVR Background:
(AVR micros are pure Harvard Architecture processors.)
The AVR family of microcontrollers have three distinctly different memory
spaces: flash, sram and eeprom. The flash is 16 bits wide and is used for
the most part to store program instructions. The sram is 8 bits wide and is
used for the stack and the heap. Some devices lack sram and some can have
an additional external sram added on as a peripheral.
The eeprom is 8 bits wide and is used to store data when the device is
powered down. Eeprom is not directly accessible, it can only be accessed
via io-registers using a special algorithm. Accessing eeprom via gdb's
remote serial protocol ('m' or 'M' packets) looks difficult to do and is
not included at this time.
[The eeprom could be read manually via ``x/b <eaddr + AVR_EMEM_START>'' or
written using ``set {unsigned char}<eaddr + AVR_EMEM_START>''. For this to
work, the remote target must be able to handle eeprom accesses and perform
the address translation.]
All three memory spaces have physical addresses beginning at 0x0. In
addition, the flash is addressed by gcc/binutils/gdb with respect to 8 bit
bytes instead of the 16 bit wide words used by the real device for the
Program Counter.
In order for remote targets to work correctly, extra bits must be added to
addresses before they are send to the target or received from the target
via the remote serial protocol. The extra bits are the MSBs and are used to
decode which memory space the address is referring to. */
#undef XMALLOC
#define XMALLOC(TYPE) ((TYPE*) xmalloc (sizeof (TYPE)))
#undef EXTRACT_INSN
#define EXTRACT_INSN(addr) extract_unsigned_integer(addr,2)
/* Constants: prefixed with AVR_ to avoid name space clashes */
enum
{
AVR_REG_W = 24,
AVR_REG_X = 26,
AVR_REG_Y = 28,
AVR_FP_REGNUM = 28,
AVR_REG_Z = 30,
AVR_SREG_REGNUM = 32,
AVR_SP_REGNUM = 33,
AVR_PC_REGNUM = 34,
AVR_NUM_REGS = 32 + 1 /*SREG*/ + 1 /*SP*/ + 1 /*PC*/,
AVR_NUM_REG_BYTES = 32 + 1 /*SREG*/ + 2 /*SP*/ + 4 /*PC*/,
AVR_PC_REG_INDEX = 35, /* index into array of registers */
AVR_MAX_PROLOGUE_SIZE = 64, /* bytes */
/* Count of pushed registers. From r2 to r17 (inclusively), r28, r29 */
AVR_MAX_PUSHES = 18,
/* Number of the last pushed register. r17 for current avr-gcc */
AVR_LAST_PUSHED_REGNUM = 17,
AVR_ARG1_REGNUM = 24, /* Single byte argument */
AVR_ARGN_REGNUM = 25, /* Multi byte argments */
AVR_RET1_REGNUM = 24, /* Single byte return value */
AVR_RETN_REGNUM = 25, /* Multi byte return value */
/* FIXME: TRoth/2002-01-??: Can we shift all these memory masks left 8
bits? Do these have to match the bfd vma values?. It sure would make
things easier in the future if they didn't need to match.
Note: I chose these values so as to be consistent with bfd vma
addresses.
TRoth/2002-04-08: There is already a conflict with very large programs
in the mega128. The mega128 has 128K instruction bytes (64K words),
thus the Most Significant Bit is 0x10000 which gets masked off my
AVR_MEM_MASK.
The problem manifests itself when trying to set a breakpoint in a
function which resides in the upper half of the instruction space and
thus requires a 17-bit address.
For now, I've just removed the EEPROM mask and changed AVR_MEM_MASK
from 0x00ff0000 to 0x00f00000. Eeprom is not accessible from gdb yet,
but could be for some remote targets by just adding the correct offset
to the address and letting the remote target handle the low-level
details of actually accessing the eeprom. */
AVR_IMEM_START = 0x00000000, /* INSN memory */
AVR_SMEM_START = 0x00800000, /* SRAM memory */
#if 1
/* No eeprom mask defined */
AVR_MEM_MASK = 0x00f00000, /* mask to determine memory space */
#else
AVR_EMEM_START = 0x00810000, /* EEPROM memory */
AVR_MEM_MASK = 0x00ff0000, /* mask to determine memory space */
#endif
};
/* Prologue types:
NORMAL and CALL are the typical types (the -mcall-prologues gcc option
causes the generation of the CALL type prologues). */
enum {
AVR_PROLOGUE_NONE, /* No prologue */
AVR_PROLOGUE_NORMAL,
AVR_PROLOGUE_CALL, /* -mcall-prologues */
AVR_PROLOGUE_MAIN,
AVR_PROLOGUE_INTR, /* interrupt handler */
AVR_PROLOGUE_SIG, /* signal handler */
};
/* Any function with a frame looks like this
....... <-SP POINTS HERE
LOCALS1 <-FP POINTS HERE
LOCALS0
SAVED FP
SAVED R3
SAVED R2
RET PC
FIRST ARG
SECOND ARG */
struct avr_unwind_cache
{
/* The previous frame's inner most stack address. Used as this
frame ID's stack_addr. */
CORE_ADDR prev_sp;
/* The frame's base, optionally used by the high-level debug info. */
CORE_ADDR base;
int size;
int prologue_type;
/* Table indicating the location of each and every register. */
struct trad_frame_saved_reg *saved_regs;
};
struct gdbarch_tdep
{
/* FIXME: TRoth: is there anything to put here? */
int foo;
};
/* Lookup the name of a register given it's number. */
static const char *
avr_register_name (int regnum)
{
static char *register_names[] = {
"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
"r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
"r24", "r25", "r26", "r27", "r28", "r29", "r30", "r31",
"SREG", "SP", "PC"
};
if (regnum < 0)
return NULL;
if (regnum >= (sizeof (register_names) / sizeof (*register_names)))
return NULL;
return register_names[regnum];
}
/* Return the GDB type object for the "standard" data type
of data in register N. */
static struct type *
avr_register_type (struct gdbarch *gdbarch, int reg_nr)
{
if (reg_nr == AVR_PC_REGNUM)
return builtin_type_uint32;
if (reg_nr == AVR_SP_REGNUM)
return builtin_type_void_data_ptr;
else
return builtin_type_uint8;
}
/* Instruction address checks and convertions. */
static CORE_ADDR
avr_make_iaddr (CORE_ADDR x)
{
return ((x) | AVR_IMEM_START);
}
/* FIXME: TRoth: Really need to use a larger mask for instructions. Some
devices are already up to 128KBytes of flash space.
TRoth/2002-04-8: See comment above where AVR_IMEM_START is defined. */
static CORE_ADDR
avr_convert_iaddr_to_raw (CORE_ADDR x)
{
return ((x) & 0xffffffff);
}
/* SRAM address checks and convertions. */
static CORE_ADDR
avr_make_saddr (CORE_ADDR x)
{
return ((x) | AVR_SMEM_START);
}
static CORE_ADDR
avr_convert_saddr_to_raw (CORE_ADDR x)
{
return ((x) & 0xffffffff);
}
/* EEPROM address checks and convertions. I don't know if these will ever
actually be used, but I've added them just the same. TRoth */
/* TRoth/2002-04-08: Commented out for now to allow fix for problem with large
programs in the mega128. */
/* static CORE_ADDR */
/* avr_make_eaddr (CORE_ADDR x) */
/* { */
/* return ((x) | AVR_EMEM_START); */
/* } */
/* static int */
/* avr_eaddr_p (CORE_ADDR x) */
/* { */
/* return (((x) & AVR_MEM_MASK) == AVR_EMEM_START); */
/* } */
/* static CORE_ADDR */
/* avr_convert_eaddr_to_raw (CORE_ADDR x) */
/* { */
/* return ((x) & 0xffffffff); */
/* } */
/* Convert from address to pointer and vice-versa. */
static void
avr_address_to_pointer (struct type *type, gdb_byte *buf, CORE_ADDR addr)
{
/* Is it a code address? */
if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_FUNC
|| TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_METHOD)
{
store_unsigned_integer (buf, TYPE_LENGTH (type),
avr_convert_iaddr_to_raw (addr >> 1));
}
else
{
/* Strip off any upper segment bits. */
store_unsigned_integer (buf, TYPE_LENGTH (type),
avr_convert_saddr_to_raw (addr));
}
}
static CORE_ADDR
avr_pointer_to_address (struct type *type, const gdb_byte *buf)
{
CORE_ADDR addr = extract_unsigned_integer (buf, TYPE_LENGTH (type));
/* Is it a code address? */
if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_FUNC
|| TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_METHOD
|| TYPE_CODE_SPACE (TYPE_TARGET_TYPE (type)))
return avr_make_iaddr (addr << 1);
else
return avr_make_saddr (addr);
}
static CORE_ADDR
avr_read_pc (ptid_t ptid)
{
ptid_t save_ptid;
ULONGEST pc;
CORE_ADDR retval;
save_ptid = inferior_ptid;
inferior_ptid = ptid;
regcache_cooked_read_unsigned (current_regcache, AVR_PC_REGNUM, &pc);
inferior_ptid = save_ptid;
retval = avr_make_iaddr (pc);
return retval;
}
static void
avr_write_pc (CORE_ADDR val, ptid_t ptid)
{
ptid_t save_ptid;
save_ptid = inferior_ptid;
inferior_ptid = ptid;
write_register (AVR_PC_REGNUM, avr_convert_iaddr_to_raw (val));
inferior_ptid = save_ptid;
}
static int
avr_scan_arg_moves (int vpc, unsigned char *prologue)
{
unsigned short insn;
for (; vpc < AVR_MAX_PROLOGUE_SIZE; vpc += 2)
{
insn = EXTRACT_INSN (&prologue[vpc]);
if ((insn & 0xff00) == 0x0100) /* movw rXX, rYY */
continue;
else if ((insn & 0xfc00) == 0x2c00) /* mov rXX, rYY */
continue;
else
break;
}
return vpc;
}
/* Function: avr_scan_prologue
This function decodes an AVR function prologue to determine:
1) the size of the stack frame
2) which registers are saved on it
3) the offsets of saved regs
This information is stored in the avr_unwind_cache structure.
Some devices lack the sbiw instruction, so on those replace this:
sbiw r28, XX
with this:
subi r28,lo8(XX)
sbci r29,hi8(XX)
A typical AVR function prologue with a frame pointer might look like this:
push rXX ; saved regs
...
push r28
push r29
in r28,__SP_L__
in r29,__SP_H__
sbiw r28,<LOCALS_SIZE>
in __tmp_reg__,__SREG__
cli
out __SP_H__,r29
out __SREG__,__tmp_reg__
out __SP_L__,r28
A typical AVR function prologue without a frame pointer might look like
this:
push rXX ; saved regs
...
A main function prologue looks like this:
ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>)
ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>)
out __SP_H__,r29
out __SP_L__,r28
A signal handler prologue looks like this:
push __zero_reg__
push __tmp_reg__
in __tmp_reg__, __SREG__
push __tmp_reg__
clr __zero_reg__
push rXX ; save registers r18:r27, r30:r31
...
push r28 ; save frame pointer
push r29
in r28, __SP_L__
in r29, __SP_H__
sbiw r28, <LOCALS_SIZE>
out __SP_H__, r29
out __SP_L__, r28
A interrupt handler prologue looks like this:
sei
push __zero_reg__
push __tmp_reg__
in __tmp_reg__, __SREG__
push __tmp_reg__
clr __zero_reg__
push rXX ; save registers r18:r27, r30:r31
...
push r28 ; save frame pointer
push r29
in r28, __SP_L__
in r29, __SP_H__
sbiw r28, <LOCALS_SIZE>
cli
out __SP_H__, r29
sei
out __SP_L__, r28
A `-mcall-prologues' prologue looks like this (Note that the megas use a
jmp instead of a rjmp, thus the prologue is one word larger since jmp is a
32 bit insn and rjmp is a 16 bit insn):
ldi r26,lo8(<LOCALS_SIZE>)
ldi r27,hi8(<LOCALS_SIZE>)
ldi r30,pm_lo8(.L_foo_body)
ldi r31,pm_hi8(.L_foo_body)
rjmp __prologue_saves__+RRR
.L_foo_body: */
/* Not really part of a prologue, but still need to scan for it, is when a
function prologue moves values passed via registers as arguments to new
registers. In this case, all local variables live in registers, so there
may be some register saves. This is what it looks like:
movw rMM, rNN
...
There could be multiple movw's. If the target doesn't have a movw insn, it
will use two mov insns. This could be done after any of the above prologue
types. */
static CORE_ADDR
avr_scan_prologue (CORE_ADDR pc, struct avr_unwind_cache *info)
{
int i;
unsigned short insn;
int scan_stage = 0;
struct minimal_symbol *msymbol;
unsigned char prologue[AVR_MAX_PROLOGUE_SIZE];
int vpc = 0;
/* FIXME: TRoth/2003-06-11: This could be made more efficient by only
reading in the bytes of the prologue. The problem is that the figuring
out where the end of the prologue is is a bit difficult. The old code
tried to do that, but failed quite often. */
read_memory (pc, prologue, AVR_MAX_PROLOGUE_SIZE);
/* Scanning main()'s prologue
ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>)
ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>)
out __SP_H__,r29
out __SP_L__,r28 */
if (1)
{
CORE_ADDR locals;
unsigned char img[] = {
0xde, 0xbf, /* out __SP_H__,r29 */
0xcd, 0xbf /* out __SP_L__,r28 */
};
insn = EXTRACT_INSN (&prologue[vpc]);
/* ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>) */
if ((insn & 0xf0f0) == 0xe0c0)
{
locals = (insn & 0xf) | ((insn & 0x0f00) >> 4);
insn = EXTRACT_INSN (&prologue[vpc + 2]);
/* ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>) */
if ((insn & 0xf0f0) == 0xe0d0)
{
locals |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
if (memcmp (prologue + vpc + 4, img, sizeof (img)) == 0)
{
info->prologue_type = AVR_PROLOGUE_MAIN;
info->base = locals;
return pc + 4;
}
}
}
}
/* Scanning `-mcall-prologues' prologue
Classic prologue is 10 bytes, mega prologue is a 12 bytes long */
while (1) /* Using a while to avoid many goto's */
{
int loc_size;
int body_addr;
unsigned num_pushes;
int pc_offset = 0;
insn = EXTRACT_INSN (&prologue[vpc]);
/* ldi r26,<LOCALS_SIZE> */
if ((insn & 0xf0f0) != 0xe0a0)
break;
loc_size = (insn & 0xf) | ((insn & 0x0f00) >> 4);
pc_offset += 2;
insn = EXTRACT_INSN (&prologue[vpc + 2]);
/* ldi r27,<LOCALS_SIZE> / 256 */
if ((insn & 0xf0f0) != 0xe0b0)
break;
loc_size |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
pc_offset += 2;
insn = EXTRACT_INSN (&prologue[vpc + 4]);
/* ldi r30,pm_lo8(.L_foo_body) */
if ((insn & 0xf0f0) != 0xe0e0)
break;
body_addr = (insn & 0xf) | ((insn & 0x0f00) >> 4);
pc_offset += 2;
insn = EXTRACT_INSN (&prologue[vpc + 6]);
/* ldi r31,pm_hi8(.L_foo_body) */
if ((insn & 0xf0f0) != 0xe0f0)
break;
body_addr |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
pc_offset += 2;
msymbol = lookup_minimal_symbol ("__prologue_saves__", NULL, NULL);
if (!msymbol)
break;
insn = EXTRACT_INSN (&prologue[vpc + 8]);
/* rjmp __prologue_saves__+RRR */
if ((insn & 0xf000) == 0xc000)
{
/* Extract PC relative offset from RJMP */
i = (insn & 0xfff) | (insn & 0x800 ? (-1 ^ 0xfff) : 0);
/* Convert offset to byte addressable mode */
i *= 2;
/* Destination address */
i += pc + 10;
if (body_addr != (pc + 10)/2)
break;
pc_offset += 2;
}
else if ((insn & 0xfe0e) == 0x940c)
{
/* Extract absolute PC address from JMP */
i = (((insn & 0x1) | ((insn & 0x1f0) >> 3) << 16)
| (EXTRACT_INSN (&prologue[vpc + 10]) & 0xffff));
/* Convert address to byte addressable mode */
i *= 2;
if (body_addr != (pc + 12)/2)
break;
pc_offset += 4;
}
else
break;
/* Resolve offset (in words) from __prologue_saves__ symbol.
Which is a pushes count in `-mcall-prologues' mode */
num_pushes = AVR_MAX_PUSHES - (i - SYMBOL_VALUE_ADDRESS (msymbol)) / 2;
if (num_pushes > AVR_MAX_PUSHES)
{
fprintf_unfiltered (gdb_stderr, _("Num pushes too large: %d\n"),
num_pushes);
num_pushes = 0;
}
if (num_pushes)
{
int from;
info->saved_regs[AVR_FP_REGNUM + 1].addr = num_pushes;
if (num_pushes >= 2)
info->saved_regs[AVR_FP_REGNUM].addr = num_pushes - 1;
i = 0;
for (from = AVR_LAST_PUSHED_REGNUM + 1 - (num_pushes - 2);
from <= AVR_LAST_PUSHED_REGNUM; ++from)
info->saved_regs [from].addr = ++i;
}
info->size = loc_size + num_pushes;
info->prologue_type = AVR_PROLOGUE_CALL;
return pc + pc_offset;
}
/* Scan for the beginning of the prologue for an interrupt or signal
function. Note that we have to set the prologue type here since the
third stage of the prologue may not be present (e.g. no saved registered
or changing of the SP register). */
if (1)
{
unsigned char img[] = {
0x78, 0x94, /* sei */
0x1f, 0x92, /* push r1 */
0x0f, 0x92, /* push r0 */
0x0f, 0xb6, /* in r0,0x3f SREG */
0x0f, 0x92, /* push r0 */
0x11, 0x24 /* clr r1 */
};
if (memcmp (prologue, img, sizeof (img)) == 0)
{
info->prologue_type = AVR_PROLOGUE_INTR;
vpc += sizeof (img);
info->saved_regs[AVR_SREG_REGNUM].addr = 3;
info->saved_regs[0].addr = 2;
info->saved_regs[1].addr = 1;
info->size += 3;
}
else if (memcmp (img + 2, prologue, sizeof (img) - 2) == 0)
{
info->prologue_type = AVR_PROLOGUE_SIG;
vpc += sizeof (img) - 2;
info->saved_regs[AVR_SREG_REGNUM].addr = 3;
info->saved_regs[0].addr = 2;
info->saved_regs[1].addr = 1;
info->size += 3;
}
}
/* First stage of the prologue scanning.
Scan pushes (saved registers) */
for (; vpc < AVR_MAX_PROLOGUE_SIZE; vpc += 2)
{
insn = EXTRACT_INSN (&prologue[vpc]);
if ((insn & 0xfe0f) == 0x920f) /* push rXX */
{
/* Bits 4-9 contain a mask for registers R0-R32. */
int regno = (insn & 0x1f0) >> 4;
info->size++;
info->saved_regs[regno].addr = info->size;
scan_stage = 1;
}
else
break;
}
if (vpc >= AVR_MAX_PROLOGUE_SIZE)
fprintf_unfiltered (gdb_stderr,
_("Hit end of prologue while scanning pushes\n"));
/* Second stage of the prologue scanning.
Scan:
in r28,__SP_L__
in r29,__SP_H__ */
if (scan_stage == 1 && vpc < AVR_MAX_PROLOGUE_SIZE)
{
unsigned char img[] = {
0xcd, 0xb7, /* in r28,__SP_L__ */
0xde, 0xb7 /* in r29,__SP_H__ */
};
unsigned short insn1;
if (memcmp (prologue + vpc, img, sizeof (img)) == 0)
{
vpc += 4;
scan_stage = 2;
}
}
/* Third stage of the prologue scanning. (Really two stages)
Scan for:
sbiw r28,XX or subi r28,lo8(XX)
sbci r29,hi8(XX)
in __tmp_reg__,__SREG__
cli
out __SP_H__,r29
out __SREG__,__tmp_reg__
out __SP_L__,r28 */
if (scan_stage == 2 && vpc < AVR_MAX_PROLOGUE_SIZE)
{
int locals_size = 0;
unsigned char img[] = {
0x0f, 0xb6, /* in r0,0x3f */
0xf8, 0x94, /* cli */
0xde, 0xbf, /* out 0x3e,r29 ; SPH */
0x0f, 0xbe, /* out 0x3f,r0 ; SREG */
0xcd, 0xbf /* out 0x3d,r28 ; SPL */
};
unsigned char img_sig[] = {
0xde, 0xbf, /* out 0x3e,r29 ; SPH */
0xcd, 0xbf /* out 0x3d,r28 ; SPL */
};
unsigned char img_int[] = {
0xf8, 0x94, /* cli */
0xde, 0xbf, /* out 0x3e,r29 ; SPH */
0x78, 0x94, /* sei */
0xcd, 0xbf /* out 0x3d,r28 ; SPL */
};
insn = EXTRACT_INSN (&prologue[vpc]);
vpc += 2;
if ((insn & 0xff30) == 0x9720) /* sbiw r28,XXX */
locals_size = (insn & 0xf) | ((insn & 0xc0) >> 2);
else if ((insn & 0xf0f0) == 0x50c0) /* subi r28,lo8(XX) */
{
locals_size = (insn & 0xf) | ((insn & 0xf00) >> 4);
insn = EXTRACT_INSN (&prologue[vpc]);
vpc += 2;
locals_size += ((insn & 0xf) | ((insn & 0xf00) >> 4) << 8);
}
else
return pc + vpc;
/* Scan the last part of the prologue. May not be present for interrupt
or signal handler functions, which is why we set the prologue type
when we saw the beginning of the prologue previously. */
if (memcmp (prologue + vpc, img_sig, sizeof (img_sig)) == 0)
{
vpc += sizeof (img_sig);
}
else if (memcmp (prologue + vpc, img_int, sizeof (img_int)) == 0)
{
vpc += sizeof (img_int);
}
if (memcmp (prologue + vpc, img, sizeof (img)) == 0)
{
info->prologue_type = AVR_PROLOGUE_NORMAL;
vpc += sizeof (img);
}
info->size += locals_size;
return pc + avr_scan_arg_moves (vpc, prologue);
}
/* If we got this far, we could not scan the prologue, so just return the pc
of the frame plus an adjustment for argument move insns. */
return pc + avr_scan_arg_moves (vpc, prologue);;
}
static CORE_ADDR
avr_skip_prologue (CORE_ADDR pc)
{
CORE_ADDR func_addr, func_end;
CORE_ADDR prologue_end = pc;
/* See what the symbol table says */
if (find_pc_partial_function (pc, NULL, &func_addr, &func_end))
{
struct symtab_and_line sal;
struct avr_unwind_cache info = {0};
struct trad_frame_saved_reg saved_regs[AVR_NUM_REGS];
info.saved_regs = saved_regs;
/* Need to run the prologue scanner to figure out if the function has a
prologue and possibly skip over moving arguments passed via registers
to other registers. */
prologue_end = avr_scan_prologue (pc, &info);
if (info.prologue_type == AVR_PROLOGUE_NONE)
return pc;
else
{
sal = find_pc_line (func_addr, 0);
if (sal.line != 0 && sal.end < func_end)
return sal.end;
}
}
/* Either we didn't find the start of this function (nothing we can do),
or there's no line info, or the line after the prologue is after
the end of the function (there probably isn't a prologue). */
return prologue_end;
}
/* Not all avr devices support the BREAK insn. Those that don't should treat
it as a NOP. Thus, it should be ok. Since the avr is currently a remote
only target, this shouldn't be a problem (I hope). TRoth/2003-05-14 */
static const unsigned char *
avr_breakpoint_from_pc (CORE_ADDR * pcptr, int *lenptr)
{
static unsigned char avr_break_insn [] = { 0x98, 0x95 };
*lenptr = sizeof (avr_break_insn);
return avr_break_insn;
}
/* Given a return value in `regbuf' with a type `valtype',
extract and copy its value into `valbuf'.
Return values are always passed via registers r25:r24:... */
static void
avr_extract_return_value (struct type *type, struct regcache *regcache,
gdb_byte *valbuf)
{
ULONGEST r24, r25;
ULONGEST c;
int len;
if (TYPE_LENGTH (type) == 1)
{
regcache_cooked_read_unsigned (regcache, 24, &c);
store_unsigned_integer (valbuf, 1, c);
}
else
{
int i;
/* The MSB of the return value is always in r25, calculate which
register holds the LSB. */
int lsb_reg = 25 - TYPE_LENGTH (type) + 1;
for (i=0; i< TYPE_LENGTH (type); i++)
{
regcache_cooked_read (regcache, lsb_reg + i,
(bfd_byte *) valbuf + i);
}
}
}
/* Put here the code to store, into fi->saved_regs, the addresses of
the saved registers of frame described by FRAME_INFO. This
includes special registers such as pc and fp saved in special ways
in the stack frame. sp is even more special: the address we return
for it IS the sp for the next frame. */
struct avr_unwind_cache *
avr_frame_unwind_cache (struct frame_info *next_frame,
void **this_prologue_cache)
{
CORE_ADDR pc;
ULONGEST prev_sp;
ULONGEST this_base;
struct avr_unwind_cache *info;
int i;
if ((*this_prologue_cache))
return (*this_prologue_cache);
info = FRAME_OBSTACK_ZALLOC (struct avr_unwind_cache);
(*this_prologue_cache) = info;
info->saved_regs = trad_frame_alloc_saved_regs (next_frame);
info->size = 0;
info->prologue_type = AVR_PROLOGUE_NONE;
pc = frame_func_unwind (next_frame, NORMAL_FRAME);
if ((pc > 0) && (pc < frame_pc_unwind (next_frame)))
avr_scan_prologue (pc, info);
if ((info->prologue_type != AVR_PROLOGUE_NONE)
&& (info->prologue_type != AVR_PROLOGUE_MAIN))
{
ULONGEST high_base; /* High byte of FP */
/* The SP was moved to the FP. This indicates that a new frame
was created. Get THIS frame's FP value by unwinding it from
the next frame. */
frame_unwind_unsigned_register (next_frame, AVR_FP_REGNUM, &this_base);
frame_unwind_unsigned_register (next_frame, AVR_FP_REGNUM+1, &high_base);
this_base += (high_base << 8);
/* The FP points at the last saved register. Adjust the FP back
to before the first saved register giving the SP. */
prev_sp = this_base + info->size;
}
else
{
/* Assume that the FP is this frame's SP but with that pushed
stack space added back. */
frame_unwind_unsigned_register (next_frame, AVR_SP_REGNUM, &this_base);
prev_sp = this_base + info->size;
}
/* Add 1 here to adjust for the post-decrement nature of the push
instruction.*/
info->prev_sp = avr_make_saddr (prev_sp+1);
info->base = avr_make_saddr (this_base);
/* Adjust all the saved registers so that they contain addresses and not
offsets. */
for (i = 0; i < gdbarch_num_regs (current_gdbarch) - 1; i++)
if (info->saved_regs[i].addr)
{
info->saved_regs[i].addr = (info->prev_sp - info->saved_regs[i].addr);
}
/* Except for the main and startup code, the return PC is always saved on
the stack and is at the base of the frame. */
if (info->prologue_type != AVR_PROLOGUE_MAIN)
{
info->saved_regs[AVR_PC_REGNUM].addr = info->prev_sp;
}
/* The previous frame's SP needed to be computed. Save the computed
value. */
trad_frame_set_value (info->saved_regs, AVR_SP_REGNUM, info->prev_sp+1);
return info;
}
static CORE_ADDR
avr_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
{
ULONGEST pc;
frame_unwind_unsigned_register (next_frame, AVR_PC_REGNUM, &pc);
return avr_make_iaddr (pc);
}
static CORE_ADDR
avr_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame)
{
ULONGEST sp;
frame_unwind_unsigned_register (next_frame, AVR_SP_REGNUM, &sp);
return avr_make_saddr (sp);
}
/* Given a GDB frame, determine the address of the calling function's
frame. This will be used to create a new GDB frame struct. */
static void
avr_frame_this_id (struct frame_info *next_frame,
void **this_prologue_cache,
struct frame_id *this_id)
{
struct avr_unwind_cache *info
= avr_frame_unwind_cache (next_frame, this_prologue_cache);
CORE_ADDR base;
CORE_ADDR func;
struct frame_id id;
/* The FUNC is easy. */
func = frame_func_unwind (next_frame, NORMAL_FRAME);
/* Hopefully the prologue analysis either correctly determined the
frame's base (which is the SP from the previous frame), or set
that base to "NULL". */
base = info->prev_sp;
if (base == 0)
return;
id = frame_id_build (base, func);
(*this_id) = id;
}
static void
avr_frame_prev_register (struct frame_info *next_frame,
void **this_prologue_cache,
int regnum, int *optimizedp,
enum lval_type *lvalp, CORE_ADDR *addrp,
int *realnump, gdb_byte *bufferp)
{
struct avr_unwind_cache *info
= avr_frame_unwind_cache (next_frame, this_prologue_cache);
if (regnum == AVR_PC_REGNUM)
{
if (trad_frame_addr_p (info->saved_regs, regnum))
{
*optimizedp = 0;
*lvalp = lval_memory;
*addrp = info->saved_regs[regnum].addr;
*realnump = -1;
if (bufferp != NULL)
{
/* Reading the return PC from the PC register is slightly
abnormal. register_size(AVR_PC_REGNUM) says it is 4 bytes,
but in reality, only two bytes (3 in upcoming mega256) are
stored on the stack.
Also, note that the value on the stack is an addr to a word
not a byte, so we will need to multiply it by two at some
point.
And to confuse matters even more, the return address stored
on the stack is in big endian byte order, even though most
everything else about the avr is little endian. Ick! */
/* FIXME: number of bytes read here will need updated for the
mega256 when it is available. */
ULONGEST pc;
unsigned char tmp;
unsigned char buf[2];
read_memory (info->saved_regs[regnum].addr, buf, 2);
/* Convert the PC read from memory as a big-endian to
little-endian order. */
tmp = buf[0];
buf[0] = buf[1];
buf[1] = tmp;
pc = (extract_unsigned_integer (buf, 2) * 2);
store_unsigned_integer (bufferp,
register_size (current_gdbarch, regnum),
pc);
}
}
}
else
trad_frame_get_prev_register (next_frame, info->saved_regs, regnum,
optimizedp, lvalp, addrp, realnump, bufferp);
}
static const struct frame_unwind avr_frame_unwind = {
NORMAL_FRAME,
avr_frame_this_id,
avr_frame_prev_register
};
const struct frame_unwind *
avr_frame_sniffer (struct frame_info *next_frame)
{
return &avr_frame_unwind;
}
static CORE_ADDR
avr_frame_base_address (struct frame_info *next_frame, void **this_cache)
{
struct avr_unwind_cache *info
= avr_frame_unwind_cache (next_frame, this_cache);
return info->base;
}
static const struct frame_base avr_frame_base = {
&avr_frame_unwind,
avr_frame_base_address,
avr_frame_base_address,
avr_frame_base_address
};
/* Assuming NEXT_FRAME->prev is a dummy, return the frame ID of that
dummy frame. The frame ID's base needs to match the TOS value
saved by save_dummy_frame_tos(), and the PC match the dummy frame's
breakpoint. */
static struct frame_id
avr_unwind_dummy_id (struct gdbarch *gdbarch, struct frame_info *next_frame)
{
ULONGEST base;
frame_unwind_unsigned_register (next_frame, AVR_SP_REGNUM, &base);
return frame_id_build (avr_make_saddr (base), frame_pc_unwind (next_frame));
}
/* When arguments must be pushed onto the stack, they go on in reverse
order. The below implements a FILO (stack) to do this. */
struct stack_item
{
int len;
struct stack_item *prev;
void *data;
};
static struct stack_item *
push_stack_item (struct stack_item *prev, const bfd_byte *contents, int len)
{
struct stack_item *si;
si = xmalloc (sizeof (struct stack_item));
si->data = xmalloc (len);
si->len = len;
si->prev = prev;
memcpy (si->data, contents, len);
return si;
}
static struct stack_item *pop_stack_item (struct stack_item *si);
static struct stack_item *
pop_stack_item (struct stack_item *si)
{
struct stack_item *dead = si;
si = si->prev;
xfree (dead->data);
xfree (dead);
return si;
}
/* Setup the function arguments for calling a function in the inferior.
On the AVR architecture, there are 18 registers (R25 to R8) which are
dedicated for passing function arguments. Up to the first 18 arguments
(depending on size) may go into these registers. The rest go on the stack.
All arguments are aligned to start in even-numbered registers (odd-sized
arguments, including char, have one free register above them). For example,
an int in arg1 and a char in arg2 would be passed as such:
arg1 -> r25:r24
arg2 -> r22
Arguments that are larger than 2 bytes will be split between two or more
registers as available, but will NOT be split between a register and the
stack. Arguments that go onto the stack are pushed last arg first (this is
similar to the d10v). */
/* NOTE: TRoth/2003-06-17: The rest of this comment is old looks to be
inaccurate.
An exceptional case exists for struct arguments (and possibly other
aggregates such as arrays) -- if the size is larger than WORDSIZE bytes but
not a multiple of WORDSIZE bytes. In this case the argument is never split
between the registers and the stack, but instead is copied in its entirety
onto the stack, AND also copied into as many registers as there is room
for. In other words, space in registers permitting, two copies of the same
argument are passed in. As far as I can tell, only the one on the stack is
used, although that may be a function of the level of compiler
optimization. I suspect this is a compiler bug. Arguments of these odd
sizes are left-justified within the word (as opposed to arguments smaller
than WORDSIZE bytes, which are right-justified).
If the function is to return an aggregate type such as a struct, the caller
must allocate space into which the callee will copy the return value. In
this case, a pointer to the return value location is passed into the callee
in register R0, which displaces one of the other arguments passed in via
registers R0 to R2. */
static CORE_ADDR
avr_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
struct regcache *regcache, CORE_ADDR bp_addr,
int nargs, struct value **args, CORE_ADDR sp,
int struct_return, CORE_ADDR struct_addr)
{
int i;
unsigned char buf[2];
CORE_ADDR return_pc = avr_convert_iaddr_to_raw (bp_addr);
int regnum = AVR_ARGN_REGNUM;
struct stack_item *si = NULL;
#if 0
/* FIXME: TRoth/2003-06-18: Not sure what to do when returning a struct. */
if (struct_return)
{
fprintf_unfiltered (gdb_stderr, "struct_return: 0x%lx\n", struct_addr);
write_register (argreg--, struct_addr & 0xff);
write_register (argreg--, (struct_addr >>8) & 0xff);
}
#endif
for (i = 0; i < nargs; i++)
{
int last_regnum;
int j;
struct value *arg = args[i];
struct type *type = check_typedef (value_type (arg));
const bfd_byte *contents = value_contents (arg);
int len = TYPE_LENGTH (type);
/* Calculate the potential last register needed. */
last_regnum = regnum - (len + (len & 1));
/* If there are registers available, use them. Once we start putting
stuff on the stack, all subsequent args go on stack. */
if ((si == NULL) && (last_regnum >= 8))
{
ULONGEST val;
/* Skip a register for odd length args. */
if (len & 1)
regnum--;
val = extract_unsigned_integer (contents, len);
for (j=0; j<len; j++)
{
regcache_cooked_write_unsigned (regcache, regnum--,
val >> (8*(len-j-1)));
}
}
/* No registers available, push the args onto the stack. */
else
{
/* From here on, we don't care about regnum. */
si = push_stack_item (si, contents, len);
}
}
/* Push args onto the stack. */
while (si)
{
sp -= si->len;
/* Add 1 to sp here to account for post decr nature of pushes. */
write_memory (sp+1, si->data, si->len);
si = pop_stack_item (si);
}
/* Set the return address. For the avr, the return address is the BP_ADDR.
Need to push the return address onto the stack noting that it needs to be
in big-endian order on the stack. */
buf[0] = (return_pc >> 8) & 0xff;
buf[1] = return_pc & 0xff;
sp -= 2;
write_memory (sp+1, buf, 2); /* Add one since pushes are post decr ops. */
/* Finally, update the SP register. */
regcache_cooked_write_unsigned (regcache, AVR_SP_REGNUM,
avr_convert_saddr_to_raw (sp));
return sp;
}
/* Initialize the gdbarch structure for the AVR's. */
static struct gdbarch *
avr_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
{
struct gdbarch *gdbarch;
struct gdbarch_tdep *tdep;
/* Find a candidate among the list of pre-declared architectures. */
arches = gdbarch_list_lookup_by_info (arches, &info);
if (arches != NULL)
return arches->gdbarch;
/* None found, create a new architecture from the information provided. */
tdep = XMALLOC (struct gdbarch_tdep);
gdbarch = gdbarch_alloc (&info, tdep);
/* If we ever need to differentiate the device types, do it here. */
switch (info.bfd_arch_info->mach)
{
case bfd_mach_avr1:
case bfd_mach_avr2:
case bfd_mach_avr3:
case bfd_mach_avr4:
case bfd_mach_avr5:
break;
}
set_gdbarch_short_bit (gdbarch, 2 * TARGET_CHAR_BIT);
set_gdbarch_int_bit (gdbarch, 2 * TARGET_CHAR_BIT);
set_gdbarch_long_bit (gdbarch, 4 * TARGET_CHAR_BIT);
set_gdbarch_long_long_bit (gdbarch, 8 * TARGET_CHAR_BIT);
set_gdbarch_ptr_bit (gdbarch, 2 * TARGET_CHAR_BIT);
set_gdbarch_addr_bit (gdbarch, 32);
set_gdbarch_float_bit (gdbarch, 4 * TARGET_CHAR_BIT);
set_gdbarch_double_bit (gdbarch, 4 * TARGET_CHAR_BIT);
set_gdbarch_long_double_bit (gdbarch, 4 * TARGET_CHAR_BIT);
set_gdbarch_float_format (gdbarch, floatformats_ieee_single);
set_gdbarch_double_format (gdbarch, floatformats_ieee_single);
set_gdbarch_long_double_format (gdbarch, floatformats_ieee_single);
set_gdbarch_read_pc (gdbarch, avr_read_pc);
set_gdbarch_write_pc (gdbarch, avr_write_pc);
set_gdbarch_num_regs (gdbarch, AVR_NUM_REGS);
set_gdbarch_sp_regnum (gdbarch, AVR_SP_REGNUM);
set_gdbarch_pc_regnum (gdbarch, AVR_PC_REGNUM);
set_gdbarch_register_name (gdbarch, avr_register_name);
set_gdbarch_register_type (gdbarch, avr_register_type);
set_gdbarch_extract_return_value (gdbarch, avr_extract_return_value);
set_gdbarch_print_insn (gdbarch, print_insn_avr);
set_gdbarch_push_dummy_call (gdbarch, avr_push_dummy_call);
set_gdbarch_address_to_pointer (gdbarch, avr_address_to_pointer);
set_gdbarch_pointer_to_address (gdbarch, avr_pointer_to_address);
set_gdbarch_skip_prologue (gdbarch, avr_skip_prologue);
set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
set_gdbarch_breakpoint_from_pc (gdbarch, avr_breakpoint_from_pc);
frame_unwind_append_sniffer (gdbarch, avr_frame_sniffer);
frame_base_set_default (gdbarch, &avr_frame_base);
set_gdbarch_unwind_dummy_id (gdbarch, avr_unwind_dummy_id);
set_gdbarch_unwind_pc (gdbarch, avr_unwind_pc);
set_gdbarch_unwind_sp (gdbarch, avr_unwind_sp);
return gdbarch;
}
/* Send a query request to the avr remote target asking for values of the io
registers. If args parameter is not NULL, then the user has requested info
on a specific io register [This still needs implemented and is ignored for
now]. The query string should be one of these forms:
"Ravr.io_reg" -> reply is "NN" number of io registers
"Ravr.io_reg:addr,len" where addr is first register and len is number of
registers to be read. The reply should be "<NAME>,VV;" for each io register
where, <NAME> is a string, and VV is the hex value of the register.
All io registers are 8-bit. */
static void
avr_io_reg_read_command (char *args, int from_tty)
{
LONGEST bufsiz = 0;
gdb_byte *buf;
char query[400];
char *p;
unsigned int nreg = 0;
unsigned int val;
int i, j, k, step;
/* Find out how many io registers the target has. */
bufsiz = target_read_alloc (&current_target, TARGET_OBJECT_AVR,
"avr.io_reg", &buf);
if (bufsiz <= 0)
{
fprintf_unfiltered (gdb_stderr,
_("ERR: info io_registers NOT supported "
"by current target\n"));
return;
}
if (sscanf (buf, "%x", &nreg) != 1)
{
fprintf_unfiltered (gdb_stderr,
_("Error fetching number of io registers\n"));
xfree (buf);
return;
}
xfree (buf);
reinitialize_more_filter ();
printf_unfiltered (_("Target has %u io registers:\n\n"), nreg);
/* only fetch up to 8 registers at a time to keep the buffer small */
step = 8;
for (i = 0; i < nreg; i += step)
{
/* how many registers this round? */
j = step;
if ((i+j) >= nreg)
j = nreg - i; /* last block is less than 8 registers */
snprintf (query, sizeof (query) - 1, "avr.io_reg:%x,%x", i, j);
bufsiz = target_read_alloc (&current_target, TARGET_OBJECT_AVR,
query, &buf);
p = buf;
for (k = i; k < (i + j); k++)
{
if (sscanf (p, "%[^,],%x;", query, &val) == 2)
{
printf_filtered ("[%02x] %-15s : %02x\n", k, query, val);
while ((*p != ';') && (*p != '\0'))
p++;
p++; /* skip over ';' */
if (*p == '\0')
break;
}
}
xfree (buf);
}
}
extern initialize_file_ftype _initialize_avr_tdep; /* -Wmissing-prototypes */
void
_initialize_avr_tdep (void)
{
register_gdbarch_init (bfd_arch_avr, avr_gdbarch_init);
/* Add a new command to allow the user to query the avr remote target for
the values of the io space registers in a saner way than just using
`x/NNNb ADDR`. */
/* FIXME: TRoth/2002-02-18: This should probably be changed to 'info avr
io_registers' to signify it is not available on other platforms. */
add_cmd ("io_registers", class_info, avr_io_reg_read_command,
_("query remote avr target for io space register values"),
&infolist);
}
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