static LONGEST
alphanbsd_sigtramp_offset (CORE_ADDR pc)
{
unsigned char ret[RETCODE_SIZE], w[4];
LONGEST off;
int i;
if (read_memory_nobpt (pc, (char *) w, 4) != 0)
return -1;
for (i = 0; i < RETCODE_NWORDS; i++)
{
if (memcmp (w, sigtramp_retcode + (i * 4), 4) == 0)
break;
}
if (i == RETCODE_NWORDS)
return (-1);
off = i * 4;
pc -= off;
if (read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
return -1;
if (memcmp (ret, sigtramp_retcode, RETCODE_SIZE) == 0)
return off;
return -1;
}
static CORE_ADDR
i386_linux_rt_sigtramp_start (CORE_ADDR pc)
{
unsigned char buf[LINUX_RT_SIGTRAMP_LEN];
/* We only recognize a signal trampoline if PC is at the start of
one of the two instructions. We optimize for finding the PC at
the start, as will be the case when the trampoline is not the
first frame on the stack. We assume that in the case where the
PC is not at the start of the instruction sequence, there will be
a few trailing readable bytes on the stack. */
if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
return 0;
if (buf[0] != LINUX_RT_SIGTRAMP_INSN0)
{
if (buf[0] != LINUX_RT_SIGTRAMP_INSN1)
return 0;
pc -= LINUX_RT_SIGTRAMP_OFFSET1;
if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
return 0;
}
if (memcmp (buf, linux_rt_sigtramp_code, LINUX_RT_SIGTRAMP_LEN) != 0)
return 0;
return pc;
}
/* Adjust a breakpoint's address to account for the FR-V architecture's
constraint that a break instruction must not appear as any but the
first instruction in the bundle. */
static CORE_ADDR
frv_gdbarch_adjust_breakpoint_address (struct gdbarch *gdbarch, CORE_ADDR bpaddr)
{
int count = max_instrs_per_bundle;
CORE_ADDR addr = bpaddr - frv_instr_size;
CORE_ADDR func_start = get_pc_function_start (bpaddr);
/* Find the end of the previous packing sequence. This will be indicated
by either attempting to access some inaccessible memory or by finding
an instruction word whose packing bit is set to one. */
while (count-- > 0 && addr >= func_start)
{
char instr[frv_instr_size];
int status;
status = read_memory_nobpt (addr, instr, sizeof instr);
if (status != 0)
break;
/* This is a big endian architecture, so byte zero will have most
significant byte. The most significant bit of this byte is the
packing bit. */
if (instr[0] & 0x80)
break;
addr -= frv_instr_size;
}
if (count > 0)
bpaddr = addr + frv_instr_size;
return bpaddr;
}
static int
get_insn (CORE_ADDR pc)
{
char buf[INST_WORD_SIZE];
int status = read_memory_nobpt (pc, buf, INST_WORD_SIZE);
if (status != 0)
return 0;
return extract_unsigned_integer (buf, INST_WORD_SIZE);
}
static CORE_ADDR
i386lynx_saved_pc_after_call (struct frame_info *frame)
{
char opcode[7];
static const unsigned char call_inst[] =
{ 0x9a, 0, 0, 0, 0, 8, 0 }; /* lcall 0x8,0x0 */
read_memory_nobpt (frame->pc - 7, opcode, 7);
if (memcmp (opcode, call_inst, 7) == 0)
return read_memory_unsigned_integer (read_register (SP_REGNUM) + 4, 4);
return read_memory_unsigned_integer (read_register (SP_REGNUM), 4);
}
/* Under GNU/Linux, signal handler invocations can be identified by the
designated code sequence that is used to return from a signal
handler. In particular, the return address of a signal handler
points to the following sequence (the first instruction is quadword
aligned):
bis $30,$30,$16
addq $31,0x67,$0
call_pal callsys
Each instruction has a unique encoding, so we simply attempt to
match the instruction the pc is pointing to with any of the above
instructions. If there is a hit, we know the offset to the start
of the designated sequence and can then check whether we really are
executing in a designated sequence. If not, -1 is returned,
otherwise the offset from the start of the desingated sequence is
returned.
There is a slight chance of false hits: code could jump into the
middle of the designated sequence, in which case there is no
guarantee that we are in the middle of a sigreturn syscall. Don't
think this will be a problem in praxis, though. */
LONGEST
alpha_linux_sigtramp_offset (CORE_ADDR pc)
{
unsigned int i[3], w;
long off;
if (read_memory_nobpt (pc, (char *) &w, 4) != 0)
return -1;
off = -1;
switch (w)
{
case 0x47de0410:
off = 0;
break; /* bis $30,$30,$16 */
case 0x43ecf400:
off = 4;
break; /* addq $31,0x67,$0 */
case 0x00000083:
off = 8;
break; /* call_pal callsys */
default:
return -1;
}
pc -= off;
if (pc & 0x7)
{
/* designated sequence is not quadword aligned */
return -1;
}
if (read_memory_nobpt (pc, (char *) i, sizeof (i)) != 0)
return -1;
if (i[0] == 0x47de0410 && i[1] == 0x43ecf400 && i[2] == 0x00000083)
return off;
return -1;
}
unsigned long
sparc_fetch_instruction (CORE_ADDR pc)
{
gdb_byte buf[4];
unsigned long insn;
int i;
/* If we can't read the instruction at PC, return zero. */
if (read_memory_nobpt (pc, buf, sizeof (buf)))
return 0;
insn = 0;
for (i = 0; i < sizeof (buf); i++)
insn = (insn << 8) | buf[i];
return insn;
}
static CORE_ADDR
mn10300_analyze_prologue (struct frame_info *fi, CORE_ADDR pc)
{
CORE_ADDR func_addr, func_end, addr, stop;
CORE_ADDR stack_size;
int imm_size;
unsigned char buf[4];
int status, movm_args = 0;
char *name;
/* Use the PC in the frame if it's provided to look up the
start of this function. */
pc = (fi ? fi->pc : pc);
/* Find the start of this function. */
status = find_pc_partial_function (pc, &name, &func_addr, &func_end);
/* Do nothing if we couldn't find the start of this function or if we're
stopped at the first instruction in the prologue. */
if (status == 0)
{
return pc;
}
/* If we're in start, then give up. */
if (strcmp (name, "start") == 0)
{
if (fi != NULL)
fi->extra_info->status = NO_MORE_FRAMES;
return pc;
}
/* At the start of a function our frame is in the stack pointer. */
if (fi)
fi->extra_info->status = MY_FRAME_IN_SP;
/* Get the next two bytes into buf, we need two because rets is a two
byte insn and the first isn't enough to uniquely identify it. */
status = read_memory_nobpt (pc, buf, 2);
if (status != 0)
return pc;
/* If we're physically on an "rets" instruction, then our frame has
already been deallocated. Note this can also be true for retf
and ret if they specify a size of zero.
In this case fi->frame is bogus, we need to fix it. */
if (fi && buf[0] == 0xf0 && buf[1] == 0xfc)
{
if (fi->next == NULL)
fi->frame = read_sp ();
return fi->pc;
}
/* Similarly if we're stopped on the first insn of a prologue as our
frame hasn't been allocated yet. */
if (fi && fi->pc == func_addr)
{
if (fi->next == NULL)
fi->frame = read_sp ();
return fi->pc;
}
/* Figure out where to stop scanning. */
stop = fi ? fi->pc : func_end;
/* Don't walk off the end of the function. */
stop = stop > func_end ? func_end : stop;
/* Start scanning on the first instruction of this function. */
addr = func_addr;
/* Suck in two bytes. */
status = read_memory_nobpt (addr, buf, 2);
if (status != 0)
{
fix_frame_pointer (fi, 0);
return addr;
}
/* First see if this insn sets the stack pointer from a register; if
so, it's probably the initialization of the stack pointer in _start,
so mark this as the bottom-most frame. */
if (buf[0] == 0xf2 && (buf[1] & 0xf3) == 0xf0)
{
if (fi)
fi->extra_info->status = NO_MORE_FRAMES;
return addr;
}
/* Now look for movm [regs],sp, which saves the callee saved registers.
At this time we don't know if fi->frame is valid, so we only note
that we encountered a movm instruction. Later, we'll set the entries
in fsr.regs as needed. */
if (buf[0] == 0xcf)
{
/* Extract the register list for the movm instruction. */
status = read_memory_nobpt (addr + 1, buf, 1);
movm_args = *buf;
addr += 2;
/* Quit now if we're beyond the stop point. */
if (addr >= stop)
{
/* Fix fi->frame since it's bogus at this point. */
if (fi && fi->next == NULL)
fi->frame = read_sp ();
/* Note if/where callee saved registers were saved. */
set_movm_offsets (fi, movm_args);
return addr;
}
/* Get the next two bytes so the prologue scan can continue. */
status = read_memory_nobpt (addr, buf, 2);
if (status != 0)
{
/* Fix fi->frame since it's bogus at this point. */
if (fi && fi->next == NULL)
fi->frame = read_sp ();
/* Note if/where callee saved registers were saved. */
set_movm_offsets (fi, movm_args);
return addr;
}
}
/* Now see if we set up a frame pointer via "mov sp,a3" */
if (buf[0] == 0x3f)
{
addr += 1;
/* The frame pointer is now valid. */
if (fi)
{
fi->extra_info->status |= MY_FRAME_IN_FP;
fi->extra_info->status &= ~MY_FRAME_IN_SP;
}
/* Quit now if we're beyond the stop point. */
if (addr >= stop)
{
/* Fix fi->frame if it's bogus at this point. */
fix_frame_pointer (fi, 0);
/* Note if/where callee saved registers were saved. */
set_movm_offsets (fi, movm_args);
return addr;
}
/* Get two more bytes so scanning can continue. */
status = read_memory_nobpt (addr, buf, 2);
if (status != 0)
{
/* Fix fi->frame if it's bogus at this point. */
fix_frame_pointer (fi, 0);
/* Note if/where callee saved registers were saved. */
set_movm_offsets (fi, movm_args);
return addr;
}
}
/* Next we should allocate the local frame. No more prologue insns
are found after allocating the local frame.
Search for add imm8,sp (0xf8feXX)
or add imm16,sp (0xfafeXXXX)
or add imm32,sp (0xfcfeXXXXXXXX).
If none of the above was found, then this prologue has no
additional stack. */
status = read_memory_nobpt (addr, buf, 2);
if (status != 0)
{
/* Fix fi->frame if it's bogus at this point. */
fix_frame_pointer (fi, 0);
/* Note if/where callee saved registers were saved. */
set_movm_offsets (fi, movm_args);
return addr;
}
imm_size = 0;
if (buf[0] == 0xf8 && buf[1] == 0xfe)
imm_size = 1;
else if (buf[0] == 0xfa && buf[1] == 0xfe)
imm_size = 2;
else if (buf[0] == 0xfc && buf[1] == 0xfe)
imm_size = 4;
if (imm_size != 0)
{
/* Suck in imm_size more bytes, they'll hold the size of the
current frame. */
status = read_memory_nobpt (addr + 2, buf, imm_size);
if (status != 0)
{
/* Fix fi->frame if it's bogus at this point. */
fix_frame_pointer (fi, 0);
/* Note if/where callee saved registers were saved. */
set_movm_offsets (fi, movm_args);
return addr;
}
/* Note the size of the stack in the frame info structure. */
stack_size = extract_signed_integer (buf, imm_size);
if (fi)
fi->extra_info->stack_size = stack_size;
/* We just consumed 2 + imm_size bytes. */
addr += 2 + imm_size;
/* No more prologue insns follow, so begin preparation to return. */
/* Fix fi->frame if it's bogus at this point. */
fix_frame_pointer (fi, stack_size);
/* Note if/where callee saved registers were saved. */
set_movm_offsets (fi, movm_args);
return addr;
}
/* We never found an insn which allocates local stack space, regardless
this is the end of the prologue. */
/* Fix fi->frame if it's bogus at this point. */
fix_frame_pointer (fi, 0);
/* Note if/where callee saved registers were saved. */
set_movm_offsets (fi, movm_args);
return addr;
}
