remote.c

嵌入式ARM的一些源代码

/*
 * taken from gdb/remote.c
 *
 * I am only interested in the write to memory stuff - everything else
 * has been ripped out
 *
 * all the copyright notices etc have been left in
 */

/* enough so that it will compile */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <alloca.h>
#include "serial.h"
#include "error.h"
#include "remote.h"
#define REGISTER_BYTES 0
#define fprintf_unfiltered fprintf
#define fprintf_filtered fprintf
#define fputs_unfiltered fputs
#define fputs_filtered fputs
#define fputc_unfiltered fputc
#define fputc_filtered fputc
#define printf_unfiltered printf
#define printf_filtered printf
#define puts_unfiltered puts
#define puts_filtered puts
#define putchar_unfiltered putchar
#define putchar_filtered putchar
#define fputstr_unfiltered(a,b,c) fputs((a), (c))
#define gdb_stdlog stderr
#define SERIAL_READCHAR(fd,timo)	serialreadchar((fd), (timo))
#define SERIAL_WRITE(fd, addr, len)	serialwrite((fd), (addr), (len))
#define error Error
#define perror_with_name Perror
#define gdb_flush fflush
#define max(a,b) (((a)>(b))?(a):(b))
#define min(a,b) (((a)<(b))?(a):(b))
#define target_mourn_inferior() {}
#define ULONGEST unsigned long
#define CORE_ADDR unsigned long

static int putpkt (char *);
static int putpkt_binary(char *, int);
static void getpkt (char *, int);

static int remote_debug = 0, remote_register_buf_size = 0, watchdog = 0;

int remote_desc = -1, remote_timeout = 10;

static void
fputstrn_unfiltered(char *s, int n, int x, FILE *fp)
{
    while (n-- > 0)
	fputc(*s++, fp);
}

void
remote_reset(void)
{
    SERIAL_WRITE(remote_desc, "+", 1);
}

void
remote_continue(void)
{
    putpkt("c");
}

/* Remote target communications for serial-line targets in custom GDB protocol
   Copyright 1988, 91, 92, 93, 94, 95, 96, 97, 98, 1999 
   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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */
/* *INDENT-OFF* */
/* Remote communication protocol.

   A debug packet whose contents are <data>
   is encapsulated for transmission in the form:

	$ <data> # CSUM1 CSUM2

	<data> must be ASCII alphanumeric and cannot include characters
	'$' or '#'.  If <data> starts with two characters followed by
	':', then the existing stubs interpret this as a sequence number.

	CSUM1 and CSUM2 are ascii hex representation of an 8-bit 
	checksum of <data>, the most significant nibble is sent first.
	the hex digits 0-9,a-f are used.

   Receiver responds with:

	+	- if CSUM is correct and ready for next packet
	-	- if CSUM is incorrect

   <data> is as follows:
   Most values are encoded in ascii hex digits.  Signal numbers are according
   to the numbering in target.h.

	Request		Packet

	set thread	Hct...		Set thread for subsequent operations.
					c = 'c' for thread used in step and 
					continue; t... can be -1 for all
					threads.
					c = 'g' for thread used in other
					operations.  If zero, pick a thread,
					any thread.
	reply		OK		for success
			ENN		for an error.

	read registers  g
	reply		XX....X		Each byte of register data
					is described by two hex digits.
					Registers are in the internal order
					for GDB, and the bytes in a register
					are in the same order the machine uses.
			or ENN		for an error.

	write regs	GXX..XX		Each byte of register data
					is described by two hex digits.
	reply		OK		for success
			ENN		for an error

        write reg	Pn...=r...	Write register n... with value r...,
					which contains two hex digits for each
					byte in the register (target byte
					order).
	reply		OK		for success
			ENN		for an error
	(not supported by all stubs).

	read mem	mAA..AA,LLLL	AA..AA is address, LLLL is length.
	reply		XX..XX		XX..XX is mem contents
					Can be fewer bytes than requested
					if able to read only part of the data.
			or ENN		NN is errno

	write mem	MAA..AA,LLLL:XX..XX
					AA..AA is address,
					LLLL is number of bytes,
					XX..XX is data
	reply		OK		for success
			ENN		for an error (this includes the case
					where only part of the data was
					written).

        write mem       XAA..AA,LLLL:XX..XX
         (binary)                       AA..AA is address,
                                        LLLL is number of bytes,
                                        XX..XX is binary data
        reply           OK              for success
                        ENN             for an error

	continue	cAA..AA		AA..AA is address to resume
					If AA..AA is omitted,
					resume at same address.

	step		sAA..AA		AA..AA is address to resume
					If AA..AA is omitted,
					resume at same address.

	continue with	Csig;AA..AA	Continue with signal sig (hex signal
	signal				number).  If ;AA..AA is omitted, 
					resume at same address.

	step with	Ssig;AA..AA	Like 'C' but step not continue.
	signal

	last signal     ?               Reply the current reason for stopping.
                                        This is the same reply as is generated
					for step or cont : SAA where AA is the
					signal number.

	detach          D               Reply OK.

	There is no immediate reply to step or cont.
	The reply comes when the machine stops.
	It is		SAA		AA is the signal number.

	or...		TAAn...:r...;n...:r...;n...:r...;
					AA = signal number
					n... = register number (hex)
					  r... = register contents
					n... = `thread'
					  r... = thread process ID.  This is
						 a hex integer.
					n... = other string not starting 
					    with valid hex digit.
					  gdb should ignore this n,r pair
					  and go on to the next.  This way
					  we can extend the protocol.
	or...		WAA		The process exited, and AA is
					the exit status.  This is only
					applicable for certains sorts of
					targets.
	or...		XAA		The process terminated with signal
					AA.
	or (obsolete)	NAA;tttttttt;dddddddd;bbbbbbbb
					AA = signal number
					tttttttt = address of symbol "_start"
					dddddddd = base of data section
					bbbbbbbb = base of bss  section.
					Note: only used by Cisco Systems 
					targets.  The difference between this
					reply and the "qOffsets" query is that
					the 'N' packet may arrive spontaneously
					whereas the 'qOffsets' is a query
					initiated by the host debugger.
        or...           OXX..XX	XX..XX  is hex encoding of ASCII data. This
					can happen at any time while the 
					program is running and the debugger 
					should continue to wait for 
					'W', 'T', etc.

	thread alive	TXX		Find out if the thread XX is alive.
	reply		OK		thread is still alive
			ENN		thread is dead
	
	remote restart	RXX		Restart the remote server

	extended ops 	!		Use the extended remote protocol.
					Sticky -- only needs to be set once.

	kill request	k

	toggle debug	d		toggle debug flag (see 386 & 68k stubs)
	reset		r		reset -- see sparc stub.
	reserved	<other>		On other requests, the stub should
					ignore the request and send an empty
					response ($#<checksum>).  This way
					we can extend the protocol and GDB
					can tell whether the stub it is
					talking to uses the old or the new.
	search		tAA:PP,MM	Search backwards starting at address
					AA for a match with pattern PP and
					mask MM.  PP and MM are 4 bytes.
					Not supported by all stubs.

	general query	qXXXX		Request info about XXXX.
	general set	QXXXX=yyyy	Set value of XXXX to yyyy.
	query sect offs	qOffsets	Get section offsets.  Reply is
					Text=xxx;Data=yyy;Bss=zzz

	Responses can be run-length encoded to save space.  A '*' means that
	the next character is an ASCII encoding giving a repeat count which
	stands for that many repititions of the character preceding the '*'.
	The encoding is n+29, yielding a printable character where n >=3 
	(which is where rle starts to win).  Don't use an n > 126.

	So 
	"0* " means the same as "0000".  */
/* *INDENT-ON* */

/* This variable (available to the user via "set remotebinarydownload")
   dictates whether downloads are sent in binary (via the 'X' packet).
   We assume that the stub can, and attempt to do it. This will be cleared if
   the stub does not understand it. This switch is still needed, though
   in cases when the packet is supported in the stub, but the connection
   does not allow it (i.e., 7-bit serial connection only). */
static int remote_binary_download = 1;

/* Have we already checked whether binary downloads work? */
static int remote_binary_checked;

/* Maximum number of bytes to read/write at once.  The value here
   is chosen to fill up a packet (the headers account for the 32).  */
#define MAXBUFBYTES(N) (((N)-32)/2)

/* Having this larger than 400 causes us to be incompatible with m68k-stub.c
   and i386-stub.c.  Normally, no one would notice because it only matters
   for writing large chunks of memory (e.g. in downloads).  Also, this needs
   to be more than 400 if required to hold the registers (see below, where
   we round it up based on REGISTER_BYTES).  */
/* Round up PBUFSIZ to hold all the registers, at least.  */
#define	PBUFSIZ ((REGISTER_BYTES > MAXBUFBYTES (400)) \
		 ? (REGISTER_BYTES * 2 + 32) \
		 : 400)


/* This variable sets the number of bytes to be written to the target
   in a single packet.  Normally PBUFSIZ is satisfactory, but some
   targets need smaller values (perhaps because the receiving end
   is slow).  */

static int remote_write_size = 0x7fffffff;

/* This variable sets the number of bits in an address that are to be
   sent in a memory ("M" or "m") packet.  Normally, after stripping
   leading zeros, the entire address would be sent. This variable
   restricts the address to REMOTE_ADDRESS_SIZE bits.  HISTORY: The
   initial implementation of remote.c restricted the address sent in
   memory packets to ``host::sizeof long'' bytes - (typically 32
   bits).  Consequently, for 64 bit targets, the upper 32 bits of an
   address was never sent.  Since fixing this bug may cause a break in
   some remote targets this variable is principly provided to
   facilitate backward compatibility. */

static int remote_address_size;

/* Convert hex digit A to a number.  */

static int
fromhex (int a)
{
  if (a >= '0' && a <= '9')
    return a - '0';
  else if (a >= 'a' && a <= 'f')
    return a - 'a' + 10;
  else if (a >= 'A' && a <= 'F')
    return a - 'A' + 10;
  else {
    error ("Reply contains invalid hex digit %d", a);
    return -1;
  }
}

/* Convert number NIB to a hex digit.  */

static int
tohex (int nib)
{
  if (nib < 10)
    return '0' + nib;
  else
    return 'a' + nib - 10;
}

/* Return the number of hex digits in num.  */

static int
hexnumlen (ULONGEST num)
{
  int i;

  for (i = 0; num != 0; i++)
    num >>= 4;

  return max (i, 1);
}

/* Set BUF to the hex digits representing NUM.  */

static int
hexnumstr (char *buf, ULONGEST num)
{
  int i;
  int len = hexnumlen (num);

  buf[len] = '\0';

  for (i = len - 1; i >= 0; i--)
    {
      buf[i] = "0123456789abcdef"[(num & 0xf)];
      num >>= 4;
    }

  return len;
}

/* Mask all but the least significant REMOTE_ADDRESS_SIZE bits. */

static CORE_ADDR
remote_address_masked (CORE_ADDR addr)
{
  if (remote_address_size > 0
      && remote_address_size < (sizeof (ULONGEST) * 8))
    {
      /* Only create a mask when that mask can safely be constructed
         in a ULONGEST variable. */
      ULONGEST mask = 1;
      mask = (mask << remote_address_size) - 1;
      addr &= mask;
    }
  return addr;
}

/* Determine whether the remote target supports binary downloading.
   This is accomplished by sending a no-op memory write of zero length
   to the target at the specified address. It does not suffice to send
   the whole packet, since many stubs strip the eighth bit and subsequently
   compute a wrong checksum, which causes real havoc with remote_write_bytes.

   NOTE: This can still lose if the serial line is not eight-bit clean. In
   cases like this, the user should clear "remotebinarydownload". */
static void
check_binary_download (CORE_ADDR addr)
{
  if (remote_binary_download && !remote_binary_checked)
    {
      char *buf = alloca (PBUFSIZ);
      char *p;
      remote_binary_checked = 1;

      p = buf;
      *p++ = 'X';
      p += hexnumstr (p, (ULONGEST) addr);
      *p++ = ',';
      p += hexnumstr (p, (ULONGEST) 0);
      *p++ = ':';
      *p = '\0';

      putpkt_binary (buf, (int) (p - buf));
      getpkt (buf, 0);

      if (buf[0] == '\0')
	remote_binary_download = 0;
    }

  if (remote_debug)
    {
      if (remote_binary_download)
	fprintf_unfiltered (gdb_stdlog,
			    "binary downloading suppported by target\n");
      else
	fprintf_unfiltered (gdb_stdlog,
			    "binary downloading NOT suppported by target\n");
    }
}

/* Write memory data directly to the remote machine.
   This does not inform the data cache; the data cache uses this.
   MEMADDR is the address in the remote memory space.
   MYADDR is the address of the buffer in our space.
   LEN is the number of bytes.

   Returns number of bytes transferred, or 0 for error.  */

int
remote_write_bytes (memaddr, myaddr, len)
     CORE_ADDR memaddr;
     char *myaddr;