grub/grub-core/gdb/cstub.c

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/* cstub.c - machine independent portion of remote GDB stub */
/*
* Copyright (C) 2006 Lubomir Kundrak
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <grub/misc.h>
#include <grub/cpu/gdb.h>
#include <grub/gdb.h>
#include <grub/serial.h>
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#include <grub/backtrace.h>
static const char hexchars[] = "0123456789abcdef";
int grub_gdb_regs[GRUB_MACHINE_NR_REGS];
#define GRUB_GDB_COMBUF_SIZE 400 /* At least sizeof(grub_gdb_regs)*2 are needed for
register packets. */
static char grub_gdb_inbuf[GRUB_GDB_COMBUF_SIZE + 1];
static char grub_gdb_outbuf[GRUB_GDB_COMBUF_SIZE + 1];
struct grub_serial_port *grub_gdb_port;
static int
hex (char ch)
{
if ((ch >= 'a') && (ch <= 'f'))
return (ch - 'a' + 10);
if ((ch >= '0') && (ch <= '9'))
return (ch - '0');
if ((ch >= 'A') && (ch <= 'F'))
return (ch - 'A' + 10);
return (-1);
}
/* Scan for the sequence $<data>#<checksum>. */
static char *
grub_gdb_getpacket (void)
{
char *buffer = &grub_gdb_inbuf[0];
unsigned char checksum;
unsigned char xmitcsum;
int count;
int ch;
while (1)
{
/* Wait around for the start character, ignore all other
characters. */
while ((ch = grub_serial_port_fetch (grub_gdb_port)) != '$');
retry:
checksum = 0;
xmitcsum = -1;
count = 0;
/* Now read until a # or end of buffer is found. */
while (count < GRUB_GDB_COMBUF_SIZE)
{
do
ch = grub_serial_port_fetch (grub_gdb_port);
while (ch < 0);
if (ch == '$')
goto retry;
if (ch == '#')
break;
checksum += ch;
buffer[count] = ch;
count = count + 1;
}
buffer[count] = 0;
if (ch == '#')
{
do
ch = grub_serial_port_fetch (grub_gdb_port);
while (ch < 0);
xmitcsum = hex (ch) << 4;
do
ch = grub_serial_port_fetch (grub_gdb_port);
while (ch < 0);
xmitcsum += hex (ch);
if (checksum != xmitcsum)
grub_serial_port_put (grub_gdb_port, '-'); /* Failed checksum. */
else
{
grub_serial_port_put (grub_gdb_port, '+'); /* Successful transfer. */
/* If a sequence char is present, reply the sequence ID. */
if (buffer[2] == ':')
{
grub_serial_port_put (grub_gdb_port, buffer[0]);
grub_serial_port_put (grub_gdb_port, buffer[1]);
return &buffer[3];
}
return &buffer[0];
}
}
}
}
/* Send the packet in buffer. */
static void
grub_gdb_putpacket (char *buffer)
{
grub_uint8_t checksum;
/* $<packet info>#<checksum>. */
do
{
char *ptr;
grub_serial_port_put (grub_gdb_port, '$');
checksum = 0;
for (ptr = buffer; *ptr; ptr++)
{
grub_serial_port_put (grub_gdb_port, *ptr);
checksum += *ptr;
}
grub_serial_port_put (grub_gdb_port, '#');
grub_serial_port_put (grub_gdb_port, hexchars[checksum >> 4]);
grub_serial_port_put (grub_gdb_port, hexchars[checksum & 0xf]);
}
while (grub_serial_port_fetch (grub_gdb_port) != '+');
}
/* Convert the memory pointed to by mem into hex, placing result in buf.
Return a pointer to the last char put in buf (NULL). */
static char *
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grub_gdb_mem2hex (char *mem, char *buf, grub_size_t count)
{
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grub_size_t i;
unsigned char ch;
for (i = 0; i < count; i++)
{
ch = *mem++;
*buf++ = hexchars[ch >> 4];
*buf++ = hexchars[ch % 16];
}
*buf = 0;
return (buf);
}
/* Convert the hex array pointed to by buf into binary to be placed in mem.
Return a pointer to the character after the last byte written. */
static char *
grub_gdb_hex2mem (char *buf, char *mem, int count)
{
int i;
unsigned char ch;
for (i = 0; i < count; i++)
{
ch = hex (*buf++) << 4;
ch = ch + hex (*buf++);
*mem++ = ch;
}
return (mem);
}
/* Convert hex characters to int and return the number of characters
processed. */
static int
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grub_gdb_hex2int (char **ptr, grub_uint64_t *int_value)
{
int num_chars = 0;
int hex_value;
*int_value = 0;
while (**ptr)
{
hex_value = hex (**ptr);
if (hex_value >= 0)
{
*int_value = (*int_value << 4) | hex_value;
num_chars++;
}
else
break;
(*ptr)++;
}
return (num_chars);
}
/* This function does all command procesing for interfacing to gdb. */
void __attribute__ ((regparm(3)))
grub_gdb_trap (int trap_no)
{
unsigned int sig_no;
int stepping;
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grub_uint64_t addr;
grub_uint64_t length;
char *ptr;
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if (!grub_gdb_port)
{
grub_printf ("Unhandled exception 0x%x at ", trap_no);
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grub_backtrace_print_address ((void *) grub_gdb_regs[PC]);
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grub_printf ("\n");
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grub_backtrace_pointer ((void *) grub_gdb_regs[EBP]);
grub_fatal ("Unhandled exception");
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}
sig_no = grub_gdb_trap2sig (trap_no);
ptr = grub_gdb_outbuf;
/* Reply to host that an exception has occurred. */
*ptr++ = 'T'; /* Notify gdb with signo, PC, FP and SP. */
*ptr++ = hexchars[sig_no >> 4];
*ptr++ = hexchars[sig_no & 0xf];
/* Stack pointer. */
*ptr++ = hexchars[SP];
*ptr++ = ':';
ptr = grub_gdb_mem2hex ((char *) &grub_gdb_regs[ESP], ptr, 4);
*ptr++ = ';';
/* Frame pointer. */
*ptr++ = hexchars[FP];
*ptr++ = ':';
ptr = grub_gdb_mem2hex ((char *) &grub_gdb_regs[EBP], ptr, 4);
*ptr++ = ';';
/* Program counter. */
*ptr++ = hexchars[PC];
*ptr++ = ':';
ptr = grub_gdb_mem2hex ((char *) &grub_gdb_regs[PC], ptr, 4);
*ptr++ = ';';
*ptr = '\0';
grub_gdb_putpacket (grub_gdb_outbuf);
stepping = 0;
while (1)
{
grub_gdb_outbuf[0] = 0;
ptr = grub_gdb_getpacket ();
switch (*ptr++)
{
case '?':
grub_gdb_outbuf[0] = 'S';
grub_gdb_outbuf[1] = hexchars[sig_no >> 4];
grub_gdb_outbuf[2] = hexchars[sig_no & 0xf];
grub_gdb_outbuf[3] = 0;
break;
/* Return values of the CPU registers. */
case 'g':
grub_gdb_mem2hex ((char *) grub_gdb_regs, grub_gdb_outbuf,
sizeof (grub_gdb_regs));
break;
/* Set values of the CPU registers -- return OK. */
case 'G':
grub_gdb_hex2mem (ptr, (char *) grub_gdb_regs,
sizeof (grub_gdb_regs));
grub_strcpy (grub_gdb_outbuf, "OK");
break;
/* Set the value of a single CPU register -- return OK. */
case 'P':
{
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grub_uint64_t regno;
if (grub_gdb_hex2int (&ptr, &regno) && *ptr++ == '=')
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if (regno < GRUB_MACHINE_NR_REGS)
{
grub_gdb_hex2mem (ptr, (char *) &grub_gdb_regs[regno], 4);
grub_strcpy (grub_gdb_outbuf, "OK");
break;
}
/* FIXME: GDB requires setting orig_eax. I don't know what's
this register is about. For now just simulate setting any
registers. */
grub_strcpy (grub_gdb_outbuf, /*"E01"*/ "OK");
break;
}
/* mAA..AA,LLLL: Read LLLL bytes at address AA..AA. */
case 'm':
/* Try to read %x,%x. Set ptr = 0 if successful. */
if (grub_gdb_hex2int (&ptr, &addr))
if (*(ptr++) == ',')
if (grub_gdb_hex2int (&ptr, &length))
{
ptr = 0;
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grub_gdb_mem2hex ((char *) (grub_addr_t) addr,
grub_gdb_outbuf, length);
}
if (ptr)
grub_strcpy (grub_gdb_outbuf, "E01");
break;
/* MAA..AA,LLLL: Write LLLL bytes at address AA.AA -- return OK. */
case 'M':
/* Try to read %x,%x. Set ptr = 0 if successful. */
if (grub_gdb_hex2int (&ptr, &addr))
if (*(ptr++) == ',')
if (grub_gdb_hex2int (&ptr, &length))
if (*(ptr++) == ':')
{
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grub_gdb_hex2mem (ptr, (char *) (grub_addr_t) addr, length);
grub_strcpy (grub_gdb_outbuf, "OK");
ptr = 0;
}
if (ptr)
{
grub_strcpy (grub_gdb_outbuf, "E02");
}
break;
/* sAA..AA: Step one instruction from AA..AA(optional). */
case 's':
stepping = 1;
/* FALLTHROUGH */
/* cAA..AA: Continue at address AA..AA(optional). */
case 'c':
/* try to read optional parameter, pc unchanged if no parm */
if (grub_gdb_hex2int (&ptr, &addr))
grub_gdb_regs[PC] = addr;
/* Clear the trace bit. */
grub_gdb_regs[PS] &= 0xfffffeff;
/* Set the trace bit if we're stepping. */
if (stepping)
grub_gdb_regs[PS] |= 0x100;
return;
/* Kill the program. */
case 'k':
/* Do nothing. */
return;
}
/* Reply to the request. */
grub_gdb_putpacket (grub_gdb_outbuf);
}
}