u-boot/common/cmd_portio.c
Wolfgang Denk 54841ab50c Make sure that argv[] argument pointers are not modified.
The hush shell dynamically allocates (and re-allocates) memory for the
argument strings in the "char *argv[]" argument vector passed to
commands.  Any code that modifies these pointers will cause serious
corruption of the malloc data structures and crash U-Boot, so make
sure the compiler can check that no such modifications are being done
by changing the code into "char * const argv[]".

This modification is the result of debugging a strange crash caused
after adding a new command, which used the following argument
processing code which has been working perfectly fine in all Unix
systems since version 6 - but not so in U-Boot:

int main (int argc, char **argv)
{
	while (--argc > 0 && **++argv == '-') {
/* ====> */	while (*++*argv) {
			switch (**argv) {
			case 'd':
				debug++;
				break;
			...
			default:
				usage ();
			}
		}
	}
	...
}

The line marked "====>" will corrupt the malloc data structures and
usually cause U-Boot to crash when the next command gets executed by
the shell.  With the modification, the compiler will prevent this with
an
	error: increment of read-only location '*argv'

N.B.: The code above can be trivially rewritten like this:

	while (--argc > 0 && **++argv == '-') {
		char *arg = *argv;
		while (*++arg) {
			switch (*arg) {
			...

Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
2010-07-04 23:55:42 +02:00

164 lines
3.5 KiB
C

/*
* (C) Copyright 2003
* Marc Singer, elf@buici.com
*
* See file CREDITS for list of people who contributed to this
* project.
*
* 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
*/
/*
* Port I/O Functions
*
* Copied from FADS ROM, Dan Malek (dmalek@jlc.net)
*/
#include <common.h>
#include <command.h>
/* Display values from last command.
* Memory modify remembered values are different from display memory.
*/
static uint in_last_addr, in_last_size;
static uint out_last_addr, out_last_size, out_last_value;
int do_portio_out (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
{
uint addr = out_last_addr;
uint size = out_last_size;
uint value = out_last_value;
if (argc != 3) {
cmd_usage(cmdtp);
return 1;
}
if ((flag & CMD_FLAG_REPEAT) == 0) {
/* New command specified. Check for a size specification.
* Defaults to long if no or incorrect specification.
*/
size = cmd_get_data_size (argv[0], 1);
addr = simple_strtoul (argv[1], NULL, 16);
value = simple_strtoul (argv[2], NULL, 16);
}
#if defined (CONFIG_X86)
{
unsigned short port = addr;
switch (size) {
default:
case 1:
{
unsigned char ch = value;
__asm__ volatile ("out %0, %%dx"::"a" (ch), "d" (port));
}
break;
case 2:
{
unsigned short w = value;
__asm__ volatile ("out %0, %%dx"::"a" (w), "d" (port));
}
break;
case 4:
__asm__ volatile ("out %0, %%dx"::"a" (value), "d" (port));
break;
}
}
#endif /* CONFIG_X86 */
out_last_addr = addr;
out_last_size = size;
out_last_value = value;
return 0;
}
U_BOOT_CMD(
out, 3, 1, do_portio_out,
"write datum to IO port",
"[.b, .w, .l] port value\n - output to IO port"
);
int do_portio_in (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
{
uint addr = in_last_addr;
uint size = in_last_size;
if (argc != 2) {
cmd_usage(cmdtp);
return 1;
}
if ((flag & CMD_FLAG_REPEAT) == 0) {
/* New command specified. Check for a size specification.
* Defaults to long if no or incorrect specification.
*/
size = cmd_get_data_size (argv[0], 1);
addr = simple_strtoul (argv[1], NULL, 16);
}
#if defined (CONFIG_X86)
{
unsigned short port = addr;
switch (size) {
default:
case 1:
{
unsigned char ch;
__asm__ volatile ("in %%dx, %0":"=a" (ch):"d" (port));
printf (" %02x\n", ch);
}
break;
case 2:
{
unsigned short w;
__asm__ volatile ("in %%dx, %0":"=a" (w):"d" (port));
printf (" %04x\n", w);
}
break;
case 4:
{
unsigned long l;
__asm__ volatile ("in %%dx, %0":"=a" (l):"d" (port));
printf (" %08lx\n", l);
}
break;
}
}
#endif /* CONFIG_X86 */
in_last_addr = addr;
in_last_size = size;
return 0;
}
U_BOOT_CMD(
in, 2, 1, do_portio_in,
"read data from an IO port",
"[.b, .w, .l] port\n"
" - read datum from IO port"
);