|
/* memrw.c
|
|
|
|
Copyright (c) 2023- GAUCHARD David (LAAS-CNRS)
|
|
Copyright (c) 2023- BLANC Frédéric (LAAS-CNRS)
|
|
|
|
memrw 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 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
memrw 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 memrw. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
// gcc -Wall -Wextra memrw.c -o memrw && ./memrw 0x40000000 1 0xfe
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <fcntl.h>
|
|
#include <sys/mman.h>
|
|
#include <unistd.h>
|
|
#include <stdint.h>
|
|
|
|
int main(int argc, char *argv[]) {
|
|
if (argc < 3) {
|
|
printf("Usage: %s <phys_addr> <read-len> [ value8bits value8bits ... ]\n", argv[0]);
|
|
return 0;
|
|
}
|
|
|
|
off_t offset = strtoul(argv[1], NULL, 0);
|
|
size_t len = strtoul(argv[2], NULL, 0);
|
|
|
|
// Truncate offset to a multiple of the page size, or mmap will fail.
|
|
size_t page_size = sysconf(_SC_PAGE_SIZE);
|
|
off_t page_base = (offset / page_size) * page_size;
|
|
off_t page_offset = offset - page_base;
|
|
|
|
printf("page_size = 0x%zx (%zd)\n", page_size, page_size);
|
|
printf("page_base = 0x%lx\n", page_base);
|
|
printf("page_offset = %lx\n", page_offset);
|
|
printf("page_offset + len = %lx\n", page_offset + len);
|
|
|
|
int fd = open("/dev/mem", O_SYNC | O_RDWR);
|
|
if (fd == -1)
|
|
{
|
|
perror("open(O_SYNC, O_RDWR)");
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
unsigned char *mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, page_base);
|
|
if (mem == MAP_FAILED) {
|
|
perror("Can't map memory");
|
|
return -1;
|
|
}
|
|
|
|
size_t i;
|
|
printf("avant:\n");
|
|
for (i = 0; i < len; ++i)
|
|
printf("%02x ", (int)mem[page_offset + i]);
|
|
printf("\n");
|
|
|
|
i = 0;
|
|
while (argv[i + 3] != NULL)
|
|
{
|
|
uint8_t v = strtoul(argv[i + 3], NULL, 0);
|
|
printf("writing 0x%02x @ %p (virtual %p)\n", v, (void*)(offset + i), &mem[page_offset + i]);
|
|
mem[page_offset + i] = v;
|
|
i++;
|
|
}
|
|
|
|
printf("apres:\n");
|
|
for (i = 0; i < len; ++i)
|
|
printf("%02x ", (int)mem[page_offset + i]);
|
|
printf("\n");
|
|
|
|
if (munmap(mem, page_size) == -1)
|
|
{
|
|
perror("munmap");
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
return 0;
|
|
}
|