3rd-party/linux-kernel-module-cheat
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This commit is contained in:
Ciro Santilli
2017-06-28 07:14:21 +01:00
parent 7ae74bfcce
commit 88f1211409
2 changed files with 20 additions and 20 deletions
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37
kernel_module/user/devmem.c
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@@ -17,26 +17,27 @@ Confirm memory from QEMU monitor with:
#include <unistd.h>
int main(int argc, char *argv[]) {
if (argc < 3) {
printf("Usage: %s <phys_addr> <len>\n", argv[0]);
return 0;
}
off_t offset = strtoul(argv[1], NULL, 0);
size_t len = strtoul(argv[2], NULL, 0);
if (argc < 3) {
printf("Usage: %s <phys_addr> <len>\n", argv[0]);
return 0;
}
off_t offset = strtoul(argv[1], NULL, 0);
size_t len = strtoul(argv[2], NULL, 0);
size_t pagesize = sysconf(_SC_PAGE_SIZE);
off_t page_base = (offset / pagesize) * pagesize;
off_t page_offset = offset - page_base;
int fd = open("/dev/mem", O_SYNC);
size_t pagesize = sysconf(_SC_PAGE_SIZE);
off_t page_base = (offset / pagesize) * pagesize;
off_t page_offset = offset - page_base;
int fd = open("/dev/mem", O_SYNC);
size_t reallen = page_offset + len;
unsigned char *mem = mmap(NULL, reallen, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, page_base);
if (mem == MAP_FAILED) {
perror("mmap");
unsigned char *mem = mmap(NULL, reallen, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, page_base);
if (mem == MAP_FAILED) {
/* TODO why does it fail for some addreses but not for others? */
perror("mmap");
exit(EXIT_FAILURE);
}
for (size_t i = 0; i < len; ++i) {
printf("%02x ", (unsigned int)mem[page_offset + i]);
/* TODO can't edit memory? */
}
for (size_t i = 0; i < len; ++i) {
printf("%02x ", (unsigned int)mem[page_offset + i]);
/* TODO can't edit memory? */
mem[page_offset + i] = i % 256;
}
puts("");
@@ -44,5 +45,5 @@ int main(int argc, char *argv[]) {
perror("munmap");
exit(EXIT_FAILURE);
}
return EXIT_SUCCESS;
return EXIT_SUCCESS;
}