1 #include <fcntl.h>
2 #include <inttypes.h>
3 #include <stdbool.h>
4 #include <stdio.h>
5 #include <stdlib.h>
6 #include <string.h>
7 #include <sys/mman.h>
8 #include <unistd.h>
9
10 #if __LP64__
11 #define strtoptr strtoull
12 #else
13 #define strtoptr strtoul
14 #endif
15
usage()16 static int usage()
17 {
18 fprintf(stderr,"r [-b|-s] <address> [<value>]\n");
19 return -1;
20 }
21
main(int argc,char * argv[])22 int main(int argc, char *argv[])
23 {
24 if(argc < 2) return usage();
25
26 int width = 4;
27 if(!strcmp(argv[1], "-b")) {
28 width = 1;
29 argc--;
30 argv++;
31 } else if(!strcmp(argv[1], "-s")) {
32 width = 2;
33 argc--;
34 argv++;
35 }
36
37 if(argc < 2) return usage();
38 uintptr_t addr = strtoptr(argv[1], 0, 16);
39
40 uintptr_t endaddr = 0;
41 char* end = strchr(argv[1], '-');
42 if (end)
43 endaddr = strtoptr(end + 1, 0, 16);
44
45 if (!endaddr)
46 endaddr = addr + width - 1;
47
48 if (endaddr <= addr) {
49 fprintf(stderr, "end address <= start address\n");
50 return -1;
51 }
52
53 bool set = false;
54 uint32_t value = 0;
55 if(argc > 2) {
56 set = true;
57 value = strtoul(argv[2], 0, 16);
58 }
59
60 int fd = open("/dev/mem", O_RDWR | O_SYNC);
61 if(fd < 0) {
62 fprintf(stderr,"cannot open /dev/mem\n");
63 return -1;
64 }
65
66 off64_t mmap_start = addr & ~(PAGE_SIZE - 1);
67 size_t mmap_size = endaddr - mmap_start + 1;
68 mmap_size = (mmap_size + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
69
70 void* page = mmap64(0, mmap_size, PROT_READ | PROT_WRITE,
71 MAP_SHARED, fd, mmap_start);
72
73 if(page == MAP_FAILED){
74 fprintf(stderr,"cannot mmap region\n");
75 return -1;
76 }
77
78 while (addr <= endaddr) {
79 switch(width){
80 case 4: {
81 uint32_t* x = (uint32_t*) (((uintptr_t) page) + (addr & 4095));
82 if(set) *x = value;
83 fprintf(stderr,"%08"PRIxPTR": %08x\n", addr, *x);
84 break;
85 }
86 case 2: {
87 uint16_t* x = (uint16_t*) (((uintptr_t) page) + (addr & 4095));
88 if(set) *x = value;
89 fprintf(stderr,"%08"PRIxPTR": %04x\n", addr, *x);
90 break;
91 }
92 case 1: {
93 uint8_t* x = (uint8_t*) (((uintptr_t) page) + (addr & 4095));
94 if(set) *x = value;
95 fprintf(stderr,"%08"PRIxPTR": %02x\n", addr, *x);
96 break;
97 }
98 }
99 addr += width;
100 }
101 return 0;
102 }
103