69 lines
1.9 KiB
C
69 lines
1.9 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <stdint.h>
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#include <libcore/libcore.h>
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#define PATCH_PRINTF(print, start, str) if (print) fprintf(stderr, "Patching (0x%04x) - "str": 0x%02x 0x%02x 0x%02x 0x%02x\n", (uint32_t) start, data[0], data[1], data[2], data[3]);
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#define PREPARE_PATCH(print, count) \
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size_t page_size = sysconf(_SC_PAGESIZE); \
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uintptr_t end = ((uintptr_t) start) + (4 * count); \
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uintptr_t page_start = ((uintptr_t) start) & -page_size; \
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mprotect((void *) page_start, end - page_start, PROT_READ | PROT_WRITE); \
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\
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unsigned char *data = (unsigned char *) start; \
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int thumb = ((size_t) start) & 1; \
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if (thumb) { \
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data--; \
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} \
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PATCH_PRINTF(print, start, "original");
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#define END_PATCH(print) \
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PATCH_PRINTF(print, start, "result"); \
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\
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mprotect((void *) page_start, end - page_start, PROT_READ | PROT_EXEC); \
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__clear_cache(start, (void *) end);
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#define ORIGINAL_SIZE 4 + sizeof (int)
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void *overwrite(void *start, void *target) {
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PREPARE_PATCH(1, 2);
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void *original = malloc(ORIGINAL_SIZE);
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memcpy(original, start, ORIGINAL_SIZE);
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if (thumb) {
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unsigned char patch[4] = {0xdf, 0xf8, 0x00, 0xf0};
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memcpy(data, patch, 4);
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} else {
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unsigned char patch[4] = {0x04, 0xf0, 0x1f, 0xe5};
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memcpy(data, patch, 4);
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}
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memcpy(&data[4], &target, sizeof (int));
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END_PATCH(1);
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return original;
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}
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void revert_overwrite(void *start, void *original) {
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PREPARE_PATCH(0, 2);
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void *temp = malloc(ORIGINAL_SIZE);
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memcpy(temp, data, ORIGINAL_SIZE);
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memcpy(data, original, ORIGINAL_SIZE);
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memcpy(original, temp, ORIGINAL_SIZE);
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free(temp);
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END_PATCH(0);
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}
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void patch(void *start, unsigned char patch[]) {
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PREPARE_PATCH(1, 1);
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memcpy(data, patch, 4);
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END_PATCH(1);
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}
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