| 1 | #include <stdint.h> |
|---|---|
| 2 | #include <stdio.h> |
| 3 | #include <string.h> |
| 4 | #include <sys/mman.h> |
| 5 | #include <unistd.h> |
| 6 | |
| 7 | extern uint8_t __start_target_section[]; |
| 8 | extern uint8_t __stop_target_section[]; |
| 9 | |
| 10 | __attribute__((used, section("target_section"))) int target_function(void) { |
| 11 | return 42; |
| 12 | } |
| 13 | |
| 14 | typedef int (*target_function_t)(void); |
| 15 | |
| 16 | int main(void) { |
| 17 | size_t target_function_size = __stop_target_section - __start_target_section; |
| 18 | size_t page_size = sysconf(_SC_PAGESIZE); |
| 19 | size_t page_aligned_size = |
| 20 | (target_function_size + page_size - 1) & ~(page_size - 1); |
| 21 | |
| 22 | void *executable_memory = |
| 23 | mmap(NULL, len: page_aligned_size, PROT_READ | PROT_WRITE | PROT_EXEC, |
| 24 | MAP_PRIVATE | MAP_ANONYMOUS, fd: -1, offset: 0); |
| 25 | if (executable_memory == MAP_FAILED) { |
| 26 | perror(s: "mmap"); |
| 27 | return 1; |
| 28 | } |
| 29 | |
| 30 | memcpy(dest: executable_memory, src: __start_target_section, n: target_function_size); |
| 31 | |
| 32 | target_function_t func = (target_function_t)executable_memory; |
| 33 | int result = func(); // Break here |
| 34 | printf(format: "Result from target function: %d\n", result); |
| 35 | |
| 36 | return 0; |
| 37 | } |
| 38 |