102 lines
2.8 KiB
C
102 lines
2.8 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <sys/wait.h>
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#include <sys/syscall.h>
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#include <time.h>
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#include <errno.h>
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#include <stdint.h>
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#define FUTEX_WAIT_REQUEUE_PI 11
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#define FUTEX_CMP_REQUEUE_PI 12
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static long futex(uint32_t *uaddr, int futex_op, uint32_t val, const struct timespec *timeout, uint32_t *uaddr2, uint32_t val3) {
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return syscall(SYS_futex, uaddr, futex_op, val, timeout, uaddr2, val3);
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}
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int main() {
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// 创建共享内存区域
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uint32_t *shared_futex = mmap(NULL, sizeof(uint32_t), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
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if (shared_futex == MAP_FAILED) {
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perror("mmap");
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exit(1);
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}
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// 初始化futex
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*shared_futex = 0;
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printf("Parent: Setting up robust futex list...\n");
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// 设置robust futex列表
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struct robust_list_head {
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struct robust_list *list;
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long futex_offset;
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struct robust_list *list_op_pending;
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};
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struct robust_list_head robust_head = {
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.list = (struct robust_list *)shared_futex,
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.futex_offset = 0,
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.list_op_pending = NULL
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};
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// 设置当前进程的robust list
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if (syscall(SYS_set_robust_list, &robust_head, sizeof(robust_head)) != 0) {
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perror("set_robust_list");
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exit(1);
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}
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pid_t pid = fork();
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if (pid == 0) {
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// 子进程
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printf("Child: Waiting for futex...\n");
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// 子进程也设置自己的robust list
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struct robust_list_head child_robust_head = {
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.list = (struct robust_list *)shared_futex,
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.futex_offset = 0,
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.list_op_pending = NULL
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};
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if (syscall(SYS_set_robust_list, &child_robust_head, sizeof(child_robust_head)) != 0) {
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perror("child set_robust_list");
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exit(1);
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}
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// 锁定futex
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__sync_lock_test_and_set(shared_futex, getpid());
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printf("Child: Acquired futex, sleeping for 1 second...\n");
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sleep(1);
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// 释放futex
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__sync_lock_release(shared_futex);
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printf("Child: Released futex, exiting...\n");
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exit(0);
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} else if (pid > 0) {
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// 父进程
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printf("Parent: Child PID = %d\n", pid);
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// 等待子进程
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int status;
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waitpid(pid, &status, 0);
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printf("Parent: Child exited, cleaning up...\n");
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// 尝试访问futex（这可能会触发VMA not mapped错误）
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printf("Parent: Futex value = %u\n", *shared_futex);
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// 清理
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munmap(shared_futex, sizeof(uint32_t));
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printf("Parent: Done\n");
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} else {
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perror("fork");
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exit(1);
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}
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return 0;
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} |