C语言 如何在xv6中实现内核级线程的克隆

Question

在尝试测试我的克隆系统调用(下面的代码)时，我一直得到以下错误:

pid 4 thread_test: trap 13 err 0 on cpu 1 eip 0xc54 addr 0x0--kill proc pid 5 thread_test: trap 14 err 4 on cpu 1 eip 0x0 addr 0x28ec83e5--kill proc

分别对应一般保护故障和页面故障。有人知道是什么原因导致新线程在创建后就被终止了吗?

int clone(void *(*func) (void *), void *arg, void *stack)
{
  int i,pid;
  struct proc *np;
  // Allocate process.
  if((np = allocproc()) == 0)
    return -1;
  np->state = UNUSED;
  np->sz = proc->sz;
  np->parent = proc;
  *np->tf = *proc->tf;
  np->pgdir = proc->pgdir;
  np->tf->eax = 0;   // Clear %eax so that fork returns 0 in the child.
  np->tf->eip = (int)func;   //change eip to new function
  np->kstack = stack;  //use given stack
  for(i = 0; i < NOFILE; i++)
    if(proc->ofile[i])
      np->ofile[i] = filedup(proc->ofile[i]);
  np->cwd = idup(proc->cwd);
  np->tf->esp = (uint)(stack+PGSIZE-4); //put esp to right spot on stack
  *((uint*)(np->tf->esp)) = (uint)arg; //arg to function
  *((uint*)(np->tf->esp)-4) = 0xFFFFFFFF; //return to nowhere
  np->tf->esp =(np->tf->esp) -4;
  safestrcpy(np->name, proc->name, sizeof(proc->name));
  pid = np->pid;
  acquire(&ptable.lock);  //lock so writes last
  np->state = RUNNABLE;
  release(&ptable.lock);
  return pid;
}

Answer 1

我找到了解决方案，我试图使用传入的堆栈作为线程的堆栈。我需要在proc.h中创建一个单独的堆栈，然后使用:

将堆栈分配给线程

np->stack = (int)stack;