/* * linux/kernel/fork.c * * (C) 1991 Linus Torvalds */ /* * 'fork.c' contains the help-routines for the 'fork' system call * (see also system_call.s), and some misc functions ('verify_area'). * Fork is rather simple, once you get the hang of it, but the memory * management can be a bitch. See 'mm/mm.c': 'copy_page_tables()' */ #include #include #include #include #include #include #include #include extern void write_verify(unsigned long address); long last_pid=0; void verify_area(void * addr,int size) { unsigned long start; start = (unsigned long) addr; size += start & 0xfff; start &= 0xfffff000; start += get_base(current->ldt[2]); while (size>0) { size -= 4096; write_verify(start); start += 4096; } } int copy_mem(int nr,struct task_struct * p) { unsigned long old_data_base,new_data_base,data_limit; unsigned long old_code_base,new_code_base,code_limit; code_limit=get_limit(0x0f); data_limit=get_limit(0x17); old_code_base = get_base(current->ldt[1]); old_data_base = get_base(current->ldt[2]); if (old_data_base != old_code_base) panic("We don't support separate I&D"); if (data_limit < code_limit) panic("Bad data_limit"); new_data_base = new_code_base = nr * 0x4000000; p->start_code = new_code_base; set_base(p->ldt[1],new_code_base); set_base(p->ldt[2],new_data_base); if (copy_page_tables(old_data_base,new_data_base,data_limit)) { free_page_tables(new_data_base,data_limit); return -ENOMEM; } return 0; } /* * Ok, this is the main fork-routine. It copies the system process * information (task[nr]) and sets up the necessary registers. It * also copies the data segment in it's entirety. */ int copy_process(int nr,long ebp,long edi,long esi,long gs,long none, long ebx,long ecx,long edx, long fs,long es,long ds, long eip,long cs,long eflags,long esp,long ss) { struct task_struct *p; int i; struct file *f; p = (struct task_struct *) get_free_page(); if (!p) return -EAGAIN; task[nr] = p; __asm__ volatile ("cld"); /* by wyj */ *p = *current; /* NOTE! this doesn't copy the supervisor stack */ p->state = TASK_UNINTERRUPTIBLE; p->pid = last_pid; p->father = current->pid; p->counter = p->priority; p->signal = 0; p->alarm = 0; p->leader = 0; /* process leadership doesn't inherit */ p->utime = p->stime = 0; p->cutime = p->cstime = 0; p->start_time = jiffies; p->tss.back_link = 0; p->tss.esp0 = PAGE_SIZE + (long) p; p->tss.ss0 = 0x10; p->tss.eip = eip; p->tss.eflags = eflags; p->tss.eax = 0; p->tss.ecx = ecx; p->tss.edx = edx; p->tss.ebx = ebx; p->tss.esp = esp; p->tss.ebp = ebp; p->tss.esi = esi; p->tss.edi = edi; p->tss.es = es & 0xffff; p->tss.cs = cs & 0xffff; p->tss.ss = ss & 0xffff; p->tss.ds = ds & 0xffff; p->tss.fs = fs & 0xffff; p->tss.gs = gs & 0xffff; p->tss.ldt = _LDT(nr); p->tss.trace_bitmap = 0x80000000; if (last_task_used_math == current) __asm__("clts ; fnsave %0"::"m" (p->tss.i387)); if (copy_mem(nr,p)) { task[nr] = NULL; free_page((long) p); return -EAGAIN; } for (i=0; ifilp[i]) f->f_count++; if (current->pwd) current->pwd->i_count++; if (current->root) current->root->i_count++; if (current->executable) current->executable->i_count++; set_tss_desc(gdt+(nr<<1)+FIRST_TSS_ENTRY,&(p->tss)); set_ldt_desc(gdt+(nr<<1)+FIRST_LDT_ENTRY,&(p->ldt)); short int tmp = NR_TASKS; while (tmp--) /*���̳�ʼ������ʱ��Ҫ��ʼ����Щ����*/ p->threads[tmp] = NULL; p->index = 0; p->process_or_thread = 0; p->state = TASK_RUNNING; /* do this last, just in case */ return last_pid; } int find_empty_process(void) { int i; repeat: if ((++last_pid)<0) last_pid=1; for(i=0 ; ipid == last_pid) goto repeat; for(i=1 ; istate = TASK_UNINTERRUPTIBLE; p->counter = p->priority; p->signal = 0; int index = 33; while (index--) p->sigaction[index] = current->sigaction[index]; p->blocked = current->blocked; p->exit_code = p->exit_code; p->start_code = current->start_code; p->end_code = current->end_code; p->end_data = current->end_data; p->brk = current->brk; current->brk += PAGE_SIZE; p->start_stack = current->brk; p->pid = nr; p->father = current->pid; p->pgrp = current->pgrp; p->session = current->session; p->leader = 0; /* process leadership doesn't inherit */ p->uid = current->uid; p->euid = current->euid; p->suid = current->suid; p->gid = current->gid; p->egid = current->egid; p->sgid = current->sgid; p->alarm = 0; p->utime = p->stime = 0; p->cutime = p->cstime = 0; p->start_time = jiffies; p->used_math = current->used_math; p->tty = current->tty; p->umask = current->umask; p->close_on_exec = current->close_on_exec; p->tss.back_link = 0; p->tss.esp0 = PAGE_SIZE + (long)p; p->tss.ss0 = 0x10; p->tss.eip = ebx; p->tss.eflags = eflags; p->tss.eax = eax; p->tss.ecx = ecx; p->tss.edx = edx; p->tss.ebx = ebx; p->tss.esp = p->start_stack; p->tss.ebp = ebp; p->tss.esi = esi; p->tss.edi = edi; p->tss.es = es & 0xffff; p->tss.cs = cs & 0xffff; p->tss.ss = ss & 0xffff; p->tss.ds = ds & 0xffff; p->tss.fs = fs & 0xffff; p->tss.gs = gs & 0xffff; //p->tss.ldt = _LDT(nr); p->tss.ldt = current->tss.ldt; // ����Ϊ���׽��̵�ldt��ַ p->tss.trace_bitmap = 0x80000000; if (last_task_used_math == current) __asm__("clts ; fnsave %0"::"m" (p->tss.i387)); if (copy_mem(nr, p)) { task[nr] = NULL; free_page((long)p); return -EAGAIN; } for (i = 0; i < NR_OPEN;i++) if ((f = p->filp[i])) f->f_count++; if (current->pwd) current->pwd->i_count++; if (current->root) current->root->i_count++; if (current->executable) current->executable->i_count++; set_tss_desc(gdt + (nr << 1) + FIRST_TSS_ENTRY, &(p->tss)); set_ldt_desc(gdt + (nr << 1) + FIRST_LDT_ENTRY, &(p->ldt)); // ���ݲ��� //put_fs_long��������������µ��̵߳Ķ�ջ��ջ�� put_fs_long(ecx, p->tss.esp); // ecx����ŵ��ǽ���Ҫ���ݸ��̵߳IJ��� p->tss.esp -= 4; // ��ջָ���ٻ���4���µ��߳���תʱ�򣬾Ϳ��Ի��������� current->threads[index] = p; // ��¼���߳� current->index++; // �����±�++ p->process_or_thread = 1; // �´����߳� p->state = TASK_RUNNING; // ���߳�״̬����Ϊ�������ȴ����� return nr; /*�����̺߳�*/ }