From 8608830d65308f45887f2ed4aece0283b879c194 Mon Sep 17 00:00:00 2001 From: ph649mxes <1347377011@qq.com> Date: Thu, 30 Jun 2022 10:47:24 +0800 Subject: [PATCH] ADD file via upload --- fork(Lab2).c | 258 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 258 insertions(+) create mode 100644 fork(Lab2).c diff --git a/fork(Lab2).c b/fork(Lab2).c new file mode 100644 index 0000000..7543123 --- /dev/null +++ b/fork(Lab2).c @@ -0,0 +1,258 @@ +/* + * 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 +/*****************************/ + +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)) { + /*****************************/ + printk("free_page_tables: from copy_mem\n"); + /*****************************/ + 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"); + *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)); + 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 = 0; + attr->stackaddr = get_base(current->ldt[1]) + current->brk + PAGE_SIZE; + attr->stacksize = PAGE_SIZE; + + return 0; +} + + +/*�����̴߳��������кܶණ����fork�Ĺ������ƣ���˲ο���copy_process��д�˺����� + ���ؼ��ѵ�֮�������̴߳������е����úʹ��ݲ��������ã��ر��Ƕ�ջ�ĵ����͸���Ĵ��������� + *�ú�����thread_fork���ã�nr�ǵ�ǰ�̵߳�task[]������ţ�ecx�д洢�����̴߳������п�ʼִ�еĵ�ַ����edx�д洢���Ǵ��ݸ��̵߳IJ���*/ + +int thread_create(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; + long func_addr = ecx; + long func_arg = edx; + + p = (struct task_struct*)get_free_page(); /*����һҳ����TCB*/ + if (!p) + return -EAGAIN; + task[nr] = p; + *p = *current; /* NOTE! this doesn't copy the supervisor stack */ + + /*����ͬһ�����ڵ��̹߳������Ե�ַ�ռ䣬������Ҫר������TCB�ĵ�ַλ���Լ���ջ��ʼ��ַ��*/ + current->brk = current->brk + PAGE_SIZE; + p->start_stack = current->brk; + + 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 = func_addr; /*���뽫ip����Ϊecx,��Ϊecx�д洢�����̴߳������п�ʼִ�еĵ�ַ*/ + p->tss.eflags = eflags; + p->tss.eax = 0; /*�˴�ӦΪ0��p->tss.eax = eax*/ + p->tss.ecx = ecx; + p->tss.edx = edx; + p->tss.ebx = ebx; + p->tss.esp = current->brk; /*�����̶߳�ջ����ʼ��ַ*/ + 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; + /*�����Ǵ����̣߳�������Ҫ�����߳�ldt��ַ��Ϊ�����̵�ldt��ַ��*/ + p->tss.ldt = current->tss.ldt; + p->tss.trace_bitmap = 0x80000000; + + if (last_task_used_math == current) + __asm__("clts ; fnsave %0"::"m" (p->tss.i387)); + /*����ҳ��*/ + if (copy_mem(nr, p)) { + task[nr] = NULL; + free_page((long)p); + return -EAGAIN; + } + /*�������̴߳��ݲ�������edx�д�ŵIJ������浽���̵߳Ķ�ջ������*/ + put_fs_long(func_arg, p->tss.esp); + p->tss.esp -= 4; /*!!!�˴�ע��!!! ��ջָ����������ƶ��ĸ��ֽڣ��Դ�ŷ��ص�ַ���������к����*/ + + 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)); + p->state = TASK_RUNNING; + + return p->pid; +}