parent
41bf089196
commit
7c4bca47bb
@ -0,0 +1,240 @@
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/*
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* linux/kernel/fork.c
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*
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* (C) 1991 Linus Torvalds
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*/
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/*
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* 'fork.c' contains the help-routines for the 'fork' system call
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* (see also system_call.s), and some misc functions ('verify_area').
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* Fork is rather simple, once you get the hang of it, but the memory
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* management can be a bitch. See 'mm/mm.c': 'copy_page_tables()'
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*/
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#include <errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <asm/segment.h>
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#include <asm/system.h>
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extern void write_verify(unsigned long address);
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long last_pid=0;
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void verify_area(void * addr,int size)
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{
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unsigned long start;
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start = (unsigned long) addr;
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size += start & 0xfff;
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start &= 0xfffff000;
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start += get_base(current->ldt[2]);
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while (size>0) {
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size -= 4096;
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write_verify(start);
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start += 4096;
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}
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}
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int copy_mem(int nr,struct task_struct * p)
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{
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unsigned long old_data_base,new_data_base,data_limit;
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unsigned long old_code_base,new_code_base,code_limit;
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code_limit=get_limit(0x0f);
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data_limit=get_limit(0x17);
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old_code_base = get_base(current->ldt[1]);
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old_data_base = get_base(current->ldt[2]);
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if (old_data_base != old_code_base)
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panic("We don't support separate I&D");
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if (data_limit < code_limit)
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panic("Bad data_limit");
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new_data_base = new_code_base = nr * 0x4000000;
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p->start_code = new_code_base;
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set_base(p->ldt[1],new_code_base);
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set_base(p->ldt[2],new_data_base);
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if (copy_page_tables(old_data_base,new_data_base,data_limit)) {
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free_page_tables(new_data_base,data_limit);
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return -ENOMEM;
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}
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return 0;
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}
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/*
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* Ok, this is the main fork-routine. It copies the system process
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* information (task[nr]) and sets up the necessary registers. It
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* also copies the data segment in it's entirety.
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*/
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int copy_process(int nr,long ebp,long edi,long esi,long gs,long none,
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long ebx,long ecx,long edx,
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long fs,long es,long ds,
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long eip,long cs,long eflags,long esp,long ss)
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{
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struct task_struct *p;
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int i;
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struct file *f;
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p = (struct task_struct *) get_free_page();
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if (!p)
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return -EAGAIN;
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task[nr] = p;
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__asm__ volatile ("cld"); /* by wyj */
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*p = *current; /* NOTE! this doesn't copy the supervisor stack */
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p->state = TASK_UNINTERRUPTIBLE;
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p->pid = last_pid;
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p->father = current->pid;
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p->counter = p->priority;
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p->signal = 0;
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p->alarm = 0;
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p->leader = 0; /* process leadership doesn't inherit */
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p->utime = p->stime = 0;
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p->cutime = p->cstime = 0;
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p->start_time = jiffies;
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p->tss.back_link = 0;
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p->tss.esp0 = PAGE_SIZE + (long) p;
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p->tss.ss0 = 0x10;
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p->tss.eip = eip;
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p->tss.eflags = eflags;
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p->tss.eax = 0;
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p->tss.ecx = ecx;
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p->tss.edx = edx;
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p->tss.ebx = ebx;
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p->tss.esp = esp;
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p->tss.ebp = ebp;
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p->tss.esi = esi;
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p->tss.edi = edi;
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p->tss.es = es & 0xffff;
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p->tss.cs = cs & 0xffff;
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p->tss.ss = ss & 0xffff;
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p->tss.ds = ds & 0xffff;
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p->tss.fs = fs & 0xffff;
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p->tss.gs = gs & 0xffff;
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p->tss.ldt = _LDT(nr);
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p->tss.trace_bitmap = 0x80000000;
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if (last_task_used_math == current)
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__asm__("clts ; fnsave %0"::"m" (p->tss.i387));
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if (copy_mem(nr,p)) {
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task[nr] = NULL;
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free_page((long) p);
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return -EAGAIN;
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}
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for (i=0; i<NR_OPEN;i++)
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if (f=p->filp[i])
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f->f_count++;
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if (current->pwd)
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current->pwd->i_count++;
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if (current->root)
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current->root->i_count++;
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if (current->executable)
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current->executable->i_count++;
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set_tss_desc(gdt+(nr<<1)+FIRST_TSS_ENTRY,&(p->tss));
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set_ldt_desc(gdt+(nr<<1)+FIRST_LDT_ENTRY,&(p->ldt));
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p->state = TASK_RUNNING; /* do this last, just in case */
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return last_pid;
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}
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int copy_mem1(int nr,struct task_struct * p)
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{
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unsigned long old_data_base,new_data_base,data_limit;
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unsigned long old_code_base,new_code_base,code_limit;
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code_limit=get_limit(0x0f);
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data_limit=get_limit(0x17);
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old_code_base = get_base(current->ldt[1]);
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old_data_base = get_base(current->ldt[2]);
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if (old_data_base != old_code_base)
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panic("We don't support separate I&D");
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if (data_limit < code_limit)
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panic("Bad data_limit");
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new_data_base = new_code_base = nr * 0x4000000;
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p->start_code = new_code_base;
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set_base(p->ldt[1],new_code_base);
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set_base(p->ldt[2],new_data_base);
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if (copy_page_tables1(old_data_base,new_data_base,data_limit)) {
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free_page_tables(new_data_base,data_limit);
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return -ENOMEM;
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}
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return 0;
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}
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int copy_clone(int nr,long ebp,long edi,long esi,long gs,long none,
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long ebx,long ecx,long edx,
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long fs,long es,long ds,
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long eip,long cs,long eflags,long esp,long ss)
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{
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struct task_struct *p;
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int i;
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struct file *f;
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p = (struct task_struct *) get_free_page();
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if (!p)
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return -EAGAIN;
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task[nr] = p;
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__asm__ volatile ("cld"); /* by wyj */
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*p = *current; /* NOTE! this doesn't copy the supervisor stack */
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p->state = TASK_UNINTERRUPTIBLE;
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p->pid = last_pid;
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p->father = current->pid;
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p->counter = p->priority;
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p->signal = 0;
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p->alarm = 0;
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p->leader = 0; /* process leadership doesn't inherit */
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p->utime = p->stime = 0;
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p->cutime = p->cstime = 0;
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p->start_time = jiffies;
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p->tss.back_link = 0;
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p->tss.esp0 = PAGE_SIZE + (long) p;
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p->tss.ss0 = 0x10;
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//p->tss.eip = eip;
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p->tss.eip = ebx;
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p->tss.eflags = eflags;
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p->tss.eax = 0;
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p->tss.ecx = ecx;
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p->tss.edx = edx;
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p->tss.ebx = ebx;
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//对这个进行改动
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//p->tss.esp = esp;
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p->tss.esp = ecx;
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p->tss.ebp = ebp;
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p->tss.esi = esi;
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p->tss.edi = edi;
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p->tss.es = es & 0xffff;
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p->tss.cs = cs & 0xffff;
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p->tss.ss = ss & 0xffff;
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p->tss.ds = ds & 0xffff;
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p->tss.fs = fs & 0xffff;
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p->tss.gs = gs & 0xffff;
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p->tss.ldt = _LDT(nr);
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p->tss.trace_bitmap = 0x80000000;
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if (last_task_used_math == current)
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__asm__("clts ; fnsave %0"::"m" (p->tss.i387));
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if (copy_mem1(nr,p)) {
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task[nr] = NULL;
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free_page((long) p);
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return -EAGAIN;
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}
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for (i=0; i<NR_OPEN;i++)
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if (f=p->filp[i])
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f->f_count++;
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if (current->pwd)
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current->pwd->i_count++;
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if (current->root)
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current->root->i_count++;
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if (current->executable)
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current->executable->i_count++;
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set_tss_desc(gdt+(nr<<1)+FIRST_TSS_ENTRY,&(p->tss));
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set_ldt_desc(gdt+(nr<<1)+FIRST_LDT_ENTRY,&(p->ldt));
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p->state = TASK_RUNNING; /* do this last, just in case */
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return last_pid;
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}
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int find_empty_process(void)
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{
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int i;
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repeat:
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if ((++last_pid)<0) last_pid=1;
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for(i=0 ; i<NR_TASKS ; i++)
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if (task[i] && task[i]->pid == last_pid) goto repeat;
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for(i=1 ; i<NR_TASKS ; i++)
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if (!task[i])
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return i;
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return -EAGAIN;
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}
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