This source file includes following definitions.
- verify_area
- find_empty_process
- sys_fork
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14 #include <linux/errno.h>
15 #include <linux/sched.h>
16 #include <linux/kernel.h>
17 #include <linux/mm.h>
18 #include <linux/stddef.h>
19
20 #include <asm/segment.h>
21 #include <asm/system.h>
22
23 #define MAX_TASKS_PER_USER ((NR_TASKS/4)*3)
24
25 long last_pid=0;
26
27 void verify_area(void * addr,int size)
28 {
29 unsigned long start;
30
31 start = (unsigned long) addr;
32 size += start & 0xfff;
33 start &= 0xfffff000;
34 while (size>0) {
35 size -= 4096;
36 write_verify(start);
37 start += 4096;
38 }
39 }
40
41 static int find_empty_process(void)
42 {
43 int i, task_nr;
44 int this_user_tasks = 0;
45
46 repeat:
47 if ((++last_pid) & 0xffff0000)
48 last_pid=1;
49 for(i=0 ; i < NR_TASKS ; i++) {
50 if (!task[i])
51 continue;
52 if (task[i]->uid == current->uid)
53 this_user_tasks++;
54 if (task[i]->pid == last_pid || task[i]->pgrp == last_pid)
55 goto repeat;
56 }
57 if (this_user_tasks > MAX_TASKS_PER_USER && !suser())
58 return -EAGAIN;
59
60 task_nr = 0;
61 for(i=1 ; i<NR_TASKS ; i++)
62 if (!task[i])
63 if (task_nr)
64 return task_nr;
65 else
66 task_nr = i;
67 if (task_nr && suser())
68 return task_nr;
69 return -EAGAIN;
70 }
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77 int sys_fork(long ebx,long ecx,long edx,
78 long esi, long edi, long ebp, long eax, long ds,
79 long es, long fs, long gs, long orig_eax,
80 long eip,long cs,long eflags,long esp,long ss)
81 {
82 struct task_struct *p;
83 int i,nr;
84 struct file *f;
85
86 p = (struct task_struct *) get_free_page(GFP_KERNEL);
87 if (!p)
88 return -EAGAIN;
89 nr = find_empty_process();
90 if (nr < 0) {
91 free_page((unsigned long) p);
92 return nr;
93 }
94 task[nr] = p;
95 *p = *current;
96 p->kernel_stack_page = 0;
97 p->state = TASK_UNINTERRUPTIBLE;
98 p->flags &= ~(PF_PTRACED|PF_TRACESYS);
99 p->pid = last_pid;
100 if (p->pid > 1)
101 p->swappable = 1;
102 p->p_pptr = p->p_opptr = current;
103 p->p_cptr = NULL;
104 SET_LINKS(p);
105 p->counter = p->priority;
106 p->signal = 0;
107 p->it_real_value = p->it_virt_value = p->it_prof_value = 0;
108 p->it_real_incr = p->it_virt_incr = p->it_prof_incr = 0;
109 p->leader = 0;
110 p->utime = p->stime = 0;
111 p->cutime = p->cstime = 0;
112 p->min_flt = p->maj_flt = 0;
113 p->cmin_flt = p->cmaj_flt = 0;
114 p->start_time = jiffies;
115 p->tss.back_link = 0;
116 p->tss.ss0 = 0x10;
117 p->tss.eip = eip;
118 p->tss.eflags = eflags & 0xffffcfff;
119 p->tss.eax = 0;
120 p->tss.ecx = ecx;
121 p->tss.edx = edx;
122 p->tss.ebx = ebx;
123 p->tss.esp = esp;
124 p->tss.ebp = ebp;
125 p->tss.esi = esi;
126 p->tss.edi = edi;
127 p->tss.es = es & 0xffff;
128 p->tss.cs = cs & 0xffff;
129 p->tss.ss = ss & 0xffff;
130 p->tss.ds = ds & 0xffff;
131 p->tss.fs = fs & 0xffff;
132 p->tss.gs = gs & 0xffff;
133 p->tss.ldt = _LDT(nr);
134 p->tss.trace_bitmap = offsetof(struct tss_struct,io_bitmap) << 16;
135 for (i = 0; i<IO_BITMAP_SIZE ; i++)
136 p->tss.io_bitmap[i] = ~0;
137 if (last_task_used_math == current)
138 __asm__("clts ; fnsave %0 ; frstor %0"::"m" (p->tss.i387));
139 p->kernel_stack_page = get_free_page(GFP_KERNEL);
140 if (!p->kernel_stack_page || copy_page_tables(p)) {
141 task[nr] = NULL;
142 REMOVE_LINKS(p);
143 free_page(p->kernel_stack_page);
144 free_page((long) p);
145 return -EAGAIN;
146 }
147 p->tss.esp0 = PAGE_SIZE + p->kernel_stack_page;
148 for (i=0; i<NR_OPEN;i++)
149 if ((f = p->filp[i]) != NULL)
150 f->f_count++;
151 if (current->pwd)
152 current->pwd->i_count++;
153 if (current->root)
154 current->root->i_count++;
155 if (current->executable)
156 current->executable->i_count++;
157 for (i=0; i < current->numlibraries ; i++)
158 if (current->libraries[i].library)
159 current->libraries[i].library->i_count++;
160 set_tss_desc(gdt+(nr<<1)+FIRST_TSS_ENTRY,&(p->tss));
161 set_ldt_desc(gdt+(nr<<1)+FIRST_LDT_ENTRY,&(p->ldt));
162 p->state = TASK_RUNNING;
163 return p->pid;
164 }