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/2)
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;
45
46 repeat:
47 if ((++last_pid) & 0xffff8000)
48 last_pid=1;
49 this_user_tasks = 0;
50 for(i=0 ; i < NR_TASKS ; i++) {
51 if (!task[i])
52 continue;
53 if (task[i]->uid == current->uid)
54 this_user_tasks++;
55 if (task[i]->pid == last_pid || task[i]->pgrp == last_pid)
56 goto repeat;
57 }
58 if (this_user_tasks > MAX_TASKS_PER_USER && !suser())
59 return -EAGAIN;
60
61 task_nr = 0;
62 for(i=1 ; i<NR_TASKS ; i++)
63 if (!task[i])
64 if (task_nr)
65 return task_nr;
66 else
67 task_nr = i;
68 if (task_nr && suser())
69 return task_nr;
70 return -EAGAIN;
71 }
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78 int sys_fork(long ebx,long ecx,long edx,
79 long esi, long edi, long ebp, long eax, long ds,
80 long es, long fs, long gs, long orig_eax,
81 long eip,long cs,long eflags,long esp,long ss)
82 {
83 struct task_struct *p;
84 int i,nr;
85 struct file *f;
86
87 p = (struct task_struct *) get_free_page(GFP_KERNEL);
88 if (!p)
89 return -EAGAIN;
90 nr = find_empty_process();
91 if (nr < 0) {
92 free_page((unsigned long) p);
93 return nr;
94 }
95 task[nr] = p;
96 *p = *current;
97 p->kernel_stack_page = 0;
98 p->state = TASK_UNINTERRUPTIBLE;
99 p->flags &= ~(PF_PTRACED|PF_TRACESYS);
100 p->pid = last_pid;
101 if (p->pid > 1)
102 p->swappable = 1;
103 p->p_pptr = p->p_opptr = current;
104 p->p_cptr = NULL;
105 SET_LINKS(p);
106 p->counter = p->priority;
107 p->signal = 0;
108 p->it_real_value = p->it_virt_value = p->it_prof_value = 0;
109 p->it_real_incr = p->it_virt_incr = p->it_prof_incr = 0;
110 p->leader = 0;
111 p->utime = p->stime = 0;
112 p->cutime = p->cstime = 0;
113 p->min_flt = p->maj_flt = 0;
114 p->cmin_flt = p->cmaj_flt = 0;
115 p->start_time = jiffies;
116 p->tss.back_link = 0;
117 p->tss.ss0 = 0x10;
118 p->tss.eip = eip;
119 p->tss.eflags = eflags & 0xffffcfff;
120 p->tss.eax = 0;
121 p->tss.ecx = ecx;
122 p->tss.edx = edx;
123 p->tss.ebx = ebx;
124 p->tss.esp = esp;
125 p->tss.ebp = ebp;
126 p->tss.esi = esi;
127 p->tss.edi = edi;
128 p->tss.es = es & 0xffff;
129 p->tss.cs = cs & 0xffff;
130 p->tss.ss = ss & 0xffff;
131 p->tss.ds = ds & 0xffff;
132 p->tss.fs = fs & 0xffff;
133 p->tss.gs = gs & 0xffff;
134 p->tss.ldt = _LDT(nr);
135 p->tss.trace_bitmap = offsetof(struct tss_struct,io_bitmap) << 16;
136 for (i = 0; i<IO_BITMAP_SIZE ; i++)
137 p->tss.io_bitmap[i] = ~0;
138 if (last_task_used_math == current)
139 __asm__("clts ; fnsave %0 ; frstor %0"::"m" (p->tss.i387));
140 p->kernel_stack_page = get_free_page(GFP_KERNEL);
141 if (!p->kernel_stack_page || copy_page_tables(p)) {
142 task[nr] = NULL;
143 REMOVE_LINKS(p);
144 free_page(p->kernel_stack_page);
145 free_page((long) p);
146 return -EAGAIN;
147 }
148 p->tss.esp0 = PAGE_SIZE + p->kernel_stack_page;
149 for (i=0; i<NR_OPEN;i++)
150 if ((f = p->filp[i]) != NULL)
151 f->f_count++;
152 if (current->pwd)
153 current->pwd->i_count++;
154 if (current->root)
155 current->root->i_count++;
156 if (current->executable)
157 current->executable->i_count++;
158 for (i=0; i < current->numlibraries ; i++)
159 if (current->libraries[i].library)
160 current->libraries[i].library->i_count++;
161 set_tss_desc(gdt+(nr<<1)+FIRST_TSS_ENTRY,&(p->tss));
162 set_ldt_desc(gdt+(nr<<1)+FIRST_LDT_ENTRY,&(p->ldt));
163 p->state = TASK_RUNNING;
164 return p->pid;
165 }