-
Notifications
You must be signed in to change notification settings - Fork 1
/
proc.c
308 lines (267 loc) · 6.29 KB
/
proc.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
#include "proc.h"
#include "param.h"
#include "x86.h"
#include "types.h"
#include "mmu.h"
#include "memlayout.h"
#include "kalloc.h"
#include "mem.h"
#include "vm.h"
#include "monitor.h"
#include "log.h"
struct context context;
void forkret(void); //context中eip的值,用于返回用户态
extern void trapret(void); //forkret中会执行这个程序,共同完成返回用户态的工作
extern void swtch(struct context **old, struct context *new);//切换context的内容,swtch.S中定义
struct proc proc[NPROC]; //系统进程结构体表
int nextpid = 1; //下一个可用的进程号
struct proc *initproc; //第一个进程
struct proc *curproc; //当前进程的进程结构体
//初始化进程
void pinit(void)
{
//本内核还没有实现锁,所以该函数不用做任何工作
}
static struct proc *
allocproc(void)
{
struct proc *p;
char *sp;
int i;
for (i = 0; i < NPROC; i++)
{
if (proc[i].state == UNUSED)
break;
}
if (i == NPROC)
return 0;
p = &proc[i];
p->state = EMBRYO;
p->pid = nextpid++;
//分配内核栈
if ((p->kstack = kalloc()) == 0)
{
p->state = UNUSED;
return 0;
}
sp = p->kstack + KSTACKSIZE;
//分配存储trapframe的空间
sp -= sizeof *p->tf;
p->tf = (struct trapframe*)sp;
//存储trapret函数指针
sp -= 4;
*(uint*)sp = (uint)trapret;
//存储context
sp -= sizeof *p->context;
p->context = (struct context*)sp;
memset(p->context, 0, sizeof *p->context);
p->context->eip = (uint)forkret;
//只要执行了forkret函数,就会从内核态返回用户态继续执行程序
//这个过程安排的很精巧
return p;
}
//设置第一个进程的进程结构体
//第一个进程执行initcode.S的start入口函数
void userinit(void)
{
struct proc *p;
extern char _binary_initcode_start[], _binary_initcode_size[];
p = allocproc();
initproc = p;
if ((p->pgdir = setupkvm()) == 0)
PANIC("out of memory");
inituvm(p->pgdir, _binary_initcode_start, (int)_binary_initcode_size);
p->sz = PGSIZE;
memset(p->tf, 0, sizeof(*p->tf));
p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
p->tf->ds = (SEG_UDATA << 3) | DPL_USER;
p->tf->es = p->tf->ds;
p->tf->ss = p->tf->ds;
p->tf->eflags = FL_IF;
p->tf->esp = PGSIZE; //用户栈
p->tf->eip = 0; //用户态代码地址
p->cwd = namei("/");
p->state = RUNNABLE;
}
//调度器
void scheduler(void)
{
struct proc *oldproc;
int i;
for ( ; ; )
{
sti();
for (i = 0; i < NPROC; i++)
{
if (proc[i].state = RUNNABLE)
break;
}
//总有一个进程状态是RUNNABLE,不用担心找不到这样的进程
oldproc = curproc;
curproc = &proc[i];
switchuvm();
curproc->state = RUNNING;
swtch(&context, curproc->context);
switchkvm();
}
}
void sched(void)
{
swtch(&curproc->context, context);
}
void yield(void)
{
curproc->state == RUNNABLE;
sched();
}
void forkret(void)
{
static int first = 1;
if (first)
{
first = 0;
initlog();
}
}
void sleep(void *chan)
{
curproc->chan = chan;
proc->state = SLEEPING;
sched();
curproc->chan = 0;
}
void wakeup(void *chan)
{
int i;
for (i = 0; i < NPROC; i++)
{
if (proc[i].state == SLEEPING && proc[i].chan == chan)
proc[i].state = RUNNABLE;
}
}
//fork函数,fork系统调用会执行此函数
int fork(void)
{
int i, pid;
struct proc *np;
if ((np = allocproc()) == 0)
return -1;
if ((np->pgdir = copyuvm(curproc->pgdir, curproc->sz)) == 0)
{
kfree(np->kstack);
np->kstack = 0;
np->state = UNUSED;
return -1;
}
np->sz = curproc->sz;
np->parent = curproc;
*np->tf = *curproc->tf;
np->tf->eax = 0;
for (i = 0; i < NFILE; i++)
{
if (curproc->ofile[i])
np->ofile[i] = filedup(curproc->ofile[i]);
}
np->cwd = idup(curproc->cwd);
pid = np->pid;
np->state = RUNNABLE;
return pid;
}
//exit系统调用会调用此函数
void exit(void)
{
struct proc *p;
int fd, i;
if (curproc == initproc)
PANIC("init exiting");
for (fd = 0; fd < NFILE; fd++)
{
if (curproc->ofile[fd])
{
fileclose(curproc->ofile[fd]);
curproc->ofile[fd] = 0;
}
}
begin_op();
iput(curproc->cwd);
end_op();
curproc->cwd = 0;
wakeup(curproc->parent);
for (i = 0; i < NPROC; i++)
{
if (proc[i].parent = curproc)
{
proc[i].parent = initproc;
if (proc[i].state == ZOMBIE)
wakeup(initproc);
}
}
curproc->state = ZOMBIE;
sched();
PANIC("zombie exit");
}
int wait(void)
{
struct proc *p;
int havekids, pid;
int i;
for ( ; ; )
{
havekids = 0;
for (i = 0; i < NPROC; i++)
{
if (proc[i].parent != curproc)
continue;
havekids = 1;
if (proc[i].state == ZOMBIE)
{
pid = proc[i].pid;
kfree(proc[i].kstack);
proc[i].kstack = 0;
freevm(proc[i].pgdir);
proc[i].state = UNUSED;
proc[i].pid = 0;
proc[i].parent = 0;
proc[i].killed = 0;
return pid;
}
}
if (!havekids || curproc->killed)
return -1;
sleep(curproc);
}
}
int kill(int pid)
{
struct proc *p;
for (p = proc, p < &proc[NPROC]; p++)
{
if (p->pid == pid)
{
p->killed = 1;
if (p->state == SLEEPING)
p->state == RUNNABLE;
return 0;
}
}
return -1;
}
//给当前进程分配n个字节的空间
int growproc(int n)
{
uint sz;
sz = curproc->sz;
if (n > 0)
{
if ((sz = allocuvm(curproc->pgdir, sz, sz + n)) == 0)
return -1;
}
else if (n < 0)
{
if ((sz = deallocuvm(curproc->pgdir, sz, sz + n)) == 0)
return -1;
}
curproc->sz = sz;
switchuvm(curproc);
return 0;
}