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1 #include "types.h"
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2 #include "defs.h"
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3 #include "param.h"
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4 #include "memlayout.h"
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5 #include "mmu.h"
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6 #include "arm.h"
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7 #include "proc.h"
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8 #include "spinlock.h"
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220
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9 #interface "vm.h"
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0
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10
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52
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11 #define __ncode __code
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12
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0
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13 //
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14 // Process initialization:
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15 // process initialize is somewhat tricky.
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16 // 1. We need to fake the kernel stack of a new process as if the process
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17 // has been interrupt (a trapframe on the stack), this would allow us
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18 // to "return" to the correct user instruction.
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19 // 2. We also need to fake the kernel execution for this new process. When
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20 // swtch switches to this (new) process, it will switch to its stack,
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21 // and reload registers with the saved context. We use forkret as the
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22 // return address (in lr register). (In x86, it will be the return address
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23 // pushed on the stack by the process.)
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24 //
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25 // The design of context switch in xv6 is interesting: after initialization,
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26 // each CPU executes in the scheduler() function. The context switch is not
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27 // between two processes, but instead, between the scheduler. Think of scheduler
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28 // as the idle process.
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29 //
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30 struct {
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31 struct spinlock lock;
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32 struct proc proc[NPROC];
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33 } ptable;
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34
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35 static struct proc *initproc;
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36 struct proc *proc;
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37
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38 int nextpid = 1;
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39 extern void forkret(void);
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40 extern void trapret(void);
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41
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42 static void wakeup1(void *chan);
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43
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44 void pinit(void)
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45 {
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46 initlock(&ptable.lock, "ptable");
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47 }
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48
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49 //PAGEBREAK: 32
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50 // Look in the process table for an UNUSED proc.
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51 // If found, change state to EMBRYO and initialize
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52 // state required to run in the kernel.
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53 // Otherwise return 0.
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54 static struct proc* allocproc(void)
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55 {
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56 struct proc *p;
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57 char *sp;
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58
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59 acquire(&ptable.lock);
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60
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61 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
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62 if(p->state == UNUSED) {
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63 goto found;
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64 }
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65
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66 }
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67
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68 release(&ptable.lock);
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69 return 0;
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70
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71 found:
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72 p->state = EMBRYO;
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73 p->pid = nextpid++;
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74 release(&ptable.lock);
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75
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76 // Allocate kernel stack.
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77 if((p->kstack = alloc_page ()) == 0){
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78 p->state = UNUSED;
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79 return 0;
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80 }
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81
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82 sp = p->kstack + KSTACKSIZE;
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83
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84 // Leave room for trap frame.
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85 sp -= sizeof (*p->tf);
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86 p->tf = (struct trapframe*)sp;
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87
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88 // Set up new context to start executing at forkret,
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89 // which returns to trapret.
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90 sp -= 4;
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91 *(uint*)sp = (uint)trapret;
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92
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93 sp -= 4;
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94 *(uint*)sp = (uint)p->kstack + KSTACKSIZE;
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95
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96 sp -= sizeof (*p->context);
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97 p->context = (struct context*)sp;
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98 memset(p->context, 0, sizeof(*p->context));
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99
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100 // skip the push {fp, lr} instruction in the prologue of forkret.
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101 // This is different from x86, in which the harderware pushes return
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102 // address before executing the callee. In ARM, return address is
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103 // loaded into the lr register, and push to the stack by the callee
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104 // (if and when necessary). We need to skip that instruction and let
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105 // it use our implementation.
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106 p->context->lr = (uint)forkret+4;
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107
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108 return p;
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109 }
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110
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111 void error_init ()
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112 {
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113 panic ("failed to craft first process\n");
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114 }
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115
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116
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117 //PAGEBREAK: 32
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118 // hand-craft the first user process. We link initcode.S into the kernel
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119 // as a binary, the linker will generate __binary_initcode_start/_size
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329
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120 void cbc_init_vmm_dummy(struct Context* cbc_context, struct proc* p, pde_t* pgdir, char* init, uint sz)
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220
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121 {
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122 // inituvm(p->pgdir, _binary_initcode_start, (int)_binary_initcode_size);
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123
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225
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124 struct vm* vm = createvm_impl(cbc_context);
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227
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125 // goto vm->init_vmm(vm, pgdir, init, sz , vm->void_ret);
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220
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126 Gearef(cbc_context, vm)->vm = (union Data*) vm;
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127 Gearef(cbc_context, vm)->pgdir = pgdir;
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128 Gearef(cbc_context, vm)->init = init;
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129 Gearef(cbc_context, vm)->sz = sz ;
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227
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130 Gearef(cbc_context, vm)->next = C_vm_void_ret ;
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229
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131 goto meta(cbc_context, vm->init_inituvm);
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220
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132 }
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133
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329
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134
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135
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136
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0
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137 void userinit(void)
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138 {
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220
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139 struct proc* p;
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140 extern char _binary_initcode_start[], _binary_initcode_size[];
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141
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142 p = allocproc();
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220
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143 initContext(&p->cbc_context);
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144
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145 initproc = p;
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146
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147 if((p->pgdir = kpt_alloc()) == NULL) {
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148 panic("userinit: out of memory?");
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149 }
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150
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329
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151 cbc_init_vmm_dummy(&p->cbc_context, p, p->pgdir, _binary_initcode_start, (int)_binary_initcode_size);
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0
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152
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153 p->sz = PTE_SZ;
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154
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155 // craft the trapframe as if
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156 memset(p->tf, 0, sizeof(*p->tf));
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157
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158 p->tf->r14_svc = (uint)error_init;
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159 p->tf->spsr = spsr_usr ();
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160 p->tf->sp_usr = PTE_SZ; // set the user stack
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161 p->tf->lr_usr = 0;
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162
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163 // set the user pc. The actual pc loaded into r15_usr is in
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164 // p->tf, the trapframe.
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165 p->tf->pc = 0; // beginning of initcode.S
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166
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167 safestrcpy(p->name, "initcode", sizeof(p->name));
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168 p->cwd = namei("/");
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169
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170 p->state = RUNNABLE;
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171 }
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172
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241
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173
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328
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174 void switchuvm_dummy(struct Context* cbc_context, struct proc* proc)
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241
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175 {
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176 struct vm* vm = createvm_impl(cbc_context);
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277
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177 Gearef(cbc_context, vm)->vm = (union Data*) vm;
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263
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178 Gearef(cbc_context, vm)->p = proc;
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179 Gearef(cbc_context, vm)->next = C_vm_void_ret ;
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241
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180 goto meta(cbc_context, vm->switchuvm);
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181 }
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182
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328
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183
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0
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184 // Grow current process's memory by n bytes.
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185 // Return 0 on success, -1 on failure.
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186 int growproc(int n)
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187 {
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188 uint sz;
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189
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190 sz = proc->sz;
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191
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192 if(n > 0){
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193 if((sz = allocuvm(proc->pgdir, sz, sz + n)) == 0) {
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194 return -1;
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195 }
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196
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197 } else if(n < 0){
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198 if((sz = deallocuvm(proc->pgdir, sz, sz + n)) == 0) {
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199 return -1;
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200 }
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201 }
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202
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203 proc->sz = sz;
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277
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204 //switchuvm(proc);
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328
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205 switchuvm_dummy(&proc->cbc_context, proc);
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0
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206 return 0;
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207 }
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208
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209 // Create a new process copying p as the parent.
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210 // Sets up stack to return as if from system call.
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211 // Caller must set state of returned proc to RUNNABLE.
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212 int fork(void)
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213 {
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214 int i, pid;
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215 struct proc *np;
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216
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217 // Allocate process.
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218 if((np = allocproc()) == 0) {
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219 return -1;
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220 }
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220
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221 initContext(&np->cbc_context);
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0
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222
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223 // Copy process state from p.
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224 if((np->pgdir = copyuvm(proc->pgdir, proc->sz)) == 0){
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225 free_page(np->kstack);
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226 np->kstack = 0;
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227 np->state = UNUSED;
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228 return -1;
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229 }
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230
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231 np->sz = proc->sz;
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232 np->parent = proc;
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19
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233 // *np->tf = *proc->tf; // This generate memcpy4 which is not in libgcc.a
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234 memmove(np->tf, proc->tf, sizeof(*np->tf));
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0
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235
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236 // Clear r0 so that fork returns 0 in the child.
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237 np->tf->r0 = 0;
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238
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239 for(i = 0; i < NOFILE; i++) {
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240 if(proc->ofile[i]) {
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241 np->ofile[i] = filedup(proc->ofile[i]);
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242 }
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243 }
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244
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245 np->cwd = idup(proc->cwd);
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246
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247 pid = np->pid;
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248 np->state = RUNNABLE;
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249 safestrcpy(np->name, proc->name, sizeof(proc->name));
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250
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251 return pid;
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252 }
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253
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254 // Exit the current process. Does not return.
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255 // An exited process remains in the zombie state
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256 // until its parent calls wait() to find out it exited.
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257 void exit(void)
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258 {
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259 struct proc *p;
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260 int fd;
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261
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262 if(proc == initproc) {
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263 panic("init exiting");
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264 }
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265
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266 // Close all open files.
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267 for(fd = 0; fd < NOFILE; fd++){
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268 if(proc->ofile[fd]){
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269 fileclose(proc->ofile[fd]);
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270 proc->ofile[fd] = 0;
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271 }
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272 }
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273
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274 iput(proc->cwd);
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275 proc->cwd = 0;
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276
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277 acquire(&ptable.lock);
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278
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279 // Parent might be sleeping in wait().
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280 wakeup1(proc->parent);
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281
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282 // Pass abandoned children to init.
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283 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
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284 if(p->parent == proc){
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285 p->parent = initproc;
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286
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287 if(p->state == ZOMBIE) {
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288 wakeup1(initproc);
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289 }
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290 }
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291 }
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292
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293 // Jump into the scheduler, never to return.
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294 proc->state = ZOMBIE;
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295 sched();
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296
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297 panic("zombie exit");
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298 }
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299
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300 // Wait for a child process to exit and return its pid.
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301 // Return -1 if this process has no children.
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302 int wait(void)
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303 {
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304 struct proc *p;
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305 int havekids, pid;
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306
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307 acquire(&ptable.lock);
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308
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309 for(;;){
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310 // Scan through table looking for zombie children.
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311 havekids = 0;
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312
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313 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
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314 if(p->parent != proc) {
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315 continue;
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316 }
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317
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318 havekids = 1;
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319
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320 if(p->state == ZOMBIE){
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321 // Found one.
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322 pid = p->pid;
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323 free_page(p->kstack);
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324 p->kstack = 0;
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325 freevm(p->pgdir);
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326 p->state = UNUSED;
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327 p->pid = 0;
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328 p->parent = 0;
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329 p->name[0] = 0;
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330 p->killed = 0;
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331 release(&ptable.lock);
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332
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333 return pid;
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334 }
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335 }
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336
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337 // No point waiting if we don't have any children.
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338 if(!havekids || proc->killed){
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339 release(&ptable.lock);
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340 return -1;
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341 }
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342
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343 // Wait for children to exit. (See wakeup1 call in proc_exit.)
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344 sleep(proc, &ptable.lock); //DOC: wait-sleep
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345 }
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346 }
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347
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348 //PAGEBREAK: 42
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349 // Per-CPU process scheduler.
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350 // Each CPU calls scheduler() after setting itself up.
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351 // Scheduler never returns. It loops, doing:
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352 // - choose a process to run
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353 // - swtch to start running that process
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354 // - eventually that process transfers control
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355 // via swtch back to the scheduler.
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356 void scheduler(void)
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357 {
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358 struct proc *p;
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359
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360 for(;;){
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361 // Enable interrupts on this processor.
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362 sti();
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363
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364 // Loop over process table looking for process to run.
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365 acquire(&ptable.lock);
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366
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367 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
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368 if(p->state != RUNNABLE) {
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369 continue;
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370 }
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371
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372 // Switch to chosen process. It is the process's job
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373 // to release ptable.lock and then reacquire it
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374 // before jumping back to us.
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375 proc = p;
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376 switchuvm(p);
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377
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378 p->state = RUNNING;
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379
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380 swtch(&cpu->scheduler, proc->context);
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381 // Process is done running for now.
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382 // It should have changed its p->state before coming back.
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383 proc = 0;
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384 }
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385
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386 release(&ptable.lock);
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387 }
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388 }
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389
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52
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390 __ncode cbc_sched(__code(*next)())
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28
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391 {
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392 int intena;
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393
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394 if(!holding(&ptable.lock)) {
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395 panic("sched ptable.lock");
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396 }
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397
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398 if(cpu->ncli != 1) {
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399 panic("sched locks");
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400 }
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401
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402 if(proc->state == RUNNING) {
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403 panic("sched running");
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404 }
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405
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406 if(int_enabled ()) {
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407 panic("sched interruptible");
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408 }
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409
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410 intena = cpu->intena;
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411 swtch(&proc->context, cpu->scheduler);
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412 cpu->intena = intena;
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413
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414 goto next();
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415 }
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416
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417
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0
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418 // Enter scheduler. Must hold only ptable.lock
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419 // and have changed proc->state.
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420 void sched(void)
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421 {
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422 int intena;
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423
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424 //show_callstk ("sched");
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425
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426 if(!holding(&ptable.lock)) {
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427 panic("sched ptable.lock");
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428 }
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429
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430 if(cpu->ncli != 1) {
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431 panic("sched locks");
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432 }
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433
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434 if(proc->state == RUNNING) {
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435 panic("sched running");
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436 }
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437
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438 if(int_enabled ()) {
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439 panic("sched interruptible");
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440 }
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441
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442 intena = cpu->intena;
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443 swtch(&proc->context, cpu->scheduler);
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444 cpu->intena = intena;
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445 }
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446
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447 // Give up the CPU for one scheduling round.
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448 void yield(void)
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449 {
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450 acquire(&ptable.lock); //DOC: yieldlock
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451 proc->state = RUNNABLE;
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452 sched();
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453 release(&ptable.lock);
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454 }
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455
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456 // A fork child's very first scheduling by scheduler()
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457 // will swtch here. "Return" to user space.
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458 void forkret(void)
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459 {
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460 static int first = 1;
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461
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462 // Still holding ptable.lock from scheduler.
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463 release(&ptable.lock);
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464
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|
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465 if (first) {
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466 // Some initialization functions must be run in the context
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467 // of a regular process (e.g., they call sleep), and thus cannot
|
|
|
468 // be run from main().
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|
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469 first = 0;
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470 initlog();
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471 }
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472
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|
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473 // Return to "caller", actually trapret (see allocproc).
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474 }
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|
|
475
|
|
52
|
476 __ncode cbc_sleep1()
|
|
24
|
477 {
|
|
|
478 struct spinlock *lk = proc->lk;
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|
|
479 // Tidy up.
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|
|
480 proc->chan = 0;
|
|
|
481
|
|
|
482 // Reacquire original lock.
|
|
|
483 if(lk != &ptable.lock){ //DOC: sleeplock2
|
|
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484 release(&ptable.lock);
|
|
|
485 acquire(lk);
|
|
|
486 }
|
|
|
487 goto proc->cbc_next();
|
|
|
488 }
|
|
|
489
|
|
52
|
490 __ncode cbc_sleep(void *chan, struct spinlock *lk, __code(*next1)())
|
|
24
|
491 {
|
|
|
492 //show_callstk("sleep");
|
|
|
493
|
|
|
494 if(proc == 0) {
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|
|
495 panic("sleep");
|
|
|
496 }
|
|
|
497
|
|
|
498 if(lk == 0) {
|
|
|
499 panic("sleep without lk");
|
|
|
500 }
|
|
|
501
|
|
|
502 if(lk != &ptable.lock){ //DOC: sleeplock0
|
|
|
503 acquire(&ptable.lock); //DOC: sleeplock1
|
|
|
504 release(lk);
|
|
|
505 }
|
|
|
506 proc->chan = chan;
|
|
|
507 proc->state = SLEEPING;
|
|
32
|
508 proc->lk = lk;
|
|
24
|
509 proc->cbc_next = next1;
|
|
|
510
|
|
|
511 goto cbc_sched(cbc_sleep1);
|
|
|
512 }
|
|
|
513
|
|
0
|
514 // Atomically release lock and sleep on chan.
|
|
|
515 // Reacquires lock when awakened.
|
|
|
516 void sleep(void *chan, struct spinlock *lk)
|
|
|
517 {
|
|
|
518 //show_callstk("sleep");
|
|
|
519
|
|
|
520 if(proc == 0) {
|
|
|
521 panic("sleep");
|
|
|
522 }
|
|
|
523
|
|
|
524 if(lk == 0) {
|
|
|
525 panic("sleep without lk");
|
|
|
526 }
|
|
|
527
|
|
|
528 // Must acquire ptable.lock in order to change p->state and then call
|
|
|
529 // sched. Once we hold ptable.lock, we can be guaranteed that we won't
|
|
|
530 // miss any wakeup (wakeup runs with ptable.lock locked), so it's okay
|
|
|
531 // to release lk.
|
|
|
532 if(lk != &ptable.lock){ //DOC: sleeplock0
|
|
|
533 acquire(&ptable.lock); //DOC: sleeplock1
|
|
|
534 release(lk);
|
|
|
535 }
|
|
|
536
|
|
|
537 // Go to sleep.
|
|
|
538 proc->chan = chan;
|
|
|
539 proc->state = SLEEPING;
|
|
|
540 sched();
|
|
|
541
|
|
|
542 // Tidy up.
|
|
|
543 proc->chan = 0;
|
|
|
544
|
|
|
545 // Reacquire original lock.
|
|
|
546 if(lk != &ptable.lock){ //DOC: sleeplock2
|
|
|
547 release(&ptable.lock);
|
|
|
548 acquire(lk);
|
|
|
549 }
|
|
|
550 }
|
|
|
551
|
|
|
552 //PAGEBREAK!
|
|
|
553 // Wake up all processes sleeping on chan. The ptable lock must be held.
|
|
|
554 static void wakeup1(void *chan)
|
|
|
555 {
|
|
|
556 struct proc *p;
|
|
|
557
|
|
|
558 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
|
|
|
559 if(p->state == SLEEPING && p->chan == chan) {
|
|
|
560 p->state = RUNNABLE;
|
|
|
561 }
|
|
|
562 }
|
|
|
563 }
|
|
|
564
|
|
52
|
565 __ncode cbc_wakeup1(void *chan)
|
|
36
|
566 {
|
|
|
567 struct proc *p;
|
|
|
568
|
|
|
569 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
|
|
|
570 if(p->state == SLEEPING && p->chan == chan) {
|
|
|
571 p->state = RUNNABLE;
|
|
|
572 }
|
|
|
573 }
|
|
|
574
|
|
|
575 release(&ptable.lock);
|
|
37
|
576 goto proc->cbc_next();
|
|
36
|
577 }
|
|
|
578
|
|
52
|
579 __ncode cbc_wakeup(void *chan, __code(*next1)())
|
|
36
|
580 {
|
|
|
581 acquire(&ptable.lock);
|
|
37
|
582 proc->cbc_next = next1;
|
|
36
|
583 cbc_wakeup1(chan);
|
|
|
584 }
|
|
|
585
|
|
0
|
586 // Wake up all processes sleeping on chan.
|
|
|
587 void wakeup(void *chan)
|
|
|
588 {
|
|
|
589 acquire(&ptable.lock);
|
|
|
590 wakeup1(chan);
|
|
|
591 release(&ptable.lock);
|
|
|
592 }
|
|
|
593
|
|
|
594 // Kill the process with the given pid. Process won't exit until it returns
|
|
|
595 // to user space (see trap in trap.c).
|
|
|
596 int kill(int pid)
|
|
|
597 {
|
|
|
598 struct proc *p;
|
|
|
599
|
|
|
600 acquire(&ptable.lock);
|
|
|
601
|
|
|
602 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
|
|
|
603 if(p->pid == pid){
|
|
|
604 p->killed = 1;
|
|
|
605
|
|
|
606 // Wake process from sleep if necessary.
|
|
|
607 if(p->state == SLEEPING) {
|
|
|
608 p->state = RUNNABLE;
|
|
|
609 }
|
|
|
610
|
|
|
611 release(&ptable.lock);
|
|
|
612 return 0;
|
|
|
613 }
|
|
|
614 }
|
|
|
615
|
|
|
616 release(&ptable.lock);
|
|
|
617 return -1;
|
|
|
618 }
|
|
|
619
|
|
|
620 //PAGEBREAK: 36
|
|
|
621 // Print a process listing to console. For debugging. Runs when user
|
|
|
622 // types ^P on console. No lock to avoid wedging a stuck machine further.
|
|
|
623 void procdump(void)
|
|
|
624 {
|
|
|
625 static char *states[] = {
|
|
22
|
626 [UNUSED] ="unused",
|
|
|
627 [EMBRYO] ="embryo",
|
|
|
628 [SLEEPING] ="sleep ",
|
|
|
629 [RUNNABLE] ="runble",
|
|
|
630 [RUNNING] ="run ",
|
|
|
631 [ZOMBIE] ="zombie"
|
|
0
|
632 };
|
|
|
633
|
|
|
634 struct proc *p;
|
|
|
635 char *state;
|
|
|
636
|
|
|
637 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
|
|
|
638 if(p->state == UNUSED) {
|
|
|
639 continue;
|
|
|
640 }
|
|
|
641
|
|
|
642 if(p->state >= 0 && p->state < NELEM(states) && states[p->state]) {
|
|
|
643 state = states[p->state];
|
|
|
644 } else {
|
|
|
645 state = "???";
|
|
|
646 }
|
|
|
647
|
|
|
648 cprintf("%d %s %d:%s %d\n", p->pid, state, p->pid, p->name, p->parent->pid);
|
|
|
649 }
|
|
|
650
|
|
|
651 show_callstk("procdump: \n");
|
|
|
652 }
|
|
|
653
|
|
|
654
|
