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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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220
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120 void dummy(struct proc *p, char _binary_initcode_start[], char _binary_initcode_size[])
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121 {
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122 // inituvm(p->pgdir, _binary_initcode_start, (int)_binary_initcode_size);
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230
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123 goto cbc_init_vmm_dummy(&p->cbc_context, p, p->pgdir, _binary_initcode_start, (int)_binary_initcode_size);
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220
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124
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125 }
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126
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127
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128
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225
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129 __ncode cbc_init_vmm_dummy(struct Context* cbc_context, struct proc* p, pde_t* pgdir, char* init, uint sz){//:skip
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220
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130
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225
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131 struct vm* vm = createvm_impl(cbc_context);
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227
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132 // goto vm->init_vmm(vm, pgdir, init, sz , vm->void_ret);
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220
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133 Gearef(cbc_context, vm)->vm = (union Data*) vm;
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134 Gearef(cbc_context, vm)->pgdir = pgdir;
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135 Gearef(cbc_context, vm)->init = init;
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136 Gearef(cbc_context, vm)->sz = sz ;
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227
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137 Gearef(cbc_context, vm)->next = C_vm_void_ret ;
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229
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138 goto meta(cbc_context, vm->init_inituvm);
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220
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139 }
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140
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141 void userinit(void)
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142 {
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220
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143 struct proc* p;
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144 extern char _binary_initcode_start[], _binary_initcode_size[];
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145
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146 p = allocproc();
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220
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147 initContext(&p->cbc_context);
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148
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149 initproc = p;
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150
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151 if((p->pgdir = kpt_alloc()) == NULL) {
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152 panic("userinit: out of memory?");
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153 }
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154
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220
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155 dummy(p, _binary_initcode_start, _binary_initcode_size);
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156
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157 p->sz = PTE_SZ;
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158
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159 // craft the trapframe as if
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160 memset(p->tf, 0, sizeof(*p->tf));
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161
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162 p->tf->r14_svc = (uint)error_init;
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163 p->tf->spsr = spsr_usr ();
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164 p->tf->sp_usr = PTE_SZ; // set the user stack
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165 p->tf->lr_usr = 0;
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166
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167 // set the user pc. The actual pc loaded into r15_usr is in
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168 // p->tf, the trapframe.
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169 p->tf->pc = 0; // beginning of initcode.S
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170
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171 safestrcpy(p->name, "initcode", sizeof(p->name));
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172 p->cwd = namei("/");
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173
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174 p->state = RUNNABLE;
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175 }
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176
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241
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177
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178 void switchuvm_dummy(struct proc* proc)
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179 {
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180 goto cbc_switchuvm_dummy(&proc->cbc_context, proc);
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181 }
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182
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183 __ncode cbc_switchuvm_dummy(struct Context* cbc_context, struct proc* proc){
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184
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185 struct vm* vm = createvm_impl(cbc_context);
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186 Gearef(cbc_context, vm)->vm = (union Data*) vm;
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187 goto meta(cbc_context, vm->switchuvm);
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188 }
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189
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0
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190 // Grow current process's memory by n bytes.
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191 // Return 0 on success, -1 on failure.
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192 int growproc(int n)
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193 {
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194 uint sz;
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195
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196 sz = proc->sz;
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197
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198 if(n > 0){
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199 if((sz = allocuvm(proc->pgdir, sz, sz + n)) == 0) {
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200 return -1;
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201 }
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202
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203 } else if(n < 0){
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204 if((sz = deallocuvm(proc->pgdir, sz, sz + n)) == 0) {
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205 return -1;
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206 }
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207 }
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208
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209 proc->sz = sz;
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241
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210 // switchuvm(proc);
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211 switchuvm_dummy(proc);
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0
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212
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213 return 0;
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214 }
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215
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216 // Create a new process copying p as the parent.
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217 // Sets up stack to return as if from system call.
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218 // Caller must set state of returned proc to RUNNABLE.
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219 int fork(void)
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220 {
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221 int i, pid;
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222 struct proc *np;
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223
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224 // Allocate process.
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225 if((np = allocproc()) == 0) {
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226 return -1;
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227 }
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220
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228 initContext(&np->cbc_context);
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0
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229
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230 // Copy process state from p.
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231 if((np->pgdir = copyuvm(proc->pgdir, proc->sz)) == 0){
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232 free_page(np->kstack);
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233 np->kstack = 0;
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234 np->state = UNUSED;
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235 return -1;
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236 }
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237
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238 np->sz = proc->sz;
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239 np->parent = proc;
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19
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240 // *np->tf = *proc->tf; // This generate memcpy4 which is not in libgcc.a
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241 memmove(np->tf, proc->tf, sizeof(*np->tf));
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0
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242
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243 // Clear r0 so that fork returns 0 in the child.
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244 np->tf->r0 = 0;
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245
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246 for(i = 0; i < NOFILE; i++) {
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247 if(proc->ofile[i]) {
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248 np->ofile[i] = filedup(proc->ofile[i]);
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249 }
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250 }
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251
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252 np->cwd = idup(proc->cwd);
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253
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254 pid = np->pid;
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255 np->state = RUNNABLE;
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256 safestrcpy(np->name, proc->name, sizeof(proc->name));
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257
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258 return pid;
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259 }
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260
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261 // Exit the current process. Does not return.
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262 // An exited process remains in the zombie state
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263 // until its parent calls wait() to find out it exited.
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264 void exit(void)
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265 {
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266 struct proc *p;
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267 int fd;
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268
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269 if(proc == initproc) {
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270 panic("init exiting");
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271 }
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272
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273 // Close all open files.
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274 for(fd = 0; fd < NOFILE; fd++){
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275 if(proc->ofile[fd]){
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276 fileclose(proc->ofile[fd]);
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277 proc->ofile[fd] = 0;
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278 }
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279 }
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280
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281 iput(proc->cwd);
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282 proc->cwd = 0;
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283
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284 acquire(&ptable.lock);
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285
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286 // Parent might be sleeping in wait().
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287 wakeup1(proc->parent);
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288
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289 // Pass abandoned children to init.
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290 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
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291 if(p->parent == proc){
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292 p->parent = initproc;
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293
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294 if(p->state == ZOMBIE) {
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295 wakeup1(initproc);
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296 }
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297 }
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298 }
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299
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300 // Jump into the scheduler, never to return.
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301 proc->state = ZOMBIE;
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302 sched();
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303
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304 panic("zombie exit");
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305 }
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306
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307 // Wait for a child process to exit and return its pid.
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308 // Return -1 if this process has no children.
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309 int wait(void)
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310 {
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311 struct proc *p;
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312 int havekids, pid;
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313
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314 acquire(&ptable.lock);
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315
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316 for(;;){
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317 // Scan through table looking for zombie children.
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318 havekids = 0;
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319
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320 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
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321 if(p->parent != proc) {
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322 continue;
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323 }
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324
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325 havekids = 1;
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326
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327 if(p->state == ZOMBIE){
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328 // Found one.
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329 pid = p->pid;
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330 free_page(p->kstack);
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331 p->kstack = 0;
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332 freevm(p->pgdir);
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333 p->state = UNUSED;
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334 p->pid = 0;
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335 p->parent = 0;
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336 p->name[0] = 0;
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337 p->killed = 0;
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338 release(&ptable.lock);
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339
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340 return pid;
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341 }
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342 }
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343
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344 // No point waiting if we don't have any children.
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345 if(!havekids || proc->killed){
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346 release(&ptable.lock);
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347 return -1;
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348 }
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349
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350 // Wait for children to exit. (See wakeup1 call in proc_exit.)
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351 sleep(proc, &ptable.lock); //DOC: wait-sleep
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352 }
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353 }
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354
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355 //PAGEBREAK: 42
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356 // Per-CPU process scheduler.
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357 // Each CPU calls scheduler() after setting itself up.
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358 // Scheduler never returns. It loops, doing:
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359 // - choose a process to run
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360 // - swtch to start running that process
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361 // - eventually that process transfers control
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362 // via swtch back to the scheduler.
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363 void scheduler(void)
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364 {
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365 struct proc *p;
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366
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367 for(;;){
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368 // Enable interrupts on this processor.
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369 sti();
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370
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371 // Loop over process table looking for process to run.
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372 acquire(&ptable.lock);
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373
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374 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
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375 if(p->state != RUNNABLE) {
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376 continue;
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377 }
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378
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379 // Switch to chosen process. It is the process's job
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380 // to release ptable.lock and then reacquire it
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381 // before jumping back to us.
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382 proc = p;
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383 switchuvm(p);
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384
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385 p->state = RUNNING;
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386
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387 swtch(&cpu->scheduler, proc->context);
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388 // Process is done running for now.
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389 // It should have changed its p->state before coming back.
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390 proc = 0;
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391 }
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392
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393 release(&ptable.lock);
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394 }
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395 }
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396
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52
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397 __ncode cbc_sched(__code(*next)())
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28
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398 {
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399 int intena;
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400
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401 if(!holding(&ptable.lock)) {
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402 panic("sched ptable.lock");
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403 }
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404
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405 if(cpu->ncli != 1) {
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406 panic("sched locks");
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407 }
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408
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409 if(proc->state == RUNNING) {
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410 panic("sched running");
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411 }
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412
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413 if(int_enabled ()) {
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414 panic("sched interruptible");
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415 }
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416
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417 intena = cpu->intena;
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418 swtch(&proc->context, cpu->scheduler);
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419 cpu->intena = intena;
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420
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421 goto next();
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422 }
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423
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424
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0
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425 // Enter scheduler. Must hold only ptable.lock
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426 // and have changed proc->state.
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427 void sched(void)
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428 {
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429 int intena;
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430
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431 //show_callstk ("sched");
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432
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433 if(!holding(&ptable.lock)) {
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434 panic("sched ptable.lock");
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435 }
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|
436
|
|
|
437 if(cpu->ncli != 1) {
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|
|
438 panic("sched locks");
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|
|
439 }
|
|
|
440
|
|
|
441 if(proc->state == RUNNING) {
|
|
|
442 panic("sched running");
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|
|
443 }
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|
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444
|
|
|
445 if(int_enabled ()) {
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|
|
446 panic("sched interruptible");
|
|
|
447 }
|
|
|
448
|
|
|
449 intena = cpu->intena;
|
|
|
450 swtch(&proc->context, cpu->scheduler);
|
|
|
451 cpu->intena = intena;
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|
|
452 }
|
|
|
453
|
|
|
454 // Give up the CPU for one scheduling round.
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|
|
455 void yield(void)
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456 {
|
|
|
457 acquire(&ptable.lock); //DOC: yieldlock
|
|
|
458 proc->state = RUNNABLE;
|
|
|
459 sched();
|
|
|
460 release(&ptable.lock);
|
|
|
461 }
|
|
|
462
|
|
|
463 // A fork child's very first scheduling by scheduler()
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|
|
464 // will swtch here. "Return" to user space.
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|
|
465 void forkret(void)
|
|
|
466 {
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|
|
467 static int first = 1;
|
|
|
468
|
|
|
469 // Still holding ptable.lock from scheduler.
|
|
|
470 release(&ptable.lock);
|
|
|
471
|
|
|
472 if (first) {
|
|
|
473 // Some initialization functions must be run in the context
|
|
|
474 // of a regular process (e.g., they call sleep), and thus cannot
|
|
|
475 // be run from main().
|
|
|
476 first = 0;
|
|
|
477 initlog();
|
|
|
478 }
|
|
|
479
|
|
|
480 // Return to "caller", actually trapret (see allocproc).
|
|
|
481 }
|
|
|
482
|
|
52
|
483 __ncode cbc_sleep1()
|
|
24
|
484 {
|
|
|
485 struct spinlock *lk = proc->lk;
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|
|
486 // Tidy up.
|
|
|
487 proc->chan = 0;
|
|
|
488
|
|
|
489 // Reacquire original lock.
|
|
|
490 if(lk != &ptable.lock){ //DOC: sleeplock2
|
|
|
491 release(&ptable.lock);
|
|
|
492 acquire(lk);
|
|
|
493 }
|
|
|
494 goto proc->cbc_next();
|
|
|
495 }
|
|
|
496
|
|
52
|
497 __ncode cbc_sleep(void *chan, struct spinlock *lk, __code(*next1)())
|
|
24
|
498 {
|
|
|
499 //show_callstk("sleep");
|
|
|
500
|
|
|
501 if(proc == 0) {
|
|
|
502 panic("sleep");
|
|
|
503 }
|
|
|
504
|
|
|
505 if(lk == 0) {
|
|
|
506 panic("sleep without lk");
|
|
|
507 }
|
|
|
508
|
|
|
509 if(lk != &ptable.lock){ //DOC: sleeplock0
|
|
|
510 acquire(&ptable.lock); //DOC: sleeplock1
|
|
|
511 release(lk);
|
|
|
512 }
|
|
|
513 proc->chan = chan;
|
|
|
514 proc->state = SLEEPING;
|
|
32
|
515 proc->lk = lk;
|
|
24
|
516 proc->cbc_next = next1;
|
|
|
517
|
|
|
518 goto cbc_sched(cbc_sleep1);
|
|
|
519 }
|
|
|
520
|
|
0
|
521 // Atomically release lock and sleep on chan.
|
|
|
522 // Reacquires lock when awakened.
|
|
|
523 void sleep(void *chan, struct spinlock *lk)
|
|
|
524 {
|
|
|
525 //show_callstk("sleep");
|
|
|
526
|
|
|
527 if(proc == 0) {
|
|
|
528 panic("sleep");
|
|
|
529 }
|
|
|
530
|
|
|
531 if(lk == 0) {
|
|
|
532 panic("sleep without lk");
|
|
|
533 }
|
|
|
534
|
|
|
535 // Must acquire ptable.lock in order to change p->state and then call
|
|
|
536 // sched. Once we hold ptable.lock, we can be guaranteed that we won't
|
|
|
537 // miss any wakeup (wakeup runs with ptable.lock locked), so it's okay
|
|
|
538 // to release lk.
|
|
|
539 if(lk != &ptable.lock){ //DOC: sleeplock0
|
|
|
540 acquire(&ptable.lock); //DOC: sleeplock1
|
|
|
541 release(lk);
|
|
|
542 }
|
|
|
543
|
|
|
544 // Go to sleep.
|
|
|
545 proc->chan = chan;
|
|
|
546 proc->state = SLEEPING;
|
|
|
547 sched();
|
|
|
548
|
|
|
549 // Tidy up.
|
|
|
550 proc->chan = 0;
|
|
|
551
|
|
|
552 // Reacquire original lock.
|
|
|
553 if(lk != &ptable.lock){ //DOC: sleeplock2
|
|
|
554 release(&ptable.lock);
|
|
|
555 acquire(lk);
|
|
|
556 }
|
|
|
557 }
|
|
|
558
|
|
|
559 //PAGEBREAK!
|
|
|
560 // Wake up all processes sleeping on chan. The ptable lock must be held.
|
|
|
561 static void wakeup1(void *chan)
|
|
|
562 {
|
|
|
563 struct proc *p;
|
|
|
564
|
|
|
565 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
|
|
|
566 if(p->state == SLEEPING && p->chan == chan) {
|
|
|
567 p->state = RUNNABLE;
|
|
|
568 }
|
|
|
569 }
|
|
|
570 }
|
|
|
571
|
|
52
|
572 __ncode cbc_wakeup1(void *chan)
|
|
36
|
573 {
|
|
|
574 struct proc *p;
|
|
|
575
|
|
|
576 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
|
|
|
577 if(p->state == SLEEPING && p->chan == chan) {
|
|
|
578 p->state = RUNNABLE;
|
|
|
579 }
|
|
|
580 }
|
|
|
581
|
|
|
582 release(&ptable.lock);
|
|
37
|
583 goto proc->cbc_next();
|
|
36
|
584 }
|
|
|
585
|
|
52
|
586 __ncode cbc_wakeup(void *chan, __code(*next1)())
|
|
36
|
587 {
|
|
|
588 acquire(&ptable.lock);
|
|
37
|
589 proc->cbc_next = next1;
|
|
36
|
590 cbc_wakeup1(chan);
|
|
|
591 }
|
|
|
592
|
|
0
|
593 // Wake up all processes sleeping on chan.
|
|
|
594 void wakeup(void *chan)
|
|
|
595 {
|
|
|
596 acquire(&ptable.lock);
|
|
|
597 wakeup1(chan);
|
|
|
598 release(&ptable.lock);
|
|
|
599 }
|
|
|
600
|
|
|
601 // Kill the process with the given pid. Process won't exit until it returns
|
|
|
602 // to user space (see trap in trap.c).
|
|
|
603 int kill(int pid)
|
|
|
604 {
|
|
|
605 struct proc *p;
|
|
|
606
|
|
|
607 acquire(&ptable.lock);
|
|
|
608
|
|
|
609 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
|
|
|
610 if(p->pid == pid){
|
|
|
611 p->killed = 1;
|
|
|
612
|
|
|
613 // Wake process from sleep if necessary.
|
|
|
614 if(p->state == SLEEPING) {
|
|
|
615 p->state = RUNNABLE;
|
|
|
616 }
|
|
|
617
|
|
|
618 release(&ptable.lock);
|
|
|
619 return 0;
|
|
|
620 }
|
|
|
621 }
|
|
|
622
|
|
|
623 release(&ptable.lock);
|
|
|
624 return -1;
|
|
|
625 }
|
|
|
626
|
|
|
627 //PAGEBREAK: 36
|
|
|
628 // Print a process listing to console. For debugging. Runs when user
|
|
|
629 // types ^P on console. No lock to avoid wedging a stuck machine further.
|
|
|
630 void procdump(void)
|
|
|
631 {
|
|
|
632 static char *states[] = {
|
|
22
|
633 [UNUSED] ="unused",
|
|
|
634 [EMBRYO] ="embryo",
|
|
|
635 [SLEEPING] ="sleep ",
|
|
|
636 [RUNNABLE] ="runble",
|
|
|
637 [RUNNING] ="run ",
|
|
|
638 [ZOMBIE] ="zombie"
|
|
0
|
639 };
|
|
|
640
|
|
|
641 struct proc *p;
|
|
|
642 char *state;
|
|
|
643
|
|
|
644 for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
|
|
|
645 if(p->state == UNUSED) {
|
|
|
646 continue;
|
|
|
647 }
|
|
|
648
|
|
|
649 if(p->state >= 0 && p->state < NELEM(states) && states[p->state]) {
|
|
|
650 state = states[p->state];
|
|
|
651 } else {
|
|
|
652 state = "???";
|
|
|
653 }
|
|
|
654
|
|
|
655 cprintf("%d %s %d:%s %d\n", p->pid, state, p->pid, p->name, p->parent->pid);
|
|
|
656 }
|
|
|
657
|
|
|
658 show_callstk("procdump: \n");
|
|
|
659 }
|
|
|
660
|
|
|
661
|
