root/proc.h

INCLUDED FROM

   1 // Segments in proc->gdt.
   2 #define NSEGS     7
   4 // Per-CPU state
   5 struct cpu {
uchar id;                    // Local APIC ID; index into cpus[] below
   7   struct context *scheduler;   // swtch() here to enter scheduler
   8   struct taskstate ts;         // Used by x86 to find stack for interrupt
   9   struct segdesc gdt[NSEGS];   // x86 global descriptor table
  10   volatile uint started;       // Has the CPU started?
  11   int ncli;                    // Depth of pushcli nesting.
  12   int intena;                  // Were interrupts enabled before pushcli?
  14   // Cpu-local storage variables; see below
  15   struct cpu *cpu;
  16   struct proc *proc;           // The currently-running process.
  17 };
  19 extern struct cpu cpus[NCPU];
  20 extern int ncpu;
  22 // Per-CPU variables, holding pointers to the
  23 // current cpu and to the current process.
  24 // The asm suffix tells gcc to use "%gs:0" to refer to cpu
  25 // and "%gs:4" to refer to proc.  seginit sets up the
  26 // %gs segment register so that %gs refers to the memory
  27 // holding those two variables in the local cpu's struct cpu.
  28 // This is similar to how thread-local variables are implemented
  29 // in thread libraries such as Linux pthreads.
  30 extern struct cpu *cpu asm("%gs:0");       // &cpus[cpunum()]
  31 extern struct proc *proc asm("%gs:4");     // cpus[cpunum()].proc
  33 //PAGEBREAK: 17
  34 // Saved registers for kernel context switches.
  35 // Don't need to save all the segment registers (%cs, etc),
  36 // because they are constant across kernel contexts.
  37 // Don't need to save %eax, %ecx, %edx, because the
  38 // x86 convention is that the caller has saved them.
  39 // Contexts are stored at the bottom of the stack they
  40 // describe; the stack pointer is the address of the context.
  41 // The layout of the context matches the layout of the stack in swtch.S
  42 // at the "Switch stacks" comment. Switch doesn't save eip explicitly,
  43 // but it is on the stack and allocproc() manipulates it.
  44 struct context {
uint edi;
uint esi;
uint ebx;
uint ebp;
uint eip;
  50 };
  52 enum procstate { UNUSED, EMBRYO, SLEEPING, RUNNABLE, RUNNING, ZOMBIE };
  54 // Per-process state
  55 struct proc {
uint sz;                     // Size of process memory (bytes)
pde_t* pgdir;                // Page table
  58   char *kstack;                // Bottom of kernel stack for this process
  59   enum procstate state;        // Process state
  60   int pid;                     // Process ID
  61   struct proc *parent;         // Parent process
  62   struct trapframe *tf;        // Trap frame for current syscall
  63   struct context *context;     // swtch() here to run process
  64   void *chan;                  // If non-zero, sleeping on chan
  65   int killed;                  // If non-zero, have been killed
  66   struct file *ofile[NOFILE];  // Open files
  67   struct inode *cwd;           // Current directory
  68   char name[16];               // Process name (debugging)
  69 };
  71 // Process memory is laid out contiguously, low addresses first:
  72 //   text
  73 //   original data and bss
  74 //   fixed-size stack
  75 //   expandable heap