// Saved registers for kernel context switches. struct context { u64 ra; u64 sp; // callee-saved u64 s0; u64 s1; u64 s2; u64 s3; u64 s4; u64 s5; u64 s6; u64 s7; u64 s8; u64 s9; u64 s10; u64 s11; }; // Per-CPU state. struct cpu { struct proc *proc; // The process running on this cpu, or null. struct context context; // swtch() here to enter scheduler(). int noff; // Depth of push_off() nesting. int intena; // Were interrupts enabled before push_off()? }; extern struct cpu cpus[NCPU]; // per-process data for the trap handling code in trampoline.S. // sits in a page by itself just under the trampoline page in the // user page table. not specially mapped in the kernel page table. // uservec in trampoline.S saves user registers in the trapframe, // then initializes registers from the trapframe's // kernel_sp, kernel_hartid, kernel_satp, and jumps to kernel_trap. // usertrapret() and userret in trampoline.S set up // the trapframe's kernel_*, restore user registers from the // trapframe, switch to the user page table, and enter user space. // the trapframe includes callee-saved user registers like s0-s11 because the // return-to-user path via usertrapret() doesn't return through // the entire kernel call stack. struct trapframe { /* 0 */ u64 kernel_satp; // kernel page table /* 8 */ u64 kernel_sp; // top of process's kernel stack /* 16 */ u64 kernel_trap; // usertrap() /* 24 */ u64 epc; // saved user program counter /* 32 */ u64 kernel_hartid; // saved kernel tp /* 40 */ u64 ra; /* 48 */ u64 sp; /* 56 */ u64 gp; /* 64 */ u64 tp; /* 72 */ u64 t0; /* 80 */ u64 t1; /* 88 */ u64 t2; /* 96 */ u64 s0; /* 104 */ u64 s1; /* 112 */ u64 a0; /* 120 */ u64 a1; /* 128 */ u64 a2; /* 136 */ u64 a3; /* 144 */ u64 a4; /* 152 */ u64 a5; /* 160 */ u64 a6; /* 168 */ u64 a7; /* 176 */ u64 s2; /* 184 */ u64 s3; /* 192 */ u64 s4; /* 200 */ u64 s5; /* 208 */ u64 s6; /* 216 */ u64 s7; /* 224 */ u64 s8; /* 232 */ u64 s9; /* 240 */ u64 s10; /* 248 */ u64 s11; /* 256 */ u64 t3; /* 264 */ u64 t4; /* 272 */ u64 t5; /* 280 */ u64 t6; }; enum procstate { UNUSED, USED, SLEEPING, RUNNABLE, RUNNING, ZOMBIE }; // Per-process state struct proc { struct spinlock lock; // p->lock must be held when using these: enum procstate state; // Process state void *chan; // If non-zero, sleeping on chan int killed; // If non-zero, have been killed int xstate; // Exit status to be returned to parent's wait int pid; // Process ID // wait_lock must be held when using this: struct proc *parent; // Parent process // these are private to the process, so p->lock need not be held. u64 kstack; // Virtual address of kernel stack u64 sz; // Size of process memory (bytes) pagetable_t pagetable; // User page table struct trapframe *trapframe; // data page for trampoline.S struct context context; // swtch() here to run process struct file *ofile[NOFILE]; // Open files struct inode *cwd; // Current directory char name[16]; // Process name (debugging) };