diff options
| -rw-r--r-- | kernel/proc.c | 20 | ||||
| -rw-r--r-- | kernel/proc.h | 32 | ||||
| -rw-r--r-- | kernel/trampoline.S | 2 | ||||
| -rw-r--r-- | kernel/trap.c | 2 |
4 files changed, 28 insertions, 28 deletions
diff --git a/kernel/proc.c b/kernel/proc.c index a947f7f..5c2d4ce 100644 --- a/kernel/proc.c +++ b/kernel/proc.c @@ -6,20 +6,16 @@ #include "proc.h" #include "defs.h" -struct proc proc[NPROC]; - struct cpu cpus[NCPU]; +struct proc proc[NPROC]; + struct proc *initproc; -struct spinlock pid_lock; int nextpid = 1; +struct spinlock pid_lock; extern void forkret(void); - -// for returning out of the kernel -extern void sysexit(void); - static void wakeup1(struct proc *chan); extern char trampout[]; // trampoline.S @@ -287,8 +283,8 @@ fork(void) return pid; } -// Pass p's abandoned children to init. p and p's parent -// are locked. +// Pass p's abandoned children to init. +// Caller must hold p->lock and parent->lock. void reparent(struct proc *p, struct proc *parent) { struct proc *pp; @@ -536,7 +532,7 @@ sleep(void *chan, struct spinlock *lk) //PAGEBREAK! // Wake up p, used by exit() -// Caller should lock p. +// Caller must hold p->lock. static void wakeup1(struct proc *p) { @@ -545,8 +541,8 @@ wakeup1(struct proc *p) } } -// Wake up all processes sleeping on chan. Never -// called when holding a p->lock +// Wake up all processes sleeping on chan. +// Must be called without any p->lock. void wakeup(void *chan) { diff --git a/kernel/proc.h b/kernel/proc.h index 687fdd1..373b605 100644 --- a/kernel/proc.h +++ b/kernel/proc.h @@ -18,33 +18,37 @@ struct context { uint64 s11; }; -// Per-CPU state +// Per-CPU state. struct cpu { - struct proc *proc; // The process running on this cpu or null - struct context scheduler; // swtch() here to enter scheduler - int noff; // Depth of push_off() nesting. - int intena; // Were interrupts enabled before push_off()? + struct proc *proc; // The process running on this cpu, or null. + struct context scheduler; // 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]; //PAGEBREAK: 17 -// per-process data for the early trap handling code in trampoline.S. +// 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. // the sscratch register points here. -// trampoline.S saves user registers, then restores kernel_sp and -// kernel_satp. -// includes callee-saved registers like s0-s11 because the +// trampin 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 trampout 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 */ uint64 kernel_satp; - /* 8 */ uint64 kernel_sp; - /* 16 */ uint64 kernel_trap; // usertrap() - /* 24 */ uint64 epc; // saved user program counter - /* 32 */ uint64 hartid; + /* 0 */ uint64 kernel_satp; // kernel page table + /* 8 */ uint64 kernel_sp; // top of process's kernel stack + /* 16 */ uint64 kernel_trap; // usertrap() + /* 24 */ uint64 epc; // saved user program counter + /* 32 */ uint64 kernel_hartid; // saved kernel tp /* 40 */ uint64 ra; /* 48 */ uint64 sp; /* 56 */ uint64 gp; diff --git a/kernel/trampoline.S b/kernel/trampoline.S index dd4eb02..b992ea6 100644 --- a/kernel/trampoline.S +++ b/kernel/trampoline.S @@ -120,7 +120,7 @@ trampin: # restore kernel stack pointer from p->tf->kernel_sp ld sp, 8(a0) - # make tp hold the current hartid, from p->tf->hartid + # make tp hold the current hartid, from p->tf->kernel_hartid ld tp, 32(a0) # remember the address of usertrap(), p->tf->kernel_trap diff --git a/kernel/trap.c b/kernel/trap.c index 018b7db..27cfd32 100644 --- a/kernel/trap.c +++ b/kernel/trap.c @@ -100,7 +100,7 @@ usertrapret(void) p->tf->kernel_satp = r_satp(); p->tf->kernel_sp = (uint64)p->kstack + PGSIZE; p->tf->kernel_trap = (uint64)usertrap; - p->tf->hartid = r_tp(); + p->tf->kernel_hartid = r_tp(); // set up the registers that trampoline.S's sret will use // to get to user space. |