tweak some comments.

This commit is contained in:
Robert Morris 2019-07-10 08:57:51 -04:00
parent 2f22a3ed6a
commit 9981bb2270
4 changed files with 28 additions and 28 deletions

View file

@ -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)
{

View file

@ -18,10 +18,10 @@ 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
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()?
};
@ -30,21 +30,25 @@ 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;
/* 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 hartid;
/* 32 */ uint64 kernel_hartid; // saved kernel tp
/* 40 */ uint64 ra;
/* 48 */ uint64 sp;
/* 56 */ uint64 gp;

View file

@ -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

View file

@ -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.