2020301918-os/kern/trap.c

#include <assert.h>
#include <string.h>
#include <x86.h>

#include <kern/keyboard.h>
#include <kern/keymap.h>
#include <kern/process.h>
#include <kern/protect.h>
#include <kern/stdio.h>
#include <kern/syscall.h>
#include <kern/time.h>
#include <kern/trap.h>

/*
 * 当前内核需要处理中断的数量
 */
int k_reenter;

void (*irq_table[16])(int) = {
	clock_interrupt_handler,
	kb_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
	default_interrupt_handler,
};

/*
 * 开启对应外设中断（将掩码对应位置为0）
 */
void
enable_irq(int irq)
{
	u8 mask = 1 << (irq % 8);
	if (irq < 8)
		outb(INT_M_CTLMASK, inb(INT_M_CTLMASK) & ~mask);
	else
		outb(INT_S_CTLMASK, inb(INT_S_CTLMASK) & ~mask);
}

/*
 * 关闭对应外设中断（将掩码对应位置为1）
 */
void
disable_irq(int irq)
{
	u8 mask = 1 << (irq % 8);
	if (irq < 8)
		outb(INT_M_CTLMASK, inb(INT_M_CTLMASK) | mask);
	else
		outb(INT_S_CTLMASK, inb(INT_S_CTLMASK) | mask);
}
/*
 * 中断默认处理函数
 * 理论上是不支持的，所以会给个warning
 */
void
default_interrupt_handler(int irq)
{
	warn("unsupport interrupt! irq = %d", irq);
}

/*
 * 异常默认处理函数
 * 由于没有任何处理异常的手段，所以会给个panic
 */
void
exception_handler(int vec_no, int err_code, int eip, int cs, int eflags)
{
	static char err_description[][64] = {	
		"#DE Divide Error",
		"#DB RESERVED",
		"—  NMI Interrupt",
		"#BP Breakpoint",
		"#OF Overflow",
		"#BR BOUND Range Exceeded",
		"#UD Invalid Opcode (Undefined Opcode)",
		"#NM Device Not Available (No Math Coprocessor)",
		"#DF Double Fault",
		"    Coprocessor Segment Overrun (reserved)",
		"#TS Invalid TSS",
		"#NP Segment Not Present",
		"#SS Stack-Segment Fault",
		"#GP General Protection",
		"#PF Page Fault",
		"—  (Intel reserved. Do not use.)",
		"#MF x87 FPU Floating-Point Error (Math Fault)",
		"#AC Alignment Check",
		"#MC Machine Check",
		"#XF SIMD Floating-Point Exception"
	};
	#define PANIC_STR_SIZE 256
	static char fmtstr[PANIC_STR_SIZE];

	if (vec_no == INT_VECTOR_PAGE_FAULT) {
		char *p_str = fmtstr;
		p_str += snprintf(
			p_str, PANIC_STR_SIZE - (p_str - fmtstr) - 1,
			"\x1b[H\x1b[2JOh, you receive a page fault!\n");
		p_str += snprintf(
			p_str, PANIC_STR_SIZE - (p_str - fmtstr) - 1,
			"CS: %%x EIP: %%x You tried to access the address: %%x\n");
		if ((err_code & FEC_PR) == 0) {
			p_str += snprintf(
			p_str, PANIC_STR_SIZE - (p_str - fmtstr) - 1,
			"You tried to access a nonexistent page!\n");
		}
		if ((err_code & FEC_WR) != 0) {
			p_str += snprintf(
			p_str, PANIC_STR_SIZE - (p_str - fmtstr) - 1,
			"You tried to write in this page!\n");
		} else {
			p_str += snprintf(
			p_str, PANIC_STR_SIZE - (p_str - fmtstr) - 1,
			"You tried to read in this page!\n");
		}
		if ((err_code & FEC_U) != 0) {
			p_str += snprintf(
			p_str, PANIC_STR_SIZE - (p_str - fmtstr) - 1,
			"You tried to access a page in user mode!\n");
		}
		panic(fmtstr, cs, eip, rcr2());
	} else {
		snprintf(fmtstr, PANIC_STR_SIZE - 1, 
			"\x1b[H\x1b[2JException! --> "
			"%%s\nEFLAGS: %%x CS: %%x EIP: %%x\nError code: %%x");
		panic(fmtstr, err_description[vec_no], 
					eflags, cs, eip, err_code);
	}
}
/*
 * 时钟中断处理函数，
 * 需要注意的是，在这次实验中时钟中断全程是
 * 关!中!断!
 * 关!中!断!
 * 关!中!断!
 * 不允许任何其他中断打扰。
 */
void
clock_interrupt_handler(int irq)
{
	timecounter_inc();
	if (!has_runnable) return; 
	// maybe do nothing would be better, try to avoid recursive call to schedule
	// because we must be in a schedule when runnable is false
	// we just need a clock int to wake up it

	// 当一个函数的时间片全用完时
	if (--p_proc_ready->pcb.ticks == 0) {
		p_proc_ready->pcb.ticks = p_proc_ready->pcb.priority;
		schedule();
	}
}

/*
 * 键盘中断处理函数
 */
void
kb_interrupt_handler(int irq)
{
	u8 ch = inb(0x60);
	if ((ch & 0x80) != 0)
		return;
	ch = keymap[ch];
	if ('a' <= ch && ch <= 'z')
		add_keyboard_buf(ch);
}

/*
 * 系统调用处理函数
 */
void
syscall_handler(void)
{
	int syscall_id = p_proc_ready->pcb.user_regs.eax;
	ssize_t ret = (*syscall_table[syscall_id])();
	p_proc_ready->pcb.user_regs.eax = ret;
}