add lab answers

labcodes_answer/lab2_result/kern/trap/trap.c

@@ -0,0 +1,197 @@
+#include <defs.h>
+#include <mmu.h>
+#include <memlayout.h>
+#include <clock.h>
+#include <trap.h>
+#include <x86.h>
+#include <stdio.h>
+#include <assert.h>
+#include <console.h>
+#include <kdebug.h>
+
+#define TICK_NUM 100
+
+static void print_ticks() {
+    cprintf("%d ticks\n",TICK_NUM);
+#ifdef DEBUG_GRADE
+    cprintf("End of Test.\n");
+    panic("EOT: kernel seems ok.");
+#endif
+}
+
+/* *
+ * Interrupt descriptor table:
+ *
+ * Must be built at run time because shifted function addresses can't
+ * be represented in relocation records.
+ * */
+static struct gatedesc idt[256] = {{0}};
+
+static struct pseudodesc idt_pd = {
+    sizeof(idt) - 1, (uintptr_t)idt
+};
+
+/* idt_init - initialize IDT to each of the entry points in kern/trap/vectors.S */
+void
+idt_init(void) {
+     /* LAB1 YOUR CODE : STEP 2 */
+     /* (1) Where are the entry addrs of each Interrupt Service Routine (ISR)?
+      *     All ISR's entry addrs are stored in __vectors. where is uintptr_t __vectors[] ?
+      *     __vectors[] is in kern/trap/vector.S which is produced by tools/vector.c
+      *     (try "make" command in lab1, then you will find vector.S in kern/trap DIR)
+      *     You can use  "extern uintptr_t __vectors[];" to define this extern variable which will be used later.
+      * (2) Now you should setup the entries of ISR in Interrupt Description Table (IDT).
+      *     Can you see idt[256] in this file? Yes, it's IDT! you can use SETGATE macro to setup each item of IDT
+      * (3) After setup the contents of IDT, you will let CPU know where is the IDT by using 'lidt' instruction.
+      *     You don't know the meaning of this instruction? just google it! and check the libs/x86.h to know more.
+      *     Notice: the argument of lidt is idt_pd. try to find it!
+      */
+    extern uintptr_t __vectors[];
+    int i;
+    for (i = 0; i < sizeof(idt) / sizeof(struct gatedesc); i ++) {
+        SETGATE(idt[i], 0, GD_KTEXT, __vectors[i], DPL_KERNEL);
+    }
+    lidt(&idt_pd);
+}
+
+static const char *
+trapname(int trapno) {
+    static const char * const excnames[] = {
+        "Divide error",
+        "Debug",
+        "Non-Maskable Interrupt",
+        "Breakpoint",
+        "Overflow",
+        "BOUND Range Exceeded",
+        "Invalid Opcode",
+        "Device Not Available",
+        "Double Fault",
+        "Coprocessor Segment Overrun",
+        "Invalid TSS",
+        "Segment Not Present",
+        "Stack Fault",
+        "General Protection",
+        "Page Fault",
+        "(unknown trap)",
+        "x87 FPU Floating-Point Error",
+        "Alignment Check",
+        "Machine-Check",
+        "SIMD Floating-Point Exception"
+    };
+
+    if (trapno < sizeof(excnames)/sizeof(const char * const)) {
+        return excnames[trapno];
+    }
+    if (trapno >= IRQ_OFFSET && trapno < IRQ_OFFSET + 16) {
+        return "Hardware Interrupt";
+    }
+    return "(unknown trap)";
+}
+
+/* trap_in_kernel - test if trap happened in kernel */
+bool
+trap_in_kernel(struct trapframe *tf) {
+    return (tf->tf_cs == (uint16_t)KERNEL_CS);
+}
+
+static const char *IA32flags[] = {
+    "CF", NULL, "PF", NULL, "AF", NULL, "ZF", "SF",
+    "TF", "IF", "DF", "OF", NULL, NULL, "NT", NULL,
+    "RF", "VM", "AC", "VIF", "VIP", "ID", NULL, NULL,
+};
+
+void
+print_trapframe(struct trapframe *tf) {
+    cprintf("trapframe at %p\n", tf);
+    print_regs(&tf->tf_regs);
+    cprintf("  ds   0x----%04x\n", tf->tf_ds);
+    cprintf("  es   0x----%04x\n", tf->tf_es);
+    cprintf("  fs   0x----%04x\n", tf->tf_fs);
+    cprintf("  gs   0x----%04x\n", tf->tf_gs);
+    cprintf("  trap 0x%08x %s\n", tf->tf_trapno, trapname(tf->tf_trapno));
+    cprintf("  err  0x%08x\n", tf->tf_err);
+    cprintf("  eip  0x%08x\n", tf->tf_eip);
+    cprintf("  cs   0x----%04x\n", tf->tf_cs);
+    cprintf("  flag 0x%08x ", tf->tf_eflags);
+
+    int i, j;
+    for (i = 0, j = 1; i < sizeof(IA32flags) / sizeof(IA32flags[0]); i ++, j <<= 1) {
+        if ((tf->tf_eflags & j) && IA32flags[i] != NULL) {
+            cprintf("%s,", IA32flags[i]);
+        }
+    }
+    cprintf("IOPL=%d\n", (tf->tf_eflags & FL_IOPL_MASK) >> 12);
+
+    if (!trap_in_kernel(tf)) {
+        cprintf("  esp  0x%08x\n", tf->tf_esp);
+        cprintf("  ss   0x----%04x\n", tf->tf_ss);
+    }
+}
+
+void
+print_regs(struct pushregs *regs) {
+    cprintf("  edi  0x%08x\n", regs->reg_edi);
+    cprintf("  esi  0x%08x\n", regs->reg_esi);
+    cprintf("  ebp  0x%08x\n", regs->reg_ebp);
+    cprintf("  oesp 0x%08x\n", regs->reg_oesp);
+    cprintf("  ebx  0x%08x\n", regs->reg_ebx);
+    cprintf("  edx  0x%08x\n", regs->reg_edx);
+    cprintf("  ecx  0x%08x\n", regs->reg_ecx);
+    cprintf("  eax  0x%08x\n", regs->reg_eax);
+}
+
+/* trap_dispatch - dispatch based on what type of trap occurred */
+static void
+trap_dispatch(struct trapframe *tf) {
+    char c;
+
+    switch (tf->tf_trapno) {
+    case IRQ_OFFSET + IRQ_TIMER:
+        /* LAB1 YOUR CODE : STEP 3 */
+        /* handle the timer interrupt */
+        /* (1) After a timer interrupt, you should record this event using a global variable (increase it), such as ticks in kern/driver/clock.c
+         * (2) Every TICK_NUM cycle, you can print some info using a funciton, such as print_ticks().
+         * (3) Too Simple? Yes, I think so!
+         */
+        ticks ++;
+        if (ticks % TICK_NUM == 0) {
+            print_ticks();
+        }
+        break;
+    case IRQ_OFFSET + IRQ_COM1:
+        c = cons_getc();
+        cprintf("serial [%03d] %c\n", c, c);
+        break;
+    case IRQ_OFFSET + IRQ_KBD:
+        c = cons_getc();
+        cprintf("kbd [%03d] %c\n", c, c);
+        break;
+    //LAB1 CHALLENGE 1 : YOUR CODE you should modify below codes.
+    case T_SWITCH_TOU:
+    case T_SWITCH_TOK:
+        panic("T_SWITCH_** ??\n");
+        break;
+    case IRQ_OFFSET + IRQ_IDE1:
+    case IRQ_OFFSET + IRQ_IDE2:
+        /* do nothing */
+        break;
+    default:
+        // in kernel, it must be a mistake
+        if ((tf->tf_cs & 3) == 0) {
+            print_trapframe(tf);
+            panic("unexpected trap in kernel.\n");
+        }
+    }
+}
+
+/* *
+ * trap - handles or dispatches an exception/interrupt. if and when trap() returns,
+ * the code in kern/trap/trapentry.S restores the old CPU state saved in the
+ * trapframe and then uses the iret instruction to return from the exception.
+ * */
+void
+trap(struct trapframe *tf) {
+    // dispatch based on what type of trap occurred
+    trap_dispatch(tf);
+}
+

labcodes_answer/lab2_result/kern/trap/trap.h

@@ -0,0 +1,91 @@
+#ifndef __KERN_TRAP_TRAP_H__
+#define __KERN_TRAP_TRAP_H__
+
+#include <defs.h>
+
+/* Trap Numbers */
+
+/* Processor-defined: */
+#define T_DIVIDE                0   // divide error
+#define T_DEBUG                 1   // debug exception
+#define T_NMI                   2   // non-maskable interrupt
+#define T_BRKPT                 3   // breakpoint
+#define T_OFLOW                 4   // overflow
+#define T_BOUND                 5   // bounds check
+#define T_ILLOP                 6   // illegal opcode
+#define T_DEVICE                7   // device not available
+#define T_DBLFLT                8   // double fault
+// #define T_COPROC             9   // reserved (not used since 486)
+#define T_TSS                   10  // invalid task switch segment
+#define T_SEGNP                 11  // segment not present
+#define T_STACK                 12  // stack exception
+#define T_GPFLT                 13  // general protection fault
+#define T_PGFLT                 14  // page fault
+// #define T_RES                15  // reserved
+#define T_FPERR                 16  // floating point error
+#define T_ALIGN                 17  // aligment check
+#define T_MCHK                  18  // machine check
+#define T_SIMDERR               19  // SIMD floating point error
+
+#define T_SYSCALL               0x80 // SYSCALL, ONLY FOR THIS PROJ
+
+/* Hardware IRQ numbers. We receive these as (IRQ_OFFSET + IRQ_xx) */
+#define IRQ_OFFSET              32  // IRQ 0 corresponds to int IRQ_OFFSET
+
+#define IRQ_TIMER               0
+#define IRQ_KBD                 1
+#define IRQ_COM1                4
+#define IRQ_IDE1                14
+#define IRQ_IDE2                15
+#define IRQ_ERROR               19
+#define IRQ_SPURIOUS            31
+
+/* *
+ * These are arbitrarily chosen, but with care not to overlap
+ * processor defined exceptions or interrupt vectors.
+ * */
+#define T_SWITCH_TOU                120    // user/kernel switch
+#define T_SWITCH_TOK                121    // user/kernel switch
+
+/* registers as pushed by pushal */
+struct pushregs {
+    uint32_t reg_edi;
+    uint32_t reg_esi;
+    uint32_t reg_ebp;
+    uint32_t reg_oesp;          /* Useless */
+    uint32_t reg_ebx;
+    uint32_t reg_edx;
+    uint32_t reg_ecx;
+    uint32_t reg_eax;
+};
+
+struct trapframe {
+    struct pushregs tf_regs;
+    uint16_t tf_gs;
+    uint16_t tf_padding0;
+    uint16_t tf_fs;
+    uint16_t tf_padding1;
+    uint16_t tf_es;
+    uint16_t tf_padding2;
+    uint16_t tf_ds;
+    uint16_t tf_padding3;
+    uint32_t tf_trapno;
+    /* below here defined by x86 hardware */
+    uint32_t tf_err;
+    uintptr_t tf_eip;
+    uint16_t tf_cs;
+    uint16_t tf_padding4;
+    uint32_t tf_eflags;
+    /* below here only when crossing rings, such as from user to kernel */
+    uintptr_t tf_esp;
+    uint16_t tf_ss;
+    uint16_t tf_padding5;
+} __attribute__((packed));
+
+void idt_init(void);
+void print_trapframe(struct trapframe *tf);
+void print_regs(struct pushregs *regs);
+bool trap_in_kernel(struct trapframe *tf);
+
+#endif /* !__KERN_TRAP_TRAP_H__ */
+

labcodes_answer/lab2_result/kern/trap/trapentry.S

@@ -0,0 +1,44 @@
+#include <memlayout.h>
+
+# vectors.S sends all traps here.
+.text
+.globl __alltraps
+__alltraps:
+    # push registers to build a trap frame
+    # therefore make the stack look like a struct trapframe
+    pushl %ds
+    pushl %es
+    pushl %fs
+    pushl %gs
+    pushal
+
+    # load GD_KDATA into %ds and %es to set up data segments for kernel
+    movl $GD_KDATA, %eax
+    movw %ax, %ds
+    movw %ax, %es
+
+    # push %esp to pass a pointer to the trapframe as an argument to trap()
+    pushl %esp
+
+    # call trap(tf), where tf=%esp
+    call trap
+
+    # pop the pushed stack pointer
+    popl %esp
+
+    # return falls through to trapret...
+.globl __trapret
+__trapret:
+    # restore registers from stack
+    popal
+
+    # restore %ds, %es, %fs and %gs
+    popl %gs
+    popl %fs
+    popl %es
+    popl %ds
+
+    # get rid of the trap number and error code
+    addl $0x8, %esp
+    iret
+