1 #include "tss.h"
 2 #include "stdint.h"
 3 #include "global.h"
 4 #include "string.h"
 5 #include "print.h"
 6 
 7 /* 任务状态段tss结构 */
 8 struct tss {
 9     uint32_t backlink;
10     uint32_t* esp0;
11     uint32_t ss0;
12     uint32_t* esp1;
13     uint32_t ss1;
14     uint32_t* esp2;
15     uint32_t ss2;
16     uint32_t cr3;
17     uint32_t (*eip) (void);
18     uint32_t eflags;
19     uint32_t eax;
20     uint32_t ecx;
21     uint32_t edx;
22     uint32_t ebx;
23     uint32_t esp;
24     uint32_t ebp;
25     uint32_t esi;
26     uint32_t edi;
27     uint32_t es;
28     uint32_t cs;
29     uint32_t ss;
30     uint32_t ds;
31     uint32_t fs;
32     uint32_t gs;
33     uint32_t ldt;
34     uint32_t trace;
35     uint32_t io_base;
36 }; 
37 static struct tss tss;
38 
39 /* 更新tss中esp0字段的值为pthread的0级线 */
40 void update_tss_esp(struct task_struct* pthread) {
41    tss.esp0 = (uint32_t*)((uint32_t)pthread + PG_SIZE);
42 }
43 
44 /* 创建gdt描述符 */
45 static struct gdt_desc make_gdt_desc(uint32_t* desc_addr, uint32_t limit, uint8_t attr_low, uint8_t attr_high) {
46    uint32_t desc_base = (uint32_t)desc_addr;
47    struct gdt_desc desc;
48    desc.limit_low_word = limit & 0x0000ffff;
49    desc.base_low_word = desc_base & 0x0000ffff;
50    desc.base_mid_byte = ((desc_base & 0x00ff0000) >> 16);
51    desc.attr_low_byte = (uint8_t)(attr_low);
52    desc.limit_high_attr_high = (((limit & 0x000f0000) >> 16) + (uint8_t)(attr_high));
53    desc.base_high_byte = desc_base >> 24;
54    return desc;
55 }
56 
57 /* 在gdt中创建tss并重新加载gdt */
58 void tss_init() {
59    put_str("tss_init start\n");
60    uint32_t tss_size = sizeof(tss);
61    memset(&tss, 0, tss_size);
62    tss.ss0 = SELECTOR_K_STACK;
63    tss.io_base = tss_size;
64 
65 /* gdt段基址为0x900,把tss放到第4个位置,也就是0x900+0x20的位置 */
66 
67   /* 在gdt中添加dpl为0的TSS描述符 */
68   *((struct gdt_desc*)(GDT_BASE_ADDR+(0x8*4)))= make_gdt_desc((uint32_t*)&tss, tss_size - 1, TSS_ATTR_LOW, TSS_ATTR_HIGH);
69 
70   /* 在gdt中添加dpl为3的数据段和代码段描述符 */
71   *((struct gdt_desc*)(GDT_BASE_ADDR+(0x8*5))) = make_gdt_desc((uint32_t*)0, 0xfffff, GDT_CODE_ATTR_LOW_DPL3, GDT_ATTR_HIGH);
72   *((struct gdt_desc*)(GDT_BASE_ADDR+(0x8*6))) = make_gdt_desc((uint32_t*)0, 0xfffff, GDT_DATA_ATTR_LOW_DPL3, GDT_ATTR_HIGH);
73    
74   /* gdt 16位的limit 32位的段基址 */
75    uint64_t gdt_operand = ((8 * 7 - 1) | ((uint64_t)(uint32_t)GDT_BASE_ADDR << 16));   // 7个描述符大小
76    asm volatile ("lgdt %0" : : "m" (gdt_operand));
77    asm volatile ("ltr %w0" : : "r" (SELECTOR_TSS));
78    put_str("tss_init and ltr done\n");
79 }

 1 struct task_struct {
 2    uint32_t* self_kstack;     // 各内核线程都用自己的内核栈
 3    pid_t pid;
 4    enum task_status status;
 5    char name[TASK_NAME_LEN];
 6    uint8_t priority;
 7    uint8_t ticks;       // 每次在处理器上执行的时间嘀嗒数
 8 /* 此任务自上cpu运行后至今占用了多少cpu嘀嗒数,
 9  * 也就是此任务执行了多久*/
10    uint32_t elapsed_ticks;
11 /* general_tag的作用是用于线程在一般的队列中的结点 */
12    struct list_elem general_tag;                    
13 /* all_list_tag的作用是用于线程队列thread_all_list中的结点 */
14    struct list_elem all_list_tag;
15    uint32_t* pgdir;              // 进程自己页表的虚拟地址
16    struct virtual_addr userprog_vaddr;   // 用户进程的虚拟地址
17    struct mem_block_desc u_block_desc[DESC_CNT];   // 用户进程内存块描述符
18    int32_t fd_table[MAX_FILES_OPEN_PER_PROC];    // 已打开文件数组
19    uint32_t cwd_inode_nr;     // 进程所在的工作目录的inode编号
20    pid_t parent_pid;         // 父进程pid
21    int8_t  exit_status;         // 进程结束时自己调用exit传入的参数
22    uint32_t stack_magic;     // 用这串数字做栈的边界标记,用于检测栈的溢出
23 };

 1 ...
 2 int test_var_a = 0, test_var_b = 0;
 3 
 4 int main(void){
 5     put_str("I am kernel\n");
 6     init_all();
 7     thread_start("threadA", 31, k_thread_a, "AOUT_");
 8     thread_start("threadB", 31, k_thread_b, "BOUT_");
 9     process_execute(u_prog_a, "userProcessA");
10     process_execute(u_prog_b, "userProcessB");
11     intr_enable();
12     while(1);
13     return 0;
14 }
15 
16 void k_thread_a(void* arg) {
17     char* para = arg;
18     while(1) {
19         console_put_str("threadA:");
20         console_put_int(test_var_a);
21         console_put_str("\n");
22     }
23 }
24 
25 void k_thread_b(void* arg) {
26     char* para = arg;
27     while(1) {
28         console_put_str("threadB:");
29         console_put_int(test_var_b);
30         console_put_str("\n");
31     }
32 }
33 
34 void u_prog_a(void) {
35     while(1) {
36         test_var_a++;
37     }
38 }
39 
40 void u_prog_b(void) {
41     while(1) {
42         test_var_b++;
43     }
44 }

 1 /* 创建用户进程 */
 2 void process_execute(void* filename, char* name) { 
 3    /* pcb内核的数据结构,由内核来维护进程信息,因此要在内核内存池中申请 */
 4    struct task_struct* thread = get_kernel_pages(1);
 5    init_thread(thread, name, default_prio); 
 6    create_user_vaddr_bitmap(thread);
 7    thread_create(thread, start_process, filename);
 8    thread->pgdir = create_page_dir();
 9    
10    enum intr_status old_status = intr_disable();
11    list_append(&thread_ready_list, &thread->general_tag);
12    list_append(&thread_all_list, &thread->all_list_tag);
13    intr_set_status(old_status);
14 }