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显示段选择符和段描述符...

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gatieme
2017-03-25 00:12:46 +08:00
parent 9922e47ccd
commit f0729595a5
1 changed files with 193 additions and 64 deletions
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study/kernel/03-vmarea/00-code/02-gdt_table/get_gdt_table.c
+193 -64
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@@ -22,14 +22,167 @@ MODULE_LICENSE("Dual BSD/GPL");
#define bit_clr(number, pos) ((number) &= ~(1 << (pos))) /// 把某位清0
#define bit_cpl(number, pos) ((number) ^= 1 << (pos)) /// 把number的POS位取反
/*
* 打印段描述符的数据
* desc 指向GDT的指针
*/
static void print_desc_struct(struct desc_struct *desc)
{
#if 0
printk("limit0 = %0x, ", desc->limit0);
printk("base0 = %0x, ", desc->base0);
printk("base1 = %0x, ", desc->base1);
printk("type = %0x, ", desc->type);
printk("s = %0x, ", desc->s);
printk("dpl = %0x, ", desc->dpl);
printk("p = %0x, ", desc->p);
printk("limit = %0x, ", desc->limit);
printk("avl = %0x, ", desc->avl);
printk("l = %0x, ", desc->l);
printk("d = %0x, ", desc->d);
printk("g = %0x, ", desc->g);
printk("base2 = %0x\n", desc->base2);
#endif
/*
段描述符
----------------------------------------------------------------------------------------
63 56/55 52/51 48/47 40/39 32/31 16/15 0
----------------------------------------------------------------------------------------
| B31-B24 | G D/B O AV | L19-L16 | P DPL S E ED/C R/W A | B23-B16 | B15-B0 | L15-L0 |
----------------------------------------------------------------------------------------
| | | | | | | | | | |
| | | | | | | --------- |
| | | | | | | | |
| | | | | | | | ------------ = 1, 已被访问过
| | | | | | | |
| | | | | | | | |-- E = 0, 数据段
| | | | | | | | ------|-- ED = 0, 向上延伸(数据段); ED = 1, 向下延伸(堆栈段)
| | | | | | | | | |-- W = 0, 不可写入; W = 1, 可写入
| | | | | | | ----------|
| | | | | | | | |-- E = 1, 代码段
| | | | | | | ------|-- C = 0, 忽视特权级别; C = 1, 依照特权级别
| | | | | | | |-- R = 0, 不能读; R = 1, 可读
| | | | | | |
| | | | | | | |-- = 0, 表示专用于系统管理的系统段, 如各类描述表
| | | | | | |---------------------|
| | | | | | |-- = 1, 表示用于一般的代码段或者数据段
| | | | | |
| | | | | ---------------------------- 特权级别
| | | | ------------------------------- = 1, 表示该段在内存中
| | | |
| | | |
| | | -------- 可由软件使用, CPU忽略该位
| | ----------- 永远为0
| -------------- = 1, 表示对该段的访问为32位指令; = 0, 为16位指令
----------------- = 1, 段长以4K字节为单位; = 0, 以字节为单位
*/
#define get_desc_struct_BASE0(gdt) (((gdt) >> 16) & 0xffff)
#define get_desc_struct_BASE1(gdt) (((gdt) >> 32) & 0xff)
#define get_desc_struct_BASE2(gdt) (((gdt) >> 56) & 0xff)
#define get_desc_struct_BASE(gdt) \
((get_desc_struct_BASE0(gdt) << 16) \
| (get_desc_struct_BASE1(gdt) << 8) \
| (get_desc_struct_BASE2(gdt)))
#define get_desc_struct_LIMIT0(gdt) ((gdt) & 0xffff)
#define get_desc_struct_LIMIT1(gdt) (((gdt) >> 48) & 0x0f)
#define get_desc_struct_LIMIT(gdt) \
((get_desc_struct_LIMIT0(gdt) << 4) \
| (get_desc_struct_LIMIT1(gdt)))
#define get_desc_struct_G(gdt) (((gdt) >> 55) & 0x01) /* 55 */
#define get_desc_struct_D_or_B(gdt) (((gdt) >> 54) & 0x01) /* 54 */
#define get_desc_struct_O(gdt) (((gdt) >> 53) & 0x01) /* 53 */
#define get_desc_struct_AV(gdt) (((gdt) >> 52) & 0x01) /* 52 */
#define get_desc_struct_P(gdt) (((gdt) >> 47) & 0x01) /* 47 */
#define get_desc_struct_DPL(gdt) (((gdt) >> 45) & 0x03) /* 46-45 */
#define get_desc_struct_S(gdt) (((gdt) >> 44) & 0x01) /* 44 */
#define get_desc_struct_E(gdt) (((gdt) >> 43) & 0x01) /* 43 */
#define get_desc_struct_ED_or_C(gdt) (((gdt) >> 42) & 0x01) /* 42 */
#define get_desc_struct_R_or_W(gdt) (((gdt) >> 41) & 0x01) /* 41 */
#define get_desc_struct_A(gdt) (((gdt) >> 40) & 0x01) /* 40 */
printk("0x%08x, 0x%08x | 0x%x | %d | %d |\n",
desc->b, desc->a, desc->type, desc->dpl, desc->s);
unsigned long data = *((unsigned long *)desc);
printk("base = 0x%0x, limit = 0x%0x, P = %d, DPL = %d, type = %d%d%d%d\n",
get_desc_struct_BASE(data), get_desc_struct_LIMIT(data),
get_desc_struct_P(data), get_desc_struct_DPL(data),
get_desc_struct_S(data), get_desc_struct_ED_or_C(data),
get_desc_struct_R_or_W(data), get_desc_struct_A(data));
}
/*
* 打印 CPU 的 GDT 的数据
* 参数
* cpu : CPU 的编号
*/
static void print_cpu_gdt_table(unsigned int cpu)
{
int i = 0;
struct desc_struct *gdt_table = get_cpu_gdt_table(cpu);
printk("GDT_ENTRIES = %d\n", GDT_ENTRIES);
printk("-----------------------------------\n");
printk("|\t\t\t\t| type | dpl | s |\n");
for(i = 0; i < GDT_ENTRIES; i++)
{
printk("| [%0x] = ", i);
print_desc_struct(gdt_table + i);
}
printk("-----------------------------------\n");
}
/*
* 打印段选择符和段描述符号的信息
*
* 段标识符(段选择符)(存放在段寄存器中)字段如下 :
* index 用来得到段描述符在GDT或LDT中的偏移（位置）
* TI 指明段描述符是在GDT中(TI=0)或在LDT中(TI=1)
* RPL 请求特权级，
*
* 由于一个段描述符是8字节,
* 因此它的地址=GDT或LDT内的首地址+(index*8).
* 能够保存在GDT中的段描述符的最大数目是8191(213-1)，其中13是index的位数.
* 不同段的段描述符构成段描述符表,
* 段描述符(8字节)存放在全局描述符表(GDT)或局部描述符表(LDT)中
* GDT在主存中的地址和大小存放在gdtr控制寄存器中,
* 当前正被使用的LDT地址和大小存放在ldtr控制寄存器中。
*/
static void print_segment_desc(unsigned long seg)
{
#define get_segment_INDEX(n) ((n) >> 3)
#define get_segment_TI(n) (((n) >> 2) & 0x01)
#define get_segment_RPL(n) ((n) & 0x03)
printk("0x%0x, index = %d, TI = %d, RPL = %d\n", seg,
get_segment_INDEX(seg),
get_segment_TI(seg),
get_segment_RPL(seg));
}
// http://lxr.free-electrons.com/source/arch/x86/include/asm/segment.h#L123
/*
* 打印 Linux 内核中分段信息,
* 打印段描述
*/
static void print_segment(void)
{
long data = 0;
long data = 0;
struct desc_struct *gdt_table = get_cpu_gdt_table(1);
/*
---------------------------------------------------------------------------------------------
@@ -51,79 +204,55 @@ static void print_segment(void)
__USER_DS = 0x0033 = | 00110011 00000000 |
__USER_DS = 0x002B = | 00101011 00000000 |
*/
data = __KERNEL_CS;
printk("__KERNEL_CS = %0x, index = %d, TI = %d, RPL = %d\n", data,
get_segment_INDEX(data),
get_segment_TI(data),
get_segment_RPL(data));
printk("=====================\n");
// 打印__KERNEL_CS的段描述符
printk("__KERNEL_CS = ");
print_segment_desc(__KERNEL_CS);
// 打印__KERNEL_CS在gdt_table中的具体值
printk("__KERNEL_CS @ index(%d) in cpu_gdt_table\n", get_segment_INDEX(__KERNEL_CS));
printk("GDT[%d] = ", get_segment_INDEX(__KERNEL_CS));
print_desc_struct(gdt_table + get_segment_INDEX(__KERNEL_CS));
printk("=====================\n\n");
data = __KERNEL_DS;
printk("__KERNEL_DS = %0x, index = %d, TI = %d, RPL = %d\n", data,
get_segment_INDEX(data),
get_segment_TI(data),
get_segment_RPL(data));
printk("=====================\n");
// 打印__KERNEL_DS的段描述符
printk("__KERNEL_DS = ");
print_segment_desc(__KERNEL_DS);
// 打印__KERNEL_DS在gdt_table中的具体值
printk("__KERNEL_DS @ index(%d) in cpu_gdt_table\n", get_segment_INDEX(__KERNEL_DS));
printk("GDT[%d] = ", get_segment_INDEX(__KERNEL_DS));
print_desc_struct(gdt_table + get_segment_INDEX(__KERNEL_DS));
printk("=====================\n\n");
data = __USER_CS;
printk("__USER_CS = %0x, index = %d, TI = %d, RPL = %d\n", data,
get_segment_INDEX(data),
get_segment_TI(data),
get_segment_RPL(data));
data = __USER_DS;
printk("__USER_DS = %0x, index = %d, TI = %d, RPL = %d\n", data,
get_segment_INDEX(data),
get_segment_TI(data),
get_segment_RPL(data));
}
static void print_desc_struct(struct desc_struct *desc)
{
#if 0
printk("limit0 = %0x, ", desc->limit0);
printk("base0 = %0x, ", desc->base0);
printk("base1 = %0x, ", desc->base1);
printk("type = %0x, ", desc->type);
printk("s = %0x, ", desc->s);
printk("dpl = %0x, ", desc->dpl);
printk("p = %0x, ", desc->p);
printk("limit = %0x, ", desc->limit);
printk("avl = %0x, ", desc->avl);
printk("l = %0x, ", desc->l);
printk("d = %0x, ", desc->d);
printk("g = %0x, ", desc->g);
printk("base2 = %0x\n", desc->base2);
#endif
printk("0x%08x, 0x%08x | 0x%x | %d | %d |\n",
desc->b, desc->a, desc->type, desc->dpl, desc->s);
}
static void print_cpu_gdt_table(struct desc_struct *desc, int size)
{
int i = 0;
printk("-----------------------------------\n");
printk("|\t\t\t\t| type | dpl | s |\n");
for(i = 0; i < size; i++)
{
printk("| [%0x] = ", i);
print_desc_struct(desc + i);
}
printk("-----------------------------------\n");
printk("=====================\n");
// 打印__USER_CS的段描述符
printk("__USER_CS = ");
print_segment_desc(__USER_CS);
// 打印__USER_CS在gdt_table中的具体值
printk("__USER_CS @ index(%d) in cpu_gdt_table\n", get_segment_INDEX(__USER_CS));
printk("GDT[%d] = ", get_segment_INDEX(__USER_CS));
print_desc_struct(gdt_table + get_segment_INDEX(__USER_CS));
printk("=====================\n\n");
printk("=====================\n");
// 打印__USER_DS的段描述符
printk("__USER_DS = ");
print_segment_desc(__USER_DS);
// 打印__USER_DS在gdt_table中的具体值
printk("__USER_DS @ index(%d) in cpu_gdt_table\n", get_segment_INDEX(__USER_DS));
printk("GDT[%d] = ", get_segment_INDEX(__USER_DS));
print_desc_struct(gdt_table + get_segment_INDEX(__USER_DS));
printk("=====================\n\n");
}
static int hello_init(void)
{
printk("GDT_ENTRIES = %d\n", GDT_ENTRIES);
struct desc_struct *gdt_table = get_cpu_gdt_table(1);
print_cpu_gdt_table(gdt_table, GDT_ENTRIES);
print_cpu_gdt_table(0);
print_segment();
return 0;
}