{"id":165,"date":"2017-08-11T14:14:08","date_gmt":"2017-08-11T06:14:08","guid":{"rendered":"http:\/\/www.sinkland.cn\/?p=165"},"modified":"2019-08-17T15:04:44","modified_gmt":"2019-08-17T07:04:44","slug":"smlos%e4%ba%94-gdt%e5%92%8cidt%e5%88%9d%e5%a7%8b%e5%8c%96","status":"publish","type":"post","link":"http:\/\/www.sinkland.cn\/?p=165","title":{"rendered":"SmlOS\u4e94-GDT\u548cIDT\u521d\u59cb\u5316"},"content":{"rendered":"

\u4ec0\u4e48\u662fGDT<\/h3>\n

\n GDT (Global Descriptor Table) \u5168\u5c40\u63cf\u8ff0\u8868\uff0c\n<\/p><\/blockquote>\n

\u7b80\u8981\u6765\u8bf4,\u5728\u4fdd\u62a4\u6a21\u5f0f\u4e0b,\u53ef\u4ee5\u901a\u8fc7\u5b83\u6765\u8bbe\u5b9a\u5404\u4e2a\u5185\u5b58\u6bb5\uff0c\u5e76\u80fd\u8bbe\u5b9a\u5185\u5b58\u6bb5\u7684\u76f8\u5173\u6743\u9650\u7b49\u3002<\/p>\n

\u9996\u5148\u5462\uff0c\u6211\u4eec\u7528windbg\u770b\u4e0b\u81ea\u8eab\u672c\u673a\u7684GDT\u957f\u5565\u6837<\/p>\n

OS:win7x86\n\n\/\/ gdtr\u5bc4\u5b58\u5668\u503c\nkd> r gdtr\ngdtr=80b95000\n\/\/ gdt\u957f\u5ea6\nkd> r gdtl\ngdtl=000003ff\n\/\/ gdt\u8868\nkd> dq gdtr\n80b95000  00000000`00000000 00cf9b00`0000ffff\n80b95010  00cf9300`0000ffff 00cffb00`0000ffff\n<\/code><\/pre>\n
\u6211\u4eec\u53ef\u4ee5\u770b\u5230\u8fd9\u91ccgdtr\u7684\u5730\u5740\u662f0x80b95000<\/p>\n
gdt\u8868\u7684\u7b2c\u4e00\u9879\u662f00000000`00000000<\/p>\n
\u540e\u9762\u5c31\u662fgdt\u7684\u6240\u6709\u7684\u6bb5\u63cf\u8ff0\u7b26<\/p>\n
\u6bd4\u598200cf9b00`0000ffff\uff0c\u5c31\u662f\u6bb5\u63cf\u8ff0\u7b26\uff0c\u5927\u5c0f\u662f64\u4f4d<\/p>\n
\n
\u6bb5\u63cf\u8ff0\u7b26\u662f\u4ec0\u4e48\u610f\u601d\uff0c\u6211\u6574\u7406\u4e86\u4ee5\u4e0b\u7684\u8868\uff1a<\/p>\n
\u6bb5\u63cf\u8ff0\u7b26<\/h3>\n
\u9ad832\u4f4d<\/h4>\n\n\n\n\n\n\n
31-24<\/th>\n23<\/th>\n22<\/th>\n21<\/th>\n20<\/th>\n19-16<\/th>\n15<\/th>\n14-13<\/th>\n12<\/th>\n11-8<\/th>\n7-0 \u4f4d<\/th>\n<\/tr>\n<\/thead>\n
Base 31-24<\/td>\nG<\/td>\nD\/B<\/td>\n0<\/td>\nAVL<\/td>\nSeg Limit 19:16<\/td>\nP<\/td>\nDPL<\/td>\nS<\/td>\nType<\/td>\nBase 23:16<\/td>\n<\/tr>\n
Base 31-24\u4f4d<\/td>\n\u6bb5\u754c\u9650\u7c92\u5ea6<\/br><\/br> G=0\uff1a\u7c92\u5ea6\u5b57\u8282<\/br><\/br>G=1\uff1a\u7c92\u5ea64k<\/td>\n\u53ef\u6267\u884c\u6bb5\u63cf\u8ff0<\/br><\/br>D=1:32\u4f4d\u4ee3\u7801\u6bb5<\/br><\/br>D=0:16\u4f4d\u4ee3\u7801\u6bb5<\/td>\n-<\/td>\n\u8f6f\u4ef6\u53ef\u5229\u7528\u4f4d,\u76ee\u524d\u88ab\u5ffd\u7565<\/td>\n\u6bb5\u754c\u9650\u9ad8\u4f4d<\/td>\nPresent\u5b58\u5728\u4f4d<\/br><\/br>P=1\u8868\u793a\u5730\u5740\u8f6c\u6362\u6709\u6548<\/br><\/br>p=0\u8868\u793a\u6bb5\u4e0d\u5b58\u5728\uff0c\u5bf9\u8be5\u6bb5\u8bbf\u95ee\u4f1a\u5f15\u8d77\u5f02\u5e38<\/td>\n\u63cf\u8ff0\u7b26\u7279\u6743\u7ea7<\/td>\nS=1\u7cfb\u7edf\u6bb5<\/br><\/br>S=0\u95e8\u63cf\u8ff0\u7b26<\/td>\nS=1:\u53ef\u8bfb,\u53ef\u5199\uff0c\u53ef\u6267\u884c\uff0c\u4e00\u81f4\u7801\u6bb5<\/br><\/br>S=0:TSS,\u4e2d\u65ad\u95e8\uff0c\u9677\u9631\u95e8<\/td>\nBase 23-16\u4f4d<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u4f4e32\u4f4d<\/h4>\n\n\n\n\n\n\n
31-16<\/th>\n15-0 \u4f4d<\/th>\n<\/tr>\n<\/thead>\n
Base 15:0<\/td>\nSeg Limit 15:0<\/td>\n<\/tr>\n
Base 15-0\u4f4d<\/td>\nSeg Limit 15-0\u4f4d<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u5728c\u8bed\u8a00\u53ef\u4ee5\u8fd9\u6837\u4f7f\u7528\u7ed3\u6784\u4f53\u8868\u793a\u6bb5\u63cf\u8ff0\u7b26:<\/p>\n
struct SEGMENT_DESCRIPTOR\n{\n short limit_low, base_low;\n char base_mid, access_right;\n char limit_high, base_high;\n};\n<\/code><\/pre>\n
\u8fd9\u4e2a\u7528\u4e8e\u6bb5\u63cf\u8ff0\u7b26\uff0c\u91ca\u4e49\u5982\u4e0b\uff1a<\/p>\n
\n  limit_low\uff1a\u6bb5\u9650\u957f\u76840~15bit<\/p>\n
  base_low\uff1a \u6bb5\u57fa\u5740\u76840~15bit<\/p>\n
  base_mid\uff1a \u6bb5\u57fa\u5740\u768416~23bit<\/p>\n
  access_right\uff1a\n<\/p><\/blockquote>\n
 (0~3bit TYPE\u5b57\u6bb5, 4bit S\u5b57\u6bb5 5~6 DPL\u5b57\u6bb5 7bit P\u5b57\u6bb5)\n<\/code><\/pre>\n
\n  limit_high\uff1a\n<\/p><\/blockquote>\n
\u6bb5\u9650\u957f\u768416~19bit + AVL + D\/B + G\u57df\n<\/code><\/pre>\n
\n  base_high\uff1a \u6bb5\u57fa\u5740\u768424~31bit\n<\/p><\/blockquote>\n
\u91cc\u9762\u7684\u542b\u4e49\u5728\u8868\u683c\u4e2d\u6709\u5217\u51fa\u3002<\/p>\n
\u5bf9\u4e8egdt\u7684\u521d\u59cb\u5316\uff0c\u9996\u5148\u627e\u4e2a\u5730\u5740\u7528\u4e8e\u5b58\u50a8\u6bb5\u8868\u4f4d\u7f6e\u3002<\/p>\n
\u5728\u8fd9\u91cc\u6211\u4eec\u8bbe\u5b9agdt\u7684\u521d\u59cb\u4f4d\u7f6e\u662f0x00270000<\/strong>\uff0cidt\u7684\u521d\u59cb\u4f4d\u7f6e\u662f0x0026f800<\/strong>\u3002<\/p>\n
\n
GDT\u8bbe\u7f6e\u7684\u9650\u5b9a<\/h4>\n
    \n
  • \u7136\u540eGDT\u9ed8\u8ba4\u521d\u59cb\u53168192\u4e2a\u4f4d\u7f6e\uff0c\u8fd9\u662fgdtr\u6700\u591a\u652f\u6301\u7684\u6570\u91cf\u3002<\/p>\n<\/li>\n
  • \n
    \u5728GDT\u7684\u521d\u59cb\u5316\u4e2d\uff0cgdt\u7684\u7b2c0\u53f7\u4f4d\u7f6e\u9700\u8981\u7559\u7a7a\uff0c\u8fd9\u662fintel\u7684\u8bbe\u7f6e\u8981\u6c42\u3002<\/p>\n<\/li>\n<\/ul>\n
    \u5728SmlOS\u4e2d:<\/p>\n
      \n
    • gdt\u76841\u53f7\u4f4d\u7f6e\u8bbe\u7f6e\u4e3a\u5185\u6838\u7684\u6570\u636e\u6bb5\uff0c\u6bb5\u9650\u957f4G-1\uff0c\u6bb5\u57fa\u5740\u4e3a0\uff0c\u53ef\u8bfb\u53ef\u5199\u3002<\/li>\n
    • gdt\u76842\u53f7\u4f4d\u7f6e\u8bbe\u7f6e\u4e3a\u5185\u6838\u7684\u4ee3\u7801\u6bb5\uff0c\u6bb5\u9650\u957f512K\uff0c\u6bb5\u57fa\u57400x280000\u3002<\/li>\n
    • \u5176\u4ed6\u6e05\u7a7a<\/li>\n<\/ul>\n
      \u8bbe\u7f6e\u597dgdt\u8868\u540e\uff0c\u91c7\u7528\u6c47\u7f16LGDT\u6307\u4ee4<\/strong>\u5c06gdt\u8868\u5730\u5740\u52a0\u8f7d\u5230gdtr\u5bc4\u5b58\u5668\u3002<\/p>\n
      \u56e0\u4e3agdtr\u662f\u7279\u6b8a\u5bc4\u5b58\u5668\uff0c48\u4f4d\u5bc4\u5b58\u5668\uff0c\u753132\u4f4d\u57fa\u5730\u5740\uff08gdt\u8868\u9996\u5730\u5740\uff09\uff0c\u548c16\u4f4d\u8868\u754c\u9650\u7ec4\u6210\u3002<\/p>\n
      \u9700\u8981\u8bfb\u53d66\u4e2a\u5b57\u8282\u5185\u5bb9,\u6240\u4ee5\u6c47\u7f16\u5199\u6210\u4e86\u8fd9\u6837\uff1a<\/p>\n
      _load_gdtr: ; void load_gdtr(int limit, int addr);\n MOV AX,[ESP+4] ; limit\n MOV [ESP+6],AX\n LGDT [ESP+6]\n RET\n<\/code><\/pre>\n
      \n
      \u6bb5\u63cf\u8ff0\u7b26\u7684\u8bbe\u7f6e<\/h4>\n
      \u800c\u5bf9\u6bb5\u63cf\u8ff0\u7b26\u8bbe\u7f6e\u4e2d\uff0c\u9700\u8981\u5bf9\u6bb5\u9650\u957f\u7684\u5927\u5c0f\u8fdb\u884c\u5224\u65ad\uff0c\u5224\u65ad\u662f\u5426\u5927\u4e8e1M\uff0c\u5219\u5bf9\u6bb5\u63cf\u8ff0\u7b26ar\u8fdb\u884c\u8bbe\u7f6e\uff0c\u5728\u6bb5\u63cf\u8ff0\u7b26\u4e2d\u6709\u4e00\u4e2aG\u4f4d\uff0c\u5f53G=1\u7684\u65f6\u5019\uff0c\u5219\u6bb5\u9650\u957f\u4fbf\u4ee54kb\u4e3a\u5355\u4f4d\u3002<\/p>\n
      \u5728\u8fd9\u91cc\u63d0\u4f9b\u6bb5\u63cf\u8ff0\u7b26\u7684\u8bbe\u7f6e\u51fd\u6570<\/p>\n
      \/\/ \u8bbe\u7f6e\u6bb5\u63cf\u8ff0\u7b26\uff0csd \u6bb5\u63cf\u8ff0\u7b26\u7ed3\u6784\u6307\u9488\uff0climit \u6bb5\u9650\u957f\uff0cbase \u6bb5\u57fa\u5740\uff0car \u6bb5\u63cf\u8ff0\u7b26\u5c5e\u6027\nvoid set_segmdesc(struct SEGMENT_DESCRIPTOR *sd, unsigned int limit, int base, int ar)\n{\n  if (limit > 0xfffff)\n  {\n     \/\/\u8bbe\u7f6eG_bit = 1\n     ar |= 0x8000; \n\n     \/\/ \u8c03\u6574\u6bb5\u9650\u957f\u7684\u503c\u5373\u9664\u4ee54K                  \n     limit \/= 0x1000;           \n  }\n\n  \/\/ \u5c06\u5404\u503c\u586b\u5165\u76f8\u5e94\u7684\u57df\u4e2d \n  sd->limit_low    = limit & 0xffff;\n  sd->base_low     = base & 0xffff;\n  sd->base_mid     = (base >> 16) & 0xff;\n  sd->access_right = ar & 0xff;\n  sd->limit_high   = ((limit >> 16) & 0x0f) | ((ar >> 8) & 0xf0);\n  sd->base_high    = (base >> 24) & 0xff;\n  return;\n}\n<\/code><\/pre>\n
      \n
      \u4ec0\u4e48\u662fIDT<\/h3>\n
      \n  IDT (Interrupt Descriptor Table)\u4e2d\u65ad\u63cf\u8ff0\u7b26\u8868\n<\/p><\/blockquote>\n
      \u7b80\u8981\u6765\u8bf4\u5c31\u662f\u7528\u6765\u8bbe\u7f6e\u53d1\u751f\u4e2d\u65ad\u540e\uff0c\u5b9a\u4e49\u8be5\u8c03\u7528\u4ec0\u4e48\u5904\u7406\u51fd\u6570\u7684\u8868\u3002<\/p>\n
      \u8fd8\u662f\u6765\u770b\u4e0b\u672c\u673a\u7684IDT\u8bbe\u7f6e<\/p>\n
      \/\/ idtr\u9996\u5730\u5740\nkd> r idtr\nidtr=80b95400\nkd> dq idtr\n80b95400  83e48e00`0008bfc0 83e48e00`0008c150\n80b95410  00008500`00580000 83e4ee00`0008c5c0\n\n\/\/ \u67e5\u770b\u6240\u6709\u4e2d\u65ad\u5904\u7406\u51fd\u6570\u7684\u5730\u5740\nkd> !idt -a\n\nDumping IDT: 80b95400\n\n00: 83e4bfc0 nt!KiTrap00\n01: 83e4c150 nt!KiTrap01\n02: Task Selector = 0x0058\n03: 83e4c5c0 nt!KiTrap03\n...\n<\/code><\/pre>\n
      \u81f3\u4e8e\u95e8\u63cf\u8ff0\u7b26\u7684\u7ed3\u6784\u5462\uff0c\u6211\u4ece\u7f51\u4e0a\u627e\u4e86\u5f20\u56fe\uff1a<\/p>\n
      \"image\"<\/p>\n
      \u5bf9\u5e94C\u8bed\u8a00\u7ed3\u6784\u4f53\uff1a<\/p>\n
      struct GATE_DESCRIPTOR\n{\n short offset_low, selector;\n char dw_count, access_right;\n short offset_high;\n};\n<\/code><\/pre>\n
      \u95e8\u63cf\u8ff0\u7b26\u4e0e\u6bb5\u63cf\u8ff0\u7b26\u7c7b\u4f3c,\u53ea\u662f\u6709\u4e9b\u5b57\u6bb5\u6709\u4e9b\u8bb8\u5dee\u522b<\/p>\n
      \n  offset_low \uff1a\u504f\u79fb\u5730\u5740\u7684\u4f4e16bit<\/p>\n
        selector\uff1a\u6bb5\u9009\u62e9\u5b5016bit<\/p>\n
        dw_count: \u53c2\u6570\u4e2a\u6570, \u53ea\u662f\u8c03\u7528\u95e8\u4e2d\u6709\u6548<\/p>\n
        access_right:\n<\/p><\/blockquote>\n
      0~3bit:TYPE\u5b57\u6bb5, 4bit:S\u5b57\u6bb5, 5~6bit:DPL\u5b57\u6bb5, 7bit:P\u5b57\u6bb5\n<\/code><\/pre>\n
      \n  offset_high: \u504f\u79fb\u5730\u5740\u7684\u9ad816bit\n<\/p><\/blockquote>\n
      \u4e0d\u540c\u7684\u4e2d\u65ad\u5bf9\u5e94\u7684\u53ef\u80fd\u662f\u4e0d\u540c\u7684\u7c7b\u578b\uff1a<\/p>\n
      \u4e3b\u8981\u662f\u4e2d\u65ad\u548c\u5f02\u5e38\uff0c\u4e0d\u540c\u7684\u4e2d\u65ad\u53f7\u5bf9\u5e94\u7684\u65f6\u4e2d\u65ad\u8fd8\u662f\u5f02\u5e38\u53ef\u4ee5\u53c2\u8003intel\u624b\u518c\uff1a<\/p>\n
      \"image\"<\/p>\n
      \n
      \u4e2d\u65ad\u548c\u5f02\u5e38\u533a\u522b<\/h4>\n\n\n\n\n\n\n
      \u7c7b\u578b<\/th>\n\u533a\u522b<\/th>\n<\/tr>\n<\/thead>\n
      \u5f02\u5e38<\/td>\n\u5f02\u5e38\u662f\u6765\u81ea\u4e8eCPU\u672c\u8eab\u4ea7\u751f\u7684\uff0c\u6bd4\u5982int3\uff0c\u7f3a\u9875\u5f02\u5e38<\/td>\n<\/tr>\n
      \u4e2d\u65ad<\/td>\n\u4e2d\u65ad\u6765\u81ea\u4e8eCPU\u5916\u90e8\uff0c\u7531\u4e2d\u65ad\u6e90\u53d1\u8d77\u7684\uff0cCPU\u662f\u88ab\u52a8\u7684\uff0c\u6bd4\u5982\u9f20\u6807\uff0c\u952e\u76d8\u4e2d\u65ad<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
      \u5f02\u5e38\u5206\u7c7b<\/h4>\n\n\n\n\n\n\n\n
      \u5206\u7c7b<\/th>\n\u4fdd\u5b58\u7684cs\u548cEip\u6307\u9488<\/th>\n\u53ef\u6062\u590d\u6027<\/th>\n<\/tr>\n<\/thead>\n
      \u9519\u8bef(fault)<\/td>\n\u5bfc\u81f4\u5f02\u5e38\u7684\u90a3\u6761\u6307\u4ee4<\/td>\n\u53ef\u6062\u590d<\/td>\n<\/tr>\n
      \u9677\u9631(trap)<\/td>\n\u5bfc\u81f4\u5f02\u5e38\u7684\u90a3\u6761\u6307\u4ee4\u7684\u4e0b\u4e00\u6761\u6307\u4ee4<\/td>\n\u53ef\u6062\u590d<\/td>\n<\/tr>\n
      \u7ec8\u6b62(abort)<\/td>\n\u4e0d\u786e\u5b9a<\/td>\n\u4e0d\u53ef\u4ee5<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
      idt \u7684\u8bbe\u7f6e\u548cgdt\u7c7b\u4f3c\uff0c\u4f46\u6700\u591a\u652f\u6301256\u4e2a\u4e2d\u65ad\u3002<\/p>\n
      \u5bc4\u5b58\u5668\u7684\u8bbe\u7f6e\u548c\u8bbe\u7f6egdtr\u8bbe\u7f6e\u7c7b\u4f3c\u3002<\/p>\n
      \u8fd9\u4e9b\u4e2d\u65ad\u51fd\u6570\u5982\u4f55\u7f16\u5199\uff0c\u5c06\u5728\u540e\u9762\u8fdb\u884c\u4ecb\u7ecd\u3002<\/p>\n
      \u8fd9\u91cc\u63d0\u4f9b\u4e0b\u95e8\u63cf\u8ff0\u7b26\u7684\u8bbe\u5b9a\u51fd\u6570\uff1a<\/p>\n
      \/\/ \u8bbe\u7f6e\u95e8\u63cf\u8ff0\u7b26 \uff0cgd \u95e8\u63cf\u8ff0\u7b26\u7ed3\u6784\u6307\u9488\uff0coffset \u8fc7\u7a0b\u5165\u53e3\u504f\u79fb\uff0cselector \u6bb5\u9009\u62e9\u5b50\uff0car \u95e8\u63cf\u8ff0\u7b26\u5c5e\u6027\nvoid set_gatedesc(struct GATE_DESCRIPTOR *gd, int offset, int selector, int ar)\n{\n  gd->offset_low   = offset & 0xffff;\n  gd->selector     = selector;\n  gd->dw_count     = (ar >> 8) & 0xff;\n  gd->access_right = ar & 0xff;\n  gd->offset_high  = (offset >> 16) & 0xffff;\n  return;\n}\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
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