{"id":262,"date":"2025-11-16T19:53:52","date_gmt":"2025-11-16T11:53:52","guid":{"rendered":"http:\/\/175.178.117.18\/?p=262"},"modified":"2025-11-21T11:35:32","modified_gmt":"2025-11-21T03:35:32","slug":"%e8%bf%9b%e7%a8%8b%e4%b8%8e%e7%ba%bf%e7%a8%8b","status":"publish","type":"post","link":"https:\/\/starhill.online\/index.php\/2025\/11\/16\/%e8%bf%9b%e7%a8%8b%e4%b8%8e%e7%ba%bf%e7%a8%8b\/","title":{"rendered":"\u54c8\u5de5\u5927\u64cd\u4f5c\u7cfb\u7edf-2-\u8fdb\u7a0b\u4e0e\u7ebf\u7a0b"},"content":{"rendered":"

CPU\u7ba1\u7406\u7684\u76f4\u89c2\u60f3\u6cd5<\/h2>\n
\"8_1\"<\/div><\/figure>\n

fprintf\u662f\u4e00\u6761IO\u6307\u4ee4\uff0c\u8fd9\u4e2a\u4f8b\u5b50\u8bf4\u660e\u5982\u679c\u628aIO\u6307\u4ee4\u6362\u6210\u4e00\u4e2a\u8ba1\u7b97\u6307\u4ee4\u540e\uff0c\u4e24\u8005\u7684\u901f\u5ea6\u5dee\u8ddd\u76f8\u5f53\u5927\uff0cIO\u6307\u4ee4\u65f6\u95f4\u957f\uff0c\u8bf4\u660e\u4e86\u6267\u884c\u4e00\u6761IO\u6307\u4ee4\u7684\u65f6\u95f4\u5206\u4e3a\u8ba1\u7b97\u4e00\u5927\u5806\u6307\u4ee4\u5f97\u5230\u4e00\u6761IO\u6307\u4ee4\uff0c\u4f46\u662f\u5982\u679c\u4ee5\u540e\u7684\u7ed3\u679c\u8981\u4f9d\u8d56\u4e8e\u591a\u4e2aIO\u6307\u4ee4\u7684\u65f6\u5019\uff0c\u6b64\u65f6CPU\u5e76\u4e0d\u80fd\u5f97\u5230\u5145\u5206\u7684\u5229\u7528\uff0c\u6700\u597d\u662f\u628a\u7b49\u5f85\u7684\u65f6\u95f4\u53d6\u6d88\u6389\uff0c\u7528\u6765\u505a\u5176\u4ed6\u7684\u4e8b\u60c5(\u4e2d\u65ad\u7684\u5f15\u51fa\uff0c\u591a\u7ebf\u7a0b\u7b49)\uff0c\u6b64\u65f6CPU\u5229\u7528\u7387\u9ad8\uff0c\u81f3\u6b64\u7ba1\u7406\u597d\u4e86CPU<\/p>\n

\"8_2\"<\/div><\/figure>\n
\"8_3\"<\/div><\/figure>\n

\u6ce8\u610f\u7d2b\u8272\u9634\u5f71\u5185\u5bb9\uff01\uff01\uff01<\/p>\n

\u591a\u8fdb\u7a0b\u56fe\u50cf<\/h2>\n
\"9_1\"<\/div><\/figure>\n
\"9_2\"<\/div><\/figure>\n
\"9_3\"<\/div><\/figure>\n

PCB(Process Control Block)<\/strong>: \u7528\u6765\u8bb0\u5f55\u8fdb\u7a0b\u4fe1\u606f\u7684\u6570\u636e\u7ed3\u6784<\/p>\n

\"9_4\"<\/div><\/figure>\n
\n

switch_to\u5177\u4f53\u5b9e\u73b0\u5982\u4e0b\uff1a<\/p>\n

\u8fdb\u7a0b\u7684\u8c03\u5ea6\u6709 FIFO<\/strong>(\u516c\u5e73) \u548c Priority<\/strong>(\u4f18\u5148\u7ea7)<\/p>\n<\/blockquote>\n

\"9_5\"<\/div><\/figure>\n

\u8fd9\u91cc\u7528\u4e00\u4e2a\u7ed3\u6784\u4f53\u6765\u5b58\u50a8\u4e00\u4e9breg\u7684\u4fe1\u606f\uff0c\u4e14\u8fd9\u91cc\u9009\u62e9\u7528\u6c47\u7f16\u6765\u7f16\u5199\uff0c\u800c\u975ec\u8bed\u8a00\u6c47\u7f16\u80fd\u7528\u6765\u8fdb\u884c\u7cbe\u7ec6\u7684\u64cd\u4f5c\uff0cc\u8bed\u8a00\u4e0d\u597d\u5b9e\u73b0<\/code><\/p>\n

\"9_6\"<\/div><\/figure>\n
\n

\u901a\u8fc7\u5bf9\u7269\u7406\u50a8\u5b58\u5730\u5740\u7684\u91cd\u6620\u5c04\u5730\u5740\uff0c\u89e3\u51b3\u4e0a\u8ff0\u95ee\u9898\uff1a<\/p>\n<\/blockquote>\n

\"9_7\"<\/div><\/figure>\n
\"9_8\"<\/div><\/figure>\n
\"9_9\"<\/div><\/figure>\n
\n

\u6240\u4ee5\u5f15\u51fa\u4e86\u9501<\/strong>\u8fd9\u4e2a\u6982\u5ff5\uff0c\u4f7f\u8fdb\u7a0b\u4e0d\u80fd\u968f\u610f\u5207\u6362\uff0c\u9700\u8981\u6709\u4e00\u5b9a\u7684\u89c4\u5219\uff01\uff01\uff01<\/p>\n<\/blockquote>\n

\"9_10\"<\/div><\/figure>\n

\u7528\u6237\u7ea7\u7ebf\u7a0b<\/h2>\n
\"10_1\"<\/div><\/figure>\n

\u7ebf\u7a0b\u5728\u8fdb\u7a0b\u7684\u5185\u90e8\uff0c\u5176\u4e2d\u5207\u6362\u7ebf\u7a0b\u53ea\u9700\u8981PC\u503c\u7684\u8df3\u8f6c\u5373\u53ef\uff0c\u65e0\u975e\u5207\u6362\u6620\u5c04\u8868\uff0c\u8fbe\u5230\u8d44\u6e90\u7684\u9ad8\u6548\u5229\u7528(\u53ef\u4ee5\u7406\u89e3\u4e3a\u7b80\u5355\u7684\u4e2d\u65ad\uff0c\u6620\u5c04\u8868\u5728\u5185\u5b58\u4e2d\u4e0d\u7528\u5207\u6362)<\/p>\n

\"10_2\"<\/div><\/figure>\n

pthread_create<\/strong>\u51fd\u6570:\u521b\u5efa\u591a\u4e2a\u7ebf\u7a0b<\/code><\/p>\n

Yield<\/strong>\u51fd\u6570\uff1a\u8fdb\u884c\u7ebf\u7a0b\u7684\u4ea4\u66ff\u6267\u884c<\/code><\/p>\n

\n

\u8fbe\u5230\u4e86\u540c\u65f6\u89e6\u53d1\u591a\u4e2a\u7ebf\u7a0b\u4ea4\u66ff\u6267\u884c<\/strong><\/p>\n<\/blockquote>\n

\"10_3\"<\/div><\/figure>\n
\n

\u5982\u679c\u8fd9\u91cc\u4f7f\u7528\u7684\u662f\u4e00\u4e2a\u6808\u6765\u7ba1\u7406\u4e24\u4e2a\u7ebf\u7a0b\uff0c\u5219\u5728\u6267\u884c\u5b8c\u84dd\u8272Yield<\/strong>\u540e\u7684\u6267\u884c\u7ea2\u8272Yield<\/strong>,\u5219\u4f1a\u8df3\u8f6c\u5230204\u53bb\u6267\u884c\uff0c\u7136\u540e\u5728\u6267\u884c204\u540e\uff0c\u6267\u884c }<\/strong> ret \u53c8\u89e6\u53d1\u5f39\u6808<\/strong>\uff0c\u5f39\u51fa404\u6267\u884c404\u5904\uff0c\uff01\uff01\uff01\u8fdb\u884c\u4e86\u8de8\u7ebf\u7a0b\u64cd\u4f5c<\/strong>\uff01\uff01\uff01\u8fdd\u89c4\uff01\uff01\uff01\uff0c\u53ea\u6709Yield\u53ef\u4ee5\u8de8\u7ebf\u7a0b<\/p>\n

\n
\n

\u89e3\u51b3\u8be5\u95ee\u9898\u5c31\u662f\u4e00\u4e2a\u7ebf\u7a0b\u5bf9\u5e94\u4e00\u4e2a\u6808\uff0c\u5404\u81ea\u7ba1\u7406\u81ea\u5df1\u7684\uff0c\u907f\u514d\u51fa\u73b0\u8fdd\u89c4\u64cd\u4f5c<\/p>\n

\"10_4\"<\/div><\/figure>\n
\n

\u540d\u8bcd\u89e3\u91ca<\/strong><\/p>\n

\n

TCB\u7b80\u4ecb<\/strong>\n\u64cd\u4f5c\u7cfb\u7edf\u4e2d\u4e00\u4e2a\u7ebf\u7a0b\u5bf9\u5e94\u7740\u4e00\u4e2aTCB\uff08Thread Control Block\uff09\uff0c\u53eb\u505a\u7ebf\u7a0b\u63a7\u5236\u6a21\u5757\uff0c\u63a7\u5236\u7740\u7ebf\u7a0b\u7684\u8fd0\u884c\u548c\u8c03\u5ea6\u3002<\/p>\n

TCB\u7ec4\u6210<\/strong>\n1\u3001threadID\uff1a\u7ebf\u7a0b\u7684\u552f\u4e00\u6807\u8bc6\u3002\n2\u3001status\uff1a\u7ebf\u7a0b\u7684\u8fd0\u884c\u72b6\u6001\n3\u3001register\uff1a\u7ebf\u7a0b\u5173\u4e8eCPU\u4e2d\u5bc4\u5b58\u5668\u7684\u60c5\u51b5\n4\u3001PC\u7a0b\u5e8f\u8ba1\u6570\u5668\uff1a\u7ebf\u7a0b\u6267\u884c\u7684\u4e0b\u4e00\u6761\u6307\u4ee4\u7684\u5730\u5740\n5\u3001\u4f18\u5148\u7ea7\uff1a\u7ebf\u7a0b\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u5ea6\u7684\u65f6\u5019\u7684\u4f18\u5148\u7ea7\n6\u3001\u7ebf\u7a0b\u7684\u4e13\u5c5e\u5b58\u50a8\u533a\uff1a\u7ebf\u7a0b\u5355\u72ec\u7684\u5b58\u50a8\u533a\u57df\n7\u3001\u7528\u6237\u6808\uff1a\u7ebf\u7a0b\u6267\u884c\u7684\u7528\u6237\u65b9\u6cd5\u6808\uff0c\u7528\u6765\u4fdd\u5b58\u7ebf\u7a0b\u5f53\u524d\u6267\u884c\u7684\u7528\u6237\u65b9\u6cd5\u7684\u4fe1\u606f\n8\u3001\u5185\u6838\u6808\uff1a\u7ebf\u7a0b\u6267\u884c\u7684\u5185\u6838\u65b9\u6cd5\u6808\uff0c\u7528\u6765\u4fdd\u5b58\u7ebf\u7a0b\u5f53\u524d\u6267\u884c\u7684\u5185\u6838\u65b9\u6cd5\u4fe1\u606f\u3002<\/p>\n<\/blockquote>\n<\/blockquote>\n

\u4e5f\u5c31\u662f\u901a\u8fc7esp\u6307\u9488\u6765\u786e\u5b9a\u51fa\u6808\u7684\u503c\uff0c\u8fdb\u884c\u8d4b\u503c\u7ed9TCB x ,\u8fdb\u884c\u8df3\u8f6c<\/p>\n

\n
\n

\u9519\u8bef\u7ed3\u679c\uff1a<\/strong><\/p>\n

\u5982\u679c\u7ea2\u8272\u90e8\u5206\u4e0d\u53bb\u6389\uff0c\u5219\u4f1a\u8df3\u5230204\u53bb\u6267\u884c\uff0c204\u6267\u884c\u5b8c\u540e\u4f1a\u6267\u884c }<\/strong> \u4e5f\u5c31\u662fret\uff0c\u8fdb\u884c\u5f39\u6808\uff0c\u5f39\u51fa204\u540e\u53c8\u6267\u884c204\uff0c\u5bfc\u81f4\u7ea2\u8272Yield\u7684 }<\/strong> \u4e0d\u80fd\u6267\u884c<\/p>\n

\u6b63\u786e\u7ed3\u679c<\/strong>\uff1a<\/p>\n

\u8fd4\u56de\u7684Yield\u4e2d\u7684jmp\u4e0d\u8df3\u8f6c\uff0c\u5219\u5f39\u51fa204\uff0c204\u6267\u884c\u5b8c\u540e\u6267\u884c }<\/strong> \u540e\u8fdb\u884c\u5f39\u6808\uff0c\u5f39\u51fa104\u987a\u5229\u6267\u884c\uff01<\/p>\n<\/blockquote>\n

\"10_5\"<\/div><\/figure>\n
\n
\n
\"10_6\"<\/div><\/figure>\n
\"10_7\"<\/div><\/figure>\n

\u7528\u6237\u7ea7\u7ebf\u7a0b<\/strong>\u5728\u7528\u6237\u6001\u4e2d\u5982\u679c\u5207\u6362\u4e86\u7ebf\u7a0b\uff0c\u539f\u7ebf\u7a0b\u9700\u7b49\u5f85\uff0c\u7ecf\u8fc7\u5185\u6838\u7684\u54cd\u5e94\u518d\u8fd4\u56de\u53bb\uff0c\u5982\u679c\u53d1\u751f\u64cd\u4f5c\u5219\u65e0\u54cd\u5e94<\/code>\uff0c\u4e5f\u5c31\u662f\u5361\u4f4f\u4e86\u3002<\/p>\n

\u6838\u5fc3\u7ea7\u7ebf\u7a0b<\/strong>\u4e2d\u7684TCB\u5728\u5185\u6838\u4e2d\uff0c\u5982\u679c\u539f\u7ebf\u7a0b\u7b49\u5f85\uff0c\u5219\u76f4\u63a5\u5728\u5185\u6838\u4e2d\u5207\u6362\uff0c\u65e0\u9700\u7b49\u5f85\u3002<\/p>\n

\u5e76\u53d1\u6027\uff1a<\/strong>\u6838\u5fc3\u7ea7\u7ebf\u7a0b > \u7528\u6237\u7ea7\u7ebf\u7a0b<\/p>\n

Yield(\u7528\u6237\u7ea7)\u5728\u6838\u5fc3\u7ea7\u7ebf\u7a0b\u4e2d\u4e3aSchedule(\u6838\u5fc3\u7ea7)<\/p>\n

\u5185\u6838\u7ea7\u7ebf\u7a0b<\/h2>\n

\u591a\u5904\u7406\u5668<\/strong> \uff1a\u591a\u4e2aCPU\uff0c\u4e00\u4e2aCPU\u4e00\u4e2aMMU(\u6620\u5c04\u8868)<\/p>\n

\u591a\u6838<\/strong> \uff1a\u4e00\u4e2aCPU\uff0c\u5904\u7406\u591a\u4e2a\u7ebf\u7a0b\uff0c\u7528\u7684<\/p>\n

\n

\u7528\u6237\u7ea7\u5207\u6362<\/strong>\uff1a\u9996\u5148TCB\u5207\u6362<\/strong>\uff0c\u968f\u540e\u6839\u636eTCB<\/strong>\u5207\u6362\u7528\u6237\u6808<\/strong><\/p>\n

\u6838\u5fc3\u7ea7\u5207\u6362<\/strong>\uff1a\u9996\u5148TCB\u5207\u6362<\/strong>,\u968f\u540e\u6839\u636eTCB<\/strong>\u5207\u6362\u4e00\u5957\u6808<\/strong>\uff0c\u5185\u6838\u6808\u5207\u6362\u7684\u540c\u65f6\u7528\u6237\u6808\u4e5f\u8981\u5207<\/strong><\/p>\n<\/blockquote>\n

\"11_1\"<\/div><\/figure>\n
\"11_2\"<\/div><\/figure>\n

INT<\/strong> \u4e2d\u65ad\u8fdb\u5185\u6838\u6808<\/p>\n

IRET<\/strong> \u51fa\u5185\u6838\u6808\u56de\u5230\u7528\u6237\u6808<\/p>\n

\"11_3\"<\/div><\/figure>\n
\"11_4\"<\/div><\/figure>\n

\u5728\u7ebf\u7a0b\u5207\u6362\u65f6\uff0c\u5148\u627e\u5230\u4e0b\u4e00\u4e2a\u7ebf\u7a0b(next),\u968f\u540e\u6267\u884cswitch_to\u51fd\u6570\uff0c\u5c06\u5f53\u524d\u7ebf\u7a0b\u7684esp\u548c\u4e0b\u4e00\u4e2a\u7ebf\u7a0b\u7684esp\u4ee3\u5165\uff0cTCB\u5728\u5185\u6838\u6001\u4e2d<\/strong>\uff0cswitch_to\u51fd\u6570\u4f5c\u7528\u5982\u56fe\u3002<\/p>\n

\"11_5\"<\/div><\/figure>\n

\uff1f\uff1f\uff1f\uff1f\uff1a\u4ee3\u8868\u7684\u4f5c\u7528\u5c24\u4e3a\u91cd\u8981<\/strong><\/p>\n

\"11_6\"<\/div><\/figure>\n
\n

\u4e94\u6bb5\u8bba\u5f88\u91cd\u8981<\/strong><\/p>\n<\/blockquote>\n

\"11_7\"<\/div><\/figure>\n

\u5de6\u8fb9\u4ee3\u7801\u5c31\u662f\u4e3a\u4e86\u5b9e\u73b0\u53f3\u8fb9\u7684\u56fe\uff0c\u5148\u7533\u8bf7\u4e00\u6bb5\u5185\u5b58\u7ed9TCB\uff0c\u5c06\u5185\u6838\u6001\u7ebf\u7a0b\u5efa\u7acb\u597d\uff0c\u4f20\u5165\u53c2\u6570\u540e\u4f7f\u5f97\u7528\u6237\u6001\u7ebf\u7a0b\u548c\u5185\u6838\u6001\u7ebf\u7a0b\u8fdb\u884c\u8054\u7cfb\u3002<\/p>\n

\n
\"11_8\"<\/div><\/figure>\n

\u5185\u6838\u7ea7\u7ebf\u7a0b\u5b9e\u73b0<\/h2>\n
\"12_1\"<\/div><\/figure>\n

\u4e94\u6bb5\u8bba<\/strong> == \u6570\u5b57\u6807\u51fa\u7684\u4e94\u6bb5<\/p>\n

\"12_2\"<\/div><\/figure>\n
\n

\u5229\u7528\u4e00\u4e2a\u51fd\u6570\u4e2d\u5d4c\u5957fork()\u51fd\u6570\u8fdb\u884c\u7528\u6237\u6001\u5207\u6362\u5230\u5185\u6838\u6001\u7684\u89e3\u91ca<\/strong><\/p>\n<\/blockquote>\n

\"12_3\"<\/div><\/figure>\n
    \n
  1. \u5c06_NR_fork\u8fd9\u4e2a\u7cfb\u7edf\u8c03\u7528\u53f7\u5b58\u5230 eax<\/code> \u4e2d<\/li>\n
  2. \u6267\u884c INT 0x80<\/strong> \u540e PC \u503c\u81ea\u52a01<\/li>\n<\/ol>\n
    \n

    \u6ce8\u610f:<\/p>\n

    \u5728\u6267\u884cINT 0x80\u8fd9\u4e2a\u4e2d\u65ad\u7684\u65f6\uff0c\u6ca1\u6709\u8fdb\u5165\u5185\u6838\u6001\uff0c\u662f\u6267\u884c\u5b8c\u540e\u624d\u8fdb\u5165\u5185\u6838\u6001\uff0c<\/p>\n

      \n
    1. \u5148\u628a\u5f53\u524d\u7684\u6808 ss:sp<\/strong> \u538b\u5165\u6808\u4e2d\uff0c\u4e14ss:sp\u6307\u5411\u7684\u662f\u7528\u6237\u6808,\u5176\u4e2dss\u4e3a\u7528\u6237\u6808\u7684\u6808\u9996\uff0csp\u6307\u5411\u7528\u6237\u6808\u7684\u5c3e\u90e8<\/li>\n
    2. \u968f\u540e\u628a\u5f53\u524d\u7684cs:sp\u538b\u6808\uff0c\u4e5f\u5c31\u662f \uff1f\uff1f \u8868\u793a\u7684<\/li>\n<\/ol>\n<\/blockquote>\n

      \u5728\u6267\u884c\u5b8c 0x80 \u540e \u6267\u884c\u4e2d\u65ad\u5904\u7406\u51fd\u6570(_system_call)<\/p>\n

      \"12_4\"<\/div><\/figure>\n
        \n
      1. _system_call<\/strong> \uff1a \u518d\u8fdb\u884c\u538b\u6808\uff0c\u5373\u539f\u6765\u7528\u6237\u6001\u7684\u4e00\u4e9b\u5bc4\u5b58\u5668<\/li>\n
      2. call sys_call<\/strong> : \u8c03\u7528system_fork\u8868\uff0c\u5728\u5185\u6838\u6001\u4e2d\u6267\u884c\u4ea7\u751f\u4e2d\u65ad\u7684\u771f\u6b63\u6548\u679c <\/li>\n
      3. cmpl $0,state(%eax)<\/strong> : \u5982\u679c\u662f0\u5219\u8868\u793a\u5c31\u7eea\u3002\u975e0\u5219\u8868\u793a\u963b\u585e\u4e86<\/li>\n
      4. cmpl $0,counter(%eax)<\/strong> : \u67e5\u770b\u65f6\u95f4\u7247\u662f\u5426\u4e3a0\uff0c\u4e3a0\u5219\u8fdb\u884c\u5207\u6362<\/li>\n
      5. je\u6307\u4ee4<\/strong> \uff1a \u5224\u65ad\u662f\u5426\u76f8\u7b49<\/li>\n<\/ol>\n
        \"12_5\"<\/div><\/figure>\n
        \"12_6\"<\/div><\/figure>\n
        \n

        \u8fd9\u91cc\u4e94\u6bb5\u8bba\u7684\u4e2d\u95f4\u4e09\u6bb5\u8bba\u53ea\u9700\u8981ljmp\u6307\u4ee4\u5373\u53ef\u5b8c\u6210\uff0c\u7f16\u7a0b\u7b80\u5355\uff0c\u4f46\u662f\u662f\u5c01\u88c5\u597d\u7684\uff0c\u628a \u539ftss<\/strong> \u6682\u5b58\uff0c\u628a \u65b0tss<\/strong> \u4ee3\u5165 CPU<\/strong> \u4e2d <\/p>\n

        TSS\uff08Task State Segment\uff09\u6982\u8ff0<\/strong>\n\u4f5c\u7528:<\/strong> TSS \u662f x86 \u67b6\u6784\u4e2d\u7684\u4e00\u79cd\u6570\u636e\u7ed3\u6784<\/strong>\uff0c\u7528\u4e8e\u5b58\u50a8\u4efb\u52a1\uff08\u4efb\u52a1\u53ef\u4ee5\u770b\u4f5c\u662f\u4e00\u4e2a\u7ebf\u7a0b\u6216\u8fdb\u7a0b\uff09\u5728\u5207\u6362\u65f6\u7684\u4e0a\u4e0b\u6587\u4fe1\u606f\u3002\u4e0a\u4e0b\u6587\u4fe1\u606f\u5305\u62ec\u5904\u7406\u5668\u5bc4\u5b58\u5668\u7684\u5185\u5bb9\u3001\u5806\u6808\u6307\u9488\u3001\u4efb\u52a1\u7684\u72b6\u6001\u7b49\u3002<\/p>\n

        \u901a\u8fc7 TSS\uff0c\u5904\u7406\u5668\u53ef\u4ee5\u5728\u4efb\u52a1\u4e4b\u95f4\u5feb\u901f\u5207\u6362\uff0c\u800c\u4e0d\u9700\u8981\u624b\u52a8\u4fdd\u5b58\u548c\u6062\u590d\u4efb\u52a1\u72b6\u6001\u3002<\/p>\n

        TSS \u5b58\u50a8\u7684\u4fe1\u606f\u901a\u5e38\u5305\u62ec : <\/strong>\nCPU \u5bc4\u5b58\u5668\u7684\u5185\u5bb9\uff08\u5982 EAX, EBX, ECX, \u7b49\uff09\n\u5806\u6808\u6307\u9488\uff08SS \u548c ESP \u5bc4\u5b58\u5668\uff09\n\u6bb5\u5bc4\u5b58\u5668\u5185\u5bb9\uff08CS\u3001DS\u3001ES\u3001FS\u3001GS\u3001SS\uff09\nI\/O \u6743\u9650\u4f4d\u56fe\u548c\u5176\u4ed6\u4efb\u52a1\u76f8\u5173\u7684\u63a7\u5236\u4fe1\u606f\n\u4efb\u52a1\u94fe\u63a5\u5b57\u6bb5\uff0c\u7528\u4e8e\u591a\u4efb\u52a1\u5d4c\u5957\uff08\u67d0\u4efb\u52a1\u5207\u6362\u5230\u53e6\u4e00\u4e2a\u4efb\u52a1\u65f6\u4f7f\u7528\uff09<\/p>\n<\/blockquote>\n

        \"12_7\"<\/div><\/figure>\n

        \u7ea2\u8272\u65b9\u6846\u5c31\u662f\u521b\u5efa\u4e00\u4e2a\u5b50\u8fdb\u7a0b\uff0ccopy\u7236\u8fdb\u7a0b\u7684reg\u4fe1\u606f\uff0c\u57fa\u672c\u4e00\u6a21\u4e00\u6837\uff0c\u800c\u4e14\u53c2\u6570\u975e\u5e38\u591a\uff0c\u4e5f\u5c31\u662f\u7236\u8fdb\u7a0breg\u4fe1\u606f <\/p>\n

        \"12_8\"<\/div><\/figure>\n
        \n

        \u8fd9\u91cc\u4e0d\u80fd\u4f7f\u7528malloc\u51fd\u6570\uff0c\u5e94\u4e3a\u8be5\u51fd\u6570\u5728\u7528\u6237\u6001\u4e2d,\u5728copy_process\u4e2d\u9700\u8981\u4f7f\u7528\u7684\u662f\u5185\u6838\u6001\u7684\u521b\u5efa\u5185\u5b58\u7a7a\u95f4\u51fd\u6570\uff0c\u5373get_free_page() (\u521b\u5efa\u9875)<\/strong><\/p>\n

        get_free_page()\u5177\u4f53\u5b9e\u73b0\u662fmem_map<\/p>\n

        \u7b2c\u4e00\u884c\u4ee3\u7801\u7684\u7ed3\u679c \uff1a\u7533\u8bf7\u7684\u5185\u5b58\u7a7a\u95f4\u5c31\u662f\u6211\u4eec\u7684PCB<\/strong><\/p>\n

        \u89e3\u91ca\uff1a<\/p>\n

        get_free_page<\/strong> \u662f\u4e00\u4e2a\u5e38\u89c1\u7684\u51fd\u6570\u540d\uff0c\u7528\u4e8e\u64cd\u4f5c\u7cfb\u7edf\u5185\u5b58\u7ba1\u7406\u5b50\u7cfb\u7edf\u4e2d\u5206\u914d\u4e00\u4e2a\u7a7a\u95f2\u7684\u7269\u7406\u9875\u9762\uff08\u901a\u5e38\u662f 4KB<\/strong> \u5927\u5c0f\uff09\u3002\u5728 Linux \u5185\u6838\u4e2d\uff0cmem_map<\/strong> \u662f\u4e00\u4e2a\u7528\u4e8e\u8ddf\u8e2a\u7269\u7406\u5185\u5b58\u9875\u9762\u7684\u7ed3\u6784<\/strong><\/p>\n

        get_free_page<\/code>\u51fd\u6570\u53ef\u4ee5\u901a\u8fc7 mem_map<\/code> \u6765\u627e\u5230\u5e76\u5206\u914d\u4e00\u4e2a\u7a7a\u95f2\u7684\u9875\u9762\u3002<\/p>\n<\/blockquote>\n

        \n

        \u968f\u540e\u5c31\u662f\u521d\u59cb\u5316\u5185\u6838\u6808\uff0c\u9ec4\u8272\u90e8\u5206\u4e3aPCB<\/strong>\uff0c\u4e0a\u9762\u7684\u767d\u8272\u90e8\u5206\u5c31\u662f\u5185\u6838\u6808<\/strong><\/p>\n

        \n

        \u7236\u8fdb\u7a0b<\/strong> \u548c \u5b50\u8fdb\u7a0b<\/strong> \u600e\u4e48\u533a\u5206\uff1a\u901a\u8fc7eax, eax == 0 \uff1f\u5b50\u8fdb\u7a0b \uff1a\u7236\u8fdb\u7a0b<\/p>\n<\/blockquote>\n

        \n
        \n
        \n

        \u603b\u7ed3 \uff1a<\/strong><\/p>\n<\/blockquote>\n

        \"12_9\"<\/div><\/figure>\n

        \u64cd\u4f5c\u7cfb\u7edf\u7684\u90a3\u68f5\u201c\u6811\u201d<\/h2>\n

        \u4ece\u6253\u5370\u4e00\u4e2aA\u540e\u6253\u5370\u4e00\u4e2aB\u7684\u4ee3\u7801\u5f00\u59cb\u4e86\u89e3<\/p>\n

        main()\n{\n    if(!fork()){while(1)printf("A");}\n    if(!fork()){while(1)printf("B");}\n    wait();\n}<\/code><\/pre>\n
        \"13_1\"<\/div><\/figure>\n
        \"13_2\"<\/div><\/figure>\n
        \"13_3\"<\/div><\/figure>\n
        \n
        \"13_4\"<\/div><\/figure>\n
        \u5728\u8fdb\u5165\u5185\u6838\u65f6,int<\/strong> 0x80<\/strong> \u5bf9\u5e94\u7684\u662f system_call<\/strong>() \uff0c\u6267\u884c system_call()<\/strong> \u5c31\u8981\u6267\u884c sys_fork<\/strong>,\u6267\u884csys_fork<\/strong>\u5c31\u8981\u6267\u884c copy_process<\/strong> \uff0c\u800c\u5728copy_process<\/strong> \u5c31\u8981\u6267\u884c reg<\/strong> \u7684\u4fdd\u5b58\uff0c\u4ee5\u53ca tss<\/strong> \u7684\u5207\u6362\u3002<\/p>\n
        p = (PCB *)get_free_page();   \/\/\u521b\u5efa\u4e00\u4e2a\u65b0\u7684PCB\np -> tss.esp0 = p+4k; \/\/\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u6808\np -> tss.esp = esp;\np -> tss.eax=0; p -> tss.eip =eip;...   \/\/eip\u662f\u7236\u8fdb\u7a0b\u7684\n    \/\/\u4e5f\u5c31\u662f\u521b\u5efa\u5b50\u8fdb\u7a0b\u7684 eip \u548c\u7236\u8fdb\u7a0b\u5728\u6267\u884c\u65f6\u5019\u7684\u4e00\u6837\uff0c\u4e0e\u7236\u8fdb\u7a0b\u5171\u540c\u6267\u884c<\/code><\/pre>\n
        \n
        \u76ee\u524d\u6253\u5370A\u7684\u8fdb\u7a0b\u53ef\u4ee5\u6267\u884c\u4e86\uff0c\u4f46\u662f\u6ca1\u6709\u5f00\u59cb\u6267\u884c\uff0c\u9700\u8981\u5728\u8fd4\u56de\u7684\u65f6\u5019\u8c03\u7528reschedule \u8ba9\u5176\u5f00\u59cb\u6267\u884c\u3002<\/p>\n<\/blockquote>\n
        \n
        \u6ce8\u610f\uff01\uff01\uff01<\/strong><\/p>\n
        \u6b64\u65f6\u7236\u8fdb\u7a0b\u6ca1\u6709\u88ab\u6253\u65ad\uff0c\u65f6\u95f4\u7247\u8fd8\u6709\u5f88\u957f\uff0c\u81f4\u4f7f\u8fdb\u884c\u6267\u884c\u4e0b\u4e00\u884c\u4ee3\u7801\uff0c\u5373\u521b\u5efa \u6253\u5370B<\/strong> \u7684\u5b50\u8fdb\u7a0b\u7684\u6808\u3002<\/p>\n
        \"13_5\"<\/div><\/figure>\n
        \u76ee\u524d \u6253\u5370A \u548c \u6253\u5370B \u7684\u5b50\u8fdb\u7a0b\u90fd\u521b\u5efa\u597d\u4e86\uff0c\u5df2\u7ecf\u5f62\u6210\u4e86\u961f\u5217\u3002\u968f\u540e\u6267\u884c\u4ee3\u7801 wait() \u7b49\u5f85\u7236\u8fdb\u7a0b\u8dd1\u5b8c<\/p>\n
        \"13_6\"<\/div><\/figure>\n
        \"13_7\"<\/div><\/figure>\n