{"id":1137,"date":"2024-03-13T18:41:21","date_gmt":"2024-03-13T10:41:21","guid":{"rendered":"https:\/\/www.yizishun.com\/?p=1137"},"modified":"2024-04-01T11:56:33","modified_gmt":"2024-04-01T03:56:33","slug":"nju-pa3","status":"publish","type":"post","link":"https:\/\/www.yizishun.com\/?p=1137","title":{"rendered":"NJU PA3\uff08\u534a\u5b8c\u7ed3\uff09"},"content":{"rendered":"\n

\u524d\u8a00<\/strong><\/mark>\uff1a\u65f6\u5149\u5189\u5189\uff0c\u60f3\u8d77pa2.2\u505a\u5b8c\u624d12\u6708\u521d\uff0c\u5c45\u7136\u62d6\u4e86\u8fd9\u4e48\u4e45\u624d\u505a\u5b8cpa2\uff0c\u4e3b\u8981\u662f\u4e2d\u95f4\u6709\u5f88\u591a\u4e8b\uff0c12\u6708\u505a\u5b8cpa2.2\uff0c\u5c31\u82b1\u4e86\u51e0\u4e4e\u4e00\u4e2a\u6708\u7684\u65f6\u95f4\u901a\u8fc7ysyx\u5165\u5b66\u7b54\u8fa9\uff0c1\u6708\u53c8\u9700\u8981\u51c6\u5907\u671f\u672b\u8003\u8bd5\uff0c2\u6708\u53c8\u662fHGAME\uff0c\u4e2d\u95f4\u8fd8\u5f97\u62bd\u51fa\u65f6\u95f4\u505aNPC\u76f8\u5173\u7684\uff0c\u597d\u57283\u6708\u75af\u72c2\u8d76\u8fdb\u5ea6\u628a\u5355\u5468\u671f\u505a\u51fa\u6765\u4e86\uff0c\u7136\u540e\u628apa2.3\u4e5f\u6574\u5b8c\u4e86\uff08\u8fd9\u4e24\u4e2a\u6211\u53ea\u82b1\u4e86\u4e00\u5468\u7684\u65f6\u95f4\u563f\u563f\u563f\uff09\uff0c\u4e3b\u8981\u662f\u4e2d\u95f4\u8fd9\u6bb5\u65f6\u95f4\u6211\u771f\u7684\u6210\u957f\u4e86\u4e0d\u5c11\uff0c\u7279\u522b\u662fRTFSC\u7684\u6c34\u5e73\u548cdebug\u7684\u80fd\u529b<\/p>\n\n\n\n

PA3.1<\/mark><\/strong><\/h1>\n\n\n\n

pa3.1\u4eff\u4f5b\u5f88\u7b80\u5355\u7684\u6837\u5b50\uff0c\u4e00\u5929\u5b66\u4e60\uff0c\u53e6\u4e00\u5929\u5199\u4ee3\u7801\u5c31\u57fa\u672c\u5199\u5b8c\u4e86<\/p>\n\n\n\n

\u6211\u6253\u7b97\u501f\u6b64\u535a\u5ba2\u68b3\u7406\u4e00\u4e0b\uff0c\u4e5f\u5c31\u662f\u8fd9\u4e2a\u5fc5\u7b54\u9898\uff0c\u4e0d\u8fc7\u6211\u4e0d\u4f1a\u8bf4\u7684\u90a3\u4e48\u8be6\u7ec6\uff0c\u6bd5\u7adf\u6211\u4e0d\u662f\u5357\u5927\u7684\u5b66\u751fhhh<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

yield test\u5b9e\u9645\u4e0a\u5c31\u662f\u4e00\u4e2a\u64cd\u4f5c\u7cfb\u7edf\u4e86\uff0c\u51c6\u786e\u6765\u8bf4\u662f\u64cd\u4f5c\u7cfb\u7edf\u7684\u89c6\u89d2\u7684\u7a0b\u5e8f\uff0c\u5176\u4e2dhello-intr\u7a0b\u5e8f\u662f\u5176\u4e2d\u4f5c\u4e3a\u7528\u6237\u89c6\u89d2\u5b58\u5728\u7684\uff0c\u9996\u5148os\u8fdb\u884cCTE\u521d\u59cb\u5316\uff0c\u770b\u4e00\u4e0b\u6c47\u7f16<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

\u6211\u4e4b\u6240\u4ee5\u79f0\u5176\u4e3aos\uff0c\u56e0\u4e3a\u4ed6\u505a\u4e86\u67d0\u4e9b\u7279\u6743\u64cd\u4f5c\uff0c\u6ca1\u9519\u5c31\u662f\u8bbe\u7f6e\u5165\u53e3\u5730\u5740\uff0c\u5bf9\u5427\uff0c\u5047\u5982\u662f\u7528\u6237\u7a0b\u5e8f\u80fd\u968f\u610f\u8bbe\u7f6e\u5165\u53e3\u5730\u5740\u90a3\u4e0d\u5c31\u4e71\u5957\u4e86\uff0c\u5e76\u4e14\u8bbe\u7f6e\u4e86\u56de\u8c03\u51fd\u6570\uff0c\u53ef\u4ee5\u53d1\u73b0\u91cc\u9762\u6709\u67b6\u6784\u76f8\u5173\u7684\u4ee3\u7801\uff0c\u6240\u4ee5\u4ed6\u88ab\u505a\u6210\u4e86\u8fd9\u4e2aam\u51fd\u6570\u63a5\u53e3\uff0c\u7d27\u63a5\u7740\u8c03\u7528hello-intr\u8fd9\u4e2a\u7528\u6237\u51fd\u6570\uff0c\u7528\u6237\u51fd\u6570\u6ca1\u6709\u7528\u4efb\u4f55\u7279\u6743\u6307\u4ee4\uff0c\u53ea\u662f\u6700\u540e\u8c03\u7528\u4e86\u4e00\u4e2aam\u63a5\u53e3yield\u6765\u62bd\u8c61\u4e0d\u540c\u67b6\u6784\uff0crv\u5c31\u662fecall\uff0cecall\u6307\u4ee4\u51fa\u53d1\u4e00\u4e2a\u5f02\u5e38\uff0c\u8c03\u7528\u4e00\u4e2a\u5f02\u5e38\u5904\u7406\u51fd\u6570isa_raise_intr()\u51fd\u6570\uff0c\u8be5\u5f02\u5e38\u5904\u7406\u51fd\u6570\u8bbe\u7f6emcause\u7b49csr\u5bc4\u5b58\u5668\uff0c\u628apc\u5148\u4fdd\u5b58\u81f3mepc\uff0c\u5e76\u8df3\u8f6c\u81f3\u4e4b\u524d\u8bbe\u7f6e\u7684\u5165\u53e3\u5730\u5740\uff0c\u7d27\u63a5\u7740\u5f00\u59cb\u4e0a\u4e0b\u6587\u5165\u6808\uff0c\u6700\u540e\u5c06\u6808\u6307\u9488\u4f20\u7ed9\u4e00\u4e2aam\u4e2d\u7684\u63a5\u53e3\u51fd\u6570\uff08\u4e5f\u5c31\u662f\u628a\u4e0a\u4e0b\u6587\u7684\u6307\u9488\u4f20\u53c2\uff09\uff0c\u8fd9\u4e2a\u51fd\u6570\u4e3b\u8981\u662f\u505a\u4e00\u4e9b\u67b6\u6784\u76f8\u5173\u7684\u4e8b\u60c5\uff0c\u6bd4\u5982\u901a\u8fc7\u8fd9\u6574\u4e2a\u4e0a\u4e0b\u6587\u4e2d\u7684mcause\u5bc4\u5b58\u5668\u8bc6\u522b\u7a76\u7adf\u662f\u4ec0\u4e48\u4e8b\u4ef6\u5bfc\u81f4\u7684\u5f02\u5e38\uff0c\u603b\u4e4b\u64cd\u4f5c\u89e3\u6790\u4e0a\u4e0b\u6587\u7684\u64cd\u4f5c\u662f\u5728\u8fd9\u4e2a\u51fd\u6570\u505a\u7684\uff0c\u4e3a\u7684\u662f\u67b6\u6784\u89e3\u8026\uff0c\u5c06\u4e0a\u4e0b\u6587\u7684\u4e00\u4e9b\u4fe1\u606f\u5305\u88c5\u5230event\u7ed3\u6784\u4f53\uff0c\u4e4b\u540e\u8c03\u7528\u56de\u8c03\u51fd\u6570\uff0c\u56de\u8c03\u51fd\u6570\u5c31\u53ea\u901a\u8fc7event\u7ed3\u6784\u4f53\u8fdb\u884c\u64cd\u4f5c\uff0c\u56de\u8c03\u51fd\u6570\u68c0\u6d4b\u5230\u4e8b\u4ef6\u662f\u81ea\u9677\uff0c\u4e8e\u662f\u8f93\u51fay\uff0c\u6700\u540e\u4e0a\u4e0b\u6587\u51fa\u6808\uff0cmret\u6307\u4ee4\u8fd4\u56demepc+4\u7684\u4f4d\u7f6e\uff08\u6ce8\u610f\uff0c\u8fd9\u91cc\u7684mepc\u7684\u8bbe\u7f6e\u5e94\u8be5\u662f\u64cd\u4f5c\u7cfb\u7edf\u505a\u7684\uff0c\u4e0d\u662fmret\u6307\u4ee4\u672c\u8eab\u7684\u64cd\u4f5c\uff0c\u6362\u53e5\u8bdd\u8bf4\uff0c\u5c31\u4e0d\u662f\u786c\u4ef6\u4e3a\u4f60\u8bbe\u7f6e\uff0c\u800c\u662f\u8f6f\u4ef6\u8bbe\u7f6e\uff0c\u5177\u4f53\u662f\u9700\u8981\u5728am\u90a3\u4e2a\u51fd\u6570\u505a\u7684\uff09\uff0c\u6700\u540e\u56de\u5230\u7528\u6237\u7ea7\u7a0b\u5e8fhello-str<\/p>\n\n\n\n

\u4e0a\u8ff0\u5e76\u4e0d\u96be\u7406\u89e3\uff0c\u6211\u4e4b\u524d\u6709\u505a\u8fc7CTF pwn\u76f8\u5173\u7684\u5b66\u4e60\uff0c\u6240\u4ee5\u5bf9\u6211\u8fd8\u662f\u4e0d\u96be\u7684\uff0c\u4e0d\u8fc7\uff0c\u8fd9\u4e00\u5957\u6d41\u7a0b\u53c8\u8ba9\u6211\u6574\u4e2a\u4f53\u7cfb\u6e05\u6670\u4e86\u4e0d\u5c11\uff0c\u867d\u7136\u6211\u6ca1\u505ax86\u7684pa\uff0c\u4f46\u662f\u6211pwn\u7ecf\u5e38\u9700\u8981\u548cx86\u6253\u4ea4\u9053\uff0c\u6240\u4ee5\u5408\u7406\u8fc1\u79fb\uff0c\u5728x86\u7a0b\u5e8f\u4e2d\uff0c\u8c03\u7528syscall\u6307\u4ee4\u4e4b\u540e\uff0c\u4e5f\u662f\u89e6\u53d1\u5f02\u5e38->\u8df3\u8f6c\u81f3\u76f8\u5173\u5165\u53e3\u5730\u5740->\u4fdd\u5b58\u4e0a\u4e0b\u6587->\u901a\u8fc7\u5f02\u5e38\u53f7\u8fdb\u884c\u529f\u80fd\u9009\u62e9->\u6062\u590d\u4e0a\u4e0b\u6587->\u8df3\u56de\u6765\u3002EZ<\/p>\n\n\n\n

PA3.2<\/mark><\/strong><\/h1>\n\n\n\n

loader<\/mark><\/strong><\/h2>\n\n\n\n

\u5982\u679c\u8bf4os\u7684\u7b2c\u4e00\u4e2a\u4efb\u52a1\u662f\u4e3a\u7528\u6237\u7a0b\u5e8f\u63d0\u4f9b\u81ea\u9677\u64cd\u4f5c\uff0c\u90a3\u7b2c\u4e8c\u4e2a\u5c31\u662f\u6709\u52a0\u8f7d\u7a0b\u5e8f\u7684\u80fd\u529b\u4e86<\/p>\n\n\n\n

\u4e4b\u524d\u5199ftrace\u662f\u89e3\u6790elf\u7684section header\uff0c\u800c\u8fd9\u6b21\u5199loader\u5c31\u662f\u89e3\u6790elf\u7684program header\u5b9e\u73b0\u52a0\u8f7d<\/p>\n\n\n\n

\u8fd9\u4e2a\u7684\u8bdd\u5e76\u4e0d\u662f\u5f88\u96be\uff0c\u53ea\u662f\u6709\u70b9\u9ebb\u70e6\uff0c\u5177\u4f53\u6765\u8bf4\u5c31\u662f\u901a\u8fc7\u6846\u67b6\u4ee3\u7801\u7ed9\u4f60\u7684ramdisk_read\u51fd\u6570\u9996\u5148\u8bfb\u51faEHDR\uff0c\u5728ehdr\u4e2d\u627e\u5230phdr\u7684\u504f\u79fb\uff0c\u518d\u5728phdr\u4e2d\u89e3\u6790offset\uff0cvaddr\uff0cmemsz\uff0cfilesz\uff0c\u628a\u76f8\u5e94offset\u7684\u5730\u65b9\u5199\u5165\u5230vaddr\uff0c\u5199filesz\u5927\u5c0f\uff0c\u6700\u540e\u88650\uff0c\u4e5f\u5c31\u662fbss\u6bb5\u7684\u5730\u5740\uff0c\u6700\u540e\u8fd4\u56dee_entry\uff08\u597d\u50cf\u53eb\u8fd9\u4e2a\u540d\u5b57\uff09\u5c31\u662f\u7a0b\u5e8f\u5165\u53e3<\/p>\n\n\n\n

syscall<\/mark><\/strong><\/h2>\n\n\n\n

syscall\u662f\u4e00\u79cd\u7279\u6b8a\u7684\u81ea\u9677\uff0c\u9700\u8981\u4e0eEVENT_YIELD\u533a\u5206\u5f00\u6765\uff0c\u533a\u5206\u7684\u65b9\u5f0f\u662f\u901a\u8fc7\u8c03\u7528ecall\u65f6\u7684a7\u5bc4\u5b58\u5668\u6765\u8bbe\u7f6emcause\u4e3aEVENT-SYSCALL\uff08\u5f02\u5e38\u53f7\uff09\uff0c\u5e76\u5c06ENENT_SYSCALL\u4f20\u7ed9nanos-lite\uff0cnanos-lite\u518d\u6839\u636ea7\uff08\u7b2c\u4e00\u4e2a\u5bc4\u5b58\u5668\uff09\u8fdb\u884c\u7cfb\u7edf\u8c03\u7528\u53f7\u7684\u8bc6\u522b\uff08\u7cfb\u7edf\u8c03\u7528\u53f7\uff09\uff0c\u4e5f\u5c31\u662f\u5176\u5b9e\u7ecf\u8fc7\u4e86\u4e24\u6b21\u4e8b\u4ef6\u5206\u53d1<\/p>\n\n\n\n

\u7b80\u5355\u6765\u8bf4\uff0cdummy\u7a0b\u5e8f\u8c03\u7528syscall\u5b9e\u9645\u4e0a\u7ecf\u5386\u4e86\uff0cecall(\u8f6f\u4ef6) -> mcause\u8bbe\u7f6e(\u786c\u4ef6) -> \u5f02\u5e38\u53f7\u5904\u7406(OS) -> \u7cfb\u7edf\u8c03\u7528\u53f7\u5904\u7406\uff08OS\uff09<\/p>\n\n\n\n

\u5177\u4f53\u5230nemu\u548cnanos\u6765\u8bf4\uff0c\u5c31\u662f_syscall_(dummy)->ecall(libos)->isa_raise_intr(nemu)->trap.S(am)->__am_irq_handle(am)->do_event(nanos-lite)->do_syscall(nanos-lite)->yield(am)->…..(\u8fd4\u56de)->dummy<\/p>\n\n\n\n

\u6240\u4ee5\u4e4b\u540e\u7684\u4efb\u52a1\u53ea\u9700\u8981\u5728nemu\u4e2d\u8bbe\u7f6e\u597d\u5f02\u5e38\u53f7\uff0cnanos\u5bf9\u5f02\u5e38\u53f7\u8fdb\u884c\u7b2c\u4e00\u6b21\u4e8b\u4ef6\u5206\u53d1\uff0c\u5982\u679c\u5f02\u5e38\u53f7\u662f\u7cfb\u7edf\u8c03\u7528\u5219\u8fdb\u884c\u7b2c\u4e8c\u6b21\u4e8b\u4ef6\u5206\u53d1\u5373\u53ef\uff0c\u4e3b\u8981\u662f\u4e2d\u95f4\u591a\u4e86\u4e00\u5c42am\uff0c\u53ef\u80fd\u4f1a\u589e\u52a0\u7406\u89e3\u7684\u56f0\u96be\uff0c\u4e0d\u8fc7\u8981\u660e\u767d\uff0cam\u4e5f\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u5c42\u9762\u4e0a\u7684\uff08\u56e0\u4e3a\u64cd\u4f5c\u7cfb\u7edf\u5c31\u662f\u4e00\u4e2aam\u7a0b\u5e8f\uff09\uff0c\u53ea\u662f\u64cd\u4f5c\u7cfb\u7edf\u4e2d\u90a3\u4e9bisa\u76f8\u5173\u7684\u90e8\u5206\u548cisa\u4e0d\u76f8\u5173\u7684\u90e8\u5206\u8fdb\u884c\u4e86\u89e3\u8026\uff0c\u4ece\u800c\u624d\u5f62\u6210\u4e86am\u8fd9\u4e00\u4e2a\u62bd\u8c61\u5c42\uff0c\u6240\u4ee5nanos\u4e0d\u5e94\u8be5\u76f4\u63a5\u8bbf\u95eemcause\u7b49\u5bc4\u5b58\u5668\uff0c\u5e76\u4e14\u5bf9\u4e8e\u901a\u7528\u5bc4\u5b58\u5668\u7684\u8bbf\u95ee\u4e5f\u5fc5\u987b\u7ecf\u8fc7am\u7684\u63a5\u53e3\uff0c\u4ece\u800c\u4fdd\u8bc1nanos\u53ef\u4ee5\u5728\u591a\u4e2a\u67b6\u6784\u8fd0\u884c\uff0c\u603b\u4e4b\u8fd9\u5c31\u662fam\u7a0b\u5e8f\u7684\u601d\u60f3\uff0c\u53ea\u8981\u662f\u9700\u8981\u8bbf\u95ee\u786c\u4ef6\u5c31\u9700\u8981\u7ecf\u8fc7am\u7684\u63a5\u53e3\uff0c\u6216\u8005\u8bf4\u786c\u4ef6\u9700\u8981\u8bbf\u95ee\u64cd\u4f5c\u7cfb\u7edf\uff08\u4e5f\u5c31\u662f\u5f02\u5e38\uff09\uff0c\u4e5f\u9700\u8981\u5148\u7ecf\u8fc7am\uff0c\u8fc7\u6ee4\u6389isa\u76f8\u5173\u7684\u90e8\u5206<\/p>\n\n\n\n

\u8349\uff0c\u4e4b\u540e\u7684write\u88ab\u5751\u4e86\uff0c\u56e0\u4e3aprintf\u5185\u90e8\u4f1a\u8c03\u7528malloc\u7684\uff0c\u54ce\u5176\u5b9e\u6211\u60f3\u5230\u7684\uff0c\u53ef\u662f\u8bb2\u4e49\u6ca1\u63d0\u6211\u5c31\u4e5f\u6709\u70b9\u6000\u7591\u81ea\u5df1\u4e86\uff0c\u6240\u4ee5\u4f60\u5fc5\u987b\u5148\u5b9e\u73b0\u540e\u9762\u7684\u518d\u6765\u6574\u8fd9\u4e2ahello.c<\/p>\n\n\n\n

PA3.2\u603b\u7ed3<\/mark><\/strong><\/h2>\n\n\n\n

\u5c0f\u603b\u7ed3\u4e00\u4e0b\uff0chello world\u7a0b\u5e8f\u7684\u771f\u6b63\u7684\u8fd0\u884c\uff08\u4e0d\u662fam\u7a0b\u5e8f\u7684hello world\uff09\uff0c\u5b9e\u9645\u4e0a\u8de8\u8d8a\u4e86\u5f88\u591a\u62bd\u8c61\u5c42\uff0c\u7c97\u7565\u6765\u8bf4\uff0c\u5c31\u662f\u9996\u5148hello.c\u7f16\u8bd1\u6210ELF\u6587\u4ef6\uff0c\u7136\u540e\u64cd\u4f5c\u7cfb\u7edf\uff08\u5c31\u662f\u4e00\u4e2a\u548cMario\u76f8\u4f3c\u7684am\u7a0b\u5e8f\uff09\u88ab\u52a0\u8f7d\u5230nemu\uff08\u786c\u4ef6\uff09\u7684\u5185\u5b58\u4e2d\uff0c\u4e4b\u540erestart pc == 0x80000000\uff0c\u5f00\u59cb\u4ece\u64cd\u4f5c\u7cfb\u7edf\u7684\u7b2c\u4e00\u6761\u6307\u4ee4\u5f00\u59cb\u6267\u884c\uff08\u636e\u6211\u4e86\u89e3\uff0c\u771f\u5b9e\u60c5\u51b5\u5e94\u8be5\u662f\u4ecefirmware\u5f00\u59cb\u6267\u884c\u518d\u5c06os\u52a0\u8f7d\u8fdb\u6765\uff0c\u4f46\u662f\u6a21\u62df\u5668\u5c31\u4e0d\u7528\u7ba1\u56fa\u4ef6\u4e4b\u7c7b\u7684\u5566\uff09\uff0c\u64cd\u4f5c\u7cfb\u7edf\u9996\u5148\u6253\u5370\u5357\u5927\u7684logo\ud83d\ude02\uff0c\u7136\u540e\u901a\u8fc7am\u63a5\u53e3\u8fdb\u884cdevice\u521d\u59cb\u5316\uff0c\u4e4b\u540e\u518d\u8bbe\u7f6emtvec\u4fdd\u8bc1\u5f02\u5e38\u5904\u7406\u673a\u5236\u53ef\u4ee5\u6b63\u5e38\u8fd0\u884c\uff0c\u4e4b\u540e\u8c03\u7528\u4e4b\u524d\u5199\u7684loader\uff0c\u6839\u636eELF\u7684\u63cf\u8ff0\u4fe1\u606f\uff08Phdr\uff09\u5c06ELF\u52a0\u8f7d\u5230nemu\u7684\u67d0\u4e00\u5757\u5185\u5b58\uff0c\u4e5f\u5c31\u662f0x83000000\uff0c\u4e4b\u540e\u7a0b\u5e8f\u8df3\u8f6c\u81f3\u7528\u6237\u7a0b\u5e8f\u7684\u8d77\u59cb\u5730\u5740\uff08e_entry\u5b9a\u4e49\uff09\uff0c\u8fd9\u4e2a\u65f6\u5019\u5c31\u4f1a\u53d1\u73b0\uff0c\u4e4b\u540e\u60f3\u518d\u56de\u5230nanos-lite\u7684\u76f8\u5173\u4ee3\u7801\u5c31\u53ea\u80fd\u901a\u8fc7\u4e2d\u65ad\u6216\u8005\u5f02\u5e38\u4e86\uff0c\u4e5f\u5c31\u662f\u73b0\u5728\u7684ecall\u6307\u4ee4\uff0c\u5047\u5982\u7a0b\u5e8f\u59cb\u7ec8\u4e0d\u8c03\u7528ecall\u6307\u4ee4\u90a3\u4e48nanos-lite\u7684\u4ee3\u7801\u5c31\u518d\u4e5f\u4e0d\u4f1a\u88ab\u8fd0\u884c\u5230\uff0c\u5f7b\u5e95\u6210\u4e3a\u4e00\u4e2a\u6b7b\u7a0b\u5e8f\u4e86\uff08\u5b9e\u9645\u4e0a\u771f\u5b9e\u7684\u73af\u5883\u8fd8\u5b58\u5728\u65f6\u949f\u4e2d\u65ad\uff09\uff0c\u4f46\u662f\u7a0b\u5e8f\u82e5\u662f\u4e0d\u548c\u64cd\u4f5c\u7cfb\u7edf\u4ea4\u4e92\u5c31\u53ea\u80fd\u505a\u4e00\u4e9b\u8ba1\u7b97\u6307\u4ee4\uff0c\u6240\u4ee5\u7a0b\u5e8f\u9700\u8981\u901a\u8fc7\u4e00\u79cd\u7279\u6b8a\u7684\u5f02\u5e38\uff1asyscall\u6765\u91cd\u56de\u64cd\u4f5c\u7cfb\u7edf\uff0c\u7531\u4e8e\u9700\u8981\u4fdd\u8bc11\uff0c\u7a0b\u5e8f\u4e0a\u4e0b\u6587\u4e0d\u4f1a\u88ab\u7834\u574f 2\uff0c\u64cd\u4f5c\u7cfb\u7edf\u80fd\u660e\u767d\u7a0b\u5e8f\u7684\u5168\u90e8\u4e0a\u4e0b\u6587\uff0c\u4e8e\u662f\u5f02\u5e38\u5904\u7406\u673a\u5236\u5c31\u662f\u5148\u5728\u786c\u4ef6\u4e0a\u8bbe\u7f6emcause\u5f02\u5e38\u53f7\uff0c\u7136\u540e\u8df3\u8f6c\u81f3mtvec\uff08\u4ece\u5b89\u5168\u7684\u89d2\u5ea6\u6765\u8bf4\uff0c\u666e\u901a\u7a0b\u5e8f\u7edd\u5bf9\u4e0d\u4f1a\u5b58\u5728\u80fd\u4fee\u6539mtvec\u7684\u6307\u4ee4\uff0c\u6240\u4ee5\u5165\u53e3\u5730\u5740\u662f\u552f\u4e00\u7684\uff09\uff0c\u4e4b\u540e\u6709\u8f6f\u4ef6\uff08am\u7684CTE\u6269\u5c55\uff09\u6765\u5148\u4fdd\u5b58\u4e0a\u4e0b\u6587\uff08trap.S\uff09\u5e76\u5c06\u5f02\u5e38\u53f7\u8fdb\u884c\u63d0\u53d6\u5e76\u6253\u5305\uff0c\u4e4b\u540e\u8fdb\u5165nanos-lite\uff08\u5176\u5b9e\u4ece\u4e00\u4e2a\u89d2\u5ea6\u6765\u8bf4\uff0c\u4e4b\u524d\u7684\u4fdd\u5b58\u4e0a\u4e0b\u6587\u7684\u64cd\u4f5c\u5c31\u662f\u64cd\u4f5c\u7cfb\u7edf\u4e86\uff0c\u53ea\u662f\u8fd9\u91cc\u4e3a\u4e86\u67b6\u6784\u89e3\u8026\u628a\u4ed6\u770b\u6210\u662f\u4e24\u4e2a\u5c42\u6b21\uff09\uff0cnanos-lite\u6839\u636e\u5f02\u5e38\u53f7\u8fdb\u884c\u7b2c\u4e00\u6b21\u4e8b\u4ef6\u5206\u53d1\uff0c\u5982\u679c\u68c0\u6d4b\u5230\u662fEVENT_SYSCALL\u5c31\u8c03\u7528\u76f8\u5e94\u7684\u51fd\u6570\u8fdb\u884c\u5904\u7406\uff08do_syscall\uff09,\u5982\u679c\u662f\u5176\u4ed6\u7684\u4e8b\u4ef6\u5c31\u8c03\u7528\u5176\u4ed6\u7684\u5f02\u5e38\u5904\u7406\u51fd\u6570\u8fdb\u884c\u5904\u7406\uff0c\u4e4b\u540e\u52a0\u5165\u662f\u7cfb\u7edf\u8c03\u7528\u5f02\u5e38\u90a3\u5c31\u8fd8\u9700\u8981\u7b2c\u4e8c\u6b21\u4e8b\u4ef6\u5206\u53d1\uff0c\u4e5f\u5c31\u662f\u5728do_syscall\u51fd\u6570\u4e2d\u901a\u8fc7\u89e3\u6790\u7528\u6237\u7a0b\u5e8f\u7684\u4e0a\u4e0b\u6587\uff08\u5c31\u662f\u4e4b\u524d\u4fdd\u5b58\u5230\u6808\u4e0a\u7684context\u7ed3\u6784\u4f53\uff0c\u5c31\u662f3.1\u8981\u6211\u4eec\u6574\u7406\u7684\u7ed3\u6784\u4f53\uff09\uff0c\u6765\u5206\u6790\u7528\u6237\u7a0b\u5e8f\u9700\u8981\u7684\u7a76\u7adf\u662f\u4ec0\u4e48\u7cfb\u7edf\u8c03\u7528\uff0c\u4e5f\u5c31\u662f\u6839\u636e\u7cfb\u7edf\u8c03\u7528\u53f7\uff08\u4e00\u822c\u5728a7\u5bc4\u5b58\u5668\u4e2d\uff09\u8fdb\u884c\u7b2c\u4e8c\u6b21\u4e8b\u4ef6\u5206\u53d1\uff0c\u8c03\u7528\u76f8\u5e94\u7684\u7cfb\u7edf\u8c03\u7528\u5904\u7406\u51fd\u6570\uff0c\u5e76\u5c06\u53c2\u6570\u4f20\u7ed9\u8fd9\u4e2a\u5904\u7406\u51fd\u6570\uff0c\u4e00\u822c\u662fa0\uff0ca1\uff0ca2\uff0c\u7136\u540e\u8fd4\u56de\u503c\u4fdd\u5b58\u5728a0\u4e2d\uff08\u4e5f\u5c31\u662f\u4fee\u6539\u6808\u4e0a\u7684\u6570\u636e\uff0c\u4e4b\u540epop\u51fa\u6765\uff09\uff0c\u8fd9\u4e2a\u7cfb\u7edf\u8c03\u7528\u5904\u7406\u51fd\u6570\u624d\u771f\u6b63\u53eb\u505a\u64cd\u4f5c\u7cfb\u7edf\u7684\u72ec\u6709\u80fd\u529b\uff08\u8d85\u8d8a\u4e86\u7528\u6237\u7a0b\u5e8f\u7684\u80fd\u529b\uff09\uff08\u6211\u4e2a\u4eba\u611f\u89c9\uff0c\u64cd\u4f5c\u7cfb\u7edf\u7684powerful\u5c31\u4f53\u73b0\u5728\u8fd9\u91cc\uff09\uff0c\u5728\u4e0d\u540c\u7684\u7cfb\u7edf\u8c03\u7528\u5904\u7406\u51fd\u6570\u4e2d\uff0c\u8fd9\u4e2aam\u7a0b\u5e8f\uff08nanos-lite\uff09\u5f00\u59cb\u4f7f\u7528am\u7684TRM\u548cIOE\u6269\u5c55\u63a5\u53e3\u548c\u786c\u4ef6\u8fdb\u884c\u4ea4\u4e92\uff0c\u6bd4\u5982write\u7cfb\u7edf\u8c03\u7528\u5904\u7406\u51fd\u6570\u548c\u786c\u4ef6nemu\u7684\u4e32\u53e3\u8fdb\u884c\u901a\u4fe1\uff08\u6211\u73b0\u5728\u4e5f\u53ea\u505a\u5230\u4e86\u8fd9\u91cc….\u4e5f\u5c31\u662f\u7528\u6237\u7a0b\u5e8f\u6682\u65f6\u53ea\u6709TRM\u7684\u529f\u80fd\uff09<\/p>\n\n\n\n

\u4e5f\u5c31\u662f\u7528\u6237\u7a0b\u5e8f\u60f3\u7528printf\u8f93\u51fahello wrold\u5230\u5c4f\u5e55\u4e0a\u65f6\uff0c\u9996\u5148\u8fdb\u884clibc printf\u7684\u5904\u7406\uff08\u4e4b\u524d\u770b\u8fc7\u4e00\u70b9\u6e90\u7801\uff0cprintf\u5728libc\u4e2d\u7684\u8c03\u7528\u94fe\u4e5f\u662f\u6781\u957f\u7684\uff09\uff0c\u6700\u540eprintf\u901a\u8fc7libc\u7684write\u8fdb\u884c\u5904\u7406\uff0cwrite\u5219\u662f\u8c03\u7528_write\uff0c\u8fd9\u4e2a\u51fd\u6570\u5c31\u4e0d\u5c5e\u4e8elibc\u4e86\uff0c\u4ed6\u7531\u64cd\u4f5c\u7cfb\u7edf\u63d0\u4f9b\uff0c\u4e5f\u5c31\u662flibos\uff0clibos\u5c06_write\u518d\u5c01\u88c5\uff0c\u76f4\u5230\u6700\u540e\u80fd\u4ee5\u4e00\u4e2a\u5b8c\u7f8e\u7684\u4e0a\u4e0b\u6587\u8fdb\u884cecall\u6307\u4ee4\uff0cecall\u6307\u4ee4\u901a\u8fc7\u5f02\u5e38\u5904\u7406\u673a\u5236\u8fdb\u5165os\u5185\u90e8\u7684sys_write\u51fd\u6570\uff08\u5c31\u662f\u4f20\u8bf4\u7684\u7cfb\u7edf\u8c03\u7528\u5904\u7406\u51fd\u6570\uff09\uff0c\u4ed6\u901a\u8fc7putch\u8f93\u51fa\uff0c\u800cputch\u662fHSL\uff08hardware abstraction layer\uff09\uff0c\u5bf9\u786c\u4ef6\u7684\u62bd\u8c61\uff0c\u5b9e\u9645\u4e0a\u662f\u57280xa00003f8\u8fdb\u884c\u5199\u64cd\u4f5c\uff0c\u4ece\u800c\u5728\u786c\u4ef6nemu\u4e2d\u8c03\u7528\u56de\u8c03\u51fd\u6570\uff08serial_io_handler\uff09\uff0c\u6700\u540e\u6a21\u62df\u8f93\u51fa\u3002<\/p>\n\n\n\n

\u5982\u679c\u518d\u7b80\u7ec3\u4e00\u70b9\uff0c\u5c31\u662f\uff0cprintf(libc)->…->write(libc)->_write(libos)->ecall(nemu intr)->do_syscall(nanos-lite)->…->printf(libc)<\/p>\n\n\n\n

\u4e00\u4e2a\u5b8c\u6574\u7684hello world\u5c31\u8fd9\u4e48\u5448\u73b0\u5728\u6211\u4eec\u9762\u524d\uff0c\u6211\u4eec\u7ec8\u4e8e\u53ef\u4ee5\u5f88\u81ea\u4fe1\u5730\u5927\u58f0\u8bf4\u51fa\uff1a\u201cHello World\uff01\u201d<\/p>\n\n\n\n

\u5b9e\u9645\u4e0a\u53ef\u4ee5\u5f88\u6e05\u695a\u7684\u731c\u6d4b\u51fapa3.3\u7684\u4efb\u52a1\u4e86\uff0cpa3.1\u662f\u5b9e\u73b0\u81ea\u9677\u6307\u4ee4\uff0cpa3.2\u662f\u52a0\u8f7d\u4e00\u4e2a\u7528\u6237\u7a0b\u5e8f\uff0c\u5e76\u901a\u8fc7\u81ea\u9677\u6307\u4ee4\u5b9e\u73b0syscall\uff0c\u90a3pa3.3\u5c31\u4e00\u5b9a\u662f\u52a0\u8f7d\u591a\u4e2a\u7a0b\u5e8f\uff0c\u800c\u8fd9\u624d\u662f\u64cd\u4f5c\u7cfb\u7edf\u5927\u653e\u5f02\u5f69\u7684\u5730\u65b9<\/p>\n\n\n\n

PA3.3<\/mark><\/strong><\/h1>\n\n\n\n

Simple File System<\/mark><\/strong><\/h2>\n\n\n\n
\"\"<\/figure>\n\n\n\n

\u8bf4\u5b9e\u8bdd\uff0c\u5728\u5199\u8fd9\u4e2a\u4e4b\u524d\uff0c\u6211\u90fd\u4e0d\u77e5\u9053fs\u662f\u4ec0\u4e48\uff0c\u4f46\u662fpa\u7ed9\u4e86\u6211\u5f88\u660e\u786e\u7684\u9700\u6c42\u5bfc\u5411\uff0c\u518d\u52a0\u4e0a\u8bb2\u4e49\u7684\u901a\u4fd7\u7684\u8bb2\u89e3\uff0c\u8fd8\u597d\u662f\u5199\u51fa\u6765\u4e86\uff0c\u6211\u5199\u5b8c\u5230\u8fd9\u4e2afile-test\u65f6\u5bf9file-system\u6709\u4e00\u4e9b\u7c97\u6d45\u7684\u7406\u89e3\u4e86\uff0c\u9996\u5148\u662f\u6587\u4ef6\u5728\u78c1\u76d8\u4e0a\u7684\u5b58\u50a8\u65b9\u5f0f\uff0cnanos-lite\u5c31\u662f\u7b80\u5355\u7684\u5c06\u5404\u79cd\u6587\u4ef6\u6253\u5305\u8d77\u6765\uff0c\u5176\u5b9e\u8fd9\u6240\u8c13\u7684\u6253\u5305\u5c31\u662f\u4ec5\u4ec5\u5c06\u5404\u79cd\u4e0d\u540c\u7684\u6587\u4ef6\u4e00\u4e2a\u4e00\u4e2a\u653e\u5728\u4e00\u8d77\uff0c\u7136\u540e\u6839\u636e\u6253\u5305\u7684\u6587\u4ef6\u7528wc\u547d\u4ee4\u6765\u5c06\u5404\u79cd\u4fe1\u606f\u8f93\u51fa\u81f3\u4e00\u4e2a.h\u6587\u4ef6\u4e2d\uff08\u4f59\u8001\u5e08\u592a\u5389\u5bb3\u4e86\uff0c\u8fd9\u4e2ashell\u547d\u4ee4\u53cd\u6b63\u6211\u662f\u770b\u4e0d\u61c2\uff0c\u66f4\u522b\u63d0\u4f1a\u7528\u4e86\ud83e\udd2f\uff09\uff0c\u4ece\u800c\u5c06\u6587\u4ef6\u5728ramdisk\u7684\u5b58\u50a8\u65b9\u5f0f\u8bb0\u5f55\u5728\u4e00\u5f20\u8868\u4e2d\uff08\u5177\u4f53\u6765\u8bf4\u662f\u4e00\u4e2a\u7ed3\u6784\u4f53\u6570\u7ec4\uff09\uff0c\u6587\u4ef6\u7cfb\u7edf\u4e0d\u4ec5\u5305\u62ec\u8fd9\u4e2a\u6587\u4ef6\u8bb0\u5f55\u8868\uff0c\u8fd8\u6709\u5bf9\u6587\u4ef6\u7684\u4e00\u7cfb\u5217\u64cd\u4f5c\uff0c\u6587\u4ef6\u7cfb\u7edf\u5411\u4e0a\u63d0\u4f9b\u63a5\u53e3\uff0c\u5185\u90e8\u63d0\u4f9b\u5bf9fd\u548cpathname\u7684\u8f6c\u6362\uff08\u8fd9\u91cc\u7b80\u5355\u7684\u5b9e\u73b0\u6210\u6570\u7ec4\u4e0b\u6807\u548c\u503c\u7684\u8f6c\u5316\uff09\uff0c\u63a5\u53e3\u5c31\u5305\u62ecopen\u554a\u4e4b\u7c7b\u7684\u8fd9\u4e9b\uff0c\u5177\u4f53\u6765\u8bf4syscall\u9700\u8981\u8fd9\u4e9b\u63a5\u53e3\uff0cloader\u4e5f\u9700\u8981\u8fd9\u4e9b\u63a5\u53e3\uff0cloader\u7684\u90a3\u4e2a\u4efb\u52a1\u5c31\u662f\u901a\u8fc7pathname\u8c03\u7528fs_open\u6253\u5f00\u7279\u5b9a\u7684ELF\u6587\u4ef6\u8fdb\u884cload\u5230\u5185\u5b58\u4e2d<\/p>\n\n\n\n

\u611f\u89c9\u8fd9\u4e2a\u6587\u4ef6\u7cfb\u7edf\u786e\u5b9e\u5f88\u7b80\u5355\uff0c\u6ca1\u6709\u76ee\u5f55\u611f\u89c9\u5f88\u5947\u602ahhh<\/p>\n\n\n\n

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Everything is a file<\/mark><\/strong><\/h2>\n\n\n\n

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\"\"<\/figure>\n\n\n\n

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\u7cbe\u5f69\u7eb7\u5448\u7684\u5e94\u7528\u7a0b\u5e8f<\/mark><\/strong><\/h2>\n\n\n\n

\u5b9a\u70b9\u7b97\u672f<\/mark><\/strong><\/h3>\n\n\n\n

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\"\"<\/figure>\n\n\n\n

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\"\"<\/figure>\n\n\n\n

\u6bcf\u6b21\u8fd9\u79cd\u795e\u5947\u7684\u5c0f\u84dd\u6846\u90fd\u8ba9\u6211\u8fd9\u4e2a\u5c0f\u83dc\u9e21\u5b66\u5230\u4e86\u5f88\u591a\ud83d\ude18\uff0cLD_REWLOAD\u662f\u4e00\u79cdtrick\uff0c\u8bbe\u7f6e\u8fd9\u4e2a\u73af\u5883\u53d8\u91cf\uff08\u6216\u8005\u8fd0\u884c\u65f6\u8bbe\u7f6e\u8fd9\u4e2a\u53d8\u91cf\uff09\u4e3a\u81ea\u5df1\u5199\u7684share lib\u90a3\u4e48\u7a0b\u5e8f\u5c31\u4f1a\u4f18\u5148\u5728\u8fd9\u4e2a\u8def\u5f84\u4e2d\u5bfb\u627e\uff0c\u5229\u7528\u8fd9\u4e2atrick\uff0c\u53ef\u4ee5\u5b9e\u73b0\u4fee\u6539\u5e93\u51fd\u6570\u7684\u64cd\u4f5c\uff0c\u4e5f\u5c31\u662f\u81ea\u5df1\u5199\u4e00\u4e2a\u7b26\u53f7\u76f8\u540c\u7684\u5e93\u51fd\u6570\uff0c\u5728\u4f60\u5199\u7684\u51fd\u6570\u4e2d\u4f60\u53ef\u4ee5\u5148\u5c06\u8fd9\u4e2a\u4e0d\u5b58\u5728\u7684\u8def\u5f84\u8f6c\u5316\u4e3a\u771f\u5b9e\u5b58\u5728\u7684\u8def\u5f84\uff0c\u518d\u7528dlsym\u548cRTLD_NEXT\u627e\u5230\u771f\u6b63\u5e93\u7684\u8fd9\u4e2a\u51fd\u6570\uff0c\u8c03\u7528\u8fd9\u4e2a\u771f\u6b63\u7684\u5e93\u51fd\u6570\uff0c\u5b9e\u73b0\u4fee\u6539\u5e93\u51fd\u6570\u7684\u64cd\u4f5c\u3002<\/p>\n\n\n\n

sdlmini<\/mark><\/strong><\/h3>\n\n\n\n

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\"\"<\/figure>\n\n\n\n

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\"\"<\/figure>\n\n\n\n

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\"\"<\/figure>\n\n\n\n
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Nterm\u4ee3\u7801\u9605\u8bfb<\/mark><\/strong><\/h2>\n\n\n\n

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\"\"<\/figure>\n\n\n\n

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