{"id":2163,"date":"2010-12-08T16:06:15","date_gmt":"2010-12-08T08:06:15","guid":{"rendered":"http:\/\/edsionte.com\/techblog\/?p=2163"},"modified":"2011-05-29T13:25:12","modified_gmt":"2011-05-29T05:25:12","slug":"%e7%b3%bb%e7%bb%9f%e8%b0%83%e7%94%a8%e7%9a%84%e6%89%a7%e8%a1%8c%e8%bf%87%e7%a8%8b","status":"publish","type":"post","link":"http:\/\/edsionte.com\/techblog\/archives\/2163","title":{"rendered":"\u7cfb\u7edf\u8c03\u7528\u7684\u6267\u884c\u8fc7\u7a0b"},"content":{"rendered":"<p>\u5f53\u7528\u6237\u6001\u7684\u8fdb\u7a0b\u8c03\u7528\u4e00\u4e2a\u7cfb\u7edf\u8c03\u7528\u65f6\uff0cCPU\u5207\u6362\u5230\u5185\u6838\u6001\u5e76\u5f00\u59cb\u6267\u884c\u4e00\u4e2a\u5185\u6838\u51fd\u6570\u3002\u5728X86\u4f53\u7cfb\u4e2d\uff0c\u53ef\u4ee5\u901a\u8fc7\u4e24\u79cd\u4e0d\u540c\u7684\u65b9\u5f0f\u8fdb\u5165\u7cfb\u7edf\u8c03\u7528\uff1a\u6267\u884cint $0x80\u6c47\u7f16\u547d\u4ee4\u548c\u6267\u884csysenter\u6c47\u7f16\u547d\u4ee4\u3002\u540e\u8005\u662fIntel\u5728PentiumII\u4e2d\u5f15\u5165\u7684\u6307\u4ee4\uff0c\u5185\u6838\u4ece2.6\u7248\u672c\u5f00\u59cb\u652f\u6301\u8fd9\u6761\u547d\u4ee4\u3002\u672c\u6587\u5c06\u96c6\u4e2d\u8ba8\u8bba\u4ee5int $0x80\u65b9\u5f0f\u8fdb\u5165\u7cfb\u7edf\u8c03\u7528\u7684\u8fc7\u7a0b\u3002<\/p>\n<p>\u901a\u8fc7int $0x80\u65b9\u5f0f\u8c03\u7528\u7cfb\u7edf\u8c03\u7528\u5b9e\u9645\u4e0a\u662f\u7528\u6237\u8fdb\u7a0b\u4ea7\u751f\u4e00\u4e2a\u4e2d\u65ad\u5411\u91cf\u53f7\u4e3a0x80\u7684\u8f6f\u4e2d\u65ad\u3002\u5f53\u7528\u6237\u6001\u8fdb\u7a0b\u53d1\u51faint $0x80\u6307\u4ee4\u65f6\uff0cCPU\u5c06\u4ece\u7528\u6237\u6001\u5207\u6362\u5230\u5185\u6838\u6001\u5e76\u5f00\u59cb\u6267\u884csystem_call()\u3002\u8fd9\u4e2a\u51fd\u6570\u662f\u901a\u8fc7\u6c47\u7f16\u547d\u4ee4\u6765\u5b9e\u73b0\u7684\uff0c\u5b83\u662f0x80\u53f7\u8f6f\u4e2d\u65ad\u5bf9\u5e94\u7684\u4e2d\u65ad\u5904\u7406\u7a0b\u5e8f\u3002\u5bf9\u4e8e\u6240\u6709\u7cfb\u7edf\u8c03\u7528\u6765\u8bf4\uff0c\u5b83\u4eec\u90fd\u5fc5\u987b\u5148\u8fdb\u5165system_call()\uff0c\u4e5f\u5c31\u662f\u6240\u8c13\u7684\u7cfb\u7edf\u8c03\u7528\u5904\u7406\u7a0b\u5e8f\u3002\u518d\u901a\u8fc7\u7cfb\u7edf\u8c03\u7528\u53f7\u8df3\u8f6c\u5230\u5177\u4f53\u7684\u7cfb\u7edf\u8c03\u7528\u670d\u52a1\u4f8b\u7a0b\u5904\u3002<\/p>\n<p>\u5728\u8be5\u51fd\u6570\u6267\u884c\u4e4b\u524d\uff0cCPU\u63a7\u5236\u5355\u5143\u5df2\u7ecf\u5c06eflags\u3001cs\u3001eip\u3001ss\u548cesp\u5bc4\u5b58\u5668\u7684\u503c\u81ea\u52a8\u4fdd\u5b58\u5230\u8be5\u8fdb\u7a0b\u5bf9\u5e94\u7684\u5185\u6838\u6808\u4e2d\u3002\u968f\u4e4b\uff0c\u5728system_call\u5185\u90e8\u9996\u5148\u5c06\u5b58\u50a8\u5728eax\u5bc4\u5b58\u5668\u4e2d\u7684\u7cfb\u7edf\u8c03\u7528\u53f7\u538b\u5165\u6808\u4e2d\u3002\u63a5\u7740\u6267\u884cSAVE_ALL\u5b8f\u3002\u8be5\u5b8f\u5728\u6808\u4e2d\u4fdd\u5b58\u63a5\u4e0b\u6765\u7684\u7cfb\u7edf\u8c03\u7528\u53ef\u80fd\u8981\u7528\u5230\u7684\u6240\u6709CPU\u5bc4\u5b58\u5668\u3002<\/p>\n<pre class=\"brush:c\"> \r\n\/linux\/arch\/i386\/kernel\/entry.S\r\n 241ENTRY(system_call)\r\n 242        pushl %eax                      # save orig_eax\r\n 243        SAVE_ALL<\/pre>\n<p>\u901a\u8fc7GET_THREAD_INFO\u5b8f\u83b7\u5f97\u5f53\u524d\u8fdb\u7a0b\u7684thread_inof\u7ed3\u6784\u7684\u5730\u5740\uff1b\u518d\u68c0\u6d4b\u5f53\u524d\u8fdb\u7a0b\u662f\u5426\u88ab\u5176\u4ed6\u8fdb\u7a0b\u6240\u8ddf\u8e2a\uff0c\u4e5f\u5c31\u662fthread_inof\u7ed3\u6784\u4e2dflag\u5b57\u6bb5\u7684_TIF_SYSCALL_TRACE\u6216_TIF_SYSCALL_AUDIT\u88ab\u7f6e1\u3002\u5982\u679c\u53d1\u751f\u88ab\u8ddf\u8e2a\u7684\u60c5\u51b5\u5219\u8f6c\u5411\u76f8\u5e94\u7684\u5904\u7406\u547d\u4ee4\u5904\u3002<\/p>\n<pre class=\"brush:c\"> \r\n 244        GET_THREAD_INFO(%ebp)\r\n 245        # system call tracing in operation\r\n 246        testb $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),TI_flags(%ebp)\r\n 247        jnz syscall_trace_entry<\/pre>\n<p>\u63a5\u7740\uff0c\u5bf9\u7528\u6237\u6001\u8fdb\u7a0b\u4f20\u9012\u8fc7\u6765\u7684\u7cfb\u7edf\u8c03\u7528\u53f7\u7684\u5408\u6cd5\u6027\u8fdb\u884c\u68c0\u67e5\u3002\u5982\u679c\u4e0d\u5408\u6cd5\u5219\u8df3\u5165\u5230syscall_badsys\u6807\u8bb0\u7684\u547d\u4ee4\u5904\u3002<\/p>\n<pre class=\"brush:c\"> \r\n 248        cmpl $(nr_syscalls), %eax\r\n 249        jae syscall_badsys<\/pre>\n<p>\u5982\u679c\u7cfb\u7edf\u8c03\u7528\u597d\u5408\u6cd5\uff0c\u5219\u8df3\u5165\u76f8\u5e94\u7cfb\u7edf\u8c03\u7528\u53f7\u6240\u5bf9\u5e94\u7684\u670d\u52a1\u4f8b\u7a0b\u5f53\u4e2d\uff0c\u4e5f\u5c31\u662f\u5728sys_call_table\u8868\u4e2d\u627e\u5230\u4e86\u76f8\u5e94\u7684\u51fd\u6570\u5165\u53e3\u70b9\u3002\u7531\u4e8esys_call_table\u8868\u7684\u8868\u9879\u53604\u5b57\u8282\uff0c\u56e0\u6b64\u83b7\u5f97\u670d\u52a1\u4f8b\u7a0b\u6307\u9488\u7684\u5177\u4f53\u65b9\u6cd5\u662f\u5c06\u7531eax\u4fdd\u5b58\u7684\u7cfb\u7edf\u8c03\u7528\u53f7\u4e58\u4ee54\u518d\u4e0esys_call_table\u8868\u7684\u57fa\u5740\u76f8\u52a0\u3002<\/p>\n<p>\u5f53\u7cfb\u7edf\u8c03\u7528\u670d\u52a1\u4f8b\u7a0b\u7ed3\u675f\u65f6\uff0c\u4eceeax\u5bc4\u5b58\u5668\u4e2d\u83b7\u5f97\u5f53\u524d\u8fdb\u7a0b\u7684\u7684\u8fd4\u56de\u503c\uff0c\u5e76\u628a\u8fd9\u4e2a\u8fd4\u56de\u503c\u5b58\u653e\u5728\u66fe\u4fdd\u5b58\u7528\u6237\u6001eax\u5bc4\u5b58\u5668\u503c\u7684\u90a3\u4e2a\u6808\u5355\u5143\u7684\u4f4d\u7f6e\u4e0a\u3002\u8fd9\u6837\uff0c\u7528\u6237\u6001\u8fdb\u7a0b\u5c31\u53ef\u4ee5\u5728eax\u5bc4\u5b58\u5668\u4e2d\u627e\u5230\u7cfb\u7edf\u8c03\u7528\u7684\u8fd4\u56de\u7801\u3002<\/p>\n<pre class=\"brush:c\">\r\n 250syscall_call:\r\n 251        call *sys_call_table(,%eax,4)\r\n 252        movl %eax,EAX(%esp)             # store the return value<\/pre>\n<p>\u81f3\u6b64\uff0c\u7528\u6237\u8fdb\u7a0b\u8fdb\u5165\u7cfb\u7edf\u8c03\u7528\u7684\u8fc7\u7a0b\u5927\u81f4\u5206\u6790\u5b8c\u6bd5\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5f53\u7528\u6237\u6001\u7684\u8fdb\u7a0b\u8c03\u7528\u4e00\u4e2a\u7cfb\u7edf\u8c03\u7528\u65f6\uff0cCPU\u5207\u6362\u5230\u5185\u6838\u6001\u5e76\u5f00\u59cb\u6267\u884c\u4e00\u4e2a\u5185\u6838\u51fd\u6570\u3002\u5728X86\u4f53\u7cfb\u4e2d\uff0c\u53ef\u4ee5\u901a\u8fc7\u4e24\u79cd\u4e0d\u540c\u7684 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[110],"tags":[161,179],"class_list":["post-2163","post","type-post","status-publish","format-standard","hentry","category-linux","tag-161","tag-179"],"views":16325,"_links":{"self":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/2163","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/comments?post=2163"}],"version-history":[{"count":0,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/2163\/revisions"}],"wp:attachment":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/media?parent=2163"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/categories?post=2163"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/tags?post=2163"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}