{"id":1922,"date":"2010-11-08T19:53:04","date_gmt":"2010-11-08T11:53:04","guid":{"rendered":"http:\/\/edsionte.com\/techblog\/?p=1922"},"modified":"2011-09-29T11:46:31","modified_gmt":"2011-09-29T03:46:31","slug":"%e8%bf%9b%e7%a8%8b%e8%99%9a%e6%8b%9f%e7%a9%ba%e9%97%b4","status":"publish","type":"post","link":"http:\/\/edsionte.com\/techblog\/archives\/1922","title":{"rendered":"\u8fdb\u7a0b\u7684\u865a\u62df\u5730\u5740\u7a7a\u95f4"},"content":{"rendered":"

\u6211\u4eec\u77e5\u9053\uff0c\u5728x86\u4f53\u7cfb\u7ed3\u6784\u4e2d\u5206\u6bb5\u673a\u5236\u662f\u5fc5\u9009\u7684\uff0c\u800c\u5206\u9875\u673a\u5236\u5219\u53ef\u7531\u5177\u4f53\u7684\u64cd\u4f5c\u7cfb\u7edf\u800c\u9009\u62e9\uff0cLinux\u901a\u8fc7\u8ba9\u6bb5\u7684\u57fa\u5730\u5740\u4e3a0\u800c\u5de7\u5999\u7684\u7ed5\u8fc7\u4e86\u57fa\u5730\u5740\u3002\u56e0\u6b64\uff0c\u5bf9\u4e8eLinux\u6765\u8bf4\uff0c\u865a\u5730\u5740\u548c\u7ebf\u6027\u5730\u5740\u662f\u4e00\u81f4\u7684\u3002\u572832\u4f4d\u7684\u5e73\u53f0\u4e0a\uff0c\u7ebf\u6027\u5730\u5740\u7684\u5927\u5c0f\u4e3a\u56fa\u5b9a\u76844GB\u3002\u5e76\u4e14\uff0c\u7531\u4e8e\u91c7\u7528\u4e86\u4fdd\u62a4\u673a\u5236\uff0cLinux\u5185\u6838\u5c06\u8fd94GB\u5206\u4e3a\u4e24\u90e8\u5206\uff0c\u865a\u5730\u5740\u8f83\u9ad8\u76841GB\uff080xC0000000\u52300xFFFFFFFF\uff09\u4e3a\u5171\u4eab\u7684\u5185\u6838\u7a7a\u95f4\uff1b\u800c\u8f83\u4f4e\u76843GB\uff080x00000000\u52300xBFFFFFFF\uff09\u4e3a\u6bcf\u4e2a\u8fdb\u7a0b\u7684\u7528\u6237\u7a7a\u95f4\u3002\u7531\u4e8e\u6bcf\u4e2a\u8fdb\u7a0b\u90fd\u4e0d\u80fd\u76f4\u63a5\u8bbf\u95ee\u5185\u6838\u7a7a\u95f4\uff0c\u800c\u662f\u901a\u8fc7\u7cfb\u7edf\u8c03\u7528\u95f4\u63a5\u8fdb\u5165\u5185\u6838\uff0c\u56e0\u6b64\uff0c\u6240\u6709\u7684\u8fdb\u7a0b\u90fd\u5171\u4eab\u5185\u6838\u7a7a\u95f4\u3002\u800c\u6bcf\u4e2a\u8fdb\u7a0b\u90fd\u62e5\u6709\u5404\u81ea\u7684\u7528\u6237\u7a7a\u95f4\uff0c\u5404\u4e2a\u8fdb\u7a0b\u4e4b\u95f4\u4e0d\u80fd\u4e92\u76f8\u8bbf\u95ee\u5f7c\u6b64\u7684\u7528\u6237\u7a7a\u95f4\u3002\u56e0\u6b64\uff0c\u5bf9\u4e8e\u6bcf\u4e00\u4e2a\u5177\u4f53\u7684\u8fdb\u7a0b\u800c\u8a00\uff0c\u90fd\u62e5\u67094GB\u7684\u865a\u62df\u5730\u5740\u7a7a\u95f4\u3002<\/p>\n

\u5730\u5740\u6620\u5c04<\/strong><\/p>\n

\u4e00\u4e2a\u7a0b\u5e8f\u5728\u7ecf\u8fc7\u7f16\u8bd1\u3001\u8fde\u63a5\u4e4b\u540e\u5f62\u6210\u7684\u5730\u5740\u7a7a\u95f4\u662f\u4e00\u4e2a\u865a\u62df\u7684\u5730\u5740\u7a7a\u95f4\uff0c\u53ea\u6709\u5f53\u7a0b\u5e8f\u8fd0\u884c\u7684\u65f6\u5019\u624d\u4f1a\u5206\u914d\u5177\u4f53\u7684\u7269\u7406\u7a7a\u95f4\u3002\u7531\u6b64\u6211\u4eec\u53ef\u4ee5\u5f97\u77e5\uff0c\u7a0b\u5e8f\u7684\u865a\u62df\u5730\u5740\u76f8\u5bf9\u6765\u8bf4\u662f\u56fa\u5b9a\u7684\uff0c\u800c\u7269\u7406\u5730\u5740\u5219\u968f\u7740\u6bcf\u4e00\u6b21\u7a0b\u5e8f\u7684\u8fd0\u884c\u800c\u6709\u6240\u4e0d\u540c\u3002<\/p>\n

\u5bf9\u4e8e\u5185\u6838\u7a7a\u95f4\u800c\u8a00\uff0c\u5b83\u4e0e\u7269\u7406\u5185\u5b58\u4e4b\u95f4\u5b58\u5728\u4e00\u4e2a\u7b80\u5355\u7684\u7ebf\u6027\u5173\u7cfb\uff0c\u5373\u5b58\u57283GB\u7684\u504f\u79fb\u91cf\u3002\u5728Linux\u5185\u6838\u4e2d\uff0c\u8fd9\u4e2a\u504f\u79fb\u91cf\u53eb\u505aPAGE_OFFSET\u3002\u5982\u679c\u5185\u6838\u7684\u67d0\u4e2a\u7269\u7406\u5730\u5740\u4e3ax\uff0c\u90a3\u4e48\u5bf9\u5e94\u7684\u5185\u6838\u865a\u5730\u5740\u5c31\u4e3ax+PAGE_OFFSET\u3002<\/p>\n

\u5bf9\u4e8e\u7528\u6237\u7a7a\u95f4\u800c\u8a00\uff0c\u5b83\u4e0e\u7269\u7406\u5185\u5b58\u4e4b\u95f4\u7684\u6620\u5c04\u8fdc\u4e0d\u6b62\u8fd9\u4e48\u7b80\u5355\u3002\u4e0e\u5185\u6838\u7a7a\u95f4\u548c\u7269\u7406\u7a7a\u95f4\u7684\u7ebf\u6027\u6620\u5c04\u4e0d\u540c\u7684\u662f\uff0c\u5206\u9875\u673a\u5236\u5c06\u865a\u62df\u7528\u6237\u7a7a\u95f4\u548c\u7269\u7406\u5730\u5740\u7a7a\u95f4\u5206\u6210\u5927\u5c0f\u76f8\u540c\u7684\u9875\uff0c\u7136\u540e\u518d\u901a\u8fc7\u9875\u8868\u5c06\u865a\u62df\u9875\u548c\u7269\u7406\u9875\u5757\u6620\u5c04\u8d77\u6765\u3002<\/p>\n

\u865a\u62df\u5730\u5740\u7a7a\u95f4\u4e3e\u4f8b<\/strong><\/p>\n

1.\u5185\u6838\u7a7a\u95f4<\/strong><\/p>\n

\u4e00\u822c\u53ef\u4ee5\u901a\u8fc7__get_free_page()\u3001kmalloc()\u548cvmalloc()\u6765\u7533\u8bf7\u5185\u6838\u7a7a\u95f4\u3002\u53ea\u4e0d\u8fc7__get_free_page\u51fd\u6570\u6bcf\u6b21\u7533\u8bf7\u7684\u90fd\u662f\u5b8c\u6574\u7684\u9875\uff1b\u800c\u540e\u4e24\u8005\u5219\u4f9d\u636e\u5177\u4f53\u53c2\u6570\u7533\u8bf7\u4ee5\u5b57\u8282\u4e3a\u5355\u4f4d\u7684\u5185\u5b58\u7a7a\u95f4\u3002\u6b64\u5916\uff0c\u524d\u4e24\u4e2a\u51fd\u6570\u7533\u8bf7\u7684\u865a\u62df\u5730\u5740\u7a7a\u95f4\u548c\u7269\u7406\u5730\u5740\u7a7a\u95f4\u90fd\u662f\u8fde\u7eed\u7684\uff1bvmalloc\u51fd\u6570\u7533\u8bf7\u7684\u7269\u7406\u5730\u5740\u7a7a\u95f4\u5e76\u4e0d\u8fde\u7eed\u3002vmalloc\u51fd\u6570\u901a\u8fc7\u91cd\u65b0\u5efa\u7acb\u865a\u62df\u5730\u5740\u7a7a\u95f4\u548c\u7269\u7406\u5730\u5740\u7a7a\u95f4\u4e4b\u95f4\u7684\u6620\u5c04\uff0c\u5373\u65b0\u5efa\u9875\u8868\u9879\uff0c\u5c06\u79bb\u6563\u7684\u7269\u7406\u5730\u5740\u7a7a\u95f4\u6620\u5c04\u5230\u8fde\u7eed\u7684\u865a\u62df\u5730\u5740\u7a7a\u95f4\u3002\u56e0\u6b64\uff0c\u4f7f\u7528\u8be5\u51fd\u6570\u7684\u5f00\u9500\u6bd4\u8f83\u5927\u3002<\/p>\n

\u4e0b\u9762\u7684\u7a0b\u5e8f\u7b80\u5355\u7684\u6f14\u793a\u4e86\u8fd9\u4e09\u4e2a\u51fd\u6570\u7684\u4f7f\u7528\u65b9\u6cd5\u3002\u4ece\u7ed3\u679c\u4e2d\u53ef\u4ee5\u770b\u51fa\uff0c\u8fd9\u4e9b\u51fd\u6570\u7533\u8bf7\u7684\u5730\u5740\u90fd\u57283GB\uff080xBFFFFFFF\uff09\u4ee5\u4e0a\u3002\u5b8c\u6574\u4ee3\u7801\u5728\u8fd9\u91cc<\/a>\u3002<\/p>\n

static int __init mmshow_init(void)\r\n{\r\n\tprintk(\"mmshow module is working\\n\");\r\n\r\n\tpagemem = __get_free_page(GFP_KERNEL);\r\n\tif(!pagemem)\r\n\t\tgoto gfp_fail;\r\n\tprintk(KERN_INFO \"pagemem = 0x%lx\\n\",pagemem);\r\n\r\n\tkmallocmem = kmalloc(100 * sizeof(char),GFP_KERNEL);\r\n\tif(!kmallocmem)\r\n\t\tgoto kmalloc_fail;\r\n\tprintk(KERN_INFO \"kmallocmem = 0x%p\\n\",kmallocmem);\r\n\r\n\tvmallocmem = vmalloc(1000000 * sizeof(char));\r\n\tif(!vmallocmem)\r\n\t\tgoto vmalloc_fail;\r\n\tprintk(KERN_INFO \"vmallocmem = 0x%p\\n\",vmallocmem);\r\n\r\n\treturn 0;\r\n\r\ngfp_fail:\r\n\tfree_page(pagemem);\r\nkmalloc_fail:\r\n\tkfree(kmallocmem);\r\nvmalloc_fail:\r\n\tvfree(vmallocmem);\r\n\r\n\treturn -1;\r\n}\r\n\/\/\u8fd0\u884c\u7ed3\u679c\uff1a\r\n[ 5542.073900] mmshow module is working\r\n[ 5542.073904] pagemem = 0xf3211000\r\n[ 5542.073907] kmallocmem = 0xd581e700\r\n[ 5542.073983] vmallocmem = 0xf9251000<\/pre>\n
2.\u7528\u6237\u7a7a\u95f4<\/strong><\/p>\n
<\/strong>\u5982\u524d\u6240\u8ff0\uff0c\u6bcf\u4e2a\u8fdb\u7a0b\u591f\u62e5\u6709\u5c5e\u4e8e\u81ea\u5df1\u76843GB\u7684\u865a\u62df\u7a7a\u95f4\uff0c\u90a3\u4e48\u8fd9\u4e2a3GB\u7684\u7a7a\u95f4\u662f\u5982\u4f55\u5212\u5206\u7684\uff1f\u901a\u5e38\uff0c\u9664\u4e86\u6211\u4eec\u719f\u6089\u7684\u4ee3\u7801\u6bb5\u548c\u6570\u636e\u6bb5\uff0c\u7528\u6237\u7a7a\u95f4\u8fd8\u5305\u62ec\u5806\u6808\u6bb5\u548c\u5806\u3002\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u4e0b\u9762\u7684\u6f14\u793a\u7a0b\u5e8f\u6765\u4e86\u89e3\u8fd9\u4e9b\u533a\u57df\u5230\u5e95\u8d1f\u8d23\u5b58\u50a8\u7a0b\u5e8f\u7684\u90a3\u4e9b\u5185\u5bb9\u3002<\/p>\n
int bss_var;\r\nint data_var0 = 1;\r\n\r\nint main(int argc,char **argv)\r\n{\r\n\tprintf(\"The user space's address division of a process as follow:\\n\");\r\n\tprintf(\"Data segment:\\n\");\r\n\tprintf(\"address of \\\"main\\\" function:%p\\n\\n\",main);\r\n\r\n        printf(\"Data segment:\\n\");\r\n\tprintf(\"address of data_var:%p\\n\",&data_var0);\r\n\tstatic int data_var1 = 4;\r\n\tprintf(\"new end of data_var:%p\\n\\n\",&data_var1);\r\n\r\n        printf(\"BSS:\\n\");\r\n\tprintf(\"address of bss_var:%p\\n\\n\",&bss_var);\r\n\r\n\tchar *str = (char *)malloc(sizeof(char)*10);\r\n\tprintf(\"initial heap end:%p\\n\",str);\r\n\tchar *buf = (char *)malloc(sizeof(char)*10);\r\n\tprintf(\"new heap end:%p\\n\\n\",buf);\r\n\r\n        int stack_var0 = 2;\r\n\tprintf(\"Stack segment:\\n\");\r\n\tprintf(\"initial end of stack:%p\\n\",&stack_var0);\r\n\tint stack_var1 = 3;\r\n\tprintf(\"new end of stack:%p\\n\",&stack_var1);\r\n\r\n\treturn 0;\r\n}\r\n\/\/\u8fd0\u884c\u7ed3\u679c\uff1a\r\nThe user space's address division of a process as follow:\r\nData segment:\r\naddress of \"main\" function:0x8048454\r\nData segment:\r\naddress of data_var:0x804a01c\r\nnew end of data_var:0x804a020\r\nBSS:\r\naddress of bss_var:0x804a02c\r\ninitial heap end:0x8f77008\r\nnew heap end:0x8f77018\r\nStack segment:\r\ninitial end of stack:0xbfe0a3b4\r\nnew end of stack:0xbfe0a3b0<\/pre>\n
\u53ef\u4ee5\u770b\u5230\uff0c\u4ee3\u7801\u6bb5\u5b58\u653e\u7a0b\u5e8f\u7684\u4ee3\u7801\uff1b\u6570\u636e\u6bb5\u5b58\u653e\u5168\u5c40\u53d8\u91cf\u548cstatic\u7c7b\u578b\u7684\u5c40\u90e8\u53d8\u91cf\u3002\u6b64\u5916\uff0c\u672a\u521d\u59cb\u5316\u7684\u5168\u5c40\u53d8\u91cf\u867d\u7136\u4e5f\u5b58\u5728\u4e8e\u6570\u636e\u6bb5\uff0c\u4f46\u662f\u8fd9\u4e9b\u672a\u521d\u59cb\u5316\u7684\u53d8\u91cf\u90fd\u96c6\u4e2d\u5728\u9760\u8fd1\u6570\u636e\u6bb5\u4e0a\u8fb9\u754c\u7684\u533a\u57df\uff0c\u8fd9\u4e2a\u533a\u57df\u79f0\u4e3aBSS\u6bb5\u3002\u4ee5\u4e0a\u8fd9\u4e9b\u7a7a\u95f4\u662f\u8fdb\u7a0b\u6240\u5fc5\u987b\u62e5\u6709\u7684\uff0c\u5b83\u4eec\u5728\u8fdb\u7a0b\u8fd0\u884c\u4e4b\u524d\u5c31\u5206\u914d\u597d\u4e86\u3002<\/p>\n
\u7a0b\u5e8f\u4e2d\u7684\u5c40\u90e8\u53d8\u91cf\u4e00\u822c\u88ab\u5206\u914d\u5728\u5806\u6808\u6bb5\uff0c\u5176\u4f4d\u4e8e\u7528\u6237\u7a7a\u95f4\u6700\u9876\u90e8\u3002\u4e0e\u56fa\u5b9a\u7684\u4ee3\u7801\u6bb5\u548c\u6570\u636e\u6bb5\u4e0d\u540c\u7684\u662f\uff0c\u5806\u6808\u6bb5\u5b58\u50a8\u6570\u636e\u662f\u4ece\u9ad8\u4f4e\u503c\u5f80\u4f4e\u5730\u5740\u5ef6\u4f38\u7684\u3002\u56e0\u6b64\uff0c\u5728\u6570\u636e\u6bb5\u5230\u5806\u6808\u6bb5\u4e4b\u95f4\uff0c\u5f62\u6210\u4e86\u4e00\u7247\u7a7a\u6d1e\uff0c\u8fd9\u7247\u7a7a\u6d1e\u7528\u4e8e\u5b58\u50a8malloc\u51fd\u6570\u6240\u52a8\u6001\u5206\u914d\u7684\u7a7a\u95f4\uff0c\u8fd9\u7247\u7a7a\u6d1e\u533a\u57df\u88ab\u79f0\u4e3a\u5806\u3002<\/p>\n
\u901a\u8fc7\u4e0b\u9762\u8fd9\u4e2a\u56fe\u53ef\u4ee5\u66f4\u8fdb\u4e00\u6b65\u7684\u4e86\u89e3\u5230\u8fdb\u7a0b\u7528\u6237\u7a7a\u95f4\u7684\u5212\u5206\u60c5\u51b5\u3002<\/p>\n
\"\"<\/a>\u4ee5\u4e0a\u662f\u5173\u4e8e\u8fdb\u7a0b\u7528\u6237\u7a7a\u95f4\u5212\u5206\u7684\u5927\u81f4\u5206\u6790\uff0c\u4e0a\u8ff0\u7406\u8bba\u5728\u5185\u6838\u4ee3\u7801\u4e2d\u5982\u4f55\u4f53\u73b0\uff1f\u5b83\u5c06\u6d89\u53ca\u5230mm_struct\u7ed3\u6784\u548cvm_area_struct\u7ed3\u6784\u3002\u4e0b\u6587\u4e2d\uff0c\u5c06\u4f1a\u5bf9\u8fd9\u4e24\u4e2a\u7ed3\u6784\u6709\u8be6\u7ec6\u5206\u6790\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
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