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34 lines
840 B
C
34 lines
840 B
C
/*
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This illustrates operations which are only possible in ring 0.
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https://stackoverflow.com/questions/7415515/how-to-access-the-control-registers-cr0-cr2-cr3-from-a-program-getting-segmenta/7419306#7419306
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It only works for x86_64.
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Then try to run this on userland and see the process be killed:
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/ring0.out
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include "ring0.h"
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static int myinit(void)
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{
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#if defined(__x86_64__) || defined(__i386__)
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Ring0Regs ring0_regs;
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ring0_get_control_regs(&ring0_regs);
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pr_info("cr0 = 0x%8.8llX\n", (unsigned long long)ring0_regs.cr0);
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pr_info("cr2 = 0x%8.8llX\n", (unsigned long long)ring0_regs.cr2);
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pr_info("cr3 = 0x%8.8llX\n", (unsigned long long)ring0_regs.cr3);
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#endif
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return 0;
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}
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static void myexit(void) {}
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module_init(myinit)
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module_exit(myexit)
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MODULE_LICENSE("GPL");
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