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/*
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 * outputs a cpuid key for use in context keyed payload encoding.
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 *
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 * Author: Dimitris Glynos <dimitris at census-labs.com>
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 */
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#include <stdio.h>
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int main()
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{
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	unsigned long eax;
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        asm (
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		"xorl %%esi, %%esi;" /* esi is key store, zero it out */
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		"xorl %%edi, %%edi;" /* edi is loop iterator, ditto */
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		"cpuid_loop: movl %%edi, %%eax;" /* iterator is first arg 
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                                                    to cpuid */
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		"xorl %%ecx, %%ecx;" /* ecx is also used as arg to cpuid but
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                                        we'll use it always as zero */
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		"cpuid;"
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		"xorl %%eax, %%esi;"
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		"cmpl %%esi, %%eax;" 	/* first time round esi = eax */
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					/* not very safe heh? */
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		"jne not_first_time;"
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		"leal 0x1(%%eax, 1), %%edi;" /* first time round ... */
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		"not_first_time: xorl %%ebx, %%esi;"
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		"xorl %%ecx, %%esi;"
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		"xorl %%edx, %%esi;"
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		"subl $1, %%edi;"
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		"jne cpuid_loop;"
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		"movl %%esi, %%eax;"
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                : "=a" (eax)
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        );
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	printf("%#.8lx\n", eax);
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	return 0;
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}
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