29 lines
651 B
C
29 lines
651 B
C
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#include <asm/processor.h>
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/*
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* __force_order is used by special_insns.h asm code to force instruction
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* serialization.
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*
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* It is not referenced from the code, but GCC < 5 with -fPIE would fail
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* due to an undefined symbol. Define it to make these ancient GCCs work.
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*/
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unsigned long __force_order;
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int l5_paging_required(void)
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{
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/* Check if leaf 7 is supported. */
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if (native_cpuid_eax(0) < 7)
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return 0;
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/* Check if la57 is supported. */
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if (!(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31))))
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return 0;
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/* Check if 5-level paging has already been enabled. */
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if (native_read_cr4() & X86_CR4_LA57)
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return 0;
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return 1;
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}
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