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