81 lines
2.8 KiB
C++
81 lines
2.8 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2013.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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Sortix. If not, see <http://www.gnu.org/licenses/>.
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sortix/kernel/cpuid.h
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Interface to using the cpuid instruction.
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*******************************************************************************/
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#ifndef INCLUDE_SORTIX_KERNEL_CPUID_H
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#define INCLUDE_SORTIX_KERNEL_CPUID_H
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#include <stdint.h>
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namespace Sortix {
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#if defined(__i386__) || defined(__x86_64__)
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__attribute__((const))
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__attribute__((unused))
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static inline bool IsCPUIdSupported()
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{
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#if defined(__x86_64__)
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// TODO: Isn't this always supported under x86_64?
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uint64_t id_supported;
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asm ("pushfq\n\t"
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"popq %%rax /* Get EFLAGS into EAX */\n\t"
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"movq %%rax, %%rcx /* Save original flags in ECX */\n\t"
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"xorq $0x200000, %%rax /* Flip ID bit in EFLAGS */\n\t"
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"pushq %%rax /* Store modified EFLAGS on stack */\n\t"
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"popfq /* Replace current EFLAGS */\n\t"
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"pushfq /* Read back the EFLAGS */\n\t"
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"popq %%rax /* Get EFLAGS into EAX */\n\t"
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"xorq %%rcx, %%rax /* Check if flag could be modified */\n\t"
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: "=a" (id_supported)
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: /* No inputs. */
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: /* Clobbered: */ "%rcx");
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#elif defined(__i386__)
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uint32_t id_supported;
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asm ("pushfl\n\t"
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"popl %%eax /* Get EFLAGS into EAX */\n\t"
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"movl %%eax, %%ecx /* Save original flags in ECX */\n\t"
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"xorl $0x200000, %%eax /* Flip ID bit in EFLAGS */\n\t"
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"pushl %%eax /* Store modified EFLAGS on stack */\n\t"
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"popfl /* Replace current EFLAGS */\n\t"
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"pushfl /* Read back the EFLAGS */\n\t"
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"popl %%eax /* Get EFLAGS into EAX */\n\t"
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"xorl %%ecx, %%eax /* Check if flag could be modified */\n\t"
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: "=a" (id_supported)
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: /* No inputs. */
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: /* Clobbered: */ "%rcx");
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#endif
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return id_supported != 0;
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}
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#define cpuid(num,a,b,c,d) \
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asm volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1" \
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: "=a" (a), "=r" (b), "=c" (c), "=d" (d) \
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: "0" (num))
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#endif
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} // namespace Sortix
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#endif
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