mirror of
https://github.com/winterknife/EVENSTAR
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winterknife
69 lines
2.8 KiB
C++
69 lines
2.8 KiB
C++
// ========================================================================
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// File: GetCurrentProcessorNumber.cpp
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//
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// Author: winterknife
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//
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// Description: Source file that contains the necessary routines to retrieve
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// the current logical processor ID
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//
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// Modifications:
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// 2025-07-01 Created
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// 2025-07-07 Updated
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// ========================================================================
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// ========================================================================
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// Includes
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// ========================================================================
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#include "../Inc/GetCurrentProcessorNumber.h"
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// ========================================================================
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// Routines
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// ========================================================================
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#pragma region ROUTINES
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_Use_decl_annotations_
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DWORD __stdcall get_current_processor_number(
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VOID
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) {
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// Init local variables
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CPUID_REGISTERS cpuidRegisters; ZERO_MEMORY(&cpuidRegisters, sizeof(CPUID_REGISTERS));
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DWORD dwIa32TscAux = 0;
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DWORD dwSegmentLimit = 0;
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QWORD qwRflags = 0;
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// Check if processor supports the RDPID instruction for reading the IA32_TSC_AUX MSR value
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// RDPID instruction support is only available since Sunny Cove Intel microarchitecture (2019)
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__cpuidex((int*)&cpuidRegisters, 0x07, 0x00);
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if (_bittest((const LONG*)&cpuidRegisters.dwECX, 22)) {
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return _rdpid_u32(); // RDPID — Read Processor ID
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}
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else {
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// Check if processor supports the RDTSCP instruction and the IA32_TSC_AUX MSR
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// RDTSCP and IA32_TSC_AUX support are only available since Nehalem Intel microarchitecture (2008)
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__cpuidex((int*)&cpuidRegisters, 0x80000001, 0x00);
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if (_bittest((const LONG*)&cpuidRegisters.dwEDX, 27)) {
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__rdtscp((unsigned int*)&dwIa32TscAux); // RDTSCP — Read Time-Stamp Counter and Processor ID
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return dwIa32TscAux;
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}
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else {
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// Get the segment limit of the 32-bit TEB segment
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dwSegmentLimit = __segmentlimit(KGDT_R3_TEB | RPL_MASK); // LSL — Load Segment Limit
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// Check if EFLAGS.ZF is set
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// If the segment descriptor cannot be accessed or is an invalid type for the instruction, the EFLAGS.ZF flag is cleared
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qwRflags = __readeflags(); // PUSHF/PUSHFD/PUSHFQ — Push EFLAGS Register Onto the Stack
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if (_bittest64((const LONG64*)&qwRflags, 6)) {
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// Read the processor ID from the segment limit
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// In Windows, the segment limit of the segment descriptor selected by the TEB selector contains the current logical processor's ID in bits 14 to 19
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return (dwSegmentLimit >> 0xE);
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}
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else {
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return 0xFFFFFFFFUL;
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}
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}
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}
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}
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#pragma endregion |