[MODERN FEATURES] CPUID and MSR

kernel/arch/cpuid.c

@@ -0,0 +1,27 @@
+#include <cpuid.h>
+#include <stdint.h>
+#include <debug.h>
+
+uint32_t cpuid_features_b, cpuid_features_c, cpuid_features_d;
+uint32_t cpuid_featuresx_b, cpuid_featuresx_c, cpuid_featuresx_d;
+uint32_t cpuid_signature;
+uint32_t cpuid_max=0x0, cpuid_maxx=0x80000000;
+
+
+void cpuid(uint32_t code, uint32_t *a, uint32_t *b, uint32_t *c, uint32_t *d)
+{
+  uint32_t scrap;
+  if(!a) a = &scrap;
+  if(!b) b = &scrap;
+  if(!c) c = &scrap;
+  if(!d) d = &scrap;
+
+  if((code < CPUID_FUNCTIONX_VENDOR && code > cpuid_max) || code > cpuid_maxx)
+  {
+    *a = *b = *c = *d = -1;
+    return;
+  }
+
+  asm volatile("cpuid" : "=a"(*a), "=b"(*b), "=c"(*c), "=d"(*d) : "a"(code));
+}
+

kernel/arch/msr.c

@@ -0,0 +1,13 @@
+#include <stdint.h>
+
+uint64_t msr_read(uint32_t msr)
+{
+  uint64_t lo, hi;
+  asm volatile("rdmsr" : "=a"(lo), "=d"(hi) : "c"(msr));
+  return ((hi&0xFFFFFFFF) << 32) | (lo&0xFFFFFFFF);
+}
+
+void msr_write(uint32_t msr, uint64_t value)
+{
+  asm volatile("wrmsr" : : "a" (value&0xFFFFFFFF), "d"(value>>32), "c"(msr));
+}

kernel/boot/boot.S

@@ -1,5 +1,6 @@
 .intel_syntax noprefix
 #include <mem.h>
+#include <cpuid.h>
 
 .section .data
 // Some room to store the bootloader return values
@@ -84,6 +85,26 @@ long_mode_start:
   mov rax, 0x0
   mov [V2P(BootP4)], rax
 
+  // CPUID
+#define CPUID(function) mov rax, (function); cpuid;
+#define STORE(reg, variable) movabs r8, offset (variable); mov dword ptr [r8], (reg);
+  // Store max CPUID function numbers
+  CPUID(CPUID_FUNCTION_VENDOR)
+  STORE(eax, cpuid_max)
+  CPUID(CPUID_FUNCTIONX_VENDOR)
+  STORE(eax, cpuid_maxx)
+  // Store CPUID features
+  CPUID(CPUID_FUNCTION_FEATURES)
+  STORE(eax, cpuid_signature)
+  STORE(ebx, cpuid_features_b)
+  STORE(ecx, cpuid_features_c)
+  STORE(edx, cpuid_features_d)
+  // ...and extended features
+  CPUID(CPUID_FUNCTIONX_FEATURES)
+  STORE(ebx, cpuid_featuresx_b)
+  STORE(ecx, cpuid_featuresx_c)
+  STORE(edx, cpuid_featuresx_d)
+
   // Get the saved bootloader data and pass to kmain
   movabs rax, MultiBootMagic
   mov rdi, rax

kernel/boot/kmain.c

@@ -6,6 +6,7 @@
 #include <scheduler.h>
 #include <thread.h>
 #include <process.h>
+#include <cpuid.h>
 
 void thread_function()
 {
@@ -31,6 +32,11 @@ int kmain(uint64_t multiboot_magic, void *multiboot_data)
   scheduler_init();
   pic_init();
 
+  debug_info("CPUID - max function number: Normal:%x, Extended:%x\n", cpuid_max, cpuid_maxx);
+  debug_info("CPUID - has MSR:%d\n", CPUID_FEATURE_MSR);
+  debug_info("CPUID - has APIC:%d\n", CPUID_FEATURE_APIC);
+  debug_info("CPUID - has SYSCALL:%d\n", CPUID_FEATURE_SYSCALL);
+
   process_t *p1 = process_spawn(0);
   process_t *p2 = process_spawn(p1);
 
@@ -52,7 +58,6 @@ int kmain(uint64_t multiboot_magic, void *multiboot_data)
   scheduler_insert(t2);
   scheduler_insert(t3);
 
-  IRQ_UNMASK(IRQ_TIMER);
   asm("sti");
   debug_info("BOOT COMPLETE\n");
   schedule();

kernel/include/cpuid.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#define CPUID_FUNCTION_VENDOR   0x00000000
+#define CPUID_FUNCTION_FEATURES 0x00000001
+#define CPUID_FUNCTION_TLB      0x00000003
+#define CPUID_FUNCTION_SERIAL   0x00000004
+
+#define CPUID_FUNCTIONX_VENDOR    0x80000000
+#define CPUID_FUNCTIONX_FEATURES  0x80000001
+#define CPUID_FUNCTIONX_BRAND0    0x80000002
+#define CPUID_FUNCTIONX_BRAND1    0x80000003
+#define CPUID_FUNCTIONX_BRAND2    0x80000004
+
+#define CPUID_FEATURE_MSR (cpuid_features_d & 1<<5)
+#define CPUID_FEATURE_APIC (cpuid_features_d & 1<<9)
+#define CPUID_FEATURE_SYSCALL (cpuid_featuresx_d & 1<<11)
+
+#ifndef __ASSEMBLER__
+
+#include <stdint.h>
+
+void cpuid(uint32_t code, uint32_t *a, uint32_t *b, uint32_t *c, uint32_t *d);
+
+extern uint32_t cpuid_features_b, cpuid_features_c, cpuid_features_d;
+extern uint32_t cpuid_featuresx_b, cpuid_featuresx_c, cpuid_featuresx_d;
+extern uint32_t cpuid_signature;
+extern uint32_t cpuid_max, cpuid_maxx;
+
+#endif

kernel/include/msr.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#define MSR_APIC_BASE     0x0000001B
+#define MSR_REG_EFER      0xc0000080
+#define MSR_REG_STAR      0xc0000081
+#define MSR_REG_LSTAR     0xc0000082
+#define MSR_REG_FMASK     0xc0000084
+#define MSR_REG_USER_GS   0xc0000101
+#define MSR_REG_KERNEL_GS 0xc0000102
+
+#ifndef __ASSEMBLER__
+
+#include <stdint.h>
+uint64_t msr_read(uint32_t msr);
+void msr_write(uint32_t msr, uint64_t value);
+
+#endif