refactor

kernel/arch/x86_64/percpu.c

@@ -10,6 +10,12 @@
 #include <x86_64/syscall.h>
 #include <x86_64/tsc.h>
 
+struct percpu* arch_percpu_get() {
+    struct percpu* result;
+    asm volatile("mov %0, gs:0" : "=r"(result)::"memory");
+    return result;
+}
+
 void arch_percpu_bsp_init() {
     asm_wrmsr(MSR_GS_BASE, (uint64_t)&percpu_bsp);
     asm_wrmsr(MSR_FS_BASE, 0);
@@ -33,9 +39,9 @@ union ia32_star {
 static_assert(sizeof(union ia32_star) == 8);
 
 static void setup_cpu(struct percpu* cpu) {
+    asm_wrmsr(MSR_KERNEL_GS_BASE, 0);
     asm_wrmsr(MSR_GS_BASE, (uint64_t)cpu);
     asm_wrmsr(MSR_FS_BASE, 0);
-    asm_wrmsr(MSR_KERNEL_GS_BASE, 0);
 
     gdt_load();
     idt_load();
@@ -49,6 +55,8 @@ static void setup_cpu(struct percpu* cpu) {
     asm_wrmsr(MSR_LSTAR, (uint64_t)arch_syscall_stub);
     asm_wrmsr(MSR_SFMASK, RFLAGS_AC | RFLAGS_DF | RFLAGS_IF);
 
+    // TODO: FRED
+
     uint64_t cr0, cr4;
     asm volatile("mov %0, cr0" : "=r"(cr0));
     asm volatile("mov %0, cr4" : "=r"(cr4));