From e21b608af4690aeee2482eb6a23c0709e0df8fa1 Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Fri, 14 Oct 2022 17:21:16 +0200
Subject: [PATCH] Utilities: Start moving utilities into specific headers in a
 utils/ subdirectory

---
 kernel/include/misc/utils.h          |  7 ----
 kernel/include/utils/Registers.h     | 52 ++++++++++++++++++++++++++++
 kernel/src/interrupts/Interrupts.cpp |  4 +--
 kernel/src/main.asm                  |  6 ++++
 kernel/src/memory/VMM.cpp            |  4 +--
 kernel/src/thread/Scheduler.cpp      |  3 +-
 6 files changed, 64 insertions(+), 12 deletions(-)
 create mode 100644 kernel/include/utils/Registers.h

diff --git a/kernel/include/misc/utils.h b/kernel/include/misc/utils.h
index 7bb36f17..c7660111 100644
--- a/kernel/include/misc/utils.h
+++ b/kernel/include/misc/utils.h
@@ -5,8 +5,6 @@
 #define PAGE_SIZE 4096
 #endif
 
-extern "C" uint64_t asm_get_rflags();
-
 namespace Utilities
 {
     inline uint64_t get_blocks_from_size(uint64_t blocksize, uint64_t size)
@@ -14,11 +12,6 @@ namespace Utilities
         return (size + (blocksize - 1)) / blocksize;
     }
 
-    inline uint64_t get_rflags()
-    {
-        return asm_get_rflags();
-    }
-
     inline uint64_t get_top_of_stack(uint64_t bottom, uint64_t stack_pages)
     {
         return bottom + (stack_pages * PAGE_SIZE) - sizeof(uintptr_t);
diff --git a/kernel/include/utils/Registers.h b/kernel/include/utils/Registers.h
new file mode 100644
index 00000000..944a0ea0
--- /dev/null
+++ b/kernel/include/utils/Registers.h
@@ -0,0 +1,52 @@
+#pragma once
+
+#include <stdint.h>
+
+extern "C" uintptr_t asm_get_rflags();
+extern "C" void asm_set_rflags(uintptr_t);
+
+inline uintptr_t read_rflags()
+{
+    return asm_get_rflags();
+}
+
+inline void write_rflags(uintptr_t value)
+{
+    asm_set_rflags(value);
+}
+
+inline uintptr_t read_cr0()
+{
+    uintptr_t value;
+    asm volatile("mov %%cr0, %0" : "=r"(value));
+    return value;
+}
+
+inline uintptr_t read_cr3()
+{
+    uintptr_t value;
+    asm volatile("mov %%cr3, %0" : "=r"(value));
+    return value;
+}
+
+inline uintptr_t read_cr4()
+{
+    uintptr_t value;
+    asm volatile("mov %%cr4, %0" : "=r"(value));
+    return value;
+}
+
+template <typename T> inline void write_cr0(T value)
+{
+    asm volatile("mov %0, %%cr0" : : "r"(value));
+}
+
+template <typename T> inline void write_cr3(T value)
+{
+    asm volatile("mov %0, %%cr3" : : "r"(value));
+}
+
+template <typename T> inline void write_cr4(T value)
+{
+    asm volatile("mov %0, %%cr4" : : "r"(value));
+}
\ No newline at end of file
diff --git a/kernel/src/interrupts/Interrupts.cpp b/kernel/src/interrupts/Interrupts.cpp
index 06d40db7..b57420d8 100644
--- a/kernel/src/interrupts/Interrupts.cpp
+++ b/kernel/src/interrupts/Interrupts.cpp
@@ -1,6 +1,6 @@
 #include "interrupts/Interrupts.h"
-#include "misc/utils.h"
 #include "trace/StackTracer.h"
+#include "utils/Registers.h"
 
 void Interrupts::disable()
 {
@@ -29,7 +29,7 @@ void Interrupts::return_from_handler(Context* context)
 
 bool Interrupts::are_enabled()
 {
-    return (Utilities::get_rflags() & 0x200) > 0;
+    return (read_rflags() & 0x200) > 0;
 }
 
 static bool saved_interrupt_state;
diff --git a/kernel/src/main.asm b/kernel/src/main.asm
index 070821d7..4593a076 100644
--- a/kernel/src/main.asm
+++ b/kernel/src/main.asm
@@ -31,4 +31,10 @@ global asm_get_rflags
 asm_get_rflags:
     pushfq
     pop rax
+    ret
+
+global asm_set_rflags
+asm_set_rflags:
+    push rdi
+    popfq
     ret
\ No newline at end of file
diff --git a/kernel/src/memory/VMM.cpp b/kernel/src/memory/VMM.cpp
index 05c3a7ce..e481088d 100644
--- a/kernel/src/memory/VMM.cpp
+++ b/kernel/src/memory/VMM.cpp
@@ -6,6 +6,7 @@
 #include "memory/PMM.h"
 #include "misc/utils.h"
 #include "std/string.h"
+#include "utils/Registers.h"
 
 static PageTable* kernel_pml4;
 static PageTable* current_pml4;
@@ -55,8 +56,7 @@ bool VMM::is_using_kernel_address_space()
 
 void VMM::init()
 {
-    asm volatile("mov %%cr3, %0" : "=r"(current_pml4));
-    kernel_pml4 = current_pml4;
+    kernel_pml4 = (PageTable*)read_cr3();
 }
 
 void VMM::unmap(uint64_t vaddr)
diff --git a/kernel/src/thread/Scheduler.cpp b/kernel/src/thread/Scheduler.cpp
index 20bbf9b9..948c8d1b 100644
--- a/kernel/src/thread/Scheduler.cpp
+++ b/kernel/src/thread/Scheduler.cpp
@@ -14,6 +14,7 @@
 #include "sys/elf/ELFLoader.h"
 #include "thread/PIT.h"
 #include "thread/Task.h"
+#include "utils/Registers.h"
 
 static uint64_t task_num = 0;
 
@@ -70,7 +71,7 @@ void Scheduler::add_kernel_task(void (*task)(void))
     new_task->regs.cs = 0x08;
     new_task->regs.ss = 0x10;
     new_task->regs.ds = 0x10;
-    new_task->regs.rflags = Utilities::get_rflags() | 0x200; // enable interrupts
+    new_task->regs.rflags = read_rflags() | 0x200; // enable interrupts
     new_task->task_sleep = 0;
     new_task->task_time = 0;
     new_task->cpu_time = 0;