Kernel: Clean up MemoryManager initialization a bit more

Move the CPU feature enabling to functions in Arch/i386/CPU.cpp.

2 files changed, 82 insertions, 2 deletions

diff --git a/Kernel/Arch/i386/CPU.cpp b/Kernel/Arch/i386/CPU.cpp
index e08a7e6acf..8a7b18223e 100644
--- a/Kernel/Arch/i386/CPU.cpp
+++ b/Kernel/Arch/i386/CPU.cpp
@@ -570,7 +570,6 @@ void detect_cpu_features()
     g_cpu_supports_umip = (extended_features.ecx() & (1 << 2));
 }
 
-
 void stac()
 {
     if (!g_cpu_supports_smap)
@@ -586,3 +585,79 @@ void clac()
     asm volatile("clac" ::
                      : "cc");
 }
+
+void x86_enable_pae()
+{
+    // Turn on CR4.PAE
+    asm volatile(
+        "mov %cr4, %eax\n"
+        "orl $0x20, %eax\n"
+        "mov %eax, %cr4\n");
+}
+
+void x86_enable_pge()
+{
+    if (g_cpu_supports_pge) {
+        // Turn on CR4.PGE so the CPU will respect the G bit in page tables.
+        asm volatile(
+            "mov %cr4, %eax\n"
+            "orl $0x80, %eax\n"
+            "mov %eax, %cr4\n");
+        kprintf("x86: PGE support enabled\n");
+    } else {
+        kprintf("x86: PGE support not detected\n");
+    }
+}
+
+void x86_enable_smep()
+{
+    if (g_cpu_supports_smep) {
+        // Turn on CR4.SMEP
+        asm volatile(
+            "mov %cr4, %eax\n"
+            "orl $0x100000, %eax\n"
+            "mov %eax, %cr4\n");
+        kprintf("x86: SMEP support enabled\n");
+    } else {
+        kprintf("x86: SMEP support not detected\n");
+    }
+}
+
+void x86_enable_smap()
+{
+    if (g_cpu_supports_smap) {
+        // Turn on CR4.SMAP
+        kprintf("x86: Enabling SMAP\n");
+        asm volatile(
+            "mov %cr4, %eax\n"
+            "orl $0x200000, %eax\n"
+            "mov %eax, %cr4\n");
+        kprintf("x86: SMAP support enabled\n");
+    } else {
+        kprintf("x86: SMAP support not detected\n");
+    }
+}
+
+void x86_enable_nx()
+{
+    if (g_cpu_supports_nx) {
+        // Turn on IA32_EFER.NXE
+        asm volatile(
+            "movl $0xc0000080, %ecx\n"
+            "rdmsr\n"
+            "orl $0x800, %eax\n"
+            "wrmsr\n");
+        kprintf("x86: NX support enabled\n");
+    } else {
+        kprintf("x86: NX support not detected\n");
+    }
+}
+
+void x86_enable_wp()
+{
+    asm volatile(
+        "movl %%cr0, %%eax\n"
+        "orl $0x00010000, %%eax\n"
+        "movl %%eax, %%cr0\n" ::
+            : "%eax", "memory");
+}
diff --git a/Kernel/Arch/i386/CPU.h b/Kernel/Arch/i386/CPU.h
index 583a66d7f9..7a73f2b458 100644
--- a/Kernel/Arch/i386/CPU.h
+++ b/Kernel/Arch/i386/CPU.h
@@ -539,8 +539,13 @@ extern bool g_cpu_supports_tsc;
 extern bool g_cpu_supports_umip;
 
 void stac();
-
 void clac();
+void x86_enable_pae();
+void x86_enable_pge();
+void x86_enable_smep();
+void x86_enable_smap();
+void x86_enable_nx();
+void x86_enable_wp();
 
 class SmapDisabler {
 public: