From cf5cfb34755fe6813cb13d6744486fd875e9a040 Mon Sep 17 00:00:00 2001
From: Zhang Junyang <junyang@stu.pku.edu.cn>
Date: Sun, 5 May 2024 22:02:43 +0800
Subject: [PATCH] Enable global page and add a global TLB flushing function

---
 framework/aster-frame/src/arch/x86/mm/mod.rs | 15 +++++++++++++++
 framework/aster-frame/src/arch/x86/mod.rs    |  6 +++++-
 framework/aster-frame/src/lib.rs             |  1 +
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/framework/aster-frame/src/arch/x86/mm/mod.rs b/framework/aster-frame/src/arch/x86/mm/mod.rs
index be7add079..f1d611fc4 100644
--- a/framework/aster-frame/src/arch/x86/mm/mod.rs
+++ b/framework/aster-frame/src/arch/x86/mm/mod.rs
@@ -60,6 +60,21 @@ pub fn tlb_flush(vaddr: Vaddr) {
     tlb::flush(VirtAddr::new(vaddr as u64));
 }
 
+pub fn tlb_flush_all_including_global() {
+    // Safety: updates to CR4 here only change the global-page bit, the side effect
+    // is only to invalidate the TLB, which doesn't affect the memory safety.
+    unsafe {
+        // To invalidate all entries, including global-page
+        // entries, disable global-page extensions (CR4.PGE=0).
+        x86_64::registers::control::Cr4::update(|cr4| {
+            *cr4 -= x86_64::registers::control::Cr4Flags::PAGE_GLOBAL;
+        });
+        x86_64::registers::control::Cr4::update(|cr4| {
+            *cr4 |= x86_64::registers::control::Cr4Flags::PAGE_GLOBAL;
+        });
+    }
+}
+
 #[derive(Clone, Copy, Pod)]
 #[repr(C)]
 pub struct PageTableEntry(usize);
diff --git a/framework/aster-frame/src/arch/x86/mod.rs b/framework/aster-frame/src/arch/x86/mod.rs
index 5d6437685..460e0f62f 100644
--- a/framework/aster-frame/src/arch/x86/mod.rs
+++ b/framework/aster-frame/src/arch/x86/mod.rs
@@ -77,7 +77,11 @@ pub fn read_tsc() -> u64 {
 fn enable_common_cpu_features() {
     use x86_64::registers::{control::Cr4Flags, model_specific::EferFlags, xcontrol::XCr0Flags};
     let mut cr4 = x86_64::registers::control::Cr4::read();
-    cr4 |= Cr4Flags::FSGSBASE | Cr4Flags::OSXSAVE | Cr4Flags::OSFXSR | Cr4Flags::OSXMMEXCPT_ENABLE;
+    cr4 |= Cr4Flags::FSGSBASE
+        | Cr4Flags::OSXSAVE
+        | Cr4Flags::OSFXSR
+        | Cr4Flags::OSXMMEXCPT_ENABLE
+        | Cr4Flags::PAGE_GLOBAL;
     unsafe {
         x86_64::registers::control::Cr4::write(cr4);
     }
diff --git a/framework/aster-frame/src/lib.rs b/framework/aster-frame/src/lib.rs
index 9982f95bf..8ee364f3e 100644
--- a/framework/aster-frame/src/lib.rs
+++ b/framework/aster-frame/src/lib.rs
@@ -79,6 +79,7 @@ pub fn init() {
             .get()
             .unwrap()
             .activate_unchecked();
+        crate::arch::mm::tlb_flush_all_including_global();
     }
     invoke_ffi_init_funcs();
 }