From d3fbbd5918a6ea5d2d947d0fcac995d02af2b751 Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Sun, 21 Aug 2022 13:21:59 -0600
Subject: [PATCH] Pre-allocate x86 kernel PD entries

---
 rmm                       | 2 +-
 src/arch/x86/rmm.rs       | 9 +++++++++
 src/scheme/sys/context.rs | 5 +----
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/rmm b/rmm
index df733ed..0d4ff5d 160000
--- a/rmm
+++ b/rmm
@@ -1 +1 @@
-Subproject commit df733ed5714aaa7f7b3e15707bd7ef8a44802779
+Subproject commit 0d4ff5d4f36f26289556c6e7a13e4b40ff736b83
diff --git a/src/arch/x86/rmm.rs b/src/arch/x86/rmm.rs
index 7827a7e..cd635d0 100644
--- a/src/arch/x86/rmm.rs
+++ b/src/arch/x86/rmm.rs
@@ -14,6 +14,7 @@ use rmm::{
     FrameCount,
     FrameUsage,
     MemoryArea,
+    PageEntry,
     PageFlags,
     PageMapper,
     PhysicalAddress,
@@ -105,6 +106,14 @@ unsafe fn inner<A: Arch>(
             &mut bump_allocator
         ).expect("failed to create Mapper");
 
+        // Pre-allocate all kernel PD entries so that when the page table is copied,
+        // these entries are synced between processes
+        for i in 512..1024 {
+            let phys = mapper.allocator_mut().allocate_one().expect("failed to map page table");
+            let flags = A::ENTRY_FLAG_READWRITE | A::ENTRY_FLAG_DEFAULT_TABLE;
+            mapper.table().set_entry(i, PageEntry::new(phys.data() | flags));
+        }
+
         // Map all physical areas at PHYS_OFFSET
         for area in areas.iter() {
             for i in 0..area.size / A::PAGE_SIZE {
diff --git a/src/scheme/sys/context.rs b/src/scheme/sys/context.rs
index 8602e9b..9555433 100644
--- a/src/scheme/sys/context.rs
+++ b/src/scheme/sys/context.rs
@@ -76,10 +76,7 @@ pub fn resource() -> Result<Vec<u8>> {
                 format!("{}", ticks)
             };
 
-            let mut memory = 0;
-            if let Some(ref kfx) = context.kstack {
-                memory += kfx.len();
-            }
+            let mut memory = context.kfx.len();
             if let Some(ref kstack) = context.kstack {
                 memory += kstack.len();
             }