From e81525d349b84bdf1bc9e8cf939eb5d19dce440e Mon Sep 17 00:00:00 2001
From: Arthur Beck <averse.abfun@gmail.com>
Date: Sun, 16 Feb 2025 21:04:55 -0600
Subject: [PATCH] CONFIG_MEMORY_UNION_ALL

---
 kernel/build.rs             |  2 ++
 kernel/config.aphro.example |  1 +
 kernel/src/kernel/mem.rs    | 18 ++++++++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/kernel/build.rs b/kernel/build.rs
index 0f79722..293a38e 100644
--- a/kernel/build.rs
+++ b/kernel/build.rs
@@ -39,6 +39,8 @@ fn main() {
     );
 
     println!(r#"cargo:rustc-check-cfg=cfg(CONFIG_BUILD_GRUB, values("true", "false", none()))"#);
+
+    println!(r#"cargo:rustc-check-cfg=cfg(CONFIG_MEMORY_UNION_ALL, values("true", "false", none()))"#);
     // End checks
 
     // Configuration name used when a config is required but should always evaluate to true
diff --git a/kernel/config.aphro.example b/kernel/config.aphro.example
index 5023f4c..ecf90c7 100644
--- a/kernel/config.aphro.example
+++ b/kernel/config.aphro.example
@@ -35,4 +35,5 @@ CONFIG_BUILD_GRUB=true
 # The precision of the allocator. The size of the allocated region is divided by this to get how much to change it by each loop iteration
 # when trying to find a allocatable region.
 CONFIG_ALLOC_PRECISION=4
+CONFIG_MEMORY_UNION_ALL=false
 # End configs
\ No newline at end of file
diff --git a/kernel/src/kernel/mem.rs b/kernel/src/kernel/mem.rs
index 9dd0dca..4ea881c 100644
--- a/kernel/src/kernel/mem.rs
+++ b/kernel/src/kernel/mem.rs
@@ -322,6 +322,9 @@ impl<'a> MemoryMapAlloc<'a> {
 
     /// Check to see if any allocations contain the given address. Returns true if so.
     fn check_addr(&self, addr: u64) -> bool {
+        if cfg!(CONFIG_MEMORY_UNION_ALL = "true") {
+            return false;
+        }
         if addr >= (self.allocationheader as u64)
             && addr < (self.allocationheader as u64 + unsafe { *self.allocationheader }.len)
         {
@@ -338,6 +341,9 @@ impl<'a> MemoryMapAlloc<'a> {
 
     /// Check to see if a range of addresses have any allocations within. Returns true if so.
     fn check_range(&self, addr: Range<u64>) -> bool {
+        if cfg!(CONFIG_MEMORY_UNION_ALL = "true") {
+            return false;
+        }
         for addr in addr {
             // REALLY inefficient, but I don't think there's a better way.
             if self.check_addr(addr) {
@@ -519,6 +525,7 @@ unsafe impl<'a> Allocator for MemoryMapAlloc<'a> {
                 continue;
             }
         }
+
         if addr == 0 {
             unsafe {
                 LAST_MEMMAP_ERR = Err(crate::Error::new(
@@ -528,6 +535,14 @@ unsafe impl<'a> Allocator for MemoryMapAlloc<'a> {
             }
             return Err(core::alloc::AllocError {});
         }
+
+        if cfg!(CONFIG_MEMORY_UNION_ALL = "true") {
+            return Ok(NonNull::from_raw_parts(
+                NonNull::<u8>::without_provenance(NonZero::new(addr as usize).unwrap()),
+                layout.size(),
+            ));
+        }
+
         if let Err(err) = self.add_allocation(Allocation {
             used: true,
             addr,
@@ -545,6 +560,9 @@ unsafe impl<'a> Allocator for MemoryMapAlloc<'a> {
 
     unsafe fn deallocate(&self, ptr: core::ptr::NonNull<u8>, _layout: core::alloc::Layout) {
         unsafe { LAST_MEMMAP_ERR = Ok(()) }
+        if cfg!(CONFIG_MEMORY_UNION_ALL = "true") {
+            return;
+        }
         let addr = ptr.addr().get() as u64;
         if self.allocations == core::ptr::null_mut() {
             unsafe {