From 02f0ba9aad127e611d62aac2cce934240187083a Mon Sep 17 00:00:00 2001
From: nub31 <oliverlhs@outlook.com>
Date: Sat, 6 Sep 2025 17:42:05 +0200
Subject: [PATCH] mem cleanup

---
 src/arch/x86_64/mem/pmm.c |  9 +++++++--
 src/arch/x86_64/mem/pmm.h |  4 ++--
 src/arch/x86_64/mem/vmm.c | 37 +++++++++++++++++++------------------
 src/arch/x86_64/mem/vmm.h |  2 +-
 4 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/src/arch/x86_64/mem/pmm.c b/src/arch/x86_64/mem/pmm.c
index 350d49d..8c4c393 100644
--- a/src/arch/x86_64/mem/pmm.c
+++ b/src/arch/x86_64/mem/pmm.c
@@ -123,9 +123,9 @@ u64 pmm_alloc()
     return 0;
 }
 
-void pmm_free(u64 address)
+void pmm_free(u64 physical_address)
 {
-    u64 page = address / PAGE_SIZE;
+    u64 page = physical_address / PAGE_SIZE;
     if (page < BITMAP_SIZE * 8)
     {
         if (page_bitmap[page / 8] & (1 << (page % 8)))
@@ -133,5 +133,10 @@ void pmm_free(u64 address)
             page_bitmap[page / 8] &= ~(1 << (page % 8));
             free_pages++;
         }
+        else
+        {
+            printf("pmm_free: Physical address %x is already free", physical_address);
+            panic("pmm_free: Failed to free");
+        }
     }
 }
\ No newline at end of file
diff --git a/src/arch/x86_64/mem/pmm.h b/src/arch/x86_64/mem/pmm.h
index dc195cb..ceecc1b 100644
--- a/src/arch/x86_64/mem/pmm.h
+++ b/src/arch/x86_64/mem/pmm.h
@@ -3,7 +3,7 @@
 #include "std.h"
 #include "x86_64/multiboot.h"
 
-// Fixed at 2mb for now
+// todo(nub31): Fixed at 2mb for now, might add support for 4k pages later
 #define PAGE_SIZE MiB(2)
 
 // Defines the theoretical max memory the kernel can allocate, not the actual memory of the system
@@ -16,4 +16,4 @@ void pmm_init(multiboot_info_t* info);
 u64 pmm_alloc();
 
 // Free the 2mb physical page at the specified address
-void pmm_free(u64 address);
\ No newline at end of file
+void pmm_free(u64 physical_address);
\ No newline at end of file
diff --git a/src/arch/x86_64/mem/vmm.c b/src/arch/x86_64/mem/vmm.c
index 5f4bdac..3194591 100644
--- a/src/arch/x86_64/mem/vmm.c
+++ b/src/arch/x86_64/mem/vmm.c
@@ -26,7 +26,7 @@ static u64 create_pte(u64 physical_address)
     return (physical_address & PTE_MASK) | PTE_PRESENT | PTE_WRITABLE | PTE_PS;
 }
 
-void vmm_map(u64 virtual_address, u64 physical_address)
+void vmm_map(u64 physical_address, u64 virtual_address)
 {
     u64 pml4_idx = PML4_INDEX(virtual_address);
     u64 pdpt_idx = PDPT_INDEX(virtual_address);
@@ -40,8 +40,8 @@ void vmm_map(u64 virtual_address, u64 physical_address)
         panic("Failed to map virtual to physical page");
     }
 
-    u64* pdpt_phys = (u64*)(pdpt & PTE_MASK);
-    u64 pd = pdpt_phys[pdpt_idx];
+    u64* pdpt_physical_address = (u64*)(pdpt & PTE_MASK);
+    u64 pd = pdpt_physical_address[pdpt_idx];
     if (!(pd & PTE_PRESENT))
     {
         // todo(nub31): Dynamically create a pd table
@@ -49,8 +49,8 @@ void vmm_map(u64 virtual_address, u64 physical_address)
         panic("Failed to map virtual to physical page");
     }
 
-    u64* pd_phys = (u64*)(pd & PTE_MASK);
-    u64 entry = pd_phys[pd_idx];
+    u64* pd_physical_address = (u64*)(pd & PTE_MASK);
+    u64 entry = pd_physical_address[pd_idx];
 
     if (entry & PTE_PRESENT)
     {
@@ -58,7 +58,7 @@ void vmm_map(u64 virtual_address, u64 physical_address)
         panic("Failed to map virtual to physical page");
     }
 
-    pd_phys[pd_idx] = create_pte(physical_address);
+    pd_physical_address[pd_idx] = create_pte(physical_address);
 }
 
 u64 vmm_unmap(u64 virtual_address)
@@ -74,42 +74,43 @@ u64 vmm_unmap(u64 virtual_address)
         panic("Failed to unmap virtual address");
     }
 
-    u64* pdpt_phys = (u64*)(pdpt_entry & PTE_MASK);
-    u64 pd_entry = pdpt_phys[pdpt_idx];
+    u64* pdpt_physical_address = (u64*)(pdpt_entry & PTE_MASK);
+    u64 pd_entry = pdpt_physical_address[pdpt_idx];
     if (!(pd_entry & PTE_PRESENT))
     {
         printf("PD not present at PDPT index %llu\n", pdpt_idx);
         panic("Failed to unmap virtual address");
     }
 
-    u64* pd_phys = (u64*)(pd_entry & PTE_MASK);
-    if (!(pd_phys[pd_idx] & PTE_PRESENT))
+    u64* pd_physical_address = (u64*)(pd_entry & PTE_MASK);
+    if (!(pd_physical_address[pd_idx] & PTE_PRESENT))
     {
         printf("Virtual address 0x%llx is not mapped\n", virtual_address);
         panic("Failed to unmap virtual address");
     }
-    u64 phys = pd_phys[pd_idx] & PTE_MASK;
-    pd_phys[pd_idx] = 0;
+
+    u64 physical_address = pd_physical_address[pd_idx] & PTE_MASK;
+    pd_physical_address[pd_idx] = 0;
 
     __asm__ volatile("invlpg (%0)" : : "r"(virtual_address) : "memory");
 
-    return phys;
+    return physical_address;
 }
 
 void* vmm_alloc(u64 virtual_address)
 {
-    u64 phys = pmm_alloc();
-    if (!phys)
+    u64 physical_address = pmm_alloc();
+    if (!physical_address)
     {
         panic("Out of physical memory");
     }
 
-    vmm_map(virtual_address, phys);
+    vmm_map(physical_address, virtual_address);
     return (void*)virtual_address;
 }
 
 void vmm_free(u64 virtual_address)
 {
-    u64 phys = vmm_unmap(virtual_address);
-    pmm_free(phys);
+    u64 physical_address = vmm_unmap(virtual_address);
+    pmm_free(physical_address);
 }
\ No newline at end of file
diff --git a/src/arch/x86_64/mem/vmm.h b/src/arch/x86_64/mem/vmm.h
index 3c37d6d..8afa56a 100644
--- a/src/arch/x86_64/mem/vmm.h
+++ b/src/arch/x86_64/mem/vmm.h
@@ -2,7 +2,7 @@
 
 #include "std.h"
 
-void vmm_map(u64 virtual_address, u64 physical_address);
+void vmm_map(u64 physical_address, u64 virtual_address);
 u64 vmm_unmap(u64 virtual_address);
 
 void* vmm_alloc(u64 virtual_address);