kernel/src/MemoryManager.cpp

@@ -43,10 +43,10 @@ namespace MemoryManager
 {
     Result<void> protect_kernel_sections()
     {
-        u64 rodata_pages = get_blocks_from_size((u64)(end_of_kernel_rodata - start_of_kernel_rodata), ARCH_PAGE_SIZE);
+        u64 rodata_pages = get_blocks_from_size((u64)(end_of_kernel_rodata - start_of_kernel_rodata), MMU::page_size());
         TRY(remap((u64)start_of_kernel_rodata, rodata_pages, MMU::NoExecute));
 
-        u64 data_pages = get_blocks_from_size((u64)(end_of_kernel_data - start_of_kernel_data), ARCH_PAGE_SIZE);
+        u64 data_pages = get_blocks_from_size((u64)(end_of_kernel_data - start_of_kernel_data), MMU::page_size());
         TRY(remap((u64)start_of_kernel_data, data_pages, MMU::NoExecute | MMU::ReadWrite));
 
         return {};
@@ -81,25 +81,25 @@ namespace MemoryManager
 
         page_bitmap_addr = (char*)biggest_memory_block;
         page_virtual_bitmap_addr = page_bitmap_addr; // we'll map this to virtual memory as soon as the MMU is ready
-        if ((total_mem / ARCH_PAGE_SIZE / 8) >= biggest_memory_block_size)
+        if ((total_mem / MMU::page_size() / 8) >= biggest_memory_block_size)
         {
             Serial::println("ERROR: No single memory block is enough to hold the page bitmap");
             for (;;)
                 ;
         }
 
-        page_bitmap_size = total_mem / ARCH_PAGE_SIZE / 8 + 1;
+        page_bitmap_size = total_mem / MMU::page_size() / 8 + 1;
         memset(page_bitmap_addr, 0xFF, page_bitmap_size);
 
         ptr = &bootboot.mmap;
         for (uint64_t i = 0; i < mmap_entries; i++)
         {
-            uint64_t index = MMapEnt_Ptr(ptr) / ARCH_PAGE_SIZE;
+            uint64_t index = MMapEnt_Ptr(ptr) / MMU::page_size();
             if (!MMapEnt_IsFree(ptr)) { reserved_mem += MMapEnt_Size(ptr); }
             else
             {
                 free_mem += MMapEnt_Size(ptr);
-                for (uint64_t j = 0; j < (MMapEnt_Size(ptr) / ARCH_PAGE_SIZE); j++)
+                for (uint64_t j = 0; j < (MMapEnt_Size(ptr) / MMU::page_size()); j++)
                 {
                     page_bitmap_set(index + j, false);
                 }
@@ -107,7 +107,7 @@ namespace MemoryManager
             ptr++;
         }
 
-        lock_pages((u64)page_bitmap_addr, page_bitmap_size / ARCH_PAGE_SIZE + 1);
+        lock_pages((u64)page_bitmap_addr, page_bitmap_size / MMU::page_size() + 1);
     }
 
     void init()
@@ -118,16 +118,16 @@ namespace MemoryManager
 
     void lock_page(u64 page)
     {
-        uint64_t index = ((uint64_t)page) / ARCH_PAGE_SIZE;
+        uint64_t index = ((uint64_t)page) / MMU::page_size();
         if (page_bitmap_read(index)) return;
         page_bitmap_set(index, true);
-        used_mem += ARCH_PAGE_SIZE;
+        used_mem += MMU::page_size();
-        free_mem -= ARCH_PAGE_SIZE;
+        free_mem -= MMU::page_size();
     }
 
     void lock_pages(u64 pages, u64 count)
     {
-        for (u64 index = 0; index < count; index++) { lock_page(pages + (index * ARCH_PAGE_SIZE)); }
+        for (u64 index = 0; index < count; index++) { lock_page(pages + (index * MMU::page_size())); }
     }
 
     Result<u64> alloc_physical_page()
@@ -137,9 +137,9 @@ namespace MemoryManager
             if (page_bitmap_read(index)) continue;
             page_bitmap_set(index, true);
             start_index = index + 1;
-            free_mem -= ARCH_PAGE_SIZE;
+            free_mem -= MMU::page_size();
-            used_mem += ARCH_PAGE_SIZE;
+            used_mem += MMU::page_size();
-            return index * ARCH_PAGE_SIZE;
+            return index * MMU::page_size();
         }
 
         return err; // FIXME: ENOMEM.
@@ -147,24 +147,24 @@ namespace MemoryManager
 
     Result<void> free_physical_page(u64 page)
     {
-        u64 index = page / ARCH_PAGE_SIZE;
+        u64 index = page / MMU::page_size();
         if (index > (page_bitmap_size * 8)) return err;
         if (!page_bitmap_read(index)) return err;
         page_bitmap_set(index, false);
-        used_mem -= ARCH_PAGE_SIZE;
+        used_mem -= MMU::page_size();
-        free_mem += ARCH_PAGE_SIZE;
+        free_mem += MMU::page_size();
         if (start_index > index) start_index = index;
         return {};
     }
 
     Result<void> remap(u64 address, usize count, int flags)
     {
-        check(is_aligned(address, ARCH_PAGE_SIZE));
+        check(is_aligned(address, MMU::page_size()));
 
         while (count--)
         {
             TRY(MMU::remap(address, flags));
-            address += ARCH_PAGE_SIZE;
+            address += MMU::page_size();
         }
 
         return {};
@@ -172,13 +172,13 @@ namespace MemoryManager
 
     Result<void> remap_unaligned(u64 address, usize count, int flags)
     {
-        if (!is_aligned(address, ARCH_PAGE_SIZE)) count++;
+        if (!is_aligned(address, MMU::page_size())) count++;
-        address = align_down(address, ARCH_PAGE_SIZE);
+        address = align_down(address, MMU::page_size());
 
         while (count--)
         {
             TRY(MMU::remap(address, flags));
-            address += ARCH_PAGE_SIZE;
+            address += MMU::page_size();
         }
 
         return {};

kernel/src/arch/MMU.h

@@ -3,8 +3,6 @@
 
 struct PageDirectory;
 
-extern const usize ARCH_PAGE_SIZE;
-
 namespace MMU
 {
     enum Flags
@@ -30,4 +28,6 @@ namespace MMU
 
     Result<PageDirectory*> create_page_directory_for_userspace();
     void setup_initial_page_directory();
+
+    usize page_size();
 }

kernel/src/arch/x86_64/MMU.cpp

@@ -4,8 +4,6 @@
 
 #define PAGE_SIZE 4096
 
-const usize ARCH_PAGE_SIZE = PAGE_SIZE;
-
 const u64 rindex = 0776;          // recursive index
 const u64 sign = 0177777UL << 48; // sign extension
 
@@ -54,6 +52,10 @@ static_assert(sizeof(PageDirectory) == PAGE_SIZE);
 
 namespace MMU
 {
+    usize page_size()
+    {
+        return PAGE_SIZE;
+    }
 
     PageDirectory* l4_table()
     {
@@ -196,9 +198,10 @@ namespace MMU
         auto& l4 = l4_entry(virt);
         if (!l4.present)
         {
-            u64 addr = TRY(MemoryManager::alloc_physical_page());
+            auto addr = MemoryManager::alloc_physical_page();
+            if (addr.has_error()) return addr.release_error();
             l4.present = true;
-            l4.set_address(addr);
+            l4.set_address(addr.release_value());
             memset(l3_table(virt), 0, PAGE_SIZE);
             l4.ignore0 = l4.ignore1 = 0;
         }
@@ -208,9 +211,10 @@ namespace MMU
         auto& l3 = l3_entry(virt);
         if (!l3.present)
         {
-            u64 addr = TRY(MemoryManager::alloc_physical_page());
+            auto addr = MemoryManager::alloc_physical_page();
+            if (addr.has_error()) return addr.release_error();
             l3.present = true;
-            l3.set_address(addr);
+            l3.set_address(addr.release_value());
             memset(l2_table(virt), 0, PAGE_SIZE);
             l3.ignore0 = l3.ignore1 = 0;
         }
@@ -222,9 +226,10 @@ namespace MMU
         auto& l2 = l2_entry(virt);
         if (!l2.present)
         {
-            u64 addr = TRY(MemoryManager::alloc_physical_page());
+            auto addr = MemoryManager::alloc_physical_page();
+            if (addr.has_error()) return addr.release_error();
             l2.present = true;
-            l2.set_address(addr);
+            l2.set_address(addr.release_value());
             memset(l1_table(virt), 0, PAGE_SIZE);
             l2.ignore0 = l2.ignore1 = 0;
         }
@@ -248,7 +253,9 @@ namespace MMU
 
     Result<void> remap(u64 virt, int flags)
     {
-        auto& l1 = *TRY(apply_cascading_flags(virt, flags));
+        auto rc = apply_cascading_flags(virt, flags);
+        if (rc.has_error()) return rc.release_error();
+        auto& l1 = *rc.release_value();
         if (!l1.present) return err;
         l1.read_write = (flags & Flags::ReadWrite);
         l1.user = (flags & Flags::User);
@@ -260,7 +267,9 @@ namespace MMU
 
     Result<u64> unmap(u64 virt)
     {
-        auto& l1 = *TRY(find_entry(virt));
+        auto rc = find_entry(virt);
+        if (rc.has_error()) return rc.release_error();
+        auto& l1 = *rc.release_value();
         if (!l1.present) return err;
         u64 address = l1.get_address();
         memset(&l1, 0, sizeof(l1));
@@ -270,14 +279,18 @@ namespace MMU
 
     Result<u64> get_physical(u64 virt)
     {
-        auto& l1 = *TRY(find_entry(virt));
+        auto rc = find_entry(virt);
+        if (rc.has_error()) return rc.release_error();
+        auto& l1 = *rc.release_value();
         if (!l1.present) return err;
         return l1.get_address();
     }
 
     Result<int> get_flags(u64 virt)
     {
-        auto& l1 = *TRY(find_entry(virt));
+        auto rc = find_entry(virt);
+        if (rc.has_error()) return rc.release_error();
+        auto& l1 = *rc.release_value();
         if (!l1.present) return err;
         return arch_flags_to_mmu(l1);
     }