Provide meaningful error numbers

kernel/src/arch/x86_64/CPU.cpp

@@ -3,6 +3,7 @@
 #include "arch/Timer.h"
 #include "arch/x86_64/IO.h"
 #include <String.h>
+#include <SystemError.h>
 #include <Types.h>
 #include <cpuid.h>
 
@@ -347,11 +348,11 @@ namespace CPU
         static char brand_string[49];
 
         u32 buf[4];
-        if (!__get_cpuid(0x80000002, &buf[0], &buf[1], &buf[2], &buf[3])) return err;
+        if (!__get_cpuid(0x80000002, &buf[0], &buf[1], &buf[2], &buf[3])) return err(ENOTSUP);
         memcpy(brand_string, buf, 16);
-        if (!__get_cpuid(0x80000003, &buf[0], &buf[1], &buf[2], &buf[3])) return err;
+        if (!__get_cpuid(0x80000003, &buf[0], &buf[1], &buf[2], &buf[3])) return err(ENOTSUP);
         memcpy(&brand_string[16], buf, 16);
-        if (!__get_cpuid(0x80000004, &buf[0], &buf[1], &buf[2], &buf[3])) return err;
+        if (!__get_cpuid(0x80000004, &buf[0], &buf[1], &buf[2], &buf[3])) return err(ENOTSUP);
         memcpy(&brand_string[32], buf, 16);
 
         brand_string[48] = 0; // null-terminate it :)

kernel/src/arch/x86_64/MMU.cpp

@@ -1,6 +1,7 @@
 #include "arch/MMU.h"
 #include "memory/MemoryManager.h"
 #include <String.h>
+#include <SystemError.h>
 
 #define PAGE_SIZE 4096
 
@@ -161,12 +162,12 @@ namespace MMU
     Result<PageTableEntry*> find_entry(u64 virt)
     {
         auto& l4 = l4_entry(virt);
-        if (!l4.present) return err;
+        if (!l4.present) return err(EFAULT);
         auto& l3 = l3_entry(virt);
-        if (!l3.present) return err;
+        if (!l3.present) return err(EFAULT);
         if (l3.larger_pages) return &l3;
         auto& l2 = l2_entry(virt);
-        if (!l2.present) return err;
+        if (!l2.present) return err(EFAULT);
         if (l2.larger_pages) return &l2;
         return &l1_entry(virt);
     }
@@ -174,16 +175,16 @@ namespace MMU
     Result<PageTableEntry*> apply_cascading_flags(u64 virt, int flags)
     {
         auto& l4 = l4_entry(virt);
-        if (!l4.present) return err;
+        if (!l4.present) return err(EFAULT);
         if (flags & Flags::ReadWrite) l4.read_write = true;
         if (flags & Flags::User) l4.user = true;
         auto& l3 = l3_entry(virt);
-        if (!l3.present) return err;
+        if (!l3.present) return err(EFAULT);
         if (l3.larger_pages) return &l3;
         if (flags & Flags::ReadWrite) l3.read_write = true;
         if (flags & Flags::User) l3.user = true;
         auto& l2 = l2_entry(virt);
-        if (!l2.present) return err;
+        if (!l2.present) return err(EFAULT);
         if (l2.larger_pages) return &l2;
         if (flags & Flags::ReadWrite) l2.read_write = true;
         if (flags & Flags::User) l2.user = true;
@@ -217,7 +218,7 @@ namespace MMU
         if (flags & Flags::ReadWrite) l3.read_write = true;
         if (flags & Flags::User) l3.user = true;
 
-        if (l3.larger_pages) return err; // FIXME: Replacing larger pages is not supported ATM
+        if (l3.larger_pages) return err(EFIXME); // FIXME: Replacing larger pages is not supported ATM
 
         auto& l2 = l2_entry(virt);
         if (!l2.present)
@@ -231,10 +232,10 @@ namespace MMU
         if (flags & Flags::ReadWrite) l2.read_write = true;
         if (flags & Flags::User) l2.user = true;
 
-        if (l2.larger_pages) return err; // FIXME: Replacing larger pages is not supported ATM
+        if (l2.larger_pages) return err(EFIXME); // FIXME: Replacing larger pages is not supported ATM
 
         auto& l1 = l1_entry(virt);
-        if (l1.present) return err; // Please explicitly unmap the page before mapping it again.
+        if (l1.present) return err(EEXIST); // Please explicitly unmap the page before mapping it again.
         l1.ignore0 = l1.ignore1 = false;
         l1.present = true;
         l1.read_write = (flags & Flags::ReadWrite);
@@ -249,7 +250,7 @@ namespace MMU
     Result<void> remap(u64 virt, int flags)
     {
         auto& l1 = *TRY(apply_cascading_flags(virt, flags));
-        if (!l1.present) return err;
+        if (!l1.present) return err(EFAULT);
         l1.read_write = (flags & Flags::ReadWrite);
         l1.user = (flags & Flags::User);
         l1.write_through = (flags & Flags::WriteThrough);
@@ -261,7 +262,7 @@ namespace MMU
     Result<u64> unmap(u64 virt)
     {
         auto& l1 = *TRY(find_entry(virt));
-        if (!l1.present) return err;
+        if (!l1.present) return err(EFAULT);
         u64 address = l1.get_address();
         memset(&l1, 0, sizeof(l1));
         flush_page(virt);
@@ -271,14 +272,14 @@ namespace MMU
     Result<u64> get_physical(u64 virt)
     {
         auto& l1 = *TRY(find_entry(virt));
-        if (!l1.present) return err;
+        if (!l1.present) return err(EFAULT);
         return l1.get_address();
     }
 
     Result<int> get_flags(u64 virt)
     {
         auto& l1 = *TRY(find_entry(virt));
-        if (!l1.present) return err;
+        if (!l1.present) return err(EFAULT);
         return arch_flags_to_mmu(l1);
     }
 

kernel/src/memory/Heap.cpp

@@ -4,6 +4,7 @@
 #include "memory/MemoryManager.h"
 #include <Alignment.h>
 #include <String.h>
+#include <SystemError.h>
 
 static constexpr int BLOCK_USED = 1 << 0;
 static constexpr int BLOCK_START_MEM = 1 << 1;
@@ -97,7 +98,7 @@ static Result<HeapBlock*> split(HeapBlock* block, usize size)
     usize old_size =
         block->full_size; // Save the old value of this variable since we are going to use it after modifying it
 
-    if (available < (size + sizeof(HeapBlock))) return err;
+    if (available < (size + sizeof(HeapBlock))) return err(0); // This error is not propagated.
 
     usize offset = get_fair_offset_to_split_at(block, size + sizeof(HeapBlock));
     block->full_size = offset; // shrink the old block to fit this offset
@@ -244,13 +245,13 @@ Result<void> kfree(void* ptr)
         else
             Serial::printf("ERROR: Attempt to free memory at %p, which wasn't allocated with kmalloc\n", ptr);
 
-        return err;
+        return err(EFAULT);
     }
 
     if (is_block_free(block))
     {
         Serial::printf("ERROR: Attempt to free memory at %p, which was already freed\n", ptr);
-        return err;
+        return err(EFAULT);
     }
     else
         block->status &= ~BLOCK_USED;
@@ -300,7 +301,7 @@ Result<void*> krealloc(void* ptr, usize size)
         else
             Serial::printf("ERROR: Attempt to realloc memory at %p, which wasn't allocated with kmalloc\n", ptr);
 
-        return err;
+        return err(EFAULT);
     }
 
     size = align_up(size, 16UL);
@@ -308,7 +309,7 @@ Result<void*> krealloc(void* ptr, usize size)
     if (is_block_free(block))
     {
         Serial::printf("ERROR: Attempt to realloc memory at %p, which was already freed\n", ptr);
-        return err;
+        return err(EFAULT);
     }
 
     if (block->full_size >= size)

kernel/src/memory/MemoryManager.cpp

@@ -4,6 +4,7 @@
 #include "boot/bootboot.h"
 #include <Alignment.h>
 #include <String.h>
+#include <SystemError.h>
 #include <Types.h>
 
 extern BOOTBOOT bootboot;
@@ -143,14 +144,14 @@ namespace MemoryManager
             return index * ARCH_PAGE_SIZE;
         }
 
-        return err; // FIXME: ENOMEM.
+        return err(ENOMEM);
     }
 
     Result<void> free_frame(u64 frame)
     {
         const u64 index = frame / ARCH_PAGE_SIZE;
-        if (index > (page_bitmap_size * 8)) return err;
+        if (index > (page_bitmap_size * 8)) return err(EFAULT);
-        if (!page_bitmap_read(index)) return err;
+        if (!page_bitmap_read(index)) return err(EFAULT);
         page_bitmap_set(index, false);
         used_mem -= ARCH_PAGE_SIZE;
         free_mem += ARCH_PAGE_SIZE;