Replaced the crappy miniVMM with a kernel scratch thing.

it starts at 0xFFFFFFFF00000000, it's mean, it's unmanaged, but you can make a heap on it later. But it broke everything, so I need to fix that.

One step closer to saner memoy management, I guess.

Kernel/include/Tier0/paging.h

@@ -91,13 +91,18 @@ const inline u64 paging_temp_page_get_virtual(void)
 }
 void             paging_temp_page_set_physical(u64 Physical);
 
-// The MiniVMM is a mini virtual memory manager that manages, similarly to the
-// basic physical frame manager, allocation of _virtual_ frames, for use by
-// paging functions. This should be only used by major parts of the kernel, for
-// example to map some data structures to physical memory, or if physmem_read
-// calls would be too slow.
-void paging_minivmm_setup(void);
-u64 paging_minivmm_allocate(void);
+// We have to prepare for virtual memory allocation from 0xFFFFFFFF00000000
+// right from the beggining, because that's the mapping that we will be using
+// in later parts of the code (see Tier1/CKernelML4.h), and there's not sense
+// in remapping everything.
+// This means we have to set up a page directory for our managed pool, fill
+// it up with a heap (from Tier0/heap.c), and attach that directory to a DPT.
+// Then, when we offload page management to CKernelML4, we have to let it know
+// about the state of all these things.
+void paging_scratch_initialize(void);
+// Allocates 4096 of physical and virtual memory in the kernel scratch buffer.
+// Warning, this memory cannot be freed.
+void *paging_scratch_allocate(void);
 
 // A simple page map call. This does no checks! Triple faults ahoy.
 void paging_map_page(u64 Virtual, u64 Physical);

Kernel/src/Tier0/apic.c

@@ -64,7 +64,8 @@ void apic_enable_lapic(void)
         system_msr_set(0x1B, APICMSR);
     }
     
-    u64 Virtual = paging_minivmm_allocate();
+    //u64 Virtual = paging_minivmm_allocate();
+    u64 Virtual = 0;
     kprintf("[i] LAPIC will be @0x%x.\n", Virtual);
     paging_map_page(Virtual, 0xFEE00000);
 

Kernel/src/Tier0/heap.c

@@ -73,10 +73,10 @@ T_HEAP *heap_create(u64 Size)
     u64 Start = 0;
     for (u32 i = 0; i < NumPages; i++)
     {
-        if (!Start)
-            Start = paging_minivmm_allocate(); 
-        else
-            paging_minivmm_allocate();
+        // if (!Start)
+        //     Start = paging_minivmm_allocate(); 
+        // else
+        //     paging_minivmm_allocate();
     }
     kprintf("[i] Heap starts at 0x%x\n", Start);
     

Kernel/src/Tier0/kmain.c

@@ -66,10 +66,14 @@ void kmain(u32 LoadContextAddress)
 
     paging_temp_page_setup();
     physmem_init();
-
-    paging_minivmm_setup();
+    paging_scratch_initialize();
+    void *a1 = paging_scratch_allocate();
+    void *a2 = paging_scratch_allocate();
+    kprintf("%x %x\n", a1, a2);
+    for (;;) {}
     // Let's create a new kernel stack
-    u64 StackVirtual = paging_minivmm_allocate();
+    //u64 StackVirtual = paging_minivmm_allocate();
+    u64 StackVirtual = 0;
     kprintf("[i] New kernel stack 0x%x\n", StackVirtual);
     
     // And now let's use it and forget ebp because we can.

Kernel/src/Tier0/paging.c

@@ -3,6 +3,7 @@
 #include "Tier0/kstdlib.h"
 #include "Tier0/panic.h"
 #include "Tier0/system.h"
+#include "Tier0/physmem.h"
 #include "types.h"
 
 struct {
@@ -10,13 +11,6 @@ struct {
     u64 TempPageVirtual;
 } g_KernelPaging;
 
-struct {
-    u64 Start;
-    u64 End;
-    
-    u64 Top;
-} g_MiniVMM;
-
 T_PAGING_ML4 *paging_get_ml4(void)
 {
 	u64 Address;
@@ -100,23 +94,87 @@ void paging_set_ml4(u64 ML4Physical)
     __asm volatile ( "mov %%rax, %%cr3\n" :: "a" (ML4Physical));
 }
 
-void paging_minivmm_setup(void)
+struct {
+    u32 UnmanagedSize;
+    u8 HeapSetUp;
+    u64 DirectoryPhysical;
+} g_PagingScratch;
+
+void paging_scratch_initialize(void)
 {
-    g_MiniVMM.Start = system_get_kernel_virtual_start() + system_get_kernel_size();
-    g_MiniVMM.End = system_get_kernel_virtual_start() + 511 * 0x1000;
-    g_MiniVMM.Top = g_MiniVMM.Start;
-    kprintf("[i] MiniVMM: %x - %x.\n", g_MiniVMM.Start, g_MiniVMM.End);
+    // let's first allocate a physical frame for the DIR
+    u64 DirPhysical = physmem_allocate_page() * 4096;
+    // map it to our trusty temp page
+    paging_temp_page_set_physical(DirPhysical);
+    T_PAGING_DIR *Directory = (T_PAGING_DIR *)paging_temp_page_get_virtual();
+    // zero the entries
+    for (u16 i = 0; i < 512; i++)
+        Directory->Entries[i].Present = 0;
+
+    // attach the scratch to the DPT. we can do this without using a temp page,
+    // as the boot paging structures lie in the 2mib identity paged zone
+    u16 ML4Entry = PAGING_GET_ML4_INDEX(0xFFFFFFFF00000000);
+    T_PAGING_ML4 *ML4 = paging_get_ml4();
+
+    ASSERT(ML4->Entries[ML4Entry].Present);
+    u64 aDPT = ML4->Entries[ML4Entry].Physical << 12;
+    T_PAGING_DPT *DPT = (T_PAGING_DPT *)aDPT;
+    u16 DPTEntry = PAGING_GET_DPT_INDEX(0xFFFFFFFF00000000);
+
+    ASSERT(!DPT->Entries[DPTEntry].Present);
+    DPT->Entries[DPTEntry].Present = 1;
+    DPT->Entries[DPTEntry].RW = 1;
+    DPT->Entries[DPTEntry].Physical = DirPhysical >> 12;
+
+    g_PagingScratch.UnmanagedSize = 0;
+    g_PagingScratch.HeapSetUp = 0;
+    g_PagingScratch.DirectoryPhysical = DirPhysical;
 }
 
-u64 paging_minivmm_allocate(void)
+void *paging_scratch_allocate(void)
 {
-    if (g_MiniVMM.Top + 0x1000 > g_MiniVMM.End)
-        PANIC("MiniVMM out of memory!");
-    
-    u64 Result = g_MiniVMM.Top;
-    g_MiniVMM.Top += 4096;
-    
-    return Result;
+    if (g_PagingScratch.HeapSetUp)
+        PANIC("Trying to allocate unmanaged scratch after heap exists, abort!");
+
+    u64 Virtual = 0xFFFFFFFF00000000 + g_PagingScratch.UnmanagedSize;
+    u64 Physical = physmem_allocate_page() * 4096;
+    u16 DirEntry = PAGING_GET_DIR_INDEX(Virtual);
+
+    paging_temp_page_set_physical(g_PagingScratch.DirectoryPhysical);
+    T_PAGING_DIR *Directory = (T_PAGING_DIR *)paging_temp_page_get_virtual();
+
+    // create table if necessary
+    u64 TablePhysical;
+    if (!Directory->Entries[DirEntry].Present)
+    {
+        // create a new page table
+        TablePhysical = physmem_allocate_page() * 4096;
+        paging_temp_page_set_physical(TablePhysical);
+        T_PAGING_TAB *Table = (T_PAGING_TAB*)paging_temp_page_get_virtual();
+        // zero the table
+        for (u16 i  = 0; i < 512; i++)
+            Table->Entries[i].Present = 0;
+
+        // set the directory to point where it should
+        paging_temp_page_set_physical(g_PagingScratch.DirectoryPhysical);
+        Directory->Entries[DirEntry].Present = 1;
+        Directory->Entries[DirEntry].RW = 1;
+        Directory->Entries[DirEntry].Physical = TablePhysical >> 12;
+    }
+    else
+        TablePhysical = Directory->Entries[DirEntry].Physical << 12;
+
+    // set the table entry to point to our new page frame
+    paging_temp_page_set_physical(TablePhysical);
+    T_PAGING_TAB *Table = (T_PAGING_TAB*)paging_temp_page_get_virtual();
+    u16 TabEntry = PAGING_GET_TAB_INDEX(Virtual);
+    Table->Entries[TabEntry].Present = 1;
+    Table->Entries[TabEntry].RW = 1;
+    Table->Entries[TabEntry].Physical = Physical >> 12;
+
+    g_PagingScratch.UnmanagedSize += 4096;
+    __asm__ __volatile__("invlpg %0" :: "m"(Virtual));
+    return (void *)Virtual;
 }
 
 void paging_map_page(u64 Virtual, u64 Physical)
@@ -130,5 +188,5 @@ void paging_map_page(u64 Virtual, u64 Physical)
     T_PAGING_TAB *Tab = (T_PAGING_TAB *)aTab;
     
     Tab->Entries[PAGING_GET_TAB_INDEX(Virtual)].Physical = Physical >> 12;    
-    __asm__ volatile("invlpg %0" :: "m"(*(u32 *)Virtual));
+    __asm__ volatile("invlpg %0" :: "m"(Virtual));
 }

Kernel/src/Tier0/physmem.c

@@ -106,7 +106,6 @@ u64 physmem_allocate_page(void)
                 {
                     PHYSMEM_METADATA_SET_BIT(Metadata, i * 64 + j);
                     g_PhysicalMemory.MemoryFree -= 4096;
-                    kprintf("-> %i\n", i * 64 + j);
                     return i * 64 + j;
                 }
         }