From ee7315089196755acf610668b804ba77a84035d1 Mon Sep 17 00:00:00 2001
From: Adrien Bourmault <neox@os-k.eu>
Date: Fri, 10 Jan 2020 23:56:07 +0100
Subject: [PATCH] Working on Paging API

---
 kaleid/kernel/mm/paging.c | 53 ++++++++++++++++++++++++++++++---------
 1 file changed, 41 insertions(+), 12 deletions(-)

diff --git a/kaleid/kernel/mm/paging.c b/kaleid/kernel/mm/paging.c
index 339e565..a049d04 100644
--- a/kaleid/kernel/mm/paging.c
+++ b/kaleid/kernel/mm/paging.c
@@ -14,6 +14,8 @@
 pml4_t MmPageMapLevel4[512] __attribute__((__aligned__(KPAGESIZE)));
 ulong *MmPhysicalPageTable;
 
+extern MemoryMap_t memoryMap;
+
 extern ulong _text;
 extern ulong _text_end;
 extern ulong _rodata;
@@ -23,7 +25,7 @@ extern ulong _data_end;
 
 ulong MmStackGuards[2] = { 0 };
 ulong MmVirtLastAddress = 0;
-ulong MmPhysLastAddress = 0;
+ulong MmPhysLastKernelAddress = 0;
 
 enum
 {
@@ -45,7 +47,6 @@ enum
 //
 void MmInitPaging(void)
 {
-    extern MemoryMap_t memoryMap;
     pdpe_t *MmPDP = NULL;
     pde_t *MmPD = NULL;
     pte_t *MmPT = NULL;
@@ -58,8 +59,8 @@ void MmInitPaging(void)
     ulong phRamSize = memoryMap.freeRamSize + memoryMap.nonfreeRamSize;
 
     // Difference between the end of kernel and the begin of userspace
-    MmPhysLastAddress = (ulong)(_heap_start + _heap_max);
-    ulong diffKernUsr = (ulong)USERSPACE - MmPhysLastAddress - KPAGESIZE;
+    MmPhysLastKernelAddress = (ulong)(_heap_start + _heap_max);
+    ulong diffKernUsr = (ulong)USERSPACE - MmPhysLastKernelAddress - KPAGESIZE;
 
     // Maximum VIRTUAL address in memory
     MmVirtLastAddress = phRamSize + diffKernUsr;
@@ -160,11 +161,11 @@ void MmInitPaging(void)
                                         //DebugLog("\tSection .rodata at %p\n", curAddrPT);
                                     }
                                     // While we're inside the kernel pages
-                                    else if ((ulong)curAddrPT <= MmPhysLastAddress) {
+                                    else if ((ulong)curAddrPT <= MmPhysLastKernelAddress) {
                                         MmPT[index] = (ulong)curAddrPT | PRESENT | READWRITE;
                                         MmPhysicalPageTable[xedni] = (ulong)curAddrPT;
 
-                                        if ((ulong)curAddrPT == MmPhysLastAddress) {
+                                        if ((ulong)curAddrPT == MmPhysLastKernelAddress) {
                                             //DebugLog("\tLast page of kernel at %p\n", curAddrPT);
                                         }
                                     }
@@ -284,23 +285,51 @@ void MmMapPage(void* virtualAddr, void* physicalAddr, ulong flags)
 //
 void MmUnmapPage(void* virtualAddr)
 {
-    MmUnsetPage(virtualAddr, PRESENT); // Removing the present flag
+    pte_t *page = MmGetPageDescriptorFromVirtual(virtualAddr);
+
+    *page &= (~PRESENT);
+
+    KeFlushTlbSingle(*page);
 }
 
 //
 // Find physical unallocated pages
 //
 void *MmGetPhyPageBlock(size_t size, bool usermode) {
-    void *startPage = 0;
+    void *startPhyPage = 0;
+    void *endPhyPage = 0;
+    size_t curSize = 0;
+
+    // Maximum PHYSICAL address in memory
+    ulong phRamSize = memoryMap.freeRamSize + memoryMap.nonfreeRamSize;
+
+    ulong curVirtAddr = 0;
 
     if (!usermode) {
-        startPage = MmTransPhyToVirtAddr(0);
+        startPhyPage = MmTransVirtToPhyAddr((void*)KPAGESIZE + 1);
+        endPhyPage = (void*)MmPhysLastKernelAddress;
     } else {
-        startPage = MmTransVirtToPhyAddr((void*)USERSPACE);
+        startPhyPage = MmTransVirtToPhyAddr((void*)USERSPACE);
+        endPhyPage = (void*)(phRamSize & ~(KPAGESIZE - 1));
     }
 
-    DebugLog("Userspace at %p\n", (void*)USERSPACE);
-    DebugLog("Userspace physical at %p\n", MmTransVirtToPhyAddr((void*)USERSPACE));
+    DebugLog("Start phy at %p\n", startPhyPage);
+    DebugLog("End phy at  %p\n", endPhyPage);
+
+    for (ulong curPhyAddr = (ulong)startPhyPage;
+         curPhyAddr <= (ulong)endPhyPage;
+         curPhyAddr += KPAGESIZE) {
+             curVirtAddr = (ulong)MmTransPhyToVirtAddr((void*)curPhyAddr);
+
+             if (curVirtAddr == 0) {
+                 DebugLog("CurrentAddr %p\n", curVirtAddr);
+                 DebugLog("\t Free !\n");
+                 curSize += KPAGESIZE;
+             }
+
+             if (curSize >= size)
+                 break;
+         }
 
     return NULL;
 }