refactor(memory): complete PMM/VMM/LMM rewrite - bitmap allocators, bug fixes, hardening

PMM Rewrite:
- Replace ~8KB record array with compact bitmaps
  (PhysPresent/PhysAlloc/PhysScanned, 128B each)
- Add PhysOwner[0..1023] for per-block ownership tracking
- new_block: O(1) amortised via NextFreeHint + dword-level BSF scan,
  returns 0 as OOM sentinel
- free_block: O(1) direct bit clear with double-free detection
- alloc_block: validates PhysPresent and PhysAlloc bits before allocation
- Add pmm_free_blocks/pmm_total_blocks stats functions

VMM Correctness Fixes:
- Fix free_page block extraction (Address SHR 10, was using
  raw Address field)
- Fix invlpg operand (use virtual address, was passing PDE index)
- Clear PDE entry on free_page before returning block to PMM
- Remove map_page double-write (delegate to map_page_ex only)
- Add OOM propagation (new_page returns false if PMM returns 0)
- Fix missing pop_trace in new_page error path

LMM Rewrite:
- Replace per-entry record array with bitmap allocator
  (93% vs 43% page efficiency)
- Layout: Header(24B) + Bitmap(64512B) + Padding + Data at 0x10000
- SIZE_PREFIX=16 for 16-byte aligned returns (SSE MOVAPS requirement)
- Next-fit bitmap scan with roving hint (NextFree) and dword-level
  fast skip
- Large alloc sentinel (LARGE_ALLOC_MAGIC=$FFFFFFFE) so kfree detects
  klalloc'd memory
- Implement klfree (was previously a no-op - pages could never
  be returned)
- Implement try_release_page (return fully-free heap pages to VMM/PMM)
- Fix interrupt safety: stack-balanced pushfd/cli/pop +
  restore_if (sti only)
  Fixes Bad TSS caused by popfd restoring dangerous EFLAGS bits (NT, IOPL)
- Zero memory via rep stosd instead of byte-by-byte loop

Hardening:
- kalloc OOM now triggers BSOD instead of returning nil
  (90% of callers don't check)
- Double-free detection in kfree (verify bitmap bits set before clearing)
- Guard bytes ({$IFDEF DEBUG_LMM}): $DEADBEEF sentinel for buffer overrun detection
- kpalloc: bounds check (block >= 1024 -> GPF) + syslog MMIO mapping audit log

Observability:
- Add MEMINFO command as src/prog/meminfo.pas (moved from inline kernel.pas)
- Displays multiboot memory, PMM block stats, LMM heap stats
- Register via progmanager.pas following standard prog pattern

Files changed:
- src/pmemorymanager.pas
- src/vmemorymanager.pas
- src/lmemorymanager.pas
- src/kernel.pas
- src/progmanager.pas
- src/prog/meminfo.pas

src/driver/net/l1/net.pas

@@ -100,8 +100,8 @@ end;
 
 procedure send(p_data : void; p_len : uint16);
 begin
-    push_trace('net.send');
+    //push_trace('net.send');
-    writeToLogLn('L1/NET: send');
+    //writeToLogLn('L1: net.send');
     if CBSend <> nil then CBSend(p_data, p_len);
     pop_trace;
 end;
@@ -111,7 +111,8 @@ var
     context : PPacketContext;
 
 begin
-    push_trace('net.recv');
+    //push_trace('net.recv');
+    //writeToLogLn('L1: net.recv');
     context:= newPacketContext;
     if CBNext <> nil then CBNext(p_data, p_len, context);
     freePacketContext(context);
@@ -128,7 +129,6 @@ end;
 procedure init;
 begin
     push_trace('net.init');
-    writeToLogLn('L1/NET: init');
     //l2
     eth2.register;
     //l3
@@ -136,7 +136,6 @@ begin
     ipv4.register;
     //l4
     icmp.register;
-    tcp.register;
     udp.register;
     //l5
     dhcp.register;

src/driver/net/l2/eth2.pas

@@ -46,7 +46,6 @@ var
 
 procedure registerTypePromisc(eType : uint16; RecvCB : TRecvCallback);
 begin
-    push_trace('eth2.registerTypePromisc');
     register;
     if EthTypes[eType] = nil then EthTypes[eType]:= RecvCB;
     Promisc[eType]:= true;
@@ -54,7 +53,6 @@ end;
 
 procedure registerType(eType : uint16; RecvCB : TRecvCallback);
 begin
-    push_trace('eth2.registerType');
     register;
     if EthTypes[eType] = nil then EthTypes[eType]:= RecvCB;
 end;
@@ -95,7 +93,7 @@ var
     buf        : puint8;
 
 begin
-    push_trace('eth2.recv');
+    //writeToLogLn('    L2: eth2.recv');
     buf:= puint8(p_data);
     
     Header:= PEthernetHeader(buf);
@@ -122,7 +120,6 @@ var
 begin
     push_trace('eth2.register');
     if not Registered then begin
-        writeToLogLn('    L2/ETH: register');
         for i:=0 to 65535 do begin
             EthTypes[i]:= nil;
             Promisc[i]:= false;

src/driver/net/l3/arp.pas

@@ -96,7 +96,6 @@ var
     hSize, pSize : uint8;
 
 begin
-    push_trace('arp.send');
     if p_context <> nil then begin
         buf:= kalloc(sizeof(TARPHeader));
         hdr:= PARPHeader(buf);
@@ -136,8 +135,6 @@ var
     context : PPacketContext;
 
 begin
-     push_trace('arp.sendGratuitous');
-     writeToLogLn('      L3/ARP: sendGratuitous');
      context:= newPacketContext;
      CopyIPv4(@getIPv4Config^.Address[0], @context^.IP.Destination[0]);
      CopyIPv4(@getIPv4Config^.Address[0], @context^.IP.Source[0]);
@@ -153,7 +150,6 @@ var
     CacheRecord : PARPCacheRecord;
 
 begin
-     push_trace('arp.sendRequestGateway');
      context:= newPacketContext;
      CacheRecord:= findCacheRecordByIP(@getIPv4Config^.Gateway[0]);
      if CacheRecord <> nil then begin
@@ -172,8 +168,6 @@ var
     CacheRecord : PARPCacheRecord;
 
 begin
-     push_trace('arp.sendRequest');
-     writeToLogLn('      L3/ARP: sendRequest');
      context:= newPacketContext;
      CopyIPv4(ip, @context^.IP.Destination[0]);
      CopyIPv4(@getIPv4Config^.Address[0], @context^.IP.Source[0]);
@@ -190,7 +184,6 @@ var
     CacheRecord : PARPCacheRecord;
 
 begin
-    push_trace('arp.resolveIP');
     CacheRecord:= findCacheRecordByIP(ip);
     resolveIP:= nil;
     if CacheRecord = nil then begin
@@ -210,7 +203,6 @@ var
     context      : PPacketContext;
 
 begin
-    push_trace('arp.recv');
     { Get our converted Header }
     Header:= PARPHeader(p_data);
     AHeader.Hardware_Type:= (Header^.Hardware_Type_Hi SHL 8) + Header^.Hardware_Type_Lo;
@@ -306,7 +298,6 @@ procedure register;
 begin
     push_trace('arp.register');
     if not Registered then begin
-        writeToLogLn('      L3/ARP: register');
         Cache:= LL_New(sizeof(TARPCacheRecord));
         eth2.registerTypePromisc($0806, @recv);
         stdio.registerCommand('ARP', @terminal_command_arp, 'Get ARP Table.');

src/driver/net/l3/ipv4.pas

@@ -46,9 +46,7 @@ var
 
 function  getIPv4Config : PIPv4Configuration;
 begin
-    push_trace('ipv4.getIPv4Config');
     getIPv4Config:= @Config;
-    pop_trace;
 end;
 
 procedure send(p_data : void; p_len : uint16; p_context : PPacketContext);
@@ -59,7 +57,6 @@ var
     buffer : void;
 
 begin
-    push_trace('ipv4.send');
     inc(CurrentID);
     Header.version:= 4;
     Header.header_len:= 5;
@@ -87,7 +84,6 @@ begin
     memcpy(uint32(p_data), uint32(Buffer) + (Header.header_len * 4), p_len);
     eth2.send(Buffer, (Header.header_len * 4) + p_len, $0800, p_context);
     kfree(Buffer);
-    pop_trace;
 end;
 
 procedure recv(p_data : void; p_len : uint16; p_context : PPacketContext);
@@ -99,7 +95,6 @@ var
     len     : uint16;
 
 begin
-    push_trace('ipv4.recv');
     Header:= PIPV4Header(p_data);
     AHeader.version:= Header^.version;
     AHeader.header_len:= Header^.header_len;
@@ -200,7 +195,6 @@ var
 begin
     push_trace('ipv4.register');
     if not Registered then begin
-        writeToLogLn('      L3/IPv4: register');
         for i:=0 to 255 do begin
             Protocols[i]:= nil;
         end;
@@ -219,7 +213,6 @@ end;
 
 procedure registerProtocol(Protocol_ID : uint8; recv_callback : TRecvCallback);
 begin
-    push_trace('ipv4.registerProtocol');
     register;
     if Protocols[Protocol_ID] = nil then Protocols[Protocol_ID]:= recv_callback;
     pop_trace;

src/driver/net/l4/icmp.pas

@@ -23,7 +23,7 @@ interface
 
 uses
     bios_data_area,
-    lmemorymanager, tracer,
+    lmemorymanager,
     net, nettypes, netutils, ipv4, arp, util;
 
 type
@@ -55,7 +55,6 @@ var
     i : uint8;
 
 begin
-    push_trace('icmp.nextInactiveHandler');
     nextInactiveHandler:= 0;
     for i:=1 to 255 do begin
         if not Handlers[i].Active then begin
@@ -81,8 +80,6 @@ var
     Size     : uint32;
 
 begin
-    push_trace('icmp.sendICMPRequest');
-    writeToLogLn('        L4/ICMP: sendICMPRequest');
     handle:= nextInactiveHandler;
     Handlers[handle].Active:= true;
     Handlers[handle].OnReply:= OnRep;
@@ -138,8 +135,6 @@ var
     Handle : uint8;
 
 begin
-    push_trace('icmp.recv');
-    writeToLogLn('        L4/ICMP: recv');
     Header:= PICMPHeader(p_data);
     //writehexlnWND(Header^.ICMP_Type, getTerminalHWND); 
     case Header^.ICMP_Type of
@@ -248,8 +243,6 @@ var
     i : uint32;
 
 begin
-    push_trace('icmp.register');
-    writeToLogLn('        L4/ICMP: register');
     for i:=0 to 255 do begin
         Handlers[i].Active:= false;
         Handlers[i].OnError:= nil;

src/driver/net/l4/udp.pas

@@ -25,7 +25,7 @@ uses
     lmemorymanager,
     nettypes, netutils,
     ipv4, net,
-    tracer, util;
+    util;
 
 procedure register();
 function bind(bindContext : PUDPBindContext) : TUDPError;
@@ -71,7 +71,6 @@ begin
             nullend:= true;
         end;
         pseudoBuffer:= kalloc(sizeof(TUDPPseudoHeader) + pseudoSize);
-        push_trace('udp.CalculateChecksum');
         pseudoBuffer8:= puint8(pseudoBuffer);
         pseudoBuffer16:= puint16(pseudoBuffer);
         pseudoBuffer32:= puint32(pseudoBuffer);
@@ -119,7 +118,6 @@ var
 
 
 begin
-    push_trace('udp.send');
     if udpContext <> nil then begin
         size:= p_len + sizeof(TUDPHeader);
         buffer:= kalloc(size);
@@ -154,7 +152,6 @@ var
     context : PUDPBindContext;
 
 begin
-    push_trace('udp.bind');
     result:= tueGenericError;
     if bindContext <> nil then begin
         if Ports[bindContext^.port] = nil then begin
@@ -177,7 +174,6 @@ var
     context : PUDPBindContext;
 
 begin
-    push_trace('udp.unbind');
     result:= tueGenericError;
     if bindContext <> nil then begin
         context:= Ports[bindContext^.port];
@@ -207,7 +203,6 @@ var
     size    : uint16;
 
 begin
-    push_trace('udp.ProcessPacket');
     header:= PUDPHeader(p_data);
     if Ports[switchendian16(header^.DstPort)] <> nil then begin
         context:= PUDPPacketContext(kalloc(sizeof(TUDPPacketContext)));
@@ -250,8 +245,6 @@ var
     Checksum      : uint32;
 
 begin
-    push_trace('udp.register');
-    writeToLogLn('        L4/UDP: register');
     for i:=0 to 65535 do begin
         Ports[i]:= nil;
     end;

src/driver/net/l5/dhcp.pas

@@ -415,7 +415,7 @@ end;
 
 procedure processPacket_NAK(Header : PDHCPHeader; Options : PDHCPOptions);
 begin
-    writeToLogLn('          L5/DHCP: Process NAK.');
+    syslog.logln('DHCP', 'Process NAK.'); 
     { Server provided a NAK, NULL configuration ready for next DISCOVER/Request } 
     nullConfiguration();  
 end;
@@ -429,7 +429,7 @@ var
     cfgopt : void;
 
 begin
-    writeToLogLn('          L5/DHCP: Process ACK.');
+    syslog.logln('DHCP', 'Process ACK.');
     getIPv4Config^.UP:= false;
     
     //Copy new address
@@ -484,7 +484,7 @@ Var
 
 begin
     syslog.logln('DHCP', 'Process OFFER.');  
-    writeToLogLn('          L5/DHCP: Process OFFER.');
+
     { Check the Transaction ID matches our stored ID, discard if not. }
     if Header^.Transaction_ID = Configuration^.Transaction then begin
         syslog.logln('DHCP', 'XID Match');
@@ -566,7 +566,6 @@ var
 
 begin
     tracer.push_trace('dhcp.processPacket.enter');
-    writeToLogLn('          L5/DHCP: processPacket');
     syslog.logln('DHCP','processPacket');
     
     { Give access to header values & process to correct endianness. }
@@ -637,7 +636,6 @@ var
 
 begin
     tracer.push_trace('dhcp.DHCPDiscover.begin');
-    writeToLogLn('          L5/DHCP: DHCPDiscover');
     { Ensure we have a socket bound. }
     if Socket <> nil then begin    
         { Clear any current configuration }
@@ -713,7 +711,6 @@ var
 
 begin
     tracer.push_trace('dhcp.register');
-    writeToLogLn('          L5/DHCP: register');
     syslog.logln('DHCP', 'Register begin.');
     
     { Kalloc our Configuration Data }

src/kernel.pas

@@ -73,23 +73,6 @@ procedure kmain(mbinfo: Pmultiboot_info_t; mbmagic: uint32); stdcall;
  
 implementation
 
-procedure terminal_command_meminfo(params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
-begin
-    push_trace('kernel.terminal_command_meminfo');
-
-    stdio.bufWriteStr(stdout_buf, 'Lower Memory = ');
-    stdio.bufWriteInt(stdout_buf, multibootinfo^.mem_lower);
-    stdio.bufWriteStrLn(stdout_buf, 'KB');
-    stdio.bufWriteStr(stdout_buf, 'Higher Memory = ');
-    stdio.bufWriteInt(stdout_buf, multibootinfo^.mem_upper);
-    stdio.bufWriteStrLn(stdout_buf, 'KB');
-    stdio.bufWriteStr(stdout_buf, 'Total Memory = ');
-    stdio.bufWriteInt(stdout_buf, ((multibootinfo^.mem_upper + 1000) div 1024) + 1);
-    stdio.bufWriteStrLn(stdout_buf, 'MB');
-
-    pop_trace;
-end;
-
 procedure terminal_command_bsod(params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
 begin
     push_trace('kernel.terminal_command_bsod');
@@ -182,7 +165,6 @@ begin
 
      { Stdio Init }
      stdio.init();
-     stdio.registerCommand('MEMINFO', @terminal_command_meminfo, 'Print Simple Memory Information.');
      stdio.registerCommand('BSOD', @terminal_command_bsod, 'Force a Panic Screen.');
 
      tss.init();

src/prog/meminfo.pas

@@ -0,0 +1,83 @@
+//  Copyright 2021 Kieron Morris
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//  http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+
+{ 
+	Prog->meminfo - Print memory statistics (PMM / LMM).
+	
+	@author(Kieron Morris <[email protected]>)
+}
+unit meminfo;
+
+interface
+
+uses
+    stdio, multiboot, pmemorymanager, lmemorymanager, tracer;
+
+procedure init();
+
+implementation
+
+procedure run(Params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
+var
+    pmm_total, pmm_free, pmm_used : uint32;
+    lmm_pages, lmm_free           : uint32;
+begin
+    { Multiboot memory info }
+    stdio.bufWriteStrLn(stdout_buf, '--- Multiboot ---');
+    stdio.bufWriteStr(stdout_buf, 'Lower Memory  : ');
+    stdio.bufWriteInt(stdout_buf, multibootinfo^.mem_lower);
+    stdio.bufWriteStrLn(stdout_buf, ' KB');
+    stdio.bufWriteStr(stdout_buf, 'Upper Memory  : ');
+    stdio.bufWriteInt(stdout_buf, multibootinfo^.mem_upper);
+    stdio.bufWriteStrLn(stdout_buf, ' KB');
+    stdio.bufWriteStr(stdout_buf, 'Total Memory  : ');
+    stdio.bufWriteInt(stdout_buf, ((multibootinfo^.mem_upper + 1000) div 1024) + 1);
+    stdio.bufWriteStrLn(stdout_buf, ' MB');
+
+    { PMM stats }
+    stdio.bufWriteStrLn(stdout_buf, '--- PMM (4 MB blocks) ---');
+    pmm_total := pmemorymanager.pmm_total_blocks;
+    pmm_free  := pmemorymanager.pmm_free_blocks;
+    pmm_used  := pmm_total - pmm_free;
+    stdio.bufWriteStr(stdout_buf, 'Total Blocks  : ');
+    stdio.bufWriteIntLn(stdout_buf, pmm_total);
+    stdio.bufWriteStr(stdout_buf, 'Free Blocks   : ');
+    stdio.bufWriteIntLn(stdout_buf, pmm_free);
+    stdio.bufWriteStr(stdout_buf, 'Used Blocks   : ');
+    stdio.bufWriteIntLn(stdout_buf, pmm_used);
+    stdio.bufWriteStr(stdout_buf, 'Free Physical : ');
+    stdio.bufWriteInt(stdout_buf, pmm_free * 4);
+    stdio.bufWriteStrLn(stdout_buf, ' MB');
+
+    { LMM heap stats }
+    stdio.bufWriteStrLn(stdout_buf, '--- LMM (Heap) ---');
+    lmm_pages := lmemorymanager.lmm_page_count;
+    lmm_free  := lmemorymanager.lmm_total_free;
+    stdio.bufWriteStr(stdout_buf, 'Heap Pages    : ');
+    stdio.bufWriteIntLn(stdout_buf, lmm_pages);
+    stdio.bufWriteStr(stdout_buf, 'Heap Size     : ');
+    stdio.bufWriteInt(stdout_buf, lmm_pages * 4);
+    stdio.bufWriteStrLn(stdout_buf, ' MB');
+    stdio.bufWriteStr(stdout_buf, 'Heap Free     : ');
+    stdio.bufWriteInt(stdout_buf, lmm_free div 1024);
+    stdio.bufWriteStrLn(stdout_buf, ' KB');
+end;
+
+procedure init();
+begin
+    tracer.push_trace('meminfo.init');
+    stdio.registerCommand('MEMINFO', @Run, 'Print memory statistics (PMM/LMM).');
+end;
+
+end.

src/progmanager.pas

@@ -24,7 +24,7 @@ interface
 uses
     tracer,
     //progs
-    base64_prog, md5sum, dhclient, vbeinfo;
+    base64_prog, md5sum, dhclient, vbeinfo, meminfo;
 
 { Initialize all baked-in programs }
 procedure init();
@@ -40,6 +40,7 @@ begin
     tracer.push_trace('progmanager.dhclient.init');
     dhclient.init();
     vbeinfo.init();
+    meminfo.init();
 end;
 
 end.

src/vmemorymanager.pas

@@ -159,20 +159,14 @@ end;
 
 function map_page(page_number : uint16; block : uint16) : boolean;
 var
-    addr  : ubit20;
-    page  : uint16;
     rldpd : uint32;
 
 begin
     push_trace('vmemorymanager.map_page');
-    map_page:= false; 
+    { Delegate to map_page_ex — no redundant direct PDE writes }
-    PageDirectory^[page_number].Present:= true;
+    map_page := map_page_ex(page_number, block, PageDirectory);
-    addr:= block;
+    { Reload CR3 to flush TLB }
-    PageDirectory^[page_number].Address:= addr SHL 10;
+    rldpd := uint32(PageDirectory) - KERNEL_VIRTUAL_BASE;
-    PageDirectory^[page_number].PageSize:= true;
-    PageDirectory^[page_number].Writable:= true;
-    map_page:= map_page_ex(page_number, block, PageDirectory);
-    rldpd:= uint32(PageDirectory) - KERNEL_VIRTUAL_BASE;
     asm
         mov eax, rldpd
         mov CR3, eax
@@ -201,14 +195,15 @@ var
 
 begin
     push_trace('vmemorymanager.new_page');
-    new_page:= false;
+    new_page := false;
     if not PageDirectory^[page_number].Present then begin
         if not PageDirectory^[page_number].Reserved then begin
-            block:= pmemorymanager.new_block(uint32(PageDirectory));
+            block := pmemorymanager.new_block(uint32(PageDirectory));
-            if block < 2 then begin
+            if block = 0 then begin
-                GPF;
+                { OOM — PMM has no free blocks. Return false gracefully. }
+                syslog.logln('VMM', 'ERROR: new_page failed — PMM OOM.');
             end else begin
-                new_page:= map_page(page_number, block);
+                new_page := map_page(page_number, block);
             end;
         end;
     end;
@@ -216,17 +211,15 @@ begin
 end;
 
 function page_mappable(page_number : uint16) : boolean;
-var
-    block : uint16;
-
 begin
     push_trace('vmemorymanager.page_mappable');
-    page_mappable:= false;
+    page_mappable := false;
     if not PageDirectory^[page_number].Present then begin
         if not PageDirectory^[page_number].Reserved then begin
-            page_mappable:= true;
+            page_mappable := true;
         end;
     end;
+    pop_trace;
 end;
 
 function new_page_at_address(address : uint32) : boolean;
@@ -243,14 +236,25 @@ end;
 procedure free_page(page_number : uint16);
 var
     block : uint16;
+    vaddr : uint32;
 
 begin
     push_trace('vmemorymanager.free_page');
     if PageDirectory^[page_number].Present then begin
-        block:= PageDirectory^[page_number].Address;
+        { Recover block index: Address stores (block SHL 10), so SHR 10 gives block }
+        block := PageDirectory^[page_number].Address SHR 10;
+        { Clear the PDE before invalidating }
+        PageDirectory^[page_number].Present    := false;
+        PageDirectory^[page_number].Writable   := false;
+        PageDirectory^[page_number].PageSize   := false;
+        PageDirectory^[page_number].Address    := 0;
+        { Invalidate TLB for this virtual address (invlpg needs a virtual addr) }
+        vaddr := uint32(page_number) SHL 22;
         asm
-            invlpg [page_number]
+            mov eax, vaddr
+            invlpg [eax]
         end;
+        { Return physical block to PMM }
         pmemorymanager.free_block(block, uint32(PageDirectory));
     end else begin
         GPF;