feat: overhaul userspace heap and virtual memory

kernel/src/Api/Syscall.cpp

@@ -118,6 +118,12 @@ namespace montauk::abi {
             case SYS_FREE:
                 Sys_Free(frame->arg1);
                 return 0;
+            case SYS_MMAP_ANON:
+                return (int64_t)Sys_MapAnonymous(frame->arg1, frame->arg2);
+            case SYS_MUNMAP:
+                return Sys_Unmap(frame->arg1, frame->arg2);
+            case SYS_MPROTECT:
+                return Sys_Protect(frame->arg1, frame->arg2, frame->arg3);
             case SYS_GETTICKS:
                 return (int64_t)Sys_GetTicks();
             case SYS_GETMILLISECONDS:
@@ -590,9 +596,9 @@ namespace montauk::abi {
     // ---- SYSCALL MSR initialization ----
 
     void InitializeSyscalls() {
-        // Enable SYSCALL/SYSRET in EFER
+        // Enable SYSCALL/SYSRET and no-execute page permissions in EFER.
         uint64_t efer = Hal::ReadMSR(Hal::IA32_EFER);
-        efer |= 1;  // SCE bit (Syscall Enable)
+        efer |= 1 | (1ULL << 11);  // SCE | NXE
         Hal::WriteMSR(Hal::IA32_EFER, efer);
 
         // STAR: kernel CS in [47:32], sysret base in [63:48]
@@ -608,7 +614,7 @@ namespace montauk::abi {
         Hal::WriteMSR(Hal::IA32_FMASK, 0x200);
 
         Kt::KernelLogStream(Kt::OK, "Syscall") << "SYSCALL/SYSRET initialized (LSTAR="
-            << kcp::hex << (uint64_t)SyscallEntry << kcp::dec << ", 154 syscall slots)";
+            << kcp::hex << (uint64_t)SyscallEntry << kcp::dec << ", 171 syscall slots)";
     }
 
 }