refactor syscall ABI and FAT32 driver to use request structs and string views natively, enforce handle access rights on object lookup, add scheduler statistics tracking, fix KiSchedule to prevent 50% idle throttling on CPU-bound threads, better document x64 initial user stack alignment, fix process teardown to properly signal exit events and manage thread counts, optimize doom file I/O with a custom handle struct to internally track position and size, add SubsystemData to TEB for generic thread-local state, apply PAGE_NX to non-executable PE sections in the loader, update native apps, tests, and shells to match new APIs, update kernel32 directory retrieval.

code/kernel/mm_virt.h

@@ -73,11 +73,6 @@ __declspec(dllexport) KSTATUS MmProbeUserWrite(void* ptr, size_t size);
 __declspec(dllexport) KSTATUS CopyFromUser(void* kernelDst, const void* userSrc, size_t size);
 __declspec(dllexport) KSTATUS CopyToUser(void* userDst, const void* kernelSrc, size_t size);
 
-// Bounded NUL-terminated string import from user memory. Always NUL-terminates
-// kernelDst when kernelDstSize is non-zero. Returns STATUS_BUFFER_TOO_SMALL if
-// no NUL byte was found within kernelDstSize bytes.
-__declspec(dllexport) KSTATUS CopyStringFromUser(char* kernelDst, size_t kernelDstSize, const char* userSrc);
-
 // ---------------------------------------------------------------------------
 // Kernel pool - ring 0 only, never PAGE_USER.
 // Best-fit free-list allocator, thread-safe via spinlock.
@@ -88,11 +83,17 @@ __declspec(dllexport) void* MmReallocatePool(void* ptr, size_t newSize);
 
 // ---------------------------------------------------------------------------
 // User heap - shared flat space, ring 3 accessible.
-// All allocations are PAGE_PRESENT | PAGE_WRITE | PAGE_USER.
+// Allocations are writable user pages with NX set by default; PE image
+// sections opt back into execution through the loader.
 // ---------------------------------------------------------------------------
 __declspec(dllexport) void* MmAllocateUserMemory(size_t size);
 __declspec(dllexport) void  MmFreeUserMemory(void* ptr);
 __declspec(dllexport) void* MmReallocateUserMemory(void* ptr, size_t newSize);
 
+// Page-aligned user image mapping.  PE section protection is page based, so
+// executable images must not be allocated from the normal sub-page heap.
+__declspec(dllexport) void* MmAllocateUserImage(size_t size);
+__declspec(dllexport) void  MmFreeUserImage(void* ptr, size_t size);
+
 size_t MmGetKernelPoolUsage(void);
 size_t MmGetUserHeapUsage(void);