Follow-up task to enforce coalesced guest memory writes within the gettimeofday subsystem, removing remaining partial-write risks on virtual memory page boundaries.
* sceKernelGettimeofday Hardening: Replaced consecutive isolated 8-byte scalar writes with a single 16-byte coalesced transaction buffer using stackalloc byte[16] and BinaryPrimitives. It preserves native Orbis semantics by returning ORBIS_GEN2_ERROR_MEMORY_FAULT on failure states without side-effect partial-writes.
* POSIX gettimeofday Compliance:
- Applied the identical single-transaction 16-byte write pattern for the timeval structure.
- Implemented a single 8-byte coalesced zero-fill transaction for the deprecated/legacy timezone buffer (timezoneAddress != 0) using BinaryPrimitives.WriteInt32LittleEndian, aligning it with standard FreeBSD stub behavior.
- Integrated proper TrySetErrno(ctx, Efault) tracking upon write failures. The method safely omits explicit manual Rax writes on error paths, allowing the import dispatcher to cleanly sign-extend the return -1 value to 0xFFFFFFFFFFFFFFFF.
Out of scope: Subsystem clock and timeval validation is now fully complete; no further temporal partial-write vulnerabilities remain within the core runtime memory compat layers.
Files: KernelRuntimeCompatExports.cs
Refactored parts of the time subsystem to improve POSIX/Orbis compliance and secure guest memory boundaries.
**1. POSIX `clock_gettime` updates:**
- Added `CLOCK_REALTIME_FAST` (10) and `CLOCK_MONOTONIC_FAST` (12) support for games using FreeBSD fast clock extensions.
- Fixed `NULL` pointer handling for `timespecAddress == 0`. It now returns `-1` with `EINVAL` (22) instead of `EFAULT` to match Orbis runtime behavior.
- Invalid `clock_id` values now properly fallback to `default` -> `-1` + `EINVAL`.
**2. Memory safety & monotonic tracking:**
- Replaced dual 8-byte scalar writes in both POSIX `clock_gettime` and Orbis `sceKernelClockGettime` with a single 16-byte write via `stackalloc byte[16]` and `BinaryPrimitives`. This prevents partial memory corruption at page boundaries.
- Bad non-NULL guest addresses now fail cleanly as `EFAULT` (POSIX) or `MEMORY_FAULT` (Orbis).
- Extracted core monotonic math into `GetProcessMonotonicTime()` in `KernelRuntimeCompatExports.cs` so both clock paths share the exact same `_processStartCounter` base.
**3. Host RDTSC optimization:**
- Fixed `CreateRdtscReader()` to copy stack-allocated opcode bytes into host `VirtualAlloc` memory via `unsafe { Buffer.MemoryCopy(...) }`. This completely gets rid of the redundant `.ToArray()` allocation on the hot path.
**Out of scope:** `sceKernelGettimeofday` / POSIX `gettimeofday` partial-write hardening; stricter clock validation in `sceKernelClockGettime`.
Read guest C strings in page-bounded chunks without heap allocations.
Return false when the buffer fills without a null terminator. Route exit
and _exit through RequestProcessExit.
Mike Saito