The AMM ranges were reserved at the last 64 GiB of the guest arena and
the reservation threw when that window was not free. On Windows the
stacks of the threads that exist before the arena is reserved (the main
thread and the loader's workers) are placed at random addresses and are
left in the arena as host regions; when one fell in the last 64 GiB, the
first AMM use threw "fixed guest mapping ... overlaps a host region in
the guest arena". Reserve the highest free 64 GiB window instead: the
last 64 GiB when it is free, and the window just below an occupied part
of it otherwise.
The arena constructor was Windows-only, so on Linux Available() was false: the guest heap fell back to the host allocator and direct memory landed wherever the kernel pleased. Titles that require a low virtual address rejected the mapping and re-issued the identical request, which surfaced as a start-up assert inside their own allocator.
Seed the window from the mappings that already exist instead of reserving it up front, because a PROT_NONE reservation of the whole range starves the kernel's own top-down mmap, which picks addresses just below the stack inside that range. Commit, reset and set-protection become portable so the arena owns its used ranges on both platforms, and fixed mappings are checked against the arena's used ranges rather than against EEXIST from a reservation.
The window-placement and no-overwrite checks in guest_memory were compiled only for Windows; they now run on Linux too, and the window check fails without this change.
Fixes#692
Retain host backing views for emulator writes and completion labels. Validate full spans, preserve write versions and GPU ordering, and keep the fallback for other mappings. Test remaps, aliases, access checks, partial failures, tracking, view lifetime, and completion ordering.
Written with AI assistance.
On Linux, direct memory is a memfd mapped MAP_SHARED. amdgpu accepts only
private anonymous memory for a host pointer import (libdrm sets
AMDGPU_GEM_USERPTR_ANONONLY), so every import of direct memory failed with
VK_ERROR_INVALID_EXTERNAL_HANDLE and its ranges were copied.
When a host pointer import fails, the range's memfd slice is turned into a
dma-buf through /dev/udmabuf and imported with VK_EXT_external_memory_dma_buf.
The direct memory backing is sealed against shrinking and growing, as
udmabuf requires. libkernel reports the backing of a guest range through
GuestArenaSharedBacking. Without /dev/udmabuf, or past its size limit, the
range is copied as before. APS5_TRACE_HOST_IMPORT now prints the mappings
behind a failed import on Linux too.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Write tracking protects shared guest pages read-only. A push on a fiber
stack in such a page faults, and Windows cannot dispatch it because the
exception frame lands on the same protected stack, so the process was
terminated without a report. Pin fiber contexts writable for their
lifetime; pinned pages are always collected as written.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A store the driver makes with the CPU into watched guest memory (a
GuestMemory::Write, a changed-bytes write-back, a completion action's label
store, the copy HLE's CPU path) faults its pages dirty in the write watch and
stamps the range with MarkWritten. The faults stayed behind: collects are
memoized per packet, so the next walk over those pages came later and stamped
them again, as a CPU write made after every check in between.
PPSA21564 fast-clears its normal G-buffer every frame with a register DCC key
fill on the GPU. While that fill is still pending, the first draw into the
target materializes the clear with a CPU store of the clear texels and a
refresh of the resident image. A dozen draws later a walk found the store's
faults, the target read as changed, and the image was uploaded again from
guest memory, dropping the draws recorded in between. Lighting then sampled
cleared normals and the level's moon and rocks went unlit in about half the
frames.
The driver's stores now consume those faults themselves: a walk before the
store stamps earlier CPU writes as such, a walk after it takes the store's
own faults as a driver store, and the range is stamped as before.
On Windows the arena's range also holds host regions that were already in
use when it was reserved (heaps, thread stacks). They are not write-watched,
so a store into one is stamped as before, without a walk.
A file read into guest memory is a host write: before the I/O it pins the shared pages it
covers, which reopens any page armed for write tracking and keeps write tracking from arming
it again until the read ends, when the pages count as written. A destination the guest cannot
write fails with EFAULT before any I/O; read and pread throw as for any failed read, AIO
reports SCE_KERNEL_ERROR_EFAULT, and APR throws. APR also throws when a read ends before the
requested size.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Only the lines this branch added lose their comments; the commits before
keep them, with the reasoning behind each change, for whoever digs into
that code later.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
libkernel:
- direct memory keeps its contents per physical page across unmap and
remap; a page mapped at two live addresses at once throws
- sceKernelDirectMemoryQuery answers from tracked allocations
- SCE protections read back as set, GPU and AMPR bits included
- APR prefix path resolve, file size and stat by id, positional reads,
fsync/pread/pwrite; directories open as descriptors on Windows
- sceKernelCheckReachability, getpeername, shutdown
- Dinkumware C11 threads (_Mtx_*, _Cnd_*, _Thrd_*) in the title libc
layout; any pthread stack size, rounded at thread creation
libc:
- unaddressed guest mappings go to the system-managed area from
0x2_0000_0000, leaving the application area to fixed mappings
- the process starts in /app0
- guest sscanf on Windows; a null %s prints as (null) as on FreeBSD
- localeconv, _FNan, _FDtest, _FExp, __udivti3, wcsncpy_s, aligned
operator new, _Throw_Cpp_error
Tests: direct memory following physical pages, guest formatting.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- libc: reserve guest memory in one arena below the PS5 map limit with
MEM_WRITE_WATCH (GuestArena) and a caching guest heap; the allocation
registry gains a generation counter, an invalidator callback for the
driver's page cache and a pin waiter for leased ranges. This replaces
the fault-based GuestMemoryTracking/GuestMemoryBacking layer, whose
files are removed.
- libkernel: mmap/mprotect/munmap on the arena, flexible memory budget,
real sceKernelVirtualQuery; POSIX pthread layer, rwlocks, timed locks,
TSD, event flags; 0.5 ms scheduler tick and high-resolution sleeps;
TSC/clock/time functions; file APIs return SCE errno codes; the APR
file-streaming API.
- libc: vectored crash reporter with backtraces for fatal exceptions,
SIGABRT, UCRT invalid parameters and process exit; SSE4a EXTRQ/INSERTQ
emulation for Intel hosts; %ls/%lc/%S/%C with the guest's 16-bit
wchar_t; hand-written setjmp/longjmp for the guest jmp_buf; a path
alias table for short save-data mount points; more string, stdio and
math exports.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0177gthrWEBBfBu5xJDXgBfo
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