fix(libkernel): throw for an unmeasured unbalanced thread atexit decrement on a module

Co-Authored-By: Claude Opus 5.5 <[email protected]>

core/libs/prx/libkernel/System/src/Rtld.cpp

@@ -66,10 +66,8 @@ int releaseThreadAtexitImage(const void* address, const char* caller) {
     {
         std::lock_guard lock(threadAtexitMutex);
         const auto found = threadAtexitReferences.find(image);
-        if (found == threadAtexitReferences.end()) {
-            APS5_LOG_OUT("%s: image holds no thread atexit reference", caller);
-            return 0;
-        }
+        if (found == threadAtexitReferences.end())
+            throw std::runtime_error(std::string(caller) + ": image holds no thread atexit reference");
         handle = found->second;
         threadAtexitReferences.erase(found);
     }

core/libs/tests/GuestDynamicLoader.cpp

@@ -229,7 +229,7 @@ int main(int argc, char** argv) {
     Require(_sceKernelRtldThreadAtexitDecrement_nid_postfix(reinterpret_cast<const void*>(add)) == 0);
     Require(_sceKernelRtldThreadAtexitIncrement_nid_postfix(reinterpret_cast<const void*>(&ThrowsRuntimeError<void (*)()>)) == 0);
     Require(_sceKernelRtldThreadAtexitDecrement_nid_postfix(reinterpret_cast<const void*>(&ThrowsRuntimeError<void (*)()>)) == 0);
-    Require(_sceKernelRtldThreadAtexitDecrement_nid_postfix(reinterpret_cast<const void*>(&Require)) == 0);
+    Require(ThrowsRuntimeError([] { _sceKernelRtldThreadAtexitDecrement_nid_postfix(reinterpret_cast<const void*>(&Require)); }));
     int local = 0;
     Require(_sceKernelRtldThreadAtexitIncrement_nid_postfix(&local) == -1);
     Require(_sceKernelRtldThreadAtexitIncrement_nid_postfix(nullptr) == -1);

docs/dev/debt/libkernel.md

@@ -77,7 +77,7 @@
 - [Map hints inside a reservation](../../../core/libs/prx/libkernel/DirectMemory/DirectMemory.cpp) (libkernel) - `sceKernelMapDirectMemory` and the flexible and anonymous maps place a mapping without `MAP_FIXED` at its hint address when the whole range lies in a range still reserved by `sceKernelReserveVirtualRange`, as if `MAP_FIXED` were set. Taken from PPSA01474, which reserves 64 GiB and then maps its heaps inside it with hints and no `MAP_FIXED`, and uses the hint addresses afterwards; not measured on the console. Hints outside a reservation, or over a range that is partly mapped, stay hints
 - [Fixed anonymous mmap](../../../core/libs/prx/libkernel/DirectMemory/PosixMemory.cpp) (libkernel) - `MAP_PRIVATE | MAP_ANON | MAP_FIXED` replaces the requested range through the existing guest mapping machinery and zeroes the new memory. `MAP_EXCL` is checked under the allocation-registry mutation lock, including virtual reservations, and returns `ENOMEM` without changing an occupied range; without `MAP_FIXED` it is `EINVAL`. Lengths are rounded to 16 KiB and fixed addresses must be aligned. The complete rounded range must lie inside the guest arena or, for POSIX fixed anonymous `mmap` on Windows, one current or registered native thread stack; other mapping APIs do not opt into stack replacement. Native stack replacement keeps the reservation, decommits and recommits fresh pages, and rejects foreign allocations, ranges spanning reservations and host `PAGE_GUARD` pages before mutation. Current-stack ranges must end at least 64 KiB below the active host frame; callers replacing another thread's stack must coordinate with that thread. If recommitting fails, the call returns `ENOMEM` with the range still reserved; thread cleanup attempts to recommit it before restoring write access. This follows FreeBSD 11.4 [argument validation and rounding](https://github.com/freebsd/freebsd-src/blob/8c639945a44588f6cfdddfb057bb5aad88735da0/sys/vm/vm_mmap.c#L226-L299), [fixed replacement](https://github.com/freebsd/freebsd-src/blob/8c639945a44588f6cfdddfb057bb5aad88735da0/sys/vm/vm_map.c#L1455-L1464), and [collision errno](https://github.com/freebsd/freebsd-src/blob/8c639945a44588f6cfdddfb057bb5aad88735da0/sys/vm/vm_mmap.c#L1604-L1613). The console behaviour has not been measured. AnyPS5 starts the guest arena at 0x200000000, so the fixed path rejects the low 0x400000 address requested by PICO-8 PPSA99808. The console address-space layout is unmeasured; executable placement outside the host arena is tracked in #5217. Static catalog disassembly finds `0x1012` in PPSA98001/PPSA99808 and `0x5012` in PPSA99808; these titles were not run.
 - [Mapping hints with no room above them](../../../core/libs/prx/libkernel/DirectMemory/DirectMemory.cpp) (libkernel) - a mapping without `MAP_FIXED` whose hint lies above the guest address space, or has no free range at or above it, is placed from the bottom of the guest arena, as FreeBSD 11.4's [`vm_mmap_object`](https://github.com/freebsd/freebsd-src/blob/8c639945a44588f6cfdddfb057bb5aad88735da0/sys/vm/vm_mmap.c#L1569) retries through [`vm_map_find_min`](https://github.com/freebsd/freebsd-src/blob/8c639945a44588f6cfdddfb057bb5aad88735da0/sys/vm/vm_map.c#L1555-L1584) from its minimum address. FreeBSD's minimum is the end of the largest possible data segment rather than the start of the arena, and the console's address-space layout is not measured. PS5CEMU-HAR (PPSA99360) gives `sceKernelReserveVirtualRange` a hint near its own code, which is a host address here because the relinked executable lies outside the guest arena, so its JIT gets memory more than 2 GiB from its code and does not start
-- [_sceKernelRtldThreadAtexitIncrement, _sceKernelRtldThreadAtexitDecrement](../../../core/libs/prx/libkernel/System/src/Rtld.cpp) (libkernel) - the argument is the `dso` address a title's `libc.prx` passes to `__cxa_thread_atexit` (PPSA14632), which fails when Increment returns nonzero. As in a payload process on a PS5 (firmware 13.60), Increment returns -1 for an address outside every module (null, stack, heap) and 0 otherwise, and Decrement never fails, also without a matching Increment; the console's Decrement returns nothing, here 0. The module's `ref_count` did not change on the console. As in [fpPS4](https://github.com/red-prig/fpPS4), Increment here takes a reference on the image and Decrement releases one. The variants without the leading underscore are not exported by firmware 13.60's `libkernel_sys`; here they match
+- [_sceKernelRtldThreadAtexitIncrement, _sceKernelRtldThreadAtexitDecrement](../../../core/libs/prx/libkernel/System/src/Rtld.cpp) (libkernel) - the argument is the `dso` address a title's `libc.prx` passes to `__cxa_thread_atexit` (PPSA14632), which fails when Increment returns nonzero. As in a payload process on a PS5 (firmware 13.60), Increment returns -1 for an address outside every module (null, stack, heap) and 0 otherwise, and Decrement never fails on an address outside every module or after a matching Increment; the console's Decrement returns nothing, here 0. A Decrement on a module's address without a matching Increment was not measured and throws here. The module's `ref_count` did not change on the console. As in [fpPS4](https://github.com/red-prig/fpPS4), Increment here takes a reference on the image and Decrement releases one. The variants without the leading underscore are not exported by firmware 13.60's `libkernel_sys`; here they match
 - [tcgetattr, tcsetattr](../../../core/libs/prx/libkernel/File/src/Terminal.cpp) (libkernel) - every file and pipe descriptor is taken as not a terminal (`ENOTTY`), and a socket gets `EADDRNOTAVAIL` for `AF_INET` and `EOPNOTSUPP` otherwise, as FreeBSD's `in_control` and `pru_control_notsupp` answer a termios ioctl; what descriptors 0 to 2 of a title are on the console, and whether any of them is a terminal there, is unknown
 - [cfsetspeed](../../../core/libs/prx/libkernel/File/src/Terminal.cpp) (libkernel, NID `C1MQ6OaXRjo`) - console behavior and module/library versions are unverified. The prototype, uint32 speed and 44-byte termios layout (input speed at 36, output speed at 40) follow the public PS5 payload SDK [termios.h](https://github.com/ps5-payload-dev/sdk/blob/a7685ce8e97ce1f8a4f38253a41d54241c9124f1/include/freebsd/termios.h) and [sys/_termios.h](https://github.com/ps5-payload-dev/sdk/blob/a7685ce8e97ce1f8a4f38253a41d54241c9124f1/include/freebsd/sys/_termios.h). The module association follows its libkernel stub table and the NID rehashes to the aerolib name. Both speed fields accept every uint32 value and no flags or control characters change, as [FreeBSD 11.4 termios.c](https://github.com/freebsd/freebsd-src/blob/d106002967eff712894ab8b5337bbbff106ce5e0/lib/libc/gen/termios.c) does. No terminal I/O is performed. Null pointers throw where the reference dereferences them.
 - [select](../../../core/libs/prx/libkernel/Socket/src/Socket.cpp) (libkernel) - descriptor 0 is never reported readable and descriptors 1 and 2 are always writable, as for a console title with no input; reads from descriptor 0 still go to the host stdin. `/dev/random` and `/dev/urandom` follow `randomdev_poll` for a seeded device under [`selscan`](https://github.com/freebsd/freebsd-src/blob/release/11.4.0/sys/kern/sys_generic.c#L1178-L1236), which asks once with the flags of every set the descriptor is in: in the read set they are readable and reported in no other set, and otherwise they are reported in the write and exception sets they were asked in. A regular file, a directory or a file read from app0.zar is always readable and writable and never in the exception set, as `vop_stdpoll` answers, on every host. Guest sockets and libSceNet sockets are polled. A kqueue is readable while one of its events is triggered and is never writable or in the exception set, as FreeBSD 11.4's [`kqueue_poll`](https://github.com/freebsd/freebsd-src/blob/release/11.4.0/sys/kern/kern_event.c#L1900-L1924) answers, on every host. Other descriptors are polled through the host on Linux, while on Windows pipes are checked every millisecond with the readiness test `poll` uses and any other descriptor throws. Dungeons (PPSA16064) selects on descriptor 0, and RetroArch (PPSA99169) selects on its web server's wake-up pipe next to its listening socket