Since guest threads get exactly the stack size they request, host code
that a guest thread calls runs on that small stack too. sceAgcCreateShader
reaches Driver::RegisterShader, whose frame alone is about 50 KiB, so a
title whose job threads ask for 48 KiB overflows the stack (#2603).
Each guest thread now gets a fixed 1 MiB of host stack below the range it
asked for. The guest still sees the requested size and address range
through scePthreadAttrGet and sceKernelIsStack; only host calls made from
the thread use the extra room. Running the prepared-shader driver tests on
a limited main-thread stack needs between 128 and 192 KiB for shader
registration, Vulkan setup included, so 1 MiB leaves several times that.
Switching to a separate host stack at each HLE entry point would need a
trampoline on every export that may go deep, handling of stack-passed
arguments and unwinding across the switch, and a list of which exports
qualify. A margin below the guest range covers every host call with no
per-export list.
On Windows the committed size was the requested size, and the margin
below it depended on the executable's default stack reserve; requests at
or above that reserve had none. The commit now includes the same margin.
macOS does not run guest threads.
guest_pthread_stack now also calls host code that uses 256 KiB of stack
below each thread's guest range; without the margin it crashes on the
16 KiB thread.
Fixes#2603
scePthreadCreate on Linux started guest threads with std::thread, so every
thread got the host default stack (RLIMIT_STACK, usually 8 MiB) whatever the
title asked for. A thread that asks for more than that and uses it crashes
with SIGSEGV. Once the thread ran, scePthreadAttrGet also reported the host
size instead of the requested one.
Create the thread with pthread_create and a stack of the requested size plus
what glibc keeps at its top (static TLS, the thread control block and the
start_thread frame). That reserve is measured once with a probe thread.
The thread reports [top - reserve - size, top - reserve) as its stack, as
Windows reports [top - size, top), and the creator waits until the range is
set, as on Windows.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
JJenkx
Dean Galvin
NevesHenry