Kernel: Make sure we free the thread stack on thread exit

This adds two new arguments to the thread_exit system call which let
a thread unmap an arbitrary VM range on thread exit. LibPthread
uses this functionality to unmap the thread stack.

Fixes #7267.

1 files changed, 7 insertions, 1 deletions

diff --git a/Kernel/Syscalls/thread.cpp b/Kernel/Syscalls/thread.cpp
index 42acab2690..3dc4852ac4 100644
--- a/Kernel/Syscalls/thread.cpp
+++ b/Kernel/Syscalls/thread.cpp
@@ -78,7 +78,7 @@ KResultOr<int> Process::sys$create_thread(void* (*entry)(void*), Userspace<const
     return thread->tid().value();
 }
 
-void Process::sys$exit_thread(Userspace<void*> exit_value)
+void Process::sys$exit_thread(Userspace<void*> exit_value, Userspace<void*> stack_location, size_t stack_size)
 {
     REQUIRE_PROMISE(thread);
 
@@ -90,6 +90,12 @@ void Process::sys$exit_thread(Userspace<void*> exit_value)
     auto current_thread = Thread::current();
     PerformanceManager::add_thread_exit_event(*current_thread);
 
+    if (stack_location) {
+        auto unmap_result = space().unmap_mmap_range(VirtualAddress { stack_location }, stack_size);
+        if (unmap_result.is_error())
+            dbgln("Failed to unmap thread stack, terminating thread anyway. Error code: {}", unmap_result.error());
+    }
+
     current_thread->exit(reinterpret_cast<void*>(exit_value.ptr()));
     VERIFY_NOT_REACHED();
 }