From fed49a29af87bd4bf5e4ad652651ffee6d6d1c11 Mon Sep 17 00:00:00 2001
From: 4lDO2 <4lDO2@protonmail.com>
Date: Mon, 5 Aug 2024 13:22:18 +0200
Subject: [PATCH] Properly deallocate thread stack on pthread_exit.

---
 redox-rt/src/thread.rs    | 20 ++++++++++++++++----
 src/platform/linux/mod.rs |  2 +-
 src/platform/pal/mod.rs   |  2 +-
 src/platform/redox/mod.rs |  4 ++--
 src/pthread/mod.rs        | 12 ++++++------
 5 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/redox-rt/src/thread.rs b/redox-rt/src/thread.rs
index 664588ab77..1791732a22 100644
--- a/redox-rt/src/thread.rs
+++ b/redox-rt/src/thread.rs
@@ -1,6 +1,8 @@
+use core::mem::size_of;
+
 use syscall::{Result, O_CLOEXEC};
 
-use crate::{arch::*, proc::*, RtTcb};
+use crate::{arch::*, proc::*, signal::tmp_disable_signals, RtTcb};
 
 /// Spawns a new context sharing the same address space as the current one (i.e. a new thread).
 pub unsafe fn rlct_clone_impl(stack: *mut usize) -> Result<FdGuard> {
@@ -48,10 +50,20 @@ pub unsafe fn rlct_clone_impl(stack: *mut usize) -> Result<FdGuard> {
     Ok(new_thr_fd)
 }
 
-pub fn exit_this_thread() -> ! {
-    let thread_fd = RtTcb::current().thread_fd();
+pub unsafe fn exit_this_thread(stack_base: *mut (), stack_size: usize) -> ! {
+    let _guard = tmp_disable_signals();
+
+    let tcb = RtTcb::current();
+    let thread_fd = tcb.thread_fd();
+
+    let _ = syscall::funmap(tcb as *const RtTcb as usize, syscall::PAGE_SIZE);
+
     // TODO: modify interface so it writes directly to the thread fd?
     let status_fd = syscall::dup(**thread_fd, b"status").unwrap();
-    syscall::write(status_fd, &usize::MAX.to_ne_bytes()).unwrap();
+    let mut buf = [0; size_of::<usize>() * 3];
+    plain::slice_from_mut_bytes(&mut buf)
+        .unwrap()
+        .copy_from_slice(&[usize::MAX, stack_base as usize, stack_size]);
+    syscall::write(status_fd, &buf).unwrap();
     unreachable!()
 }
diff --git a/src/platform/linux/mod.rs b/src/platform/linux/mod.rs
index 0646f1b78c..b258b52da5 100644
--- a/src/platform/linux/mod.rs
+++ b/src/platform/linux/mod.rs
@@ -157,7 +157,7 @@ impl Pal for Sys {
         }
         loop {}
     }
-    fn exit_thread() -> ! {
+    unsafe fn exit_thread(_stack_base: *mut (), _stack_size: usize) -> ! {
         // TODO
         Self::exit(0)
     }
diff --git a/src/platform/pal/mod.rs b/src/platform/pal/mod.rs
index 3a234dfec3..09dea6cba9 100644
--- a/src/platform/pal/mod.rs
+++ b/src/platform/pal/mod.rs
@@ -55,7 +55,7 @@ pub trait Pal {
 
     fn exit(status: c_int) -> !;
 
-    fn exit_thread() -> !;
+    unsafe fn exit_thread(stack_base: *mut (), stack_size: usize) -> !;
 
     fn fchdir(fildes: c_int) -> c_int;
 
diff --git a/src/platform/redox/mod.rs b/src/platform/redox/mod.rs
index a3bda34315..57482b4d9b 100644
--- a/src/platform/redox/mod.rs
+++ b/src/platform/redox/mod.rs
@@ -1137,7 +1137,7 @@ impl Pal for Sys {
         (unsafe { syscall::syscall5(syscall::number::SYS_GETPID, !0, !0, !0, !0, !0) }).is_ok()
     }
 
-    fn exit_thread() -> ! {
-        redox_rt::thread::exit_this_thread()
+    unsafe fn exit_thread(stack_base: *mut (), stack_size: usize) -> ! {
+        redox_rt::thread::exit_this_thread(stack_base, stack_size)
     }
 }
diff --git a/src/pthread/mod.rs b/src/pthread/mod.rs
index 2d2fc7b20f..d7b97fe1de 100644
--- a/src/pthread/mod.rs
+++ b/src/pthread/mod.rs
@@ -2,7 +2,7 @@
 
 use core::{
     cell::{Cell, UnsafeCell},
-    mem::MaybeUninit,
+    mem::{offset_of, MaybeUninit},
     ptr::{addr_of, NonNull},
     sync::atomic::{AtomicBool, AtomicUsize, Ordering},
 };
@@ -22,8 +22,6 @@ use crate::{
 
 use crate::sync::{waitval::Waitval, Mutex};
 
-const MAIN_PTHREAD_ID: usize = 1;
-
 /// Called only by the main thread, as part of relibc_start.
 pub unsafe fn init() {
     Tcb::current()
@@ -269,7 +267,7 @@ pub unsafe fn join(thread: &Pthread) -> Result<Retval, Errno> {
 pub unsafe fn detach(thread: &Pthread) -> Result<(), Errno> {
     thread
         .flags
-        .fetch_or(PthreadFlags::DETACHED.bits(), Ordering::Release);
+        .fetch_or(PthreadFlags::DETACHED.bits(), Ordering::AcqRel);
     Ok(())
 }
 
@@ -294,6 +292,8 @@ pub unsafe fn exit_current_thread(retval: Retval) -> ! {
     header::tls::run_all_destructors();
 
     let this = current_thread().expect("failed to obtain current thread when exiting");
+    let stack_base = this.stack_base;
+    let stack_size = this.stack_size;
 
     if this.flags.load(Ordering::Acquire) & PthreadFlags::DETACHED.bits() != 0 {
         // When detached, the thread state no longer makes any sense, and can immediately be
@@ -304,12 +304,12 @@ pub unsafe fn exit_current_thread(retval: Retval) -> ! {
         this.waitval.post(retval);
     }
 
-    Sys::exit_thread()
+    Sys::exit_thread(stack_base.cast(), stack_size)
 }
 
 unsafe fn dealloc_thread(thread: &Pthread) {
+    // TODO: How should this be handled on Linux?
     OS_TID_TO_PTHREAD.lock().remove(&thread.os_tid.get().read());
-    //drop(Box::from_raw(thread as *const Pthread as *mut Pthread));
 }
 pub const SIGRT_RLCT_CANCEL: usize = 33;
 pub const SIGRT_RLCT_TIMER: usize = 34;