kernel: sched: Add exit1()

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 104 insertions, 5 deletions

diff --git a/sys/include/sys/proc.h b/sys/include/sys/proc.h
index 684742a..5303072 100644
--- a/sys/include/sys/proc.h
+++ b/sys/include/sys/proc.h
@@ -33,6 +33,7 @@
 #include <sys/types.h>
 #include <sys/spinlock.h>
 #include <sys/queue.h>
+#include <sys/param.h>
 #if defined(_KERNEL)
 #include <machine/frame.h>
 #include <machine/pcb.h>
@@ -47,13 +48,17 @@ struct proc {
     struct trapframe tf;
     struct pcb pcb;
     size_t priority;
+    uint32_t flags;
     uintptr_t stack_base;
     TAILQ_ENTRY(proc) link;
 };
 
+#define PROC_EXITING    BIT(0)  /* Exiting */
+
 struct proc *this_td(void);
 int md_fork(struct proc *p, struct proc *parent, uintptr_t ip);
 int fork1(struct proc *cur, int flags, void(*ip)(void), struct proc **newprocp);
+int exit1(struct proc *td);
 
 #endif  /* _KERNEL */
 #endif  /* !_SYS_PROC_H_ */
diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
new file mode 100644
index 0000000..9995f51
--- /dev/null
+++ b/sys/kern/kern_exit.c
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/proc.h>
+#include <sys/sched.h>
+#include <vm/physmem.h>
+#include <vm/dynalloc.h>
+#include <vm/vm.h>
+
+/*
+ * Kill a thread and deallocate its resources.
+ *
+ * @td: Thread to exit
+ */
+int
+exit1(struct proc *td)
+{
+    struct pcb *pcbp;
+    struct proc *curtd;
+    uintptr_t stack;
+    pid_t target_pid, curpid;
+
+    target_pid = td->pid;
+    curtd = this_td();
+    pcbp = &td->pcb;
+
+    curpid = curtd->pid;
+    stack = td->stack_base;
+    td->flags |= PROC_EXITING;
+
+    /*
+     * If this is on the higher half, it is kernel
+     * mapped and we need to convert it to a physical
+     * address.
+     */
+    if (stack >= VM_HIGHER_HALF) {
+        stack -= VM_HIGHER_HALF;
+    }
+
+    vm_free_frame(stack, PROC_STACK_PAGES);
+    pmap_destroy_vas(pcbp->addrsp);
+    dynfree(td);
+
+    /*
+     * If we are the thread exiting, reenter the scheduler
+     * and do not return.
+     */
+    if (target_pid == curpid)
+        sched_enter();
+
+    return 0;
+}
diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c
index f1bd067..9df541e 100644
--- a/sys/kern/kern_sched.c
+++ b/sys/kern/kern_sched.c
@@ -31,6 +31,7 @@
 #include <sys/sched.h>
 #include <sys/schedvar.h>
 #include <sys/cdefs.h>
+#include <sys/param.h>
 #include <sys/syslog.h>
 #include <machine/frame.h>
 #include <machine/cpu.h>
@@ -130,15 +131,30 @@ sched_switch(struct trapframe *tf)
     struct cpu_info *ci;
     struct pcb *pcbp;
     struct proc *next_td, *td;
+    bool use_current = true;
+    bool inexec;
 
     ci = this_cpu();
     td = ci->curtd;
 
-    /* Do we have threads to switch to? */
-    if ((next_td = sched_dequeue_td()) == NULL) {
-        sched_oneshot(false);
-        return;
-    }
+    /*
+     * Get the next thread and use it only if it isn't
+     * in the middle of an exit, exec, or whatever.
+     */
+    do {
+        if ((next_td = sched_dequeue_td()) == NULL) {
+            sched_oneshot(false);
+            return;
+        }
+
+        /*
+         * Don't use this thread if we are currently
+         * exiting.
+         */
+        if (ISSET(next_td->flags, PROC_EXITING)) {
+            use_current = false;
+        }
+    } while (!use_current);
 
     /* Re-enqueue the old thread */
     if (td != NULL) {