From 3ac9a53caabcb8b9f43b5e1638968c027c2c79d6 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Sun, 11 Feb 2024 23:33:25 -0500
Subject: kernel: sched: Add initial sched related code

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/kern/init_main.c  | 13 +++++--
 sys/kern/kern_sched.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 108 insertions(+), 2 deletions(-)
 create mode 100644 sys/kern/kern_sched.c

(limited to 'sys/kern')

diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 99f1e87..2fe84ed 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -32,6 +32,8 @@
 #include <sys/syslog.h>
 #include <sys/machdep.h>
 #include <sys/timer.h>
+#include <sys/sched.h>
+#include <machine/cpu_mp.h>
 #include <firmware/acpi/acpi.h>
 #include <vm/physseg.h>
 #include <logo.h>
@@ -72,6 +74,8 @@ list_timers(void)
 void
 main(void)
 {
+    struct cpu_info *ci;
+
     pre_init();
     tty_init();
     syslog_init();
@@ -86,6 +90,11 @@ main(void)
     processor_init();
     list_timers();
 
-    /* We're done here, halt the processor */
-    __ASMV("cli; hlt");
+    ci = this_cpu();
+    if (ap_bootstrap != NULL) {
+        ap_bootstrap(ci);
+    }
+
+    sched_init_processor(ci);
+    __builtin_unreachable();
 }
diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c
new file mode 100644
index 0000000..da4c6c5
--- /dev/null
+++ b/sys/kern/kern_sched.c
@@ -0,0 +1,97 @@
+/*
+ * 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/sched.h>
+#include <sys/sched_state.h>
+#include <sys/types.h>
+#include <sys/cdefs.h>
+#include <sys/spinlock.h>
+#include <assert.h>
+
+/*
+ * This is the processor ready list, processors
+ * (cores) that have no task assigned live here.
+ *
+ * Assigning a task to a core is done by popping from
+ * this list. However, it must be done carefully and
+ * must be serialized. You *must* acquire ci_ready_lock
+ * before performing *any* operations on ci_ready_list!!!
+ */
+static TAILQ_HEAD(, cpu_info) ci_ready_list;
+static struct spinlock ci_ready_lock = {0};
+
+/*
+ * Push a processor into the ready list.
+ */
+static void
+sched_enqueue_ci(struct cpu_info *ci)
+{
+    spinlock_acquire(&ci_ready_lock);
+    TAILQ_INSERT_TAIL(&ci_ready_list, ci, link);
+    spinlock_release(&ci_ready_lock);
+}
+
+/*
+ * Processor awaiting tasks to be assigned will be here spinning.
+ *
+ * XXX: We are not using the PAUSE instruction for the sake of
+ *      ensuring compatibility... PAUSE is F3 90, REP NOP is
+ *      F3 90... REP NOP will be read as a PAUSE on processors
+ *      that support it.
+ */
+__noreturn static void
+sched_enter(void)
+{
+    for (;;) {
+        __ASMV("rep; nop");
+    }
+}
+
+/*
+ * Setup scheduler related things and enqueue AP.
+ */
+void
+sched_init_processor(struct cpu_info *ci)
+{
+    struct sched_state *sched_state = &ci->sched_state;
+    static bool is_init = true;
+
+    if (is_init) {
+        /* Setup ready list if first call */
+        TAILQ_INIT(&ci_ready_list);
+        is_init = false;
+    }
+
+    TAILQ_INIT(&sched_state->queue);
+    sched_enqueue_ci(ci);
+
+    sched_enter();
+
+    __builtin_unreachable();
+}
-- 
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