kern/amd64: Add reboot function

Add a function that reboots the system by attempting the softest method
and incrementally becoming forceful if previous methods fail

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

2 files changed, 128 insertions, 0 deletions

diff --git a/src/sys/arch/amd64/os/os_reboot.c b/src/sys/arch/amd64/os/os_reboot.c
new file mode 100644
index 0000000..e414822
--- /dev/null
+++ b/src/sys/arch/amd64/os/os_reboot.c
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * 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 the project 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/types.h>
+#include <sys/reboot.h>
+#include <sys/cdefs.h>
+#include <os/reboot.h>
+#include <machine/pio.h>
+
+/*
+ * Actual reboot core
+ */
+__dead static void
+__reboot(void)
+{
+    void *dmmy_null = NULL;
+
+    /*
+     * Try to be gentle and simply put the CPU into a
+     * reboot cycle through the i8042 reset line, though
+     * some chipsets may not like this.
+     */
+    outb(0x64, 0xFE);
+
+    /*
+     * If somehow nothing we've tried worked, be very
+     * violent and force it to reboot via faulty IDT.
+     */
+    __ASMV(
+        "lidt %0\n"
+        "int $0\n"
+        :
+        : "m" (dmmy_null)
+        : "memory"
+    );
+
+    __builtin_unreachable();
+}
+
+void
+reboot(int method)
+{
+    __reboot();
+    __builtin_unreachable();
+}
+
+/*
+ * ARG0: Method
+ */
+scret_t
+sys_reboot(struct syscall_args *scargs)
+{
+    int method = SCARG(scargs, int, 0);
+
+    reboot(method);
+    __builtin_unreachable();
+}
diff --git a/src/sys/include/sys/reboot.h b/src/sys/include/sys/reboot.h
new file mode 100644
index 0000000..539eeab
--- /dev/null
+++ b/src/sys/include/sys/reboot.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * 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 the project 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.
+ */
+
+#ifndef _SYS_REBOOT_H_
+#define _SYS_REBOOT_H_
+
+#include <sys/types.h>
+#include <sys/cdefs.h>
+
+#define RB_RESET  0x0000
+
+/*
+ * Reboot the system
+ *
+ * @method: What should be done
+ */
+__dead void reboot(int method);
+
+#endif  /* !_SYS_REBOOT_H_ */