From f63ad250f45f7d41e704c785870de861402567b2 Mon Sep 17 00:00:00 2001
From: Ashwin Naren <arihant2math@gmail.com>
Date: Sun, 14 Dec 2025 14:48:59 -0800
Subject: [PATCH] implement restarting

---
 src/arch/arm64/mod.rs | 10 ++++++++++
 src/arch/mod.rs       |  3 +++
 src/kernel/power.rs   |  3 ++-
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/arch/arm64/mod.rs b/src/arch/arm64/mod.rs
index 25adea3..fc03dba 100644
--- a/src/arch/arm64/mod.rs
+++ b/src/arch/arm64/mod.rs
@@ -121,6 +121,16 @@ impl Arch for Aarch64 {
         Self::halt()
     }
 
+    fn restart() -> ! {
+        const PSCI_SYSTEM_RESET: u32 = 0x8400_0009;
+        unsafe {
+            psci::do_psci_hyp_call(PSCI_SYSTEM_RESET, 0, 0, 0);
+        }
+
+        // Fallback: halt the CPU indefinitely.
+        Self::halt()
+    }
+
     unsafe fn copy_from_user(
         src: UA,
         dst: *mut (),
diff --git a/src/arch/mod.rs b/src/arch/mod.rs
index 8886252..ef58ca0 100644
--- a/src/arch/mod.rs
+++ b/src/arch/mod.rs
@@ -42,6 +42,9 @@ pub trait Arch: CpuOps + VirtualMemory {
     /// Powers off the machine. Implementations must never return.
     fn power_off() -> !;
 
+    /// Restarts the machine. Implementations must never return.
+    fn restart() -> !;
+
     /// Call a user-specified signal handler in the current process.
     fn do_signal(
         sig: SigId,
diff --git a/src/kernel/power.rs b/src/kernel/power.rs
index 72d9d31..e0cd0f7 100644
--- a/src/kernel/power.rs
+++ b/src/kernel/power.rs
@@ -12,7 +12,7 @@ pub async fn sys_reboot(magic: u32, magic2: u32, op: u32, _arg: usize) -> Result
     // const LINUX_REBOOT_CMD_HALT: u32 = 0xcdef_0123;
     // const LINUX_REBOOT_CMD_KEXEC: u32 = 0x4558_4543;
     const LINUX_REBOOT_CMD_POWER_OFF: u32 = 0x4321_fedc;
-    // const LINUX_REBOOT_CMD_RESTART: u32 = 0x0123_4567;
+    const LINUX_REBOOT_CMD_RESTART: u32 = 0x0123_4567;
     // const LINUX_REBOOT_CMD_RESTART2: u32 = 0xa1b2_c3d4;
     // const LINUX_REBOOT_CMD_SW_SUSPEND: u32 = 0xd000_fce1;
     if magic != LINUX_REBOOT_MAGIC1
@@ -28,6 +28,7 @@ pub async fn sys_reboot(magic: u32, magic2: u32, op: u32, _arg: usize) -> Result
             // User is supposed to sync first.
             ArchImpl::power_off()
         }
+        LINUX_REBOOT_CMD_RESTART => ArchImpl::restart(),
         // TODO: Implement other reboot operations.
         _ => Err(KernelError::InvalidValue),
     }