Implementation of uptime for sysinfo

kernel/src/syscall/sysinfo.rs

@@ -1,11 +1,34 @@
 // SPDX-License-Identifier: MPL-2.0
 
 use super::SyscallReturn;
+use crate::prelude::*;
+use aster_time::read_monotonic_time;
+
+#[derive(Debug, Default, Clone, Copy, Pod)]
+#[repr(C)]
+pub struct sysinfo {
+    uptime: i64,
+    loads: [u64; 3],
+    totalram: u64,
+    freeram: u64,
+    sharedram: u64,
+    bufferram: u64,
+    totalswap: u64,
+    freeswap: u64,
+    procs: u16,
+    totalhigh: u64,
+    freehigh: u64,
+    mem_unit: u32
+}
 
 pub fn sys_sysinfo(
     sysinfo_addr: Vaddr,
     ctx: &Context,
 ) -> Result<SyscallReturn> {
-    unimplemented!("sysinfo implementation in process");
-    Ok(SyscallReturn::Return(-1))
-}
+    let info = sysinfo {
+        uptime: read_monotonic_time().as_secs() as i64,
+        ..Default::default() // TODO: add other system information
+    };
+    ctx.user_space().write_val(sysinfo_addr, &info)?;
+    Ok(SyscallReturn::Return(0))
+}