新增系统调用，并对照linux-6.1.9改写sys_wait4 (#440)

* 1. 新增以下系统调用
            - SYS_LSTAT
            - SYS_READV
            - SYS_ACCESS
            - SYS_UNLINK
            - SYS_CHMOD
            - SYS_FCHMOD
            - SYS_UMASK
            - SYS_SYSINFO
            - SYS_CLOCK_GETTIME
            - SYS_FCHMODAT
            - SYS_FACCESSAT

2. 修改sys_wait4,使得其部分符合Linux的行为(还是有些地方不符合的,详情请对比linux-6.1.9的sys_wait4接口)

kernel/src/syscall/misc.rs

@@ -0,0 +1,57 @@
+use crate::arch::mm::LockedFrameAllocator;
+
+use super::{user_access::UserBufferWriter, Syscall, SystemError};
+
+#[repr(C)]
+
+/// 系统信息
+///
+/// 参考 https://opengrok.ringotek.cn/xref/linux-6.1.9/include/uapi/linux/sysinfo.h#8
+#[derive(Debug, Default, Copy, Clone)]
+pub struct SysInfo {
+    uptime: u64,
+    loads: [u64; 3],
+    totalram: u64,
+    freeram: u64,
+    sharedram: u64,
+    bufferram: u64,
+    totalswap: u64,
+    freeswap: u64,
+    procs: u16,
+    pad: u16,
+    totalhigh: u64,
+    freehigh: u64,
+    mem_unit: u32,
+    // 这后面还有一小段，但是我们不需要
+}
+
+impl Syscall {
+    pub fn sysinfo(info: *mut SysInfo) -> Result<usize, SystemError> {
+        let mut writer = UserBufferWriter::new(info, core::mem::size_of::<SysInfo>(), true)?;
+        let mut sysinfo = SysInfo::default();
+
+        let mem = LockedFrameAllocator.get_usage();
+        sysinfo.uptime = 0;
+        sysinfo.loads = [0; 3];
+        sysinfo.totalram = mem.total().bytes() as u64;
+        sysinfo.freeram = mem.free().bytes() as u64;
+        sysinfo.sharedram = 0;
+        sysinfo.bufferram = 0;
+        sysinfo.totalswap = 0;
+        sysinfo.freeswap = 0;
+        sysinfo.procs = 0;
+        sysinfo.pad = 0;
+        sysinfo.totalhigh = 0;
+        sysinfo.freehigh = 0;
+        sysinfo.mem_unit = 0;
+
+        writer.copy_one_to_user(&sysinfo, 0)?;
+
+        return Ok(0);
+    }
+
+    pub fn umask(_mask: u32) -> Result<usize, SystemError> {
+        kwarn!("SYS_UMASK has not yet been implemented\n");
+        return Ok(0o777);
+    }
+}