Add shutdown syscall and program

Makefile

@@ -130,6 +130,7 @@ UPROGS=\
 	$P/_usertests\
 	$P/_wc\
 	$P/_zombie\
+	$P/_shutdown\
 
 fs.img: mkfs/mkfs README $(UPROGS)
 	mkfs/mkfs fs.img README $(UPROGS)

kernel/memlayout.h

@@ -17,6 +17,9 @@
 // end -- start of kernel page allocation area
 // PHYSTOP -- end RAM used by the kernel
 
+// QEMU test interface. Used for poweroff and on.
+#define QEMU_POWER 0x100000
+
 // qemu puts UART registers here in physical memory.
 #define UART0 0x10000000L
 #define UART0_IRQ 10

kernel/rustkernel/src/riscv/memlayout.rs

@@ -18,6 +18,9 @@
 
 use super::{MAXVA, PGSIZE};
 
+// QEMU test interface. Used for power off and on.
+pub const QEMU_POWER: u64 = 0x100000u64;
+
 // QEMU puts UART registers here in physical memory.
 pub const UART0: u64 = 0x10000000;
 pub const UART0_IRQ: i32 = 10;

kernel/rustkernel/src/syscall.rs

@@ -1,7 +1,7 @@
 use crate::{
     console::printf::print,
     proc::{self, myproc, sleep_lock},
-    riscv::Pagetable,
+    riscv::{Pagetable, memlayout::QEMU_POWER},
     string::strlen,
 };
 use core::{mem::size_of, ptr::addr_of_mut};
@@ -47,6 +47,7 @@ pub enum Syscall {
     Link,
     Mkdir,
     Close,
+    Shutdown,
 }
 impl Syscall {
     pub unsafe fn call(&self) -> u64 {
@@ -113,6 +114,11 @@ impl Syscall {
             Syscall::Link => sys_link(),
             Syscall::Mkdir => sys_mkdir(),
             Syscall::Close => sys_close(),
+            Syscall::Shutdown => {
+                let qemu_power = QEMU_POWER as usize as *mut u32;
+                qemu_power.write_volatile(0x5555u32);
+                panic!("shutdown");
+            }
         }
     }
 }
@@ -142,6 +148,7 @@ impl TryFrom<usize> for Syscall {
             19 => Ok(Syscall::Link),
             20 => Ok(Syscall::Mkdir),
             21 => Ok(Syscall::Close),
+            22 => Ok(Syscall::Shutdown),
             _ => Err(()),
         }
     }
@@ -170,6 +177,7 @@ impl From<Syscall> for usize {
             Syscall::Link => 19,
             Syscall::Mkdir => 20,
             Syscall::Close => 21,
+            Syscall::Shutdown => 22,
         }
     }
 }

kernel/syscall.h

@@ -20,3 +20,4 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
+#define SYS_shutdown  22

kernel/vm.c

@@ -24,6 +24,9 @@ kvmmake(void)
   kpgtbl = (pagetable_t) kalloc();
   memset(kpgtbl, 0, PGSIZE);
 
+  // QEMU test interface used for power management.
+  kvmmap(kpgtbl, QEMU_POWER, QEMU_POWER, PGSIZE, PTE_R | PTE_W);
+
   // uart registers
   kvmmap(kpgtbl, UART0, UART0, PGSIZE, PTE_R | PTE_W);
 

programs/shutdown.c

@@ -0,0 +1,10 @@
+#include "kernel/types.h"
+#include "kernel/stat.h"
+#include "user/user.h"
+
+int main(int argc, char *argv[])
+{
+  shutdown();
+  // Unreachable
+  exit(1);
+}

user/user.h

@@ -22,6 +22,7 @@ int getpid(void);
 char* sbrk(int);
 int sleep(int);
 int uptime(void);
+void shutdown(void);
 
 // ulib.c
 int stat(const char*, struct stat*);

user/usys.pl

@@ -36,3 +36,4 @@ entry("getpid");
 entry("sbrk");
 entry("sleep");
 entry("uptime");
+entry("shutdown");