add sbrk and a usertest

user/src/bin/sbrk_test.rs

@@ -0,0 +1,47 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+use user_lib::sbrk;
+use core::ptr::slice_from_raw_parts_mut;
+
+#[no_mangle]
+fn main() -> i32 {
+    println!("Test sbrk start.");
+    const PAGE_SIZE: usize = 0x1000;
+    let origin_brk = sbrk(0);
+    println!("origin break point = {:x}", origin_brk);
+    let brk = sbrk(PAGE_SIZE as i32);
+    if brk != origin_brk {
+        return -1
+    }
+    let brk = sbrk(0);
+    println!("one page allocated,  break point = {:x}", brk);
+    println!("try write to allocated page");
+    let new_page = unsafe { &mut *slice_from_raw_parts_mut(origin_brk as usize as *const u8 as *mut u8, PAGE_SIZE) };
+    for pos in 0..PAGE_SIZE {
+        new_page[pos] = 1;
+    }
+    println!("write ok");
+    sbrk(PAGE_SIZE as i32 * 10);
+    let brk = sbrk(0);
+    println!("10 page allocated,  break point = {:x}", brk);
+    sbrk(PAGE_SIZE as i32 * -11);
+    let brk = sbrk(0);
+    println!("11 page DEALLOCATED,  break point = {:x}", brk);
+    println!("try DEALLOCATED more one page, should be failed.");
+    let ret = sbrk(PAGE_SIZE as i32 * -1);
+    if ret != -1 {
+        println!("Test sbrk failed!");
+        return -1
+    }
+    println!("Test sbrk almost OK!");
+    println!("now write to deallocated page, should cause page fault.");
+    for pos in 0..PAGE_SIZE {
+        new_page[pos] = 2;
+    }
+    println!("Test sbrk OK!");
+    0
+}

user/src/lib.rs

@@ -34,3 +34,7 @@ pub fn yield_() -> isize {
 pub fn get_time() -> isize {
     sys_get_time()
 }
+
+pub fn sbrk(size: i32) -> isize {
+    sys_sbrk(size)
+}

user/src/syscall.rs

@@ -4,6 +4,7 @@ const SYSCALL_WRITE: usize = 64;
 const SYSCALL_EXIT: usize = 93;
 const SYSCALL_YIELD: usize = 124;
 const SYSCALL_GET_TIME: usize = 169;
+const SYSCALL_SBRK: usize = 214;
 
 fn syscall(id: usize, args: [usize; 3]) -> isize {
     let mut ret: isize;
@@ -34,3 +35,7 @@ pub fn sys_yield() -> isize {
 pub fn sys_get_time() -> isize {
     syscall(SYSCALL_GET_TIME, [0, 0, 0])
 }
+
+pub fn sys_sbrk(size: i32) -> isize {
+    syscall(SYSCALL_SBRK, [size as usize, 0, 0])
+}