lab-04: mmap, munmap

os/src/mm/memory_set.rs

@@ -266,6 +266,9 @@ impl MemorySet {
             false
         }
     }
+    pub fn unmap(&mut self, vpn: VirtPageNum) {
+        self.page_table.unmap(vpn)
+    }
 }
 
 /// map area structure, controls a contiguous piece of virtual memory

os/src/mm/mod.rs

@@ -13,7 +13,8 @@ mod memory_set;
 mod page_table;
 
 pub use address::{PhysAddr, PhysPageNum, VirtAddr, VirtPageNum};
-use address::{StepByOne, VPNRange};
+use address::StepByOne;
+pub use address::VPNRange;
 pub use frame_allocator::{frame_alloc, FrameTracker};
 pub use memory_set::remap_test;
 pub use memory_set::{MapPermission, MemorySet, KERNEL_SPACE};

os/src/syscall/mod.rs

@@ -15,6 +15,8 @@ const SYSCALL_EXIT: usize = 93;
 const SYSCALL_YIELD: usize = 124;
 const SYSCALL_GET_TIME: usize = 169;
 const SYSCALL_SBRK: usize = 214;
+const SYSCALL_MMAP: usize = 222;
+const SYSCALL_MUNMAP: usize = 215;
 
 mod fs;
 mod process;
@@ -30,6 +32,8 @@ pub fn syscall(syscall_id: usize, args: [usize; 3]) -> isize {
         SYSCALL_YIELD => sys_yield(),
         SYSCALL_GET_TIME => sys_get_time(),
         SYSCALL_SBRK => sys_sbrk(args[0] as i32),
+        SYSCALL_MMAP => sys_mmap(args[0], args[1], args[2]),
+        SYSCALL_MUNMAP => sys_munmap(args[0], args[1]),
         _ => panic!("Unsupported syscall_id: {}", syscall_id),
     }
 }

os/src/syscall/process.rs

@@ -1,6 +1,8 @@
 //! Process management syscalls
 
-use crate::task::{change_program_brk, exit_current_and_run_next, suspend_current_and_run_next};
+use crate::config::PAGE_SIZE;
+use crate::mm::{MapPermission, VPNRange, VirtAddr};
+use crate::task::{change_program_brk, create_new_map_area, exit_current_and_run_next, get_current_task_page_table_entry, suspend_current_and_run_next, unmap_virtual_page};
 use crate::timer::get_time_ms;
 
 /// task exits and submit an exit code
@@ -29,3 +31,47 @@ pub fn sys_sbrk(size: i32) -> isize {
         -1
     }
 }
+
+/// map files or devices into memory
+pub fn sys_mmap(start: usize, len: usize, prot: usize) -> isize {
+    if start % PAGE_SIZE != 0 || prot & !0x7 != 0 || prot & 0x7 == 0 {
+        return -1;
+    }
+    let vpn_start = VirtAddr::from(start).floor();
+    let vpn_end = VirtAddr::from(start + len).ceil();
+    let vpn_range = VPNRange::new(vpn_start, vpn_end);
+    for vpn in vpn_range {
+        if let Some(pte) = get_current_task_page_table_entry(vpn) {
+            if pte.is_valid() {
+                return -1;
+            }
+        }
+    }
+    create_new_map_area(
+        vpn_start.into(),
+        vpn_end.into(),
+        MapPermission::from_bits_truncate((prot << 1) as u8) | MapPermission::U
+    );
+    0
+}
+
+/// unmap files or devices into memory
+pub fn sys_munmap(start: usize, len: usize) -> isize {
+    if start % PAGE_SIZE != 0 {
+        return -1;
+    }
+    let vpn_start = VirtAddr::from(start).floor();
+    let vpn_end = VirtAddr::from(start + len).ceil();
+    let vpn_range = VPNRange::new(vpn_start, vpn_end);
+    for vpn in vpn_range {
+        if let Some(pte) = get_current_task_page_table_entry(vpn) {
+            if !pte.is_valid() {
+                return -1;
+            }
+            unmap_virtual_page(vpn)
+        } else {
+            return -1;
+        }
+    }
+    0
+}

os/src/task/mod.rs

@@ -15,6 +15,7 @@ mod switch;
 mod task;
 
 use crate::loader::{get_app_data, get_num_app};
+use crate::mm::{MapPermission, PageTableEntry, VirtAddr, VirtPageNum};
 use crate::sbi::shutdown;
 use crate::sync::UPSafeCell;
 use crate::trap::TrapContext;
@@ -204,3 +205,24 @@ pub fn current_trap_cx() -> &'static mut TrapContext {
 pub fn change_program_brk(size: i32) -> Option<usize> {
     TASK_MANAGER.change_current_program_brk(size)
 }
+
+/// Get the curent 'Running' task's PTE
+pub fn get_current_task_page_table_entry(vpn: VirtPageNum) -> Option<PageTableEntry> {
+    let inner = TASK_MANAGER.inner.exclusive_access();
+    let current = inner.current_task;
+    inner.tasks[current].memory_set.translate(vpn)
+}
+
+/// create new mapping area
+pub fn create_new_map_area(start_va: VirtAddr, end_va: VirtAddr, perm: MapPermission) {
+    let mut inner = TASK_MANAGER.inner.exclusive_access();
+    let current = inner.current_task;
+    inner.tasks[current].memory_set.insert_framed_area(start_va, end_va, perm);
+}
+
+/// unmap virtual page
+pub fn unmap_virtual_page(vpn: VirtPageNum) {
+    let mut inner = TASK_MANAGER.inner.exclusive_access();
+    let current = inner.current_task;
+    inner.tasks[current].memory_set.unmap(vpn);
+}