Remap memory on timer tick

mrgian · Jul 12, 2023 · 51bfab9 · 51bfab9
1 parent df106c8
commit 51bfab9
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Showing 4 changed files with 31 additions and 6 deletions.
diff --git a/kernel/src/interrupts/timer.rs b/kernel/src/interrupts/timer.rs
@@ -6,8 +6,14 @@ use crate::multitasking::task::CPUState;
 use crate::multitasking::task::TASK_MANAGER;
 use core::arch::asm;
 
+use crate::memory::paging::PAGING;
+use crate::memory::paging::TABLES;
+
 pub const TIMER_INT: u8 = 32;
 
+const APP_TARGET: u32 = 0x00a0_0000;
+const APP_SIZE: u32 = 0x0001_0000;
+
 //TIMER IRQ
 #[naked]
 pub extern "C" fn timer() {
@@ -51,6 +57,13 @@ pub extern "C" fn timer_handler(esp: u32) -> u32 {
     unsafe {
         let new_esp: u32 = TASK_MANAGER.schedule(esp as *mut CPUState) as u32;
 
+        let slot = TASK_MANAGER.get_current_slot();
+        let target = APP_TARGET + (slot as u32 * APP_SIZE);
+
+        //map table 8 (0x02000000) to the address where the executable is loaded 
+        TABLES[8].set(target);
+        PAGING.set_table(8, &TABLES[8]);
+
         PICS.end_interrupt(TIMER_INT);
 
         return new_esp;

diff --git a/kernel/src/main.rs b/kernel/src/main.rs
@@ -54,9 +54,6 @@ pub extern "C" fn _start() -> ! {
     unsafe {
         PAGING.identity();
 
-        TABLES[8].set(0x00a0_0000);
-        PAGING.set_table(8, &TABLES[8]);
-
         PAGING.enable();
     }
 

diff --git a/kernel/src/multitasking/task.rs b/kernel/src/multitasking/task.rs
@@ -162,6 +162,10 @@ impl TaskManager {
         slot
     }
 
+    pub fn get_current_slot(&self) -> i8 {
+        self.current_task
+    }
+
     pub fn list_tasks(&self) {
         libfelix::println!("Running tasks:");
 

diff --git a/kernel/src/shell/shell.rs b/kernel/src/shell/shell.rs
@@ -4,7 +4,11 @@ use crate::filesystem::fat::FAT;
 use crate::multitasking::task::TASK_MANAGER;
 use crate::syscalls::print::PRINTER;
 
+use crate::memory::paging::PAGING;
+use crate::memory::paging::TABLES;
+
 const APP_TARGET: u32 = 0x00a0_0000;
+const APP_SIZE: u32 = 0x0001_0000;
 const APP_SIGNATURE: u32 = 0xB16B00B5;
 
 const HELP: &'static str = "Available commands:
@@ -183,13 +187,20 @@ impl Shell {
 
         let entry = FAT.search_file(&self.arg);
         if entry.name[0] != 0 {
-            FAT.read_file_to_target(&entry, APP_TARGET as *mut u32);
+            let slot = TASK_MANAGER.get_free_slot();
+            let target = APP_TARGET + (slot as u32 * APP_SIZE);
+
+            //map table 8 (0x02000000) to the address where the executable is loaded 
+            TABLES[8].set(target);
+            PAGING.set_table(8, &TABLES[8]);
+
+            FAT.read_file_to_target(&entry, target as *mut u32);
 
             unsafe {
-                let signature = *(APP_TARGET as *mut u32);
+                let signature = *(target as *mut u32);
 
                 if signature == APP_SIGNATURE {
-                    TASK_MANAGER.add_task((APP_TARGET + 4) as u32);
+                    TASK_MANAGER.add_task((target + 4) as u32);
                 } else {
                     libfelix::println!("File is not a valid executable!");
                 }