Trying to fix exception in el1

.vscode/launch.json

@@ -1,5 +1,12 @@
 {
   "version": "0.2.0",
+  "compounds": [
+    {
+      "name": "Run QEMU + Attach LLDB",
+      "configurations": ["Attach LLDB"],
+      "preLaunchTask": "Run QEMU"
+    }
+  ],
   "configurations": [
     {
       "name": "Attach to QEMU (AArch64)",
@@ -20,11 +27,21 @@
         },
         {
           "description": "Show assembly on stop",
-    "text": "layout asm",
+          "text": "set disassemble-next-line on",
           "ignoreFailures": true
         }
       ],
       "preLaunchTask": "Run QEMU"
+    },
+
+    {
+      "name": "Attach LLDB",
+      "type": "lldb",
+      "request": "attach",
+      "debugServer": 1234,
+      "program": "${workspaceFolder}/target/aarch64-unknown-none/debug/nova",
+      "stopOnEntry": true,
+      "processCreateCommands": ["gdb-remote localhost:1234"]
     }
   ]
 }

.vscode/settings.json

@@ -0,0 +1,6 @@
+{
+  "lldb.displayFormat": "auto",
+  "lldb.showDisassembly": "always",
+  "lldb.dereferencePointers": true,
+  "lldb.consoleMode": "commands"
+}

.vscode/tasks.json

@@ -14,7 +14,7 @@
     {
       "label": "Run QEMU",
       "type": "shell",
-      "command": "qemu-system-aarch64 -M raspi3b -cpu cortex-a53 -serial stdio -sd sd.img -display none -kernel ${workspaceFolder}/target/aarch64-unknown-none/debug/kernel8.img -S -s",
+      "command": "qemu-system-aarch64 -M raspi3b -cpu cortex-a53 -serial stdio -sd sd.img -display none -kernel ${workspaceFolder}/target/aarch64-unknown-none/debug/kernel8.img -S -s -m 1024",
       "isBackground": true,
       "dependsOn": ["Build"]
     }

Cargo.toml

@@ -6,6 +6,8 @@ edition = "2021"
 
 [profile.dev]
 panic = "abort"
+debug = true
+opt-level = 0
 
 [profile.release]
 panic = "abort"

src/irq_interrupt.rs

@@ -3,7 +3,10 @@ use core::{
     sync::atomic::{compiler_fence, Ordering},
 };
 
-use crate::{mmio_read, mmio_write, peripherals::uart::print};
+use crate::{
+    mmio_read, mmio_write,
+    peripherals::{gpio::blink_gpio, uart::print},
+};
 
 const INTERRUPT_BASE: u32 = 0x3F00_B000;
 const IRQ_PENDING_BASE: u32 = INTERRUPT_BASE + 0x204;
@@ -35,7 +38,18 @@ unsafe extern "C" fn irq_handler() {
     handle_gpio_interrupt();
 }
 
+#[no_mangle]
+unsafe extern "C" fn synchronous_interrupt() {
+    loop {
+        let el: u64;
+        asm!("mrs x5, FAR_EL1");
+        blink_gpio(29, 100);
+        print("Sync Exception \r\n");
+    }
+}
+
 fn handle_gpio_interrupt() {
+    print("Interrupt\r\n");
     for i in 0..=53u32 {
         let val = read_gpio_event_detect_status(i);
 

src/mailbox.rs

@@ -1,26 +1,33 @@
-use crate::{mmio_read, mmio_write};
+use core::ptr::read_volatile;
 
-const MBOX_BASE: u32 = 0x3F00_B880;
+use crate::{
+    mmio_read, mmio_write,
+    peripherals::uart::{print, print_u32},
+};
+
+const MBOX_BASE: u32 = 0x3F00_0000 + 0xB880;
 
 // MB0
 const MBOX_READ: u32 = MBOX_BASE + 0x00;
-const MBOX_READ_STATUS: u32 = MBOX_BASE + 0x18;
+const MBOX_STATUS: u32 = MBOX_BASE + 0x18;
 
 // MB1
 const MBOX_WRITE: u32 = MBOX_BASE + 0x20;
-const MBOX_WRITE_STATUS: u32 = MBOX_BASE + 0x38;
 
 // Status
 const MAIL_FULL: u32 = 0x80000000;
 const MAIL_EMPTY: u32 = 0x40000000;
 
-#[repr(align(16))]
+#[repr(C, align(16))]
 struct MailboxBuffer([u32; 36]);
 
+#[no_mangle]
+static mut MBOX: MailboxBuffer = MailboxBuffer([0; 36]);
+
 pub fn read_mailbox(channel: u32) -> u32 {
     // Wait until mailbox is not empty
     loop {
-        while (mmio_read(MBOX_READ_STATUS) & MAIL_EMPTY != 0) {}
+        while mmio_read(MBOX_STATUS) & MAIL_EMPTY != 0 {}
         let mut data = mmio_read(MBOX_READ);
         let read_channel = data & 0xF;
 
@@ -33,25 +40,35 @@ pub fn read_mailbox(channel: u32) -> u32 {
 }
 
 pub fn write_mailbox(channel: u32, data: u32) {
-    while (mmio_read(MBOX_WRITE_STATUS) & MAIL_FULL != 0) {}
-    mmio_write(MBOX_WRITE, data << 4 | (channel & 0xF));
+    while mmio_read(MBOX_STATUS) & MAIL_FULL != 0 {}
+    mmio_write(MBOX_WRITE, (data & !0xF) | (channel & 0xF));
 }
 
 pub fn read_soc_temp() -> u32 {
-    let mut mbox = MailboxBuffer([0; 36]);
+    unsafe {
+        // MBOX.0[0] = 7 * 4; // Total size in bytes
+        // MBOX.0[1] = 0; // Request
+        // MBOX.0[2] = 0x00010002; // Tag
+        // MBOX.0[3] = 4; // Maximum buffer lenb
+        // MBOX.0[4] = 0; // Request length
+        // MBOX.0[5] = 0; // Value Buffer
+        // MBOX.0[6] = 0; // End
+        // core::arch::asm!("dsb sy"); // Ensure write reaches RAM
+        // core::arch::asm!("dmb sy"); // Memory barrier
 
-    mbox.0[0] = 8 * 4; // Total size in bytes
-    mbox.0[1] = 0; // Request
-    mbox.0[2] = 0x00030006; // Tag: Get temperature
-    mbox.0[3] = 8; // Value buffer size (bytes)
-    mbox.0[4] = 4; // Request size (bytes)
-    mbox.0[5] = 0; // Temp ID: 0 = SoC
-    mbox.0[6] = 0; // Response will be written here
-    mbox.0[7] = 0; // End tag
+        print("Reading address\r\n");
+        //let addr = core::ptr::addr_of!(MBOX.0[0]);
+
+        print("Write address\r\n");
+
+        // write_mailbox(8, addr);
 
-    let addr = &mbox.0 as *const u32 as u32;
-    write_mailbox(8, addr);
         let _ = read_mailbox(8);
-    let raw_temp = mbox.0[6];
-    raw_temp / 1000
+
+        if MBOX.0[1] == 0 {
+            print("Failed\r\n");
+        }
+        let raw_temp = MBOX.0[5];
+        raw_temp
+    }
 }

src/main.rs

@@ -5,6 +5,7 @@
 use core::{
     arch::{asm, global_asm},
     panic::PanicInfo,
+    ptr::write_volatile,
 };
 
 use nova::{
@@ -12,18 +13,19 @@ use nova::{
     mailbox::read_soc_temp,
     peripherals::{
         gpio::{
-            gpio_get_state, gpio_high, gpio_low, gpio_pull_up, set_falling_edge_detect,
-            set_gpio_function, GPIOFunction,
+            blink_gpio, gpio_pull_up, set_falling_edge_detect, set_gpio_function, GPIOFunction,
         },
-        uart::{print, uart_init},
+        uart::{print, print_u32, uart_init},
     },
-    timer::{delay_nops, sleep_ms, sleep_us},
+    timer::{delay_nops, sleep_us},
 };
 
 global_asm!(include_str!("vector.S"));
 
 extern "C" {
     fn el2_to_el1();
+    static mut __bss_start: u32;
+    static mut __bss_end: u32;
 }
 
 #[panic_handler]
@@ -47,6 +49,9 @@ pub unsafe extern "C" fn _start() {
 
 #[no_mangle]
 pub extern "C" fn main() -> ! {
+    unsafe {
+        zero_bss();
+    }
     enable_uart();
 
     // Set ACT Led to Outout
@@ -59,14 +64,24 @@ pub extern "C" fn main() -> ! {
     print("Hello World!\r\n");
 
     unsafe {
+        asm!("mrs x0, SCTLR_EL1");
         el2_to_el1();
     }
 
     loop {}
 }
 
+unsafe fn zero_bss() {
+    let mut bss: *mut u32 = &raw mut __bss_start as *mut u32;
+    while bss < &raw mut __bss_end as *mut u32 {
+        write_volatile(bss, 0);
+        bss = bss.add(1);
+    }
+}
+
 #[no_mangle]
 pub extern "C" fn kernel_main() -> ! {
+    print("AAA\r\n");
     print_current_el_str();
 
     sleep_us(500_000);
@@ -78,38 +93,13 @@ pub extern "C" fn kernel_main() -> ! {
     set_falling_edge_detect(26, true);
 
     loop {
-        //let temp = read_soc_temp();
-        //u32_to_ascii(temp as u8);
+        let temp = read_soc_temp();
+        print_u32(temp);
 
-        let _ = gpio_high(29);
-
-        sleep_ms(500); // 0.5s
-        let _ = gpio_low(29);
-        sleep_ms(500); // 0.5s
-        print_gpio_state();
+        blink_gpio(29, 500);
     }
 }
 
-fn print_gpio_state() {
-    let state = gpio_get_state(26);
-
-    let ascii_byte = b'0' + state;
-    let data = [ascii_byte];
-
-    let s = str::from_utf8(&data).unwrap();
-    print(s);
-    print("\r\n");
-}
-
-fn u32_to_ascii(val: u8) {
-    let ascii_byte = b'0' + val;
-    let data = [ascii_byte];
-
-    let s = str::from_utf8(&data).unwrap();
-    print(s);
-    print("C\r\n");
-}
-
 pub fn get_current_el() -> u64 {
     let el: u64;
     unsafe {

src/peripherals/gpio.rs

@@ -1,7 +1,7 @@
 use core::result::Result;
 use core::result::Result::Ok;
 
-use crate::timer::delay_nops;
+use crate::timer::{delay_nops, sleep_ms};
 use crate::{mmio_read, mmio_write};
 
 const GPFSEL_BASE: u32 = 0x3F20_0000;
@@ -164,3 +164,11 @@ pub fn set_rising_edge_detect(gpio: u8, enable: bool) {
 
     mmio_write(register_addr, new_val);
 }
+
+pub fn blink_gpio(gpio: u8, duration_ms: u32) {
+    let _ = gpio_high(gpio);
+
+    sleep_ms(duration_ms);
+    let _ = gpio_low(gpio);
+    sleep_ms(duration_ms);
+}

src/peripherals/uart.rs

@@ -1,3 +1,5 @@
+use core::{arch::asm, fmt};
+
 use crate::{mmio_read, mmio_write};
 
 const BAUD: u32 = 115200;
@@ -21,11 +23,34 @@ const UART0_LCRH_FEN: u32 = 1 << 4;
 /// Print `s` over UART
 pub fn print(s: &str) {
     for byte in s.bytes() {
-        while mmio_read(UART0_FR) & UART0_FR_TXFF != 0 {}
+        while (mmio_read(UART0_FR) & UART0_FR_TXFF) != 0 {
+            unsafe { asm!("nop") }
+        }
         mmio_write(UART0_DR, byte as u32);
     }
     // wait till uart is not busy anymore
-    while (mmio_read(UART0_FR) >> 3) & 0b1 != 0 {}
+    while ((mmio_read(UART0_FR) >> 3) & 0b1) != 0 {}
+}
+
+pub fn print_u32(mut val: u32) {
+    let mut values = [0u32; 10];
+    for c in &mut values {
+        if val == 0 {
+            break;
+        }
+
+        *c = val % 10;
+        val /= 10;
+    }
+
+    for c in values.iter().rev() {
+        let ascii_byte = b'0' + *c as u8;
+        let data = [ascii_byte];
+
+        let s = str::from_utf8(&data).unwrap();
+        print(s);
+    }
+    print("\r\n");
 }
 
 /// Initialize UART peripheral

src/vector.S

@@ -14,7 +14,7 @@ vector_table:
     ventry .
     ventry .
 
-    ventry .
+    ventry synchronous_interrupt      // Synchronous Exception  0x200
     ventry irq_handler                // IRQ(Interrupt Request) 0x280
     ventry .
     ventry .
@@ -44,6 +44,11 @@ el2_to_el1:
     adr x0, vector_table
     msr VBAR_EL1, x0
 
+    // Disable MMU
+    mrs x0, sctlr_el1
+    bic x0, x0, #1
+    msr sctlr_el1, x0
+
     isb
 
     // Return to EL1

tools/start_simulator_debug.sh

@@ -10,4 +10,5 @@ qemu-system-aarch64 \
   -serial stdio \
   -sd ../sd.img \
   -display none \
-  -kernel ../target/aarch64-unknown-none/debug/kernel8.img
+  -kernel ../target/aarch64-unknown-none/debug/kernel8.img \
+  -s -S