feat: move EL0 stack to virtual space

link.ld

@@ -4,14 +4,15 @@ SECTIONS {
     .text ALIGN(4) : {
         KEEP(*(.text._start))
         *(.text .text.*)
+        . = ALIGN(4K);
+        __text_end = .;
     }
 
     .rodata : {
         *(.rodata .rodata.*)
     }
 
-    .data ALIGN(2M) : {
+    .data  : {
-        _data = .;
         *(.data .data.*)
     }
 
@@ -21,6 +22,10 @@ SECTIONS {
         __bss_end = .;
     }
 
+    . = ALIGN(2M);
+
+    __share_end = .;
+
     .vector_table ALIGN(2K) : {
         KEEP(*(.vector_table))
     }
@@ -36,15 +41,6 @@ SECTIONS {
     . = ALIGN(2M);
 
     __kernel_end = .;
-
-    .stack_el0 : {
-    __stack_start_el0 = .;
-    . += 10K; #10kB stack
-    __stack_end_el0 = .;
-    }
-
-    . = ALIGN(2M);
-    _end = .;
 }
 
 __bss_size = (__bss_end - __bss_start) >> 3;

src/aarch64/mmu.rs

@@ -8,13 +8,6 @@ use crate::{
     get_current_el,
 };
 
-unsafe extern "C" {
-    static mut __translation_table_l2_start: u64;
-    static __stack_start_el0: u64;
-    static __kernel_end: u64;
-    static _data: u64;
-}
-
 const BLOCK: u64 = 0b01;
 const TABLE: u64 = 0b11;
 const PAGE: u64 = 0b11;
@@ -111,21 +104,21 @@ fn map_range_explicit(
 
     while virt % LEVEL2_BLOCK_SIZE != 0 {
         map_page(virt, phys, base, flags)?;
-        virt += GRANULARITY;
+        (virt, _) = virt.overflowing_add(GRANULARITY);
         phys += GRANULARITY;
         remaining -= GRANULARITY;
     }
 
     while remaining >= LEVEL2_BLOCK_SIZE {
         map_l2_block(virt, phys, base, flags)?;
-        virt += LEVEL2_BLOCK_SIZE;
+        (virt, _) = virt.overflowing_add(LEVEL2_BLOCK_SIZE);
         phys += LEVEL2_BLOCK_SIZE;
         remaining -= LEVEL2_BLOCK_SIZE;
     }
 
     while remaining > 0 {
         map_page(virt, phys, base, flags)?;
-        virt += GRANULARITY;
+        (virt, _) = virt.overflowing_add(GRANULARITY);
         phys += GRANULARITY;
         remaining -= GRANULARITY;
     }
@@ -143,13 +136,13 @@ fn map_range_dynamic(
 
     while remaining >= LEVEL2_BLOCK_SIZE {
         map_l2_block(virt, reserve_block(), base, flags)?;
-        virt += LEVEL2_BLOCK_SIZE;
+        (virt, _) = virt.overflowing_add(LEVEL2_BLOCK_SIZE);
         remaining -= LEVEL2_BLOCK_SIZE;
     }
 
     while remaining > 0 {
         map_page(virt, reserve_page(), base, flags)?;
-        virt += GRANULARITY;
+        (virt, _) = virt.overflowing_add(GRANULARITY);
         remaining -= GRANULARITY;
     }
 
@@ -186,7 +179,7 @@ pub fn alloc_page_explicit(
     )
 }
 
-fn map_page(
+pub fn map_page(
     virtual_address: usize,
     physical_address: usize,
     base_table_ptr: *mut PageTable,

src/config.S

@@ -87,8 +87,9 @@ el1_to_el0:
     msr ELR_EL1, x0
 
     // Set SP_EL1 to stack base
-    ldr x0, =__stack_end_el0
+    adrp x0, EL0_STACK_TOP
-    msr SP_EL0, x0
+    ldr  x1, [x0, :lo12:EL0_STACK_TOP]
+    msr SP_EL0, x1
 
     isb
 

src/configuration.rs

@@ -34,9 +34,9 @@ pub static TCR_EL1_CONF: u64 = IPS | TG0 | TG1 | T0SZ | T1SZ | SH0 | SH1 | AS;
 pub mod mmu {
     use crate::{
         aarch64::mmu::{
-            alloc_block_l2_explicit, allocate_memory, map_l2_block, reserve_range, PhysSource,
+            alloc_block_l2_explicit, allocate_memory, map_l2_block, map_page, reserve_range,
-            DEVICE_MEM, EL0_ACCESSIBLE, KERNEL_VIRTUAL_MEM_SPACE, LEVEL1_BLOCK_SIZE,
+            PhysSource, DEVICE_MEM, EL0_ACCESSIBLE, GRANULARITY, KERNEL_VIRTUAL_MEM_SPACE,
-            LEVEL2_BLOCK_SIZE, NORMAL_MEM, PXN, READ_ONLY, STACK_START_ADDR,
+            LEVEL1_BLOCK_SIZE, LEVEL2_BLOCK_SIZE, NORMAL_MEM, PXN, READ_ONLY, STACK_START_ADDR,
             TRANSLATIONTABLE_TTBR0, UXN, WRITABLE,
         },
         PERIPHERAL_BASE,
@@ -45,22 +45,24 @@ pub mod mmu {
     #[no_mangle]
     static EL1_STACK_TOP: usize = STACK_START_ADDR | KERNEL_VIRTUAL_MEM_SPACE;
     const EL1_STACK_SIZE: usize = LEVEL2_BLOCK_SIZE * 2;
-
+    #[no_mangle]
+    static EL0_STACK_TOP: usize = STACK_START_ADDR;
+    const EL0_STACK_SIZE: usize = LEVEL2_BLOCK_SIZE * 2;
     extern "C" {
-        static _data: u64;
+        static __text_end: u64;
-        static _end: u64;
+        static __share_end: u64;
         static __kernel_end: u64;
     }
 
     pub fn initialize_mmu_translation_tables() {
-        let shared_segment_end = unsafe { &_data } as *const _ as usize;
+        let text_end = unsafe { &__text_end } as *const _ as usize;
+        let shared_segment_end = unsafe { &__share_end } as *const _ as usize;
         let kernel_end = unsafe { &__kernel_end } as *const _ as usize;
-        let user_space_end = unsafe { &_end } as *const _ as usize;
 
-        reserve_range(0x0, user_space_end).unwrap();
+        reserve_range(0x0, kernel_end).unwrap();
 
-        for addr in (0..shared_segment_end).step_by(LEVEL2_BLOCK_SIZE) {
+        for addr in (0..text_end).step_by(GRANULARITY) {
-            map_l2_block(
+            map_page(
                 addr,
                 addr,
                 core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
@@ -69,6 +71,16 @@ pub mod mmu {
             .unwrap();
         }
 
+        for addr in (text_end..shared_segment_end).step_by(GRANULARITY) {
+            map_page(
+                addr,
+                addr,
+                core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
+                EL0_ACCESSIBLE | WRITABLE | NORMAL_MEM,
+            )
+            .unwrap();
+        }
+
         for addr in (shared_segment_end..kernel_end).step_by(LEVEL2_BLOCK_SIZE) {
             map_l2_block(
                 addr,
@@ -79,16 +91,6 @@ pub mod mmu {
             .unwrap();
         }
 
-        for addr in (kernel_end..user_space_end).step_by(LEVEL2_BLOCK_SIZE) {
-            map_l2_block(
-                addr,
-                addr,
-                core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
-                EL0_ACCESSIBLE | WRITABLE | PXN | NORMAL_MEM,
-            )
-            .unwrap();
-        }
-
         for addr in (PERIPHERAL_BASE..LEVEL1_BLOCK_SIZE).step_by(LEVEL2_BLOCK_SIZE) {
             alloc_block_l2_explicit(
                 addr,
@@ -99,6 +101,15 @@ pub mod mmu {
             .unwrap();
         }
 
+        // Frame Buffer memory range
+        allocate_memory(
+            0x3c100000,
+            1080 * 1920 * 4,
+            PhysSource::Explicit(0x3c100000),
+            NORMAL_MEM | PXN | UXN | WRITABLE | EL0_ACCESSIBLE,
+        )
+        .unwrap();
+
         allocate_memory(
             EL1_STACK_TOP - EL1_STACK_SIZE + 0x10,
             EL1_STACK_SIZE,
@@ -106,5 +117,13 @@ pub mod mmu {
             WRITABLE | NORMAL_MEM,
         )
         .unwrap();
+
+        allocate_memory(
+            EL0_STACK_TOP - EL0_STACK_SIZE + 0x10,
+            EL0_STACK_SIZE,
+            PhysSource::Any,
+            WRITABLE | EL0_ACCESSIBLE | NORMAL_MEM,
+        )
+        .unwrap();
     }
 }

src/main.rs

@@ -11,10 +11,7 @@ extern crate alloc;
 
 use alloc::vec::Vec;
 use nova::{
-    aarch64::{
+    aarch64::registers::{daif, read_id_aa64mmfr0_el1},
-        mmu::{allocate_memory, PhysSource, EL0_ACCESSIBLE, NORMAL_MEM, PXN, UXN, WRITABLE},
-        registers::{daif, read_id_aa64mmfr0_el1},
-    },
     configuration::mmu::initialize_mmu_translation_tables,
     framebuffer::{FrameBuffer, BLUE, GREEN, RED},
     get_current_el,
@@ -26,13 +23,14 @@ use nova::{
         },
         uart::uart_init,
     },
-    pi3::mailbox,
     println,
 };
 
 global_asm!(include_str!("vector.S"));
 global_asm!(include_str!("config.S"));
 
+static mut FRAMEBUFFER: Option<FrameBuffer> = None;
+
 extern "C" {
     fn el2_to_el1();
     fn el1_to_el0();
@@ -74,6 +72,8 @@ pub extern "C" fn main() -> ! {
 
     println!("Register: AA64MMFR0_EL1: {:064b}", read_id_aa64mmfr0_el1());
     println!("Moving El2->EL1");
+    unsafe { FRAMEBUFFER = Some(FrameBuffer::default()) };
+
     unsafe {
         el2_to_el1();
     }
@@ -100,15 +100,6 @@ pub extern "C" fn kernel_main() -> ! {
     }
     println!("heap allocation test: {:?}", test_vector);
 
-    // Frame Buffer memory range
-    // TODO: this is just temporary
-    allocate_memory(
-        0x3c100000,
-        1080 * 1920 * 4,
-        PhysSource::Explicit(0x3c100000),
-        NORMAL_MEM | PXN | UXN | WRITABLE | EL0_ACCESSIBLE,
-    )
-    .unwrap();
     println!("Exception Level: {}", get_current_el());
     daif::unmask_all();
 
@@ -132,8 +123,7 @@ pub extern "C" fn el0() -> ! {
 
     enable_irq_source(IRQSource::UartInt);
 
-    let fb = FrameBuffer::default();
+    if let Some(fb) = unsafe { FRAMEBUFFER.as_mut() } {
-
         for i in 0..1080 {
             fb.draw_pixel(50, i, BLUE);
         }
@@ -144,10 +134,14 @@ pub extern "C" fn el0() -> ! {
         fb.draw_string("Hello World! :D\nTest next Line", 500, 5, 3, BLUE);
 
         fb.draw_function(cos, 0, 101, RED);
+    }
 
     loop {
-        let temp = mailbox::read_soc_temp([0]).unwrap();
+        // TODO: Mailbox requires a physical address. The stack is now in VA space causing an issue.
-        println!("{} °C", temp[1] / 1000);
+        // Fix with SVCs ?
+
+        // let temp = mailbox::read_soc_temp([0]).unwrap();
+        // println!("{} °C", temp[1] / 1000);
 
         blink_gpio(SpecificGpio::OnboardLed as u8, 500);
     }