feat: ✨ Update linker script

* Add MMIO remap region
* Move script to appropriate place

machine/build.rs

@@ -1,5 +1,7 @@
-const LINKER_SCRIPT: &str = "linker/aarch64.ld";
+/// This build script is used to create lib tests.
-const LINKER_SCRIPT_AUX: &str = "linker/aarch64-exceptions.ld";
+
+const LINKER_SCRIPT: &str = "machine/src/platform/raspberrypi/linker/kernel.ld";
+const LINKER_SCRIPT_AUX: &str = "machine/src/arch/aarch64/linker/aarch64-exceptions.ld";
 
 fn main() {
     println!("cargo:rerun-if-changed={}", LINKER_SCRIPT);

machine/src/arch/aarch64/cpu/boot.rs

@@ -65,10 +65,10 @@ pub unsafe extern "C" fn _boot_cores() -> ! {
     extern "Rust" {
         // Stack top
         // Stack placed before first executable instruction
-        static __STACK_START: UnsafeCell<()>;
+        static __STACK_TOP: UnsafeCell<()>;
     }
     // Set stack pointer. Used in case we started in EL1.
-    SP.set(__STACK_START.get() as u64);
+    SP.set(__STACK_TOP.get() as u64);
 
     shared_setup_and_enter_pre();
 
@@ -122,12 +122,12 @@ fn shared_setup_and_enter_pre() {
 fn shared_setup_and_enter_post() -> ! {
     extern "Rust" {
         // Stack top
-        static __STACK_START: UnsafeCell<()>;
+        static __STACK_TOP: UnsafeCell<()>;
     }
     // Set up SP_EL1 (stack pointer), which will be used by EL1 once
     // we "return" to it.
     unsafe {
-        SP_EL1.set(__STACK_START.get() as u64);
+        SP_EL1.set(__STACK_TOP.get() as u64);
     }
 
     // Use `eret` to "return" to EL1. This will result in execution of

machine/src/platform/raspberrypi/linker/kernel.ld

@@ -5,11 +5,14 @@
  * Original code distributed under MIT, additional changes are under BlueOak-1.0.0
  */
 
+PAGE_SIZE = 64K;
+PAGE_MASK = PAGE_SIZE - 1;
+
+__phys_mem_start = 0x0;
+
 __phys_load_addr = 0x80000;
 ENTRY(__phys_load_addr);
 
-PAGE_SIZE = 65536;
-
 /* Flags:
  *     4 == R
  *     5 == RX
@@ -26,13 +29,26 @@ PHDRS
 }
 
 /* Symbols between __BOOT_START and __BOOT_END should be dropped after init is complete.
-   Symbols between __RO_START and __RO_END are the kernel code.
+   Symbols between __CODE_START and __CODE_END are the kernel code.
    Symbols between __BSS_START and __BSS_END must be initialized to zero by startup code in the kernel.
 */
 SECTIONS
 {
-    __STACK_START = __phys_load_addr; /* Stack grows from here towards 0x0. */
+    . = __phys_mem_start;
-    . = __phys_load_addr; /* AArch64 boot address is 0x80000, 4K-aligned */
+
+    /***********************************************************************************************
+    * Boot Core Stack
+    ***********************************************************************************************/
+    .boot_core_stack (NOLOAD) :
+    {
+         __STACK_BOTTOM = .;                 /*   ^             */
+                                             /*   | stack       */
+        . = __phys_load_addr;                /*   | growth      AArch64 boot address is 0x80000, 4K-aligned */
+                                             /*   | direction   */
+        __STACK_TOP = .;                     /*   | Stack grows from here towards 0x0. */
+    } :segment_boot_core_stack
+
+    ASSERT((. & PAGE_MASK) == 0, "End of boot core stack is not page aligned")
 
     /***********************************************************************************************
     * Code + RO Data
@@ -43,19 +59,19 @@ SECTIONS
         /*******************************************************************************************
         * Boot Code + Boot Data
         *******************************************************************************************/
-
         __BOOT_START = .;
         KEEP(*(.text.main.entry))
         *(.text.boot)
         *(.data.boot)
-        . = ALIGN(PAGE_SIZE); /* Here the boot code ends */
+        . = ALIGN(PAGE_SIZE);
-        __BOOT_END = .; // __BOOT_END must be PAGE_SIZE aligned
+        __BOOT_END = .; /* Here the boot code ends */
+        ASSERT((__BOOT_END & PAGE_MASK) == 0, "End of boot code is not page aligned")
 
         /*******************************************************************************************
         * Regular Kernel Code
         *******************************************************************************************/
 
-        __RO_START = .;
+        __CODE_START = .;
         *(.text*)
     } :segment_code
 
@@ -72,7 +88,8 @@ SECTIONS
         *(.rodata*)
         FILL(0x00)
         . = ALIGN(PAGE_SIZE); /* Fill up to page size */
-        __RO_END = .; /* __RO_END must be PAGE_SIZE aligned */
+        __CODE_END = .;
+        ASSERT((__CODE_END & PAGE_MASK) == 0, "End of kernel code is not page aligned")
     } :segment_code
 
     /***********************************************************************************************
@@ -81,7 +98,8 @@ SECTIONS
 
     .data :
     {
-        __DATA_START = .; /* __DATA_START must be PAGE_SIZE aligned */
+        __DATA_START = .;
+        ASSERT((__DATA_START & PAGE_MASK) == 0, "Start of kernel data is not page aligned")
         *(.data*)
         FILL(0x00)
     } :segment_data
@@ -96,6 +114,17 @@ SECTIONS
         __BSS_SIZE_U64S = (__BSS_END - __BSS_START) / 8;
     } :segment_data
 
+    __DATA_END = .;
+
+    /***********************************************************************************************
+    * MMIO Remap Reserved
+    ***********************************************************************************************/
+    __MMIO_REMAP_START = .;
+    . += 8 * 1024 * 1024;
+    __MMIO_REMAP_END = .;
+
+    ASSERT((. & PAGE_MASK) == 0, "MMIO remap reservation is not page aligned")
+
     /***********************************************************************************************
     * Misc
     ***********************************************************************************************/
@@ -106,4 +135,4 @@ SECTIONS
     /DISCARD/ : { *(.comment*) *(.gnu*) *(.note*) *(.eh_frame*) *(.text.chainboot*) }
 }
 
-INCLUDE linker/aarch64-exceptions.ld
+INCLUDE machine/src/arch/aarch64/linker/aarch64-exceptions.ld

machine/src/platform/raspberrypi/memory/mmu.rs

@@ -288,14 +288,14 @@ mod tests {
     #[test_case]
     fn kernel_tables_in_bss() {
         extern "Rust" {
-            static __bss_start: UnsafeCell<u64>;
+            static __BSS_START: UnsafeCell<u64>;
-            static __bss_end_exclusive: UnsafeCell<u64>;
+            static __BSS_END: UnsafeCell<u64>;
         }
 
         let bss_range = unsafe {
             Range {
-                start: __bss_start.get(),
+                start: __BSS_START.get(),
-                end: __bss_end_exclusive.get(),
+                end: __BSS_END.get(),
             }
         };
         let kernel_tables_addr = &KERNEL_TABLES as *const _ as usize as *mut u64;

machine/src/platform/raspberrypi/memory/mod.rs

@@ -93,26 +93,32 @@ extern "Rust" {
     //
     // The inclusive start of the read-only area, aka the address of the
     // first byte of the area.
-    static __RO_START: UnsafeCell<()>;
+    static __CODE_START: UnsafeCell<()>;
     // The exclusive end of the read-only area, aka the address of
     // the first byte _after_ the RO area.
-    static __RO_END: UnsafeCell<()>;
+    static __CODE_END: UnsafeCell<()>;
-}
 
-// Symbols from the linker script.
+    // The inclusive start of the kernel data/BSS area, aka the address of the
-// extern "Rust" {
+    // first byte of the area.
-//     static __code_start: UnsafeCell<()>; // __RO_START
+    static __DATA_START: UnsafeCell<()>;
-//     static __code_end_exclusive: UnsafeCell<()>; // __RO_END
+    // The exclusive end of the kernel data/BSS area, aka the address of
-//
+    // the first byte _after_ the data/BSS area.
-//     static __data_start: UnsafeCell<()>;
+    static __DATA_END: UnsafeCell<()>;
-//     static __data_end_exclusive: UnsafeCell<()>;
+
-//
+    // The inclusive start of the kernel data/BSS area, aka the address of the
-//     static __mmio_remap_start: UnsafeCell<()>;
+    // first byte of the area.
-//     static __mmio_remap_end_exclusive: UnsafeCell<()>;
+    static __STACK_BOTTOM: UnsafeCell<()>;
-//
+    // The exclusive end of the kernel data/BSS area, aka the address of
-//     static __boot_core_stack_start: UnsafeCell<()>;
+    // the first byte _after_ the data/BSS area.
-//     static __boot_core_stack_end_exclusive: UnsafeCell<()>;
+    static __STACK_TOP: UnsafeCell<()>;
-// }
+
+    // The inclusive start of the kernel MMIO remap area, aka the address of the
+    // first byte of the area.
+    static __MMIO_REMAP_START: UnsafeCell<()>;
+    // The exclusive end of the kernel MMIO remap area, aka the address of
+    // the first byte _after_ the MMIO remap area.
+    static __MMIO_REMAP_END: UnsafeCell<()>;
+}
 
 //--------------------------------------------------------------------------------------------------
 // Public Definitions
@@ -254,7 +260,7 @@ fn boot_end_exclusive() -> usize {
 /// - Value is provided by the linker script and must be trusted as-is.
 #[inline(always)]
 fn code_start() -> usize {
-    unsafe { __RO_START.get() as usize }
+    unsafe { __CODE_START.get() as usize }
 }
 
 /// Start page address of the code segment.
@@ -264,7 +270,7 @@ fn code_start() -> usize {
 /// - Value is provided by the linker script and must be trusted as-is.
 #[inline(always)]
 fn virt_code_start() -> PageAddress<Virtual> {
-    PageAddress::from(unsafe { __RO_START.get() as usize })
+    PageAddress::from(unsafe { __CODE_START.get() as usize })
 }
 
 /// Size of the code segment.
@@ -274,7 +280,7 @@ fn virt_code_start() -> PageAddress<Virtual> {
 /// - Value is provided by the linker script and must be trusted as-is.
 #[inline(always)]
 fn code_size() -> usize {
-    unsafe { (__RO_END.get() as usize) - (__RO_START.get() as usize) }
+    unsafe { (__CODE_END.get() as usize) - (__CODE_START.get() as usize) }
 }
 
 /// Exclusive end page address of the code segment.
@@ -289,7 +295,7 @@ fn code_size() -> usize {
 /// Start page address of the data segment.
 #[inline(always)]
 fn virt_data_start() -> PageAddress<Virtual> {
-    PageAddress::from(unsafe { __data_start.get() as usize })
+    PageAddress::from(unsafe { __DATA_START.get() as usize })
 }
 
 /// Size of the data segment.
@@ -299,7 +305,7 @@ fn virt_data_start() -> PageAddress<Virtual> {
 /// - Value is provided by the linker script and must be trusted as-is.
 #[inline(always)]
 fn data_size() -> usize {
-    unsafe { (__data_end_exclusive.get() as usize) - (__data_start.get() as usize) }
+    unsafe { (__DATA_END.get() as usize) - (__DATA_START.get() as usize) }
 }
 
 /// Start page address of the MMIO remap reservation.
@@ -309,7 +315,7 @@ fn data_size() -> usize {
 /// - Value is provided by the linker script and must be trusted as-is.
 #[inline(always)]
 fn virt_mmio_remap_start() -> PageAddress<Virtual> {
-    PageAddress::from(unsafe { __mmio_remap_start.get() as usize })
+    PageAddress::from(unsafe { __MMIO_REMAP_START.get() as usize })
 }
 
 /// Size of the MMIO remap reservation.
@@ -319,21 +325,19 @@ fn virt_mmio_remap_start() -> PageAddress<Virtual> {
 /// - Value is provided by the linker script and must be trusted as-is.
 #[inline(always)]
 fn mmio_remap_size() -> usize {
-    unsafe { (__mmio_remap_end_exclusive.get() as usize) - (__mmio_remap_start.get() as usize) }
+    unsafe { (__MMIO_REMAP_END.get() as usize) - (__MMIO_REMAP_START.get() as usize) }
 }
 
 /// Start page address of the boot core's stack.
 #[inline(always)]
 fn virt_boot_core_stack_start() -> PageAddress<Virtual> {
-    PageAddress::from(unsafe { __boot_core_stack_start.get() as usize })
+    PageAddress::from(unsafe { __STACK_BOTTOM.get() as usize })
 }
 
 /// Size of the boot core's stack.
 #[inline(always)]
 fn boot_core_stack_size() -> usize {
-    unsafe {
+    unsafe { (__STACK_TOP.get() as usize) - (__STACK_BOTTOM.get() as usize) }
-        (__boot_core_stack_end_exclusive.get() as usize) - (__boot_core_stack_start.get() as usize)
-    }
 }
 
 //--------------------------------------------------------------------------------------------------

nucleus/build.rs

@@ -1,5 +1,7 @@
-const LINKER_SCRIPT: &str = "linker/aarch64.ld";
+/// This build script is used to link main kernel binary.
-const LINKER_SCRIPT_AUX: &str = "linker/aarch64-exceptions.ld";
+
+const LINKER_SCRIPT: &str = "machine/src/platform/raspberrypi/linker/kernel.ld";
+const LINKER_SCRIPT_AUX: &str = "machine/src/arch/aarch64/linker/aarch64-exceptions.ld";
 
 fn main() {
     println!("cargo:rerun-if-changed={}", LINKER_SCRIPT);