Add Aarch64 test

.github/workflows/aarch64.yml

@@ -49,3 +49,6 @@ jobs:
       if: ${{ matrix.os == 'macOS-latest' }}
     - name: Build loader (unix)
       run: make arch=aarch64
+    - name: Test loader
+      run: qemu-system-aarch64 -display none -smp 4 -m 1G -serial stdio -kernel target/aarch64-unknown-hermit-loader/debug/rusty-loader -machine raspi3 -semihosting
+      timeout-minutes: 1

Makefile

@@ -1,7 +1,6 @@
 arch ?= x86_64
 target ?= $(arch)-unknown-hermit
 release ?= 0
-app ?= "$(PWD)/data/hello_world"
 
 opt :=
 rdir := debug
@@ -14,6 +13,7 @@ endif
 # Todo - make this feature toggleable
 ifeq ($(arch), aarch64)
 opt += --features "aarch64-qemu-stdout"
+export HERMIT_APP ?= $(PWD)/data/hello_world_aarch64
 endif
 
 CONVERT :=
@@ -42,5 +42,6 @@ docs:
 
 loader:
 	@echo Build loader
-	HERMIT_APP=$(app) cargo build $(opt) -Z build-std=core,alloc -Z build-std-features=compiler-builtins-mem --target $(target)-loader.json
+	echo "hermit app: $(HERMIT_APP)"
+	cargo build $(opt) -Z build-std=core,alloc -Z build-std-features=compiler-builtins-mem --target $(target)-loader.json
 	$(CONVERT)

src/arch/aarch64/entry.rs

@@ -11,12 +11,8 @@ extern "C" {
 	fn loader_main();
 }
 
-const BOOT_STACK_SIZE: usize = 4096;
 const BOOT_CORE_ID: u64 = 0; // ID of CPU for booting on SMP systems - this might be board specific in the future
 
-#[link_section = ".data"]
-static STACK: [u8; BOOT_STACK_SIZE] = [0; BOOT_STACK_SIZE];
-
 /*
  * Memory types available.
  */
@@ -57,10 +53,6 @@ global_asm!(include_str!("entry.s"));
 #[inline(never)]
 #[no_mangle]
 pub unsafe fn _start_rust() -> ! {
-	// Pointer to stack base
-	llvm_asm!("mov sp, $0"
-		:: "r"(&STACK[BOOT_STACK_SIZE - 0x10] as *const u8 as usize)
-        :: "volatile");
 	pre_init()
 }
 

src/arch/aarch64/entry.s

@@ -2,6 +2,19 @@
 
 .equ _core_id_mask, 0b11    //Assume 4 core raspi3
 
+
+// Load the address of a symbol into a register, PC-relative.
+//
+// The symbol must lie within +/- 4 GiB of the Program Counter.
+//
+// # Resources
+//
+// - https://sourceware.org/binutils/docs-2.36/as/AArch64_002dRelocations.html
+.macro ADR_REL register, symbol
+	adrp	\register, \symbol
+	add	\register, \register, #:lo12:\symbol
+.endm
+
 .section .text._start
 
 _start:
@@ -13,7 +26,12 @@ _start:
 	b.ne	1f
 
 	// If execution reaches here, it is the boot core. Now, prepare the jump to Rust code.
-
+
+	// This loads the physical address of the Stack end. For details see
+	// 	https://github.com/rust-embedded/rust-raspberrypi-OS-tutorials/blob/master/16_virtual_mem_part4_higher_half_kernel/src/bsp/raspberrypi/link.ld
+	ADR_REL	x4, __boot_core_stack_end_exclusive
+	mov	sp, x4
+
 	// Jump to Rust code.
 	b	_start_rust
 

src/arch/aarch64/link.ld

@@ -1,31 +1,64 @@
+/* Parts of this linker script are directly taken from Andre Richters Project:
+ * https://github.com/rust-embedded/rust-raspberrypi-OS-tutorials/blob/master/16_virtual_mem_part4_higher_half_kernel/src/bsp/raspberrypi/link.ld 
+*/
+
 OUTPUT_FORMAT("elf64-littleaarch64")
 OUTPUT_ARCH("aarch64")
 ENTRY(_start)
 
 /* start address of the RAM, below belongs to the flash */
 phys = 0x00080000;
 
+PHDRS
+{
+    segment_rx PT_LOAD FLAGS(5); /* 5 == RX */
+    segment_rw PT_LOAD FLAGS(6); /* 6 == RW */
+}
+
 SECTIONS
 {
   . = phys;
   kernel_start = .;
-  .text ALIGN(4096) : AT(ADDR(.text)) {
-    *(.text)
-    *(.text.*)
-  }
-  .rodata ALIGN(4096) : AT(ADDR(.rodata)) {
-    *(.rodata)
-    *(.rodata.*)
-  }
-  .data ALIGN(4096) : AT(ADDR(.data)) {
-    *(.data)
-    *(.data.*)
-  }
-  .bss ALIGN(4096) : AT(ADDR(.bss)) {
+  __rx_start = .;
+  .text ALIGN(4096) : AT(phys) {
+      KEEP(*(.text._start))
+      *(.text._start_arguments) /* Constants (or statics in Rust speak) read by _start(). */
+      *(.text._start_rust)      /* The Rust entry point */
+      *(.text*)                 /* Everything else */
+  } :segment_rx
+  .rodata : ALIGN(8) { *(.rodata*) } :segment_rx
+  .got    : ALIGN(8) { *(.got)     } :segment_rx /* Global offset table Todo - do we use this?*/
+  . = ALIGN(64K); /* Align to page boundary */
+  __rx_end_exclusive = .;
+
+  __rw_start = .;
+  .data : { *(.data*) } :segment_rw
+
+  .bss : ALIGN(8) {
     bss_start = .;
-    *(.bss)
-    *(.bss.*)
-  }
-  bss_end = .;
+    *(.bss*);
+    . = ALIGN(8);
+    . += 8;
+    bss_end = .;
+  } :NONE
+
+  . = ALIGN(64K); /* Align to page boundary */
+  __rw_end_exclusive = .;
+
+  /***********************************************************************************************
+  * Guard Page between boot core stack and data
+  ***********************************************************************************************/
+  __boot_core_stack_guard_page_start = .;
+  . += 64K;
+  __boot_core_stack_guard_page_end_exclusive = .;
+
+  /***********************************************************************************************
+  * Boot Core Stack
+  ***********************************************************************************************/
+  __boot_core_stack_start = .;         /*   ^             */
+                                       /*   | stack       */
+  . += 512K;                           /*   | growth      */
+                                       /*   | direction   */
+  __boot_core_stack_end_exclusive = .; /*   |             */
   kernel_end = .;
 }