From 1af7591e37d09ddcd734ea07d0e999cf61c8bc5e Mon Sep 17 00:00:00 2001
From: vetch <vetch97@gmail.com>
Date: Mon, 13 Jan 2020 12:40:38 +0100
Subject: Great Reorganisation, modify structure and makefile

---
 src/arm/PL1/loader/loader_stage1.S         | 55 ++++++++++++++++++++++++++++++
 src/arm/PL1/loader/loader_stage1_linker.ld | 16 +++++++++
 src/arm/PL1/loader/loader_stage2.c         | 33 ++++++++++++++++++
 src/arm/PL1/loader/loader_stage2_linker.ld | 16 +++++++++
 4 files changed, 120 insertions(+)
 create mode 100644 src/arm/PL1/loader/loader_stage1.S
 create mode 100644 src/arm/PL1/loader/loader_stage1_linker.ld
 create mode 100644 src/arm/PL1/loader/loader_stage2.c
 create mode 100644 src/arm/PL1/loader/loader_stage2_linker.ld

(limited to 'src/arm/PL1/loader')

diff --git a/src/arm/PL1/loader/loader_stage1.S b/src/arm/PL1/loader/loader_stage1.S
new file mode 100644
index 0000000..69d78c5
--- /dev/null
+++ b/src/arm/PL1/loader/loader_stage1.S
@@ -0,0 +1,55 @@
+/* arm mode, cortex-a7 compatibility
+ *
+ * _boot is entry point for the loader.
+ *
+ * Loader copies it's embedded stage 2 to address 0x4000
+ * and jumps to it. Registers r0 - r2 are arguments for the kernel
+ * and should be left intact.
+ */
+	
+.global _boot
+_boot:
+        // Only let the first core execute
+        mrc p15, 0, r3, c0, c0, 5
+        and r3, r3, #3
+        cmp r3, #0
+        beq proceed
+	// this is a kind of blef - races can theoretically still occur
+	// when the main core overwrites this part of memory
+	wfe
+
+proceed:
+	// copy stage2 of the loader to address 0x4000
+
+	// first, load address of stage2_start to r3 (a PIC way)
+	adr r3, stage2_start
+
+	// load destination address for stage2 code to r4
+	mov r4, #0x4000
+
+	// load blob size to r5
+	mov r5, #(stage2_end - stage2_start)
+
+	// r6 is the counter - counts the bytes copied
+	mov r6, #0
+
+	// each word of the blob is loaded to r7 and stored
+	// from r7 to it's destination in a loop
+loop:
+	ldr r7, [r3, r6]
+	str r7, [r4, r6]
+	add r6, r6, #4
+	cmp r6, r5
+	blo loop
+	
+        // Initialize the stack
+	// _stack_top is defined in loader_stage1_linker.ld
+	ldr sp, =_stack_top
+	
+        // Call stage2 of the loader (branch to 0x4000)
+        bx r4
+
+.align 4
+stage2_start:
+	.incbin "loader_stage2.img"
+stage2_end:
diff --git a/src/arm/PL1/loader/loader_stage1_linker.ld b/src/arm/PL1/loader/loader_stage1_linker.ld
new file mode 100644
index 0000000..711fcbf
--- /dev/null
+++ b/src/arm/PL1/loader/loader_stage1_linker.ld
@@ -0,0 +1,16 @@
+ENTRY(_boot)
+ 
+SECTIONS
+{
+	/* see linker.ld for details */
+	. = 0x2000000;
+
+	__start = .;
+	loader_stage1 :
+	{
+		KEEP(loader_stage1.o)
+	}
+	__end = .;
+
+    _stack_top = 0x8000;
+}
diff --git a/src/arm/PL1/loader/loader_stage2.c b/src/arm/PL1/loader/loader_stage2.c
new file mode 100644
index 0000000..fc3ae1c
--- /dev/null
+++ b/src/arm/PL1/loader/loader_stage2.c
@@ -0,0 +1,33 @@
+#include <stddef.h>
+#include <stdint.h>
+#include "uart.h"
+#include "io.h"
+#include "global.h"
+
+void *const kernel_load_addr = ((void*) 0x8000);
+
+void _stage2_main(uint32_t r0, uint32_t r1, uint32_t atags)
+{
+  uart_init();
+
+  // get kernel size via uart (little endian)
+  uint32_t b0, b1, b2, b3;
+  
+  b0 = getchar();
+  b1 = getchar();
+  b2 = getchar();
+  b3 = getchar();
+  
+  uint32_t kernel_size = b0 | (b1 << 8) | (b2 << 16) | (b3 << 24);
+
+  // load kernel at kernel_load_addr
+  char *dst = kernel_load_addr, *end = dst + kernel_size;
+
+  while (dst < end)
+    *(dst++) = getchar();
+
+  // jump to kernel
+  ((void(*)(uint32_t, uint32_t, uint32_t)) kernel_load_addr)
+    (r0, r1, atags);
+}
+
diff --git a/src/arm/PL1/loader/loader_stage2_linker.ld b/src/arm/PL1/loader/loader_stage2_linker.ld
new file mode 100644
index 0000000..33e79e9
--- /dev/null
+++ b/src/arm/PL1/loader/loader_stage2_linker.ld
@@ -0,0 +1,16 @@
+ENTRY(_stage2_main)
+ 
+SECTIONS
+{
+	/* see loader_stage1.S for details */
+	. = 0x4000;
+
+	__start = .;
+	loader_stage2 :
+	{
+		KEEP(loader_stage2.o(.text))
+		loader_stage2.o
+		uart.o
+	}
+	__end = .;
+}
-- 
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