From c81fd8b758917968b8bfc02f8264b38a062cb52d Mon Sep 17 00:00:00 2001
From: Achilleas Anagnostopoulos <achilleas.imap.mbox@gmail.com>
Date: Sat, 17 Jun 2017 08:18:07 +0100
Subject: [PATCH] Pass kernel start/end physical address to Kmain

---
 arch/x86_64/asm/rt0_64.s        | 7 +++++++
 arch/x86_64/script/linker.ld.in | 4 ++++
 kernel/kmain/kmain.go           | 4 ++--
 stub.go                         | 2 +-
 4 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/x86_64/asm/rt0_64.s b/arch/x86_64/asm/rt0_64.s
index e39a2f9..19fd1b1 100644
--- a/arch/x86_64/asm/rt0_64.s
+++ b/arch/x86_64/asm/rt0_64.s
@@ -1,4 +1,5 @@
 ; vim: set ft=nasm :
+%include "constants.inc"
 
 section .bss
 align 8
@@ -55,8 +56,14 @@ _rt0_64_entry:
 	; Call the kernel entry point passing a pointer to the multiboot data
 	; copied by the 32-bit entry code
 	extern multiboot_data
+	extern _kernel_start
+	extern _kernel_end
 	extern kernel.Kmain
 	
+	mov rax, _kernel_end - PAGE_OFFSET
+	push rax
+	mov rax, _kernel_start - PAGE_OFFSET
+	push rax
 	mov rax, multiboot_data
 	push rax
 	call kernel.Kmain
diff --git a/arch/x86_64/script/linker.ld.in b/arch/x86_64/script/linker.ld.in
index 7d3cf53..31a8ae0 100644
--- a/arch/x86_64/script/linker.ld.in
+++ b/arch/x86_64/script/linker.ld.in
@@ -7,6 +7,8 @@ SECTIONS {
 	 * but load it at physical address 1M */
 	. = VMA;
 
+	_kernel_start = .;
+
 	.text BLOCK(4K) : AT(ADDR(.text) - PAGE_OFFSET)
 	{
 		/* The multiboot header must be present in the first 4K of the kernel 
@@ -36,4 +38,6 @@ SECTIONS {
 		*(COMMON)
 		*(.bss)
 	}
+	
+	_kernel_end = ALIGN(4K);
 }
diff --git a/kernel/kmain/kmain.go b/kernel/kmain/kmain.go
index cd9f81d..e9d3f63 100644
--- a/kernel/kmain/kmain.go
+++ b/kernel/kmain/kmain.go
@@ -13,12 +13,12 @@ import (
 // allocated by the assembly code.
 //
 // The rt0 code passes the address of the multiboot info payload provided by the
-// bootloader.
+// bootloader as well as the physical addresses for the kernel start/end.
 //
 // Kmain is not expected to return. If it does, the rt0 code will halt the CPU.
 //
 //go:noinline
-func Kmain(multibootInfoPtr uintptr) {
+func Kmain(multibootInfoPtr, kernelStart, kernelEnd uintptr) {
 	multiboot.SetInfoPtr(multibootInfoPtr)
 
 	hal.InitTerminal()
diff --git a/stub.go b/stub.go
index 5263408..0e62711 100644
--- a/stub.go
+++ b/stub.go
@@ -11,5 +11,5 @@ var multibootInfoPtr uintptr
 // A global variable is passed as an argument to Kmain to prevent the compiler
 // from inlining the actual call and removing Kmain from the generated .o file.
 func main() {
-	kmain.Kmain(multibootInfoPtr)
+	kmain.Kmain(multibootInfoPtr, 0, 0)
 }