From d2d9affddff44d68e7f3ad4acf84daf14458de19 Mon Sep 17 00:00:00 2001
From: WangRunji <wangrunji0408@163.com>
Date: Wed, 20 Jun 2018 11:08:47 +0800
Subject: [PATCH] Use multiboot2 to locate RSDT

---
 src/arch/x86_64/driver/acpi/mod.rs | 38 ++----------------------------
 src/arch/x86_64/driver/mod.rs      |  6 ++---
 src/lib.rs                         |  3 ++-
 3 files changed, 6 insertions(+), 41 deletions(-)

diff --git a/src/arch/x86_64/driver/acpi/mod.rs b/src/arch/x86_64/driver/acpi/mod.rs
index 0e4a755..c7acf30 100644
--- a/src/arch/x86_64/driver/acpi/mod.rs
+++ b/src/arch/x86_64/driver/acpi/mod.rs
@@ -4,19 +4,11 @@ mod structs;
 use self::structs::*;
 use consts::*;
 
-pub fn init() -> Result<AcpiResult, AcpiError> {
-	let rsdp = find_rsdp().expect("acpi: rsdp not found.");
-	if rsdp.rsdt_physical_address > PHYSICAL_MEMORY_LIMIT {
-		return Err(AcpiError::NotMapped);
-	}
-    trace!("RSDT at {:#x}", rsdp.rsdt_physical_address);
-	let rsdt = unsafe{ &*(rsdp.rsdt_physical_address as *const Rsdt) };
+pub fn init(rsdt_addr: usize) -> Result<AcpiResult, AcpiError> {
+	let rsdt = unsafe { &*(rsdt_addr as *const Rsdt) };
 	let mut madt: Option<&'static Madt> = None;
 	for i in 0 .. rsdt.entry_count() {
 		let entry = rsdt.entry_at(i);
-		if entry > PHYSICAL_MEMORY_LIMIT {
-			return Err(AcpiError::NotMapped);
-		}
 		let header = unsafe{ &*(entry as *const Header) };
         trace!("{:?}", header);
 		if &header.signature == b"APIC" {
@@ -27,11 +19,6 @@ pub fn init() -> Result<AcpiResult, AcpiError> {
 	config_smp(madt.expect("acpi: madt not found."))
 }
 
-#[cfg(target_arch="x86")]
-const PHYSICAL_MEMORY_LIMIT: u32 = 0x0E000000;
-#[cfg(target_arch="x86_64")]
-const PHYSICAL_MEMORY_LIMIT: u32 = 0x80000000;
-
 #[derive(Debug)]
 pub struct AcpiResult {
 	pub cpu_num: u8,
@@ -72,24 +59,3 @@ fn config_smp(madt: &'static Madt) -> Result<AcpiResult, AcpiError> {
 	let ioapic_id = ioapic_id.unwrap();
 	Ok(AcpiResult { cpu_num, cpu_acpi_ids, ioapic_id, lapic_addr })
 }
-
-/// See https://wiki.osdev.org/RSDP -- Detecting the RSDP
-fn find_rsdp() -> Option<&'static Rsdp> {
-	use util::{Checkable, find_in_memory};
-	let ebda = unsafe { *(0x40E as *const u16) as usize } << 4;
-    trace!("EBDA at {:#x}", ebda);
-
-	macro_rules! return_if_find_in {
-		($begin:expr, $end:expr) => (
-			if let Some(addr) = unsafe{ find_in_memory::<Rsdp>($begin, $end, 4) } {
-				return Some(unsafe{ &*(addr as *const Rsdp) });
-			}
-		)
-	}
-	
-	if ebda != 0 {
-		return_if_find_in!(ebda as usize, 1024);
-	}
-	return_if_find_in!(0xE0000, 0x20000);
-	None
-} 
\ No newline at end of file
diff --git a/src/arch/x86_64/driver/mod.rs b/src/arch/x86_64/driver/mod.rs
index caa4763..be45add 100644
--- a/src/arch/x86_64/driver/mod.rs
+++ b/src/arch/x86_64/driver/mod.rs
@@ -8,15 +8,13 @@ pub mod keyboard;
 pub mod pit;
 pub mod ide;
 
-pub fn init(mut page_map: impl FnMut(usize, usize)) -> acpi::AcpiResult {
+pub fn init(rsdt_addr: usize, mut page_map: impl FnMut(usize, usize)) -> acpi::AcpiResult {
     assert_has_not_been_called!();
 
-    page_map(0, 1); // EBDA
-    page_map(0xe0_000, 0x100 - 0xe0);
     page_map(0x07fe1000, 1); // RSDT
     page_map(0xfec00000, 1);  // IOAPIC
 
-    let acpi = acpi::init().expect("Failed to init ACPI");
+    let acpi = acpi::init(rsdt_addr).expect("Failed to init ACPI");
     assert_eq!(acpi.lapic_addr as usize, 0xfee00000);
     trace!("acpi = {:?}", acpi);
 
diff --git a/src/lib.rs b/src/lib.rs
index 595cc2e..ed52957 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -73,6 +73,7 @@ pub extern "C" fn rust_main(multiboot_information_address: usize) -> ! {
     println!("Hello World{}", "!");
 
     let boot_info = unsafe { multiboot2::load(multiboot_information_address) };
+    let rsdt_addr = boot_info.rsdp_v1_tag().unwrap().rsdt_address();
 
     // set up guard page and map the heap pages
     let mut kernel_memory = memory::init(boot_info);
@@ -85,7 +86,7 @@ pub extern "C" fn rust_main(multiboot_information_address: usize) -> ! {
     test!(find_mp);
 
     use memory::*;
-    let acpi = arch::driver::init(|addr: usize, count: usize| {
+    let acpi = arch::driver::init(rsdt_addr, |addr: usize, count: usize| {
         kernel_memory.push(MemoryArea::new_identity(addr, addr + count * 0x1000, MemoryAttr::default(), "acpi"))
     });