swicht from llvm_asm! to asm!

- llvm_asm is deprecated => remove it from eduOS

Author: stlankes

src/arch/x86_64/irq.rs

@@ -23,19 +23,19 @@ const KERNEL_CODE_SELECTOR: SegmentSelector = SegmentSelector::new(1, Ring::Ring
 
 /// Enable Interrupts
 pub fn irq_enable() {
-	unsafe { llvm_asm!("sti" ::: "memory" : "volatile") };
+	unsafe { asm!("sti", options(nomem, nostack, preserves_flags)) };
 }
 
 /// Disable Interrupts
 pub fn irq_disable() {
-	unsafe { llvm_asm!("cli" ::: "memory" : "volatile") };
+	unsafe { asm!("cli", options(nomem, nostack, preserves_flags)) };
 }
 
 /// Determines, if the interrupt flags (IF) is set
 pub fn is_irq_enabled() -> bool {
 	let rflags: u64;
 
-	unsafe { llvm_asm!("pushf; pop $0": "=r"(rflags) :: "memory" : "volatile") };
+	unsafe { asm!("pushf; pop {}", lateout(reg) rflags, options(nomem, nostack, preserves_flags)) };
 	if (rflags & (1u64 << 9)) != 0 {
 		return true;
 	}

src/arch/x86_64/processor.rs

@@ -15,11 +15,17 @@ pub fn mb() {
 /// Search the most significant bit
 #[inline(always)]
 pub fn msb(value: u64) -> Option<u64> {
+	println!("value {}", value);
 	if value > 0 {
 		let ret: u64;
 		unsafe {
-			llvm_asm!("bsr $1, $0" : "=r"(ret) : "r"(value) : "cc" : "volatile");
+			asm!("bsr {0}, {1}",
+			    out(reg) ret,
+				in(reg) value,
+			    options(nomem, nostack)
+			);
 		}
+		println!("value {} {}", value, ret);
 		Some(ret)
 	} else {
 		None
@@ -32,7 +38,11 @@ pub fn lsb(value: u64) -> Option<u64> {
 	if value > 0 {
 		let ret: u64;
 		unsafe {
-			llvm_asm!("bsf $1, $0" : "=r"(ret) : "r"(value) : "cc" : "volatile");
+			asm!("bsf {0}, {1}",
+			    out(reg) ret,
+				in(reg) value,
+			    options(nomem, nostack)
+			);
 		}
 		Some(ret)
 	} else {
@@ -42,13 +52,13 @@ pub fn lsb(value: u64) -> Option<u64> {
 
 pub fn halt() {
 	unsafe {
-		llvm_asm!("hlt" :::: "volatile");
+		asm!("hlt", options(nomem, nostack));
 	}
 }
 
 pub fn pause() {
 	unsafe {
-		llvm_asm!("pause" :::: "volatile");
+		asm!("pause", options(nomem, nostack));
 	}
 }
 

src/arch/x86_64/start.rs

@@ -5,7 +5,7 @@
 // http://opensource.org/licenses/MIT>, at your option. This file may not be
 // copied, modified, or distributed except according to those terms.
 
-#[allow(unused_imports)]
+use crate::consts::STACK_SIZE;
 use crate::scheduler::task::BOOT_STACK;
 
 extern "C" {
@@ -14,12 +14,24 @@ extern "C" {
 
 #[cfg(not(test))]
 #[no_mangle]
-#[naked]
-pub unsafe extern "C" fn _start() {
-	// be sure that rsp is a valid stack pointer
-	llvm_asm!("mov $0, %rsp" :: "r"(BOOT_STACK.top()) :: "volatile");
-
+pub unsafe extern "C" fn pre_main() -> ! {
 	main();
 
 	loop {}
 }
+
+#[cfg(not(test))]
+#[no_mangle]
+#[naked]
+pub unsafe extern "C" fn _start() -> ! {
+	asm!(
+		// initialize stack pointer
+		"mov rsp, {stack}",
+		"add rsp, {size}",
+		"call {pre_main}",
+		stack = sym BOOT_STACK,
+		size = const STACK_SIZE - 16,
+		pre_main = sym pre_main,
+		options(noreturn)
+	);
+}

src/arch/x86_64/switch.rs

@@ -5,52 +5,69 @@
 // http://opensource.org/licenses/MIT>, at your option. This file may not be
 // copied, modified, or distributed except according to those terms.
 
-#[inline(never)]
+macro_rules! save_context {
+	() => {
+		concat!(
+			r#"
+			pushfq
+			push rax
+			push rcx
+			push rdx
+			push rbx
+			push rbp
+			push rsi
+			push rdi
+			push r8
+			push r9
+			push r10
+			push r11
+			push r12
+			push r13
+			push r14
+			push r15
+			"#,
+		)
+	};
+}
+
+macro_rules! restore_context {
+	() => {
+		concat!(
+			r#"
+			pop r15
+			pop r14
+			pop r13
+			pop r12
+			pop r11
+			pop r10
+			pop r9
+			pop r8
+			pop rdi
+			pop rsi
+			pop rbp
+			pop rbx
+			pop rdx
+			pop rcx
+			pop rax
+			popfq
+			ret
+			"#
+		)
+	};
+}
+
 #[naked]
-pub extern "C" fn switch(_old_stack: *mut usize, _new_stack: usize) {
+pub unsafe extern "C" fn switch(_old_stack: *mut usize, _new_stack: usize) {
 	// rdi = old_stack => the address to store the old rsp
 	// rsi = new_stack => stack pointer of the new task
 
-	unsafe {
-		llvm_asm!(
-			// store context
-			"pushfq\n\t\
-			push %rax\n\t\
-			push %rcx\n\t\
-			push %rdx\n\t\
-			push %rbx\n\t\
-			sub  $$8, %rsp	// ignore rsp\n\t\
-			push %rbp\n\t\
-			push %rsi\n\t\
-			push %rdi\n\t\
-			push %r8\n\t\
-			push %r9\n\t\
-			push %r10\n\t\
-			push %r11\n\t\
-			push %r12\n\t\
-			push %r13\n\t\
-			push %r14\n\t\
-			push %r15\n\t\
-			mov %rsp, (%rdi)\n\t\
-			mov %rsi, %rsp\n\t\
-			// restore context \n\t\
-			pop %r15\n\t\
-			pop %r14\n\t\
-			pop %r13\n\t\
-			pop %r12\n\t\
-			pop %r11\n\t\
-			pop %r10\n\t\
-			pop %r9\n\t\
-			pop %r8\n\t\
-			pop %rdi\n\t\
-			pop %rsi\n\t\
-			pop %rbp\n\t\
-			add $$8, %rsp\n\t\
-			pop %rbx\n\t\
-			pop %rdx\n\t\
-			pop %rcx\n\t\
-			pop %rax\n\t\
-			popfq" :::: "volatile"
-		);
-	}
+	asm!(
+		save_context!(),
+		// Store the old `rsp` behind `old_stack`
+		"mov [rdi], rsp",
+		// Set `rsp` to `new_stack`
+		"mov rsp, rsi",
+		restore_context!(),
+		options(noreturn)
+	);
 }

src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(llvm_asm, const_fn, lang_items)]
+#![feature(const_ptr_offset, asm, lang_items)]
 #![feature(allocator_api)]
 #![feature(naked_functions)]
 #![feature(abi_x86_interrupt)]

src/scheduler/scheduler.rs

@@ -234,7 +234,9 @@ impl Scheduler {
 
 				self.current_task = new_task;
 
-				switch(current_stack_pointer, new_stack_pointer);
+				unsafe {
+					switch(current_stack_pointer, new_stack_pointer);
+				}
 			}
 			_ => {}
 		}

x86_64-eduos.json

@@ -8,7 +8,6 @@
     "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
     "features": "-mmx,-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-3dnow,-3dnowa,-avx,-avx2,+soft-float",
     "disable-redzone": true,
-    "eliminate-frame-pointer": true,
     "executables": true,
     "linker-flavor": "ld.lld",
     "linker": "rust-lld",