From c9b82feb34dd0e92b9a6aa0d928880bb7fea23dc Mon Sep 17 00:00:00 2001
From: Matthias Kruk <m@m10k.eu>
Date: Sat, 23 Nov 2019 15:32:04 +0900
Subject: [PATCH] Add spinlock implementation (should have been in commit
 aa0e4586dd3efe434b34ae7956a4c27220cb798d)

---
 kernel/klibc/spinlock.S | 54 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 kernel/klibc/spinlock.S

diff --git a/kernel/klibc/spinlock.S b/kernel/klibc/spinlock.S
new file mode 100644
index 0000000..a82c2a5
--- /dev/null
+++ b/kernel/klibc/spinlock.S
@@ -0,0 +1,54 @@
+	.section .text
+
+	.global spinlock_lock
+	.global spinlock_trylock
+	.global spinlock_unlock
+
+spinlock_lock:
+	movl		4(%esp), %edx
+0:	xorl		%eax, %eax
+	movl		$1, %ecx
+	lock
+	cmpxchgl	%ecx, (%edx)
+	jnz			0b /* lock failed */
+	ret			/* lock succeeded */
+
+spinlock_trylock:
+	movl		4(%esp), %edx
+	xorl		%eax, %eax
+	movl		$1, %ecx
+	lock
+	cmpxchgl	%ecx, (%edx)
+	ret
+
+spinlock_unlock:
+	movl		4(%esp), %edx
+	xorl		%eax, %eax
+	lock
+	xchgl		%eax, (%edx)
+	ret
+
+	/* 序でにamd64の実装
+
+spinlock_lock:
+	xorq		%rax, %rax
+	movl		$1, %ecx
+	lock
+	cmpxchgl	%ecx, (%rdi)
+	jnz			spinlock_lock
+	ret
+
+spinlock_trylock:
+	xorl		%rax, %rax
+	movl		$1, %ecx
+	lock
+	cmpxchgl	%ecx, (%rdi)
+	ret
+
+spinlock_unlock:
+	xorq		%rax, %rax
+	lock
+	xchgl		%eax, (%rdi)
+	ret
+
+	*/
-- 
2.47.3