From 5e0b8d508ed51004bd836384293be00950ee62c9 Mon Sep 17 00:00:00 2001
From: Pasha <pasha@member.fsf.org>
Date: Tue, 20 Feb 2024 18:49:50 +0000
Subject: init gnumach copy

---
 linux/src/include/asm-i386/semaphore.h | 133 +++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 linux/src/include/asm-i386/semaphore.h

(limited to 'linux/src/include/asm-i386/semaphore.h')

diff --git a/linux/src/include/asm-i386/semaphore.h b/linux/src/include/asm-i386/semaphore.h
new file mode 100644
index 0000000..18e12c1
--- /dev/null
+++ b/linux/src/include/asm-i386/semaphore.h
@@ -0,0 +1,133 @@
+#ifndef _I386_SEMAPHORE_H
+#define _I386_SEMAPHORE_H
+
+#include <linux/linkage.h>
+#include <asm/system.h>
+
+/*
+ * SMP- and interrupt-safe semaphores..
+ *
+ * (C) Copyright 1996 Linus Torvalds
+ *
+ * Modified 1996-12-23 by Dave Grothe <dave@gcom.com> to fix bugs in
+ *                     the original code and to make semaphore waits
+ *                     interruptible so that processes waiting on
+ *                     semaphores can be killed.
+ *
+ * If you would like to see an analysis of this implementation, please
+ * ftp to gcom.com and download the file
+ * /pub/linux/src/semaphore/semaphore-2.0.24.tar.gz.
+ *
+ */
+
+struct semaphore {
+	int count;
+	int waking;
+	int lock ;			/* to make waking testing atomic */
+	struct wait_queue * wait;
+};
+
+#define MUTEX ((struct semaphore) { 1, 0, 0, NULL })
+#define MUTEX_LOCKED ((struct semaphore) { 0, 0, 0, NULL })
+
+/* Special register calling convention:
+ * eax contains return address
+ * ecx contains semaphore address
+ */
+asmlinkage void down_failed(void /* special register calling convention */);
+asmlinkage void up_wakeup(void /* special register calling convention */);
+
+extern void __down(struct semaphore * sem);
+extern void __up(struct semaphore * sem);
+
+/*
+ * This is ugly, but we want the default case to fall through.
+ * "down_failed" is a special asm handler that calls the C
+ * routine that actually waits. See arch/i386/lib/semaphore.S
+ */
+static inline void down(struct semaphore * sem)
+{
+	int d0;
+	__asm__ __volatile__(
+		"# atomic down operation\n\t"
+		"movl $1f,%%eax\n\t"
+#ifdef __SMP__
+		"lock ; "
+#endif
+		"decl %1\n\t"
+		"js " SYMBOL_NAME_STR(down_failed) "\n"
+		"1:\n"
+		:"=&a" (d0), "=m" (sem->count)
+		:"c" (sem)
+		:"memory");
+}
+
+/*
+ * Primitives to spin on a lock.  Needed only for SMP version.
+ */
+extern inline void get_buzz_lock(int *lock_ptr)
+{
+#ifdef __SMP__
+        while (xchg(lock_ptr,1) != 0) ;
+#endif
+} /* get_buzz_lock */
+
+extern inline void give_buzz_lock(int *lock_ptr)
+{
+#ifdef __SMP__
+        *lock_ptr = 0 ;
+#endif
+} /* give_buzz_lock */
+
+asmlinkage int down_failed_interruptible(void);  /* params in registers */
+
+/*
+ * This version waits in interruptible state so that the waiting
+ * process can be killed.  The down_failed_interruptible routine
+ * returns negative for signalled and zero for semaphore acquired.
+ */
+static inline int down_interruptible(struct semaphore * sem)
+{
+	int	ret ;
+
+        __asm__ __volatile__(
+                "# atomic interruptible down operation\n\t"
+                "movl $2f,%%eax\n\t"
+#ifdef __SMP__
+                "lock ; "
+#endif
+                "decl %1\n\t"
+                "js " SYMBOL_NAME_STR(down_failed_interruptible) "\n\t"
+                "xorl %%eax,%%eax\n"
+                "2:\n"
+                :"=&a" (ret), "=m" (sem->count)
+                :"c" (sem)
+                :"memory");
+
+	return(ret) ;
+}
+
+/*
+ * Note! This is subtle. We jump to wake people up only if
+ * the semaphore was negative (== somebody was waiting on it).
+ * The default case (no contention) will result in NO
+ * jumps for both down() and up().
+ */
+static inline void up(struct semaphore * sem)
+{
+	int d0;
+	__asm__ __volatile__(
+		"# atomic up operation\n\t"
+		"movl $1f,%%eax\n\t"
+#ifdef __SMP__
+		"lock ; "
+#endif
+		"incl %1\n\t"
+		"jle " SYMBOL_NAME_STR(up_wakeup)
+		"\n1:"
+		:"=&a" (d0), "=m" (sem->count)
+		:"c" (sem)
+		:"memory");
+}
+
+#endif
-- 
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