1 files changed, 176 insertions, 0 deletions

diff --git a/include/asm-x86/semaphore_32.h b/include/asm-x86/semaphore_32.h
new file mode 100644
index 000000000000..4e34a468c383
--- /dev/null
+++ b/include/asm-x86/semaphore_32.h
@@ -0,0 +1,176 @@
+#ifndef _I386_SEMAPHORE_H
+#define _I386_SEMAPHORE_H
+
+#include <linux/linkage.h>
+
+#ifdef __KERNEL__
+
+/*
+ * 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.
+ * Modified 1999-02-14 by Andrea Arcangeli, split the sched.c helper
+ *                     functions in asm/sempahore-helper.h while fixing a
+ *                     potential and subtle race discovered by Ulrich Schmid
+ *                     in down_interruptible(). Since I started to play here I
+ *                     also implemented the `trylock' semaphore operation.
+ *          1999-07-02 Artur Skawina <skawina@geocities.com>
+ *                     Optimized "0(ecx)" -> "(ecx)" (the assembler does not
+ *                     do this). Changed calling sequences from push/jmp to
+ *                     traditional call/ret.
+ * Modified 2001-01-01 Andreas Franck <afranck@gmx.de>
+ *                     Some hacks to ensure compatibility with recent
+ *                     GCC snapshots, to avoid stack corruption when compiling
+ *                     with -fomit-frame-pointer. It's not sure if this will
+ *                     be fixed in GCC, as our previous implementation was a
+ *                     bit dubious.
+ *
+ * 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.
+ *
+ */
+
+#include <asm/system.h>
+#include <asm/atomic.h>
+#include <linux/wait.h>
+#include <linux/rwsem.h>
+
+struct semaphore {
+        atomic_t count;
+        int sleepers;
+        wait_queue_head_t wait;
+};
+
+
+#define __SEMAPHORE_INITIALIZER(name, n)                                \
+{                                                                       \
+        .count          = ATOMIC_INIT(n),                               \
+        .sleepers       = 0,                                            \
+        .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
+}
+
+#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
+        struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
+
+#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
+#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
+
+static inline void sema_init (struct semaphore *sem, int val)
+{
+/*
+ *      *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
+ *
+ * i'd rather use the more flexible initialization above, but sadly
+ * GCC 2.7.2.3 emits a bogus warning. EGCS doesn't. Oh well.
+ */
+        atomic_set(&sem->count, val);
+        sem->sleepers = 0;
+        init_waitqueue_head(&sem->wait);
+}
+
+static inline void init_MUTEX (struct semaphore *sem)
+{
+        sema_init(sem, 1);
+}
+
+static inline void init_MUTEX_LOCKED (struct semaphore *sem)
+{
+        sema_init(sem, 0);
+}
+
+fastcall void __down_failed(void /* special register calling convention */);
+fastcall int  __down_failed_interruptible(void  /* params in registers */);
+fastcall int  __down_failed_trylock(void  /* params in registers */);
+fastcall void __up_wakeup(void /* special register calling convention */);
+
+/*
+ * 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/kernel/semaphore.c
+ */
+static inline void down(struct semaphore * sem)
+{
+        might_sleep();
+        __asm__ __volatile__(
+                "# atomic down operation\n\t"
+                LOCK_PREFIX "decl %0\n\t"     /* --sem->count */
+                "jns 2f\n"
+                "\tlea %0,%%eax\n\t"
+                "call __down_failed\n"
+                "2:"
+                :"+m" (sem->count)
+                :
+                :"memory","ax");
+}
+
+/*
+ * Interruptible try to acquire a semaphore.  If we obtained
+ * it, return zero.  If we were interrupted, returns -EINTR
+ */
+static inline int down_interruptible(struct semaphore * sem)
+{
+        int result;
+
+        might_sleep();
+        __asm__ __volatile__(
+                "# atomic interruptible down operation\n\t"
+                "xorl %0,%0\n\t"
+                LOCK_PREFIX "decl %1\n\t"     /* --sem->count */
+                "jns 2f\n\t"
+                "lea %1,%%eax\n\t"
+                "call __down_failed_interruptible\n"
+                "2:"
+                :"=&a" (result), "+m" (sem->count)
+                :
+                :"memory");
+        return result;
+}
+
+/*
+ * Non-blockingly attempt to down() a semaphore.
+ * Returns zero if we acquired it
+ */
+static inline int down_trylock(struct semaphore * sem)
+{
+        int result;
+
+        __asm__ __volatile__(
+                "# atomic interruptible down operation\n\t"
+                "xorl %0,%0\n\t"
+                LOCK_PREFIX "decl %1\n\t"     /* --sem->count */
+                "jns 2f\n\t"
+                "lea %1,%%eax\n\t"
+                "call __down_failed_trylock\n\t"
+                "2:\n"
+                :"=&a" (result), "+m" (sem->count)
+                :
+                :"memory");
+        return result;
+}
+
+/*
+ * Note! This is subtle. We jump to wake people up only if
+ * the semaphore was negative (== somebody was waiting on it).
+ */
+static inline void up(struct semaphore * sem)
+{
+        __asm__ __volatile__(
+                "# atomic up operation\n\t"
+                LOCK_PREFIX "incl %0\n\t"     /* ++sem->count */
+                "jg 1f\n\t"
+                "lea %0,%%eax\n\t"
+                "call __up_wakeup\n"
+                "1:"
+                :"+m" (sem->count)
+                :
+                :"memory","ax");
+}
+
+#endif
+#endif