Multithreaded locking fixes.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4692 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 249 insertions, 0 deletions

diff --git a/qemu-lock.h b/qemu-lock.h
new file mode 100644
index 0000000..fdd8da9
--- /dev/null
+++ b/qemu-lock.h
@@ -0,0 +1,249 @@
+/*
+ *  Copyright (c) 2003 Fabrice Bellard
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/* Locking primitives.  Most of this code should be redundant -
+   system emulation doesn't need/use locking, NPTL userspace uses
+   pthread mutexes, and non-NPTL userspace isn't threadsafe anyway.
+   In either case a spinlock is probably the wrong kind of lock.
+   Spinlocks are only good if you know annother CPU has the lock and is
+   likely to release it soon.  In environments where you have more threads
+   than physical CPUs (the extreme case being a single CPU host) a spinlock
+   simply wastes CPU until the OS decides to preempt it.  */
+#if defined(USE_NPTL)
+
+#include <pthread.h>
+#define spin_lock pthread_mutex_lock
+#define spin_unlock pthread_mutex_unlock
+#define spinlock_t pthread_mutex_t
+#define SPIN_LOCK_UNLOCKED PTHREAD_MUTEX_INITIALIZER
+
+#else
+
+#if defined(__hppa__)
+
+typedef int spinlock_t[4];
+
+#define SPIN_LOCK_UNLOCKED { 1, 1, 1, 1 }
+
+static inline void resetlock (spinlock_t *p)
+{
+    (*p)[0] = (*p)[1] = (*p)[2] = (*p)[3] = 1;
+}
+
+#else
+
+typedef int spinlock_t;
+
+#define SPIN_LOCK_UNLOCKED 0
+
+static inline void resetlock (spinlock_t *p)
+{
+    *p = SPIN_LOCK_UNLOCKED;
+}
+
+#endif
+
+#if defined(__powerpc__)
+static inline int testandset (int *p)
+{
+    int ret;
+    __asm__ __volatile__ (
+                          "0:    lwarx %0,0,%1\n"
+                          "      xor. %0,%3,%0\n"
+                          "      bne 1f\n"
+                          "      stwcx. %2,0,%1\n"
+                          "      bne- 0b\n"
+                          "1:    "
+                          : "=&r" (ret)
+                          : "r" (p), "r" (1), "r" (0)
+                          : "cr0", "memory");
+    return ret;
+}
+#elif defined(__i386__)
+static inline int testandset (int *p)
+{
+    long int readval = 0;
+
+    __asm__ __volatile__ ("lock; cmpxchgl %2, %0"
+                          : "+m" (*p), "+a" (readval)
+                          : "r" (1)
+                          : "cc");
+    return readval;
+}
+#elif defined(__x86_64__)
+static inline int testandset (int *p)
+{
+    long int readval = 0;
+
+    __asm__ __volatile__ ("lock; cmpxchgl %2, %0"
+                          : "+m" (*p), "+a" (readval)
+                          : "r" (1)
+                          : "cc");
+    return readval;
+}
+#elif defined(__s390__)
+static inline int testandset (int *p)
+{
+    int ret;
+
+    __asm__ __volatile__ ("0: cs    %0,%1,0(%2)\n"
+			  "   jl    0b"
+			  : "=&d" (ret)
+			  : "r" (1), "a" (p), "0" (*p)
+			  : "cc", "memory" );
+    return ret;
+}
+#elif defined(__alpha__)
+static inline int testandset (int *p)
+{
+    int ret;
+    unsigned long one;
+
+    __asm__ __volatile__ ("0:	mov 1,%2\n"
+			  "	ldl_l %0,%1\n"
+			  "	stl_c %2,%1\n"
+			  "	beq %2,1f\n"
+			  ".subsection 2\n"
+			  "1:	br 0b\n"
+			  ".previous"
+			  : "=r" (ret), "=m" (*p), "=r" (one)
+			  : "m" (*p));
+    return ret;
+}
+#elif defined(__sparc__)
+static inline int testandset (int *p)
+{
+	int ret;
+
+	__asm__ __volatile__("ldstub	[%1], %0"
+			     : "=r" (ret)
+			     : "r" (p)
+			     : "memory");
+
+	return (ret ? 1 : 0);
+}
+#elif defined(__arm__)
+static inline int testandset (int *spinlock)
+{
+    register unsigned int ret;
+    __asm__ __volatile__("swp %0, %1, [%2]"
+                         : "=r"(ret)
+                         : "0"(1), "r"(spinlock));
+
+    return ret;
+}
+#elif defined(__mc68000)
+static inline int testandset (int *p)
+{
+    char ret;
+    __asm__ __volatile__("tas %1; sne %0"
+                         : "=r" (ret)
+                         : "m" (p)
+                         : "cc","memory");
+    return ret;
+}
+#elif defined(__hppa__)
+
+/* Because malloc only guarantees 8-byte alignment for malloc'd data,
+   and GCC only guarantees 8-byte alignment for stack locals, we can't
+   be assured of 16-byte alignment for atomic lock data even if we
+   specify "__attribute ((aligned(16)))" in the type declaration.  So,
+   we use a struct containing an array of four ints for the atomic lock
+   type and dynamically select the 16-byte aligned int from the array
+   for the semaphore.  */
+#define __PA_LDCW_ALIGNMENT 16
+static inline void *ldcw_align (void *p) {
+    unsigned long a = (unsigned long)p;
+    a = (a + __PA_LDCW_ALIGNMENT - 1) & ~(__PA_LDCW_ALIGNMENT - 1);
+    return (void *)a;
+}
+
+static inline int testandset (spinlock_t *p)
+{
+    unsigned int ret;
+    p = ldcw_align(p);
+    __asm__ __volatile__("ldcw 0(%1),%0"
+                         : "=r" (ret)
+                         : "r" (p)
+                         : "memory" );
+    return !ret;
+}
+
+#elif defined(__ia64)
+
+#include <ia64intrin.h>
+
+static inline int testandset (int *p)
+{
+    return __sync_lock_test_and_set (p, 1);
+}
+#elif defined(__mips__)
+static inline int testandset (int *p)
+{
+    int ret;
+
+    __asm__ __volatile__ (
+	"	.set push		\n"
+	"	.set noat		\n"
+	"	.set mips2		\n"
+	"1:	li	$1, 1		\n"
+	"	ll	%0, %1		\n"
+	"	sc	$1, %1		\n"
+	"	beqz	$1, 1b		\n"
+	"	.set pop		"
+	: "=r" (ret), "+R" (*p)
+	:
+	: "memory");
+
+    return ret;
+}
+#else
+#error unimplemented CPU support
+#endif
+
+#if defined(CONFIG_USER_ONLY)
+static inline void spin_lock(spinlock_t *lock)
+{
+    while (testandset(lock));
+}
+
+static inline void spin_unlock(spinlock_t *lock)
+{
+    resetlock(lock);
+}
+
+static inline int spin_trylock(spinlock_t *lock)
+{
+    return !testandset(lock);
+}
+#else
+static inline void spin_lock(spinlock_t *lock)
+{
+}
+
+static inline void spin_unlock(spinlock_t *lock)
+{
+}
+
+static inline int spin_trylock(spinlock_t *lock)
+{
+    return 1;
+}
+#endif
+
+#endif