From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Thu, 8 Oct 2009 13:22:05 +0000 (-0400)
Subject: Remove whitespace
X-Git-Tag: v0.2.3~17
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=d45599f4bfd3283dbab0f023d051b9b9b0639c0d;p=userspace-rcu.git

Remove whitespace

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---

diff --git a/compat_arch_x86.c b/compat_arch_x86.c
new file mode 100644
index 0000000..e08ac89
--- /dev/null
+++ b/compat_arch_x86.c
@@ -0,0 +1,129 @@
+/*
+ * compat_arch_x86.c
+ *
+ * Userspace RCU library - x86 compatibility checks
+ *
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ *
+ * 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 2.1 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdio.h>
+#include <pthread.h>
+#include <signal.h>
+#include <assert.h>
+#include <urcu/uatomic_arch.h>
+
+/*
+ * It does not really matter if the constructor is called before using
+ * the library, as long as the caller checks if __urcu_cas_avail < 0 and calls
+ * compat_arch_init() explicitely if needed.
+ */
+int __attribute__((constructor)) __urcu_cas_init(void);
+
+static pthread_mutex_t compat_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * -1: unknown
+ *  1: available
+ *  0: unavailable
+ */
+int __urcu_cas_avail = -1;
+
+/*
+ * Imported from glibc 2.3.5. linuxthreads/sysdeps/i386/pt-machine.h.
+ */
+
+int get_eflags (void)
+{
+	int res;
+	__asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : );
+	return res;
+}
+
+void set_eflags (int newflags)
+{
+	__asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc");
+}
+
+int compare_and_swap_is_available (void)
+{
+	int oldflags = get_eflags ();
+	int changed;
+	/* Flip AC bit in EFLAGS.  */
+	set_eflags (oldflags ^ 0x40000);
+	/* See if bit changed.  */
+	changed = (get_eflags () ^ oldflags) & 0x40000;
+	/* Restore EFLAGS.  */
+	set_eflags (oldflags);
+	/* If the AC flag did not change, it's a 386 and it lacks cmpxchg.
+	Otherwise, it's a 486 or above and it has cmpxchg.  */
+	return changed != 0;
+}
+
+unsigned long _compat_uatomic_cmpxchg(void *addr, unsigned long old,
+			      unsigned long _new, int len)
+{
+	sigset_t newmask, oldmask;
+	int ret;
+
+	/* Disable signals */
+	ret = sigemptyset(&newmask);
+	assert(!ret);
+	ret = pthread_sigmask(SIG_SETMASK, &newmask, &oldmask);
+	assert(!ret);
+	ret = pthread_mutex_lock(&compat_mutex);
+	assert(!ret);
+
+	switch (len) {
+	case 1:
+	{
+		unsigned char result = *(unsigned char *)addr;
+		if (result == old)
+			*(unsigned char *)addr = (unsigned char)_new;
+		return result;
+	}
+	case 2:
+	{
+		unsigned short result = *(unsigned short *)addr;
+		if (result == old)
+			*(unsigned short *)addr = (unsigned short)_new;
+		return result;
+	}
+	case 4:
+	{
+		unsigned int result = *(unsigned int *)addr;
+		if (result == old)
+			*(unsigned int *)addr = (unsigned int)_new;
+		return result;
+	}
+	}
+	/* generate an illegal instruction. Cannot catch this with linker tricks
+	 * when optimizations are disabled. */
+	__asm__ __volatile__("ud2");
+	return 0;
+
+	ret = pthread_mutex_unlock(&compat_mutex);
+	assert(!ret);
+	ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
+	assert(!ret);
+}
+
+int __urcu_cas_init(void)
+{
+	if (__urcu_cas_avail < 0)
+		__urcu_cas_avail = compare_and_swap_is_available();
+	return __urcu_cas_avail;
+}