New apr_atomic implementation for PowerPC native atomic operations.

PR: 42806


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@553293 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 189 insertions, 0 deletions

diff --git a/atomic/unix/ppc.c b/atomic/unix/ppc.c
new file mode 100644
index 000000000..149347eae
--- /dev/null
+++ b/atomic/unix/ppc.c
@@ -0,0 +1,178 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "apr_arch_atomic.h"
+
+#ifdef USE_ATOMICS_PPC
+
+#ifdef PPC405_ERRATA
+#   define PPC405_ERR77_SYNC   "	sync\n"
+#else
+#   define PPC405_ERR77_SYNC
+#endif
+
+APR_DECLARE(apr_status_t) apr_atomic_init(apr_pool_t *p)
+{
+    return APR_SUCCESS;
+}
+
+APR_DECLARE(apr_uint32_t) apr_atomic_read32(volatile apr_uint32_t *mem)
+{
+    return *mem;
+}
+
+APR_DECLARE(void) apr_atomic_set32(volatile apr_uint32_t *mem, apr_uint32_t val)
+{
+    *mem = val;
+}
+
+APR_DECLARE(apr_uint32_t) apr_atomic_add32(volatile apr_uint32_t *mem, apr_uint32_t val)
+{
+    apr_uint32_t prev, temp;
+
+    asm volatile ("loop_%=:\n"                  /* lost reservation     */
+                  "	lwarx   %0,0,%3\n"      /* load and reserve     */
+                  "	add     %1,%0,%4\n"     /* add val and prev     */
+                  PPC405_ERR77_SYNC             /* ppc405 Erratum 77    */
+                  "	stwcx.  %1,0,%3\n"      /* store new value      */
+                  "	bne-    loop_%=\n"      /* loop if lost         */
+                  : "=&r" (prev), "=&r" (temp), "=m" (*mem)
+                  : "b" (mem), "r" (val)
+                  : "cc", "memory");
+
+    return prev;
+}
+
+APR_DECLARE(void) apr_atomic_sub32(volatile apr_uint32_t *mem, apr_uint32_t val)
+{
+    apr_uint32_t temp;
+
+    asm volatile ("loop_%=:\n"                  /* lost reservation     */
+                  "	lwarx   %0,0,%2\n"      /* load and reserve     */
+                  "	subf    %0,%3,%0\n"     /* subtract val         */
+                  PPC405_ERR77_SYNC             /* ppc405 Erratum 77    */
+                  "	stwcx.  %0,0,%2\n"      /* store new value      */
+                  "	bne-    loop_%=\n"      /* loop if lost         */
+                  : "=&r" (temp), "=m" (*mem)
+                  : "b" (mem), "r" (val)
+                  : "cc", "memory");
+}
+
+APR_DECLARE(apr_uint32_t) apr_atomic_inc32(volatile apr_uint32_t *mem)
+{
+    apr_uint32_t prev;
+
+    asm volatile ("loop_%=:\n"                  /* lost reservation     */
+                  "	lwarx   %0,0,%2\n"      /* load and reserve     */
+                  "	addi    %0,%0,1\n"      /* add immediate        */
+                  PPC405_ERR77_SYNC             /* ppc405 Erratum 77    */
+                  "	stwcx.  %0,0,%2\n"      /* store new value      */
+                  "	bne-    loop_%=\n"      /* loop if lost         */
+                  "	subi    %0,%0,1\n"      /* return old value     */
+                  : "=&b" (prev), "=m" (*mem)
+                  : "b" (mem), "m" (*mem)
+                  : "cc", "memory");
+
+    return prev;
+}
+
+APR_DECLARE(int) apr_atomic_dec32(volatile apr_uint32_t *mem)
+{
+    apr_uint32_t prev;
+
+    asm volatile ("loop_%=:\n"                  /* lost reservation     */
+                  "	lwarx   %0,0,%2\n"      /* load and reserve     */
+                  "	subi    %0,%0,1\n"      /* subtract immediate   */
+                  PPC405_ERR77_SYNC             /* ppc405 Erratum 77    */
+                  "	stwcx.  %0,0,%2\n"      /* store new value      */
+                  "	bne-    loop_%=\n"      /* loop if lost         */
+                  : "=&b" (prev), "=m" (*mem)
+                  : "b" (mem), "m" (*mem)
+                  : "cc", "memory");
+
+    return prev;
+}
+
+APR_DECLARE(apr_uint32_t) apr_atomic_cas32(volatile apr_uint32_t *mem, apr_uint32_t with,
+                                           apr_uint32_t cmp)
+{
+    apr_uint32_t prev;
+
+    asm volatile ("loop_%=:\n"                  /* lost reservation     */
+                  "	lwarx   %0,0,%1\n"      /* load and reserve     */
+                  "	cmpw    %0,%3\n"        /* compare operands     */
+                  "	bne-    exit_%=\n"      /* skip if not equal    */
+                  PPC405_ERR77_SYNC             /* ppc405 Erratum 77    */
+                  "	stwcx.  %2,0,%1\n"      /* store new value      */
+                  "	bne-    loop_%=\n"      /* loop if lost         */
+                  "exit_%=:\n"                  /* not equal            */
+                  : "=&r" (prev)
+                  : "b" (mem), "r" (with), "r" (cmp)
+                  : "cc", "memory");
+
+    return prev;
+}
+
+APR_DECLARE(apr_uint32_t) apr_atomic_xchg32(volatile apr_uint32_t *mem, apr_uint32_t val)
+{
+    apr_uint32_t prev;
+
+    asm volatile ("loop_%=:\n"                  /* lost reservation     */
+                  "	lwarx   %0,0,%1\n"      /* load and reserve     */
+                  PPC405_ERR77_SYNC             /* ppc405 Erratum 77    */
+                  "	stwcx.  %2,0,%1\n"      /* store new value      */
+                  "	bne-    loop_%="        /* loop if lost         */
+                  : "=&r" (prev)
+                  : "b" (mem), "r" (val)
+                  : "cc", "memory");
+
+    return prev;
+}
+
+APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *with, const void *cmp)
+{
+    void *prev;
+#if APR_SIZEOF_VOIDP == 4
+    asm volatile ("loop_%=:\n"                  /* lost reservation     */
+                  "	lwarx   %0,0,%1\n"      /* load and reserve     */
+                  "	cmpw    %0,%3\n"        /* compare operands     */
+                  "	bne-    exit_%=\n"      /* skip if not equal    */
+                  PPC405_ERR77_SYNC             /* ppc405 Erratum 77    */
+                  "	stwcx.  %2,0,%1\n"      /* store new value      */
+                  "	bne-    loop_%=\n"      /* loop if lost         */
+                  "exit_%=:\n"                  /* not equal            */
+                  : "=&r" (prev)
+                  : "b" (mem), "r" (with), "r" (cmp)
+                  : "cc", "memory");
+#elif APR_SIZEOF_VOIDP == 8
+    asm volatile ("loop_%=:\n"                  /* lost reservation     */
+                  "	ldarx   %0,0,%1\n"      /* load and reserve     */
+                  "	cmpd    %0,%3\n"        /* compare operands     */
+                  "	bne-    exit_%=\n"      /* skip if not equal    */
+                  PPC405_ERR77_SYNC             /* ppc405 Erratum 77    */
+                  "	stdcx.  %2,0,%1\n"      /* store new value      */
+                  "	bne-    loop_%=\n"      /* loop if lost         */
+                  "exit_%=:\n"                  /* not equal            */
+                  : "=&r" (prev)
+                  : "b" (mem), "r" (with), "r" (cmp)
+                  : "cc", "memory");
+#else
+#error APR_SIZEOF_VOIDP value not supported
+#endif
+    return prev;
+}
+
+#endif /* USE_ATOMICS_PPC */
diff --git a/configure.in b/configure.in
index c026dc033..ce4250131 100644
--- a/configure.in
+++ b/configure.in
@@ -392,6 +392,15 @@ if test "$atomic_builtins" = "yes"; then
     AC_DEFINE(HAVE_ATOMIC_BUILTINS, 1, [Define if compiler provides atomic builtins])
 fi
 
+case $host in
+    powerpc-405-*)
+        # The IBM ppc405cr processor has a bugged stwcx instruction.
+        AC_DEFINE(PPC405_ERRATA, 1, [Define on PowerPC 405 where errata 77 applies])
+        ;;
+    *)
+        ;;
+esac
+
 dnl Check the depend program we can use
 APR_CHECK_DEPEND
 
diff --git a/include/arch/unix/apr_arch_atomic.h b/include/arch/unix/apr_arch_atomic.h
index f506fb797..6b020c898 100644
--- a/include/arch/unix/apr_arch_atomic.h
+++ b/include/arch/unix/apr_arch_atomic.h
@@ -34,6 +34,8 @@
 #   define USE_ATOMICS_IA32
 #elif defined(SOLARIS2) && SOLARIS2 >= 10
 #   define USE_ATOMICS_SOLARIS
+#elif defined(__GNUC__) && (defined(__PPC__) || defined(__ppc__))
+#   define USE_ATOMICS_PPC
 #else
 #   define USE_ATOMICS_GENERIC
 #endif