From fc48f4fb0506b2ea6ef3bb33037be3a4da2874bc Mon Sep 17 00:00:00 2001
From: Max Filippov <jcmvbkbc@gmail.com>
Date: Sat, 8 Aug 2020 23:28:17 -0700
Subject: xtensa: add exclusive access support

Add XCHAL definitions for S32C1I and EXCLUSIVE options to
xtensa-config.h, include it in places that implement atomic operations
and add implementations with exclusive access option opcodes.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 .../linuxthreads/sysdeps/xtensa/pt-machine.h       | 56 ++++++++++++++++++++++
 libpthread/nptl/sysdeps/xtensa/pthread_spin_lock.S | 16 +++++++
 .../nptl/sysdeps/xtensa/pthread_spin_trylock.S     | 17 +++++++
 3 files changed, 89 insertions(+)

(limited to 'libpthread')

diff --git a/libpthread/linuxthreads/sysdeps/xtensa/pt-machine.h b/libpthread/linuxthreads/sysdeps/xtensa/pt-machine.h
index 82d9b540c..0b7f58b63 100644
--- a/libpthread/linuxthreads/sysdeps/xtensa/pt-machine.h
+++ b/libpthread/linuxthreads/sysdeps/xtensa/pt-machine.h
@@ -21,6 +21,7 @@
 #ifndef _PT_MACHINE_H
 #define _PT_MACHINE_H   1
 
+#include <bits/xtensa-config.h>
 #include <sys/syscall.h>
 #include <asm/unistd.h>
 
@@ -34,6 +35,55 @@
 extern long int testandset (int *spinlock);
 extern int __compare_and_swap (long int *p, long int oldval, long int newval);
 
+#if XCHAL_HAVE_EXCLUSIVE
+
+/* Spinlock implementation; required.  */
+PT_EI long int
+testandset (int *spinlock)
+{
+	unsigned long tmp;
+	__asm__ volatile (
+"	memw				\n"
+"1:	l32ex	%0, %1			\n"
+"	bnez	%0, 2f			\n"
+"	movi	%0, 1			\n"
+"	s32ex	%0, %1			\n"
+"	getex	%0			\n"
+"	beqz	%0, 1b			\n"
+"	movi	%0, 0			\n"
+"	memw				\n"
+"2:					\n"
+	: "=&a" (tmp)
+	: "a" (spinlock)
+	: "memory"
+	);
+	return tmp;
+}
+
+PT_EI int
+__compare_and_swap (long int *p, long int oldval, long int newval)
+{
+        unsigned long tmp;
+        unsigned long value;
+        __asm__ volatile (
+"       memw                         \n"
+"1:     l32ex   %0, %2               \n"
+"       bne     %0, %4, 2f           \n"
+"       mov     %1, %3               \n"
+"       s32ex   %1, %2               \n"
+"       getex   %1                   \n"
+"       beqz    %1, 1b               \n"
+"       memw                         \n"
+"2:                                  \n"
+          : "=&a" (tmp), "=&a" (value)
+          : "a" (p), "a" (newval), "a" (oldval)
+          : "memory" );
+
+        return tmp == oldval;
+}
+
+#elif XCHAL_HAVE_S32C1I
+
 /* Spinlock implementation; required.  */
 PT_EI long int
 testandset (int *spinlock)
@@ -71,6 +121,12 @@ __compare_and_swap (long int *p, long int oldval, long int newval)
         return tmp == oldval;
 }
 
+#else
+
+#error No hardware atomic operations
+
+#endif
+
 /* Get some notion of the current stack.  Need not be exactly the top
    of the stack, just something somewhere in the current frame.  */
 #define CURRENT_STACK_FRAME __builtin_frame_address (0)
diff --git a/libpthread/nptl/sysdeps/xtensa/pthread_spin_lock.S b/libpthread/nptl/sysdeps/xtensa/pthread_spin_lock.S
index 3386afae9..3faac36da 100644
--- a/libpthread/nptl/sysdeps/xtensa/pthread_spin_lock.S
+++ b/libpthread/nptl/sysdeps/xtensa/pthread_spin_lock.S
@@ -15,16 +15,32 @@
    License along with the GNU C Library; see the file COPYING.LIB.  If
    not, see <http://www.gnu.org/licenses/>.  */
 
+#include <bits/xtensa-config.h>
 #include <sysdep.h>
 
 	.text
 ENTRY (pthread_spin_lock)
 
+#if XCHAL_HAVE_EXCLUSIVE
+	memw
+1:	l32ex	a3, a2
+	bnez	a3, 1b
+	movi	a3, 1
+	s32ex	a3, a2
+	getex	a3
+	beqz	a3, 1b
+	memw
+#elif XCHAL_HAVE_S32C1I
 	movi	a3, 0
 	wsr 	a3, scompare1
 	movi	a3, 1
 1:	s32c1i	a3, a2, 0
 	bnez	a3, 1b
+#else
+
+#error No hardware atomic operations
+
+#endif
 	movi	a2, 0
 
 	abi_ret
diff --git a/libpthread/nptl/sysdeps/xtensa/pthread_spin_trylock.S b/libpthread/nptl/sysdeps/xtensa/pthread_spin_trylock.S
index 72b2dda92..0669682ec 100644
--- a/libpthread/nptl/sysdeps/xtensa/pthread_spin_trylock.S
+++ b/libpthread/nptl/sysdeps/xtensa/pthread_spin_trylock.S
@@ -17,15 +17,32 @@
 
 #define _ERRNO_H 1
 #include <bits/errno.h>
+#include <bits/xtensa-config.h>
 #include <sysdep.h>
 
 	.text
 ENTRY (pthread_spin_trylock)
 
+#if XCHAL_HAVE_EXCLUSIVE
+	memw
+	l32ex	a3, a2
+	bnez	a3, 1f
+	movi	a3, 1
+	s32ex	a3, a2
+	getex	a3
+	addi	a3, a3, -1
+	memw
+1:
+#elif XCHAL_HAVE_S32C1I
 	movi	a3, 0
 	wsr 	a3, scompare1
 	movi	a3, 1
 	s32c1i	a3, a2, 0
+#else
+
+#error No hardware atomic operations
+
+#endif
 	movi	a2, EBUSY
 	moveqz	a2, a3, a3
 
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