RISC-V: Atomic and Locking Routines

This patch implements various atomic and locking routines on RISC-V.  We
mandate the A extension on Linux-capable RISC-V systems, so this can
rely on always having the various atomic instructions availiable.

2018-01-29  Palmer Dabbelt  <palmer@sifive.com>

        * sysdeps/riscv/nptl/bits/pthreadtypes-arch.h: New file.
        * sysdeps/riscv/nptl/bits/semaphore.h: Likewise.
        * sysdeps/riscv/nptl/libc-lowlevellock.c: Likewise.
        * sysdeps/unix/sysv/linux/riscv/atomic-machine.h: Likewise.

3 files changed, 109 insertions, 0 deletions

diff --git a/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h b/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h
new file mode 100644
index 0000000..f6a55b6
--- /dev/null
+++ b/sysdeps/riscv/nptl/bits/pthreadtypes-arch.h
@@ -0,0 +1,68 @@
+/* Machine-specific pthread type layouts.  RISC-V version.
+   Copyright (C) 2011-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C 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.
+
+   The GNU C 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 the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _BITS_PTHREADTYPES_ARCH_H
+#define _BITS_PTHREADTYPES_ARCH_H	1
+
+#include <endian.h>
+
+#if __riscv_xlen == 64
+# define __SIZEOF_PTHREAD_ATTR_T 		56
+# define __SIZEOF_PTHREAD_MUTEX_T 		40
+# define __SIZEOF_PTHREAD_MUTEXATTR_T 		 4
+# define __SIZEOF_PTHREAD_COND_T 		48
+# define __SIZEOF_PTHREAD_CONDATTR_T 		 4
+# define __SIZEOF_PTHREAD_RWLOCK_T 		56
+# define __SIZEOF_PTHREAD_RWLOCKATTR_T 		 8
+# define __SIZEOF_PTHREAD_BARRIER_T 		32
+# define __SIZEOF_PTHREAD_BARRIERATTR_T 	 4
+#else
+# error "rv32i-based systems are not supported"
+#endif
+
+#define __PTHREAD_COMPAT_PADDING_MID
+#define __PTHREAD_COMPAT_PADDING_END
+#define __PTHREAD_MUTEX_LOCK_ELISION		0
+#define __PTHREAD_MUTEX_USE_UNION	 	0
+#define __PTHREAD_MUTEX_NUSERS_AFTER_KIND	0
+
+#define __LOCK_ALIGNMENT
+#define __ONCE_ALIGNMENT
+
+/* There is a lot of padding in this structure.  While it's not strictly
+   necessary on RISC-V, we're going to leave it in to be on the safe side in
+   case it's needed in the future.  Most other architectures have the padding,
+   so this gives us the same extensibility as everyone else has.  */
+struct __pthread_rwlock_arch_t
+{
+  unsigned int __readers;
+  unsigned int __writers;
+  unsigned int __wrphase_futex;
+  unsigned int __writers_futex;
+  unsigned int __pad3;
+  unsigned int __pad4;
+  int __cur_writer;
+  int __shared;
+  unsigned long int __pad1;
+  unsigned long int __pad2;
+  unsigned int __flags;
+};
+
+#define __PTHREAD_RWLOCK_ELISION_EXTRA 		0
+
+#endif	/* bits/pthreadtypes.h */
diff --git a/sysdeps/riscv/nptl/bits/semaphore.h b/sysdeps/riscv/nptl/bits/semaphore.h
new file mode 100644
index 0000000..2fed17d
--- /dev/null
+++ b/sysdeps/riscv/nptl/bits/semaphore.h
@@ -0,0 +1,33 @@
+/* Machine-specific POSIX semaphore type layouts.  RISC-V version.
+   Copyright (C) 2002-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C 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.
+
+   The GNU C 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 the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _SEMAPHORE_H
+# error "Never use <bits/semaphore.h> directly; include <semaphore.h> instead."
+#endif
+
+#define __SIZEOF_SEM_T	(4 * __SIZEOF_POINTER__)
+
+/* Value returned if `sem_open' failed.  */
+#define SEM_FAILED      ((sem_t *) 0)
+
+
+typedef union
+{
+  char __size[__SIZEOF_SEM_T];
+  long int __align;
+} sem_t;
diff --git a/sysdeps/riscv/nptl/libc-lowlevellock.c b/sysdeps/riscv/nptl/libc-lowlevellock.c
new file mode 100644
index 0000000..9523fb4
--- /dev/null
+++ b/sysdeps/riscv/nptl/libc-lowlevellock.c
@@ -0,0 +1,8 @@
+/* This kludge works around a libpthread static linking problem:
+   https://sourceware.org/bugzilla/show_bug.cgi?id=15648.  */
+
+#ifndef SHARED
+# define __lll_lock_wait_private weak_function __lll_lock_wait_private
+#endif
+
+#include <lowlevellock.c>