Add <machine/tls.h> header to hold MD constants and helpers for TLS.

The header exports the following:

- Definition of struct tcb.
- Helpers to get/set the tcb for the current thread.
- TLS_TCB_SIZE (size of TCB)
- TLS_TCB_ALIGN (alignment of TCB)
- TLS_VARIANT_I or TLS_VARIANT_II
- TLS_DTV_OFFSET (bias of pointers in dtv[])
- TLS_TP_OFFSET (bias of "thread pointer" relative to TCB)

Note that TLS_TP_OFFSET does not account for if the unbiased thread
pointer points to the start of the TCB (arm and x86) or the end of the
TCB (MIPS, PowerPC, and RISC-V).

Note also that for amd64, the struct tcb does not include the unused
tcb_spare field included in the current structure in libthr.  libthr
does not use this field, and the existing calls in libc and rtld that
allocate a TCB for amd64 assume it is the size of 3 Elf_Addr's (and
thus do not allocate room for tcb_spare).

A <sys/_tls_variant_i.h> header is used by architectures using
Variant I TLS which uses a common struct tcb.

Reviewed by:	kib (older version of x86/tls.h), jrtc27
Sponsored by:	The University of Cambridge, Google Inc.
Differential Revision:	https://reviews.freebsd.org/D33351

1 files changed, 60 insertions, 0 deletions

diff --git a/sys/riscv/include/tls.h b/sys/riscv/include/tls.h
new file mode 100644
index 000000000000..4dd1fa8415ef
--- /dev/null
+++ b/sys/riscv/include/tls.h
@@ -0,0 +1,60 @@
+/*-
+ * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
+ * Copyright (c) 2015 Ruslan Bukin <br@bsdpad.com>
+ * All rights reserved.
+ *
+ * Portions of this software were developed by SRI International and the
+ * University of Cambridge Computer Laboratory under DARPA/AFRL contract
+ * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
+ *
+ * Portions of this software were developed by the University of Cambridge
+ * Computer Laboratory as part of the CTSRD Project, with support from the
+ * UK Higher Education Innovation Fund (HEIF).
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _MACHINE_TLS_H_
+#define	_MACHINE_TLS_H_
+
+#include <sys/_tls_variant_i.h>
+
+#define	TLS_DTV_OFFSET	0x800
+#define	TLS_TCB_ALIGN	16
+#define	TLS_TP_OFFSET	0
+
+static __inline void
+_tcb_set(struct tcb *tcb)
+{
+	__asm __volatile("addi tp, %0, %1" :: "r" (tcb), "I" (TLS_TCB_SIZE));
+}
+
+static __inline struct tcb *
+_tcb_get(void)
+{
+	struct tcb *tcb;
+
+	__asm __volatile("addi %0, tp, %1" : "=r" (tcb) : "I" (-TLS_TCB_SIZE));
+	return (tcb);
+}
+
+#endif /* !_MACHINE_TLS_H_ */