RISC-V: Thread-Local Storage Support

This patch implements TLS support for RISC-V.  We support all four
standard TLS addressing modes (LE, IE, LD, and GD) when running on
Linux via NPTL.  There is a draft psABI document that defines our TLS
ABI here

  https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md#thread-local-storage

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

        * sysdeps/riscv/dl-tls.h: New file.
        * sysdeps/riscv/libc-tls.c: Likewise.
        * sysdeps/riscv/nptl/tcb-offsets.sym: Likewise.
        * sysdeps/riscv/nptl/tls.h: Likewise.
        * sysdeps/riscv/stackinfo.h: Likewise.

1 files changed, 32 insertions, 0 deletions

diff --git a/sysdeps/riscv/libc-tls.c b/sysdeps/riscv/libc-tls.c
new file mode 100644
index 0000000000..c72abc1d34
--- /dev/null
+++ b/sysdeps/riscv/libc-tls.c
@@ -0,0 +1,32 @@
+/* Thread-local storage handling in the ELF dynamic linker.  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/>.  */
+
+#include <csu/libc-tls.c>
+#include <dl-tls.h>
+
+/* On RISC-V, linker optimizations are not required, so __tls_get_addr
+   can be called even in statically linked binaries.  In this case module
+   must be always 1 and PT_TLS segment exist in the binary, otherwise it
+   would not link.  */
+
+void *
+__tls_get_addr (tls_index *ti)
+{
+  dtv_t *dtv = THREAD_DTV ();
+  return (char *) dtv[1].pointer.val + GET_ADDR_OFFSET;
+}