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.

5 files changed, 264 insertions, 0 deletions

diff --git a/sysdeps/riscv/dl-tls.h b/sysdeps/riscv/dl-tls.h
new file mode 100644
index 0000000000..ab2d860314
--- /dev/null
+++ b/sysdeps/riscv/dl-tls.h
@@ -0,0 +1,48 @@
+/* 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/>.  */
+
+
+/* Type used for the representation of TLS information in the GOT.  */
+typedef struct
+{
+  unsigned long int ti_module;
+  unsigned long int ti_offset;
+} tls_index;
+
+/* The thread pointer points to the first static TLS block.  */
+#define TLS_TP_OFFSET		0
+
+/* Dynamic thread vector pointers point 0x800 past the start of each
+   TLS block.  */
+#define TLS_DTV_OFFSET		0x800
+
+/* Compute the value for a GOTTPREL reloc.  */
+#define TLS_TPREL_VALUE(sym_map, sym) \
+  ((sym_map)->l_tls_offset + (sym)->st_value - TLS_TP_OFFSET)
+
+/* Compute the value for a DTPREL reloc.  */
+#define TLS_DTPREL_VALUE(sym) \
+  ((sym)->st_value - TLS_DTV_OFFSET)
+
+extern void *__tls_get_addr (tls_index *ti);
+
+#define GET_ADDR_OFFSET	(ti->ti_offset + TLS_DTV_OFFSET)
+#define __TLS_GET_ADDR(__ti)	(__tls_get_addr (__ti) - TLS_DTV_OFFSET)
+
+/* Value used for dtv entries for which the allocation is delayed.  */
+#define TLS_DTV_UNALLOCATED	((void *) -1l)
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;
+}
diff --git a/sysdeps/riscv/nptl/tcb-offsets.sym b/sysdeps/riscv/nptl/tcb-offsets.sym
new file mode 100644
index 0000000000..ab4981f2e2
--- /dev/null
+++ b/sysdeps/riscv/nptl/tcb-offsets.sym
@@ -0,0 +1,6 @@
+#include <sysdep.h>
+#include <tls.h>
+
+#define thread_offsetof(mem)	(long)(offsetof (struct pthread, mem) - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE)
+
+MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
diff --git a/sysdeps/riscv/nptl/tls.h b/sysdeps/riscv/nptl/tls.h
new file mode 100644
index 0000000000..4c92afc58b
--- /dev/null
+++ b/sysdeps/riscv/nptl/tls.h
@@ -0,0 +1,145 @@
+/* Definition for thread-local data handling.  NPTL/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 _RISCV_TLS_H
+#define _RISCV_TLS_H	1
+
+#include <dl-sysdep.h>
+
+#ifndef __ASSEMBLER__
+# include <stdbool.h>
+# include <stddef.h>
+# include <stdint.h>
+# include <dl-dtv.h>
+
+register void *__thread_self asm ("tp");
+# define READ_THREAD_POINTER() ({ __thread_self; })
+
+/* Get system call information.  */
+# include <sysdep.h>
+
+/* The TP points to the start of the thread blocks.  */
+# define TLS_DTV_AT_TP	1
+# define TLS_TCB_AT_TP	0
+
+/* Get the thread descriptor definition.  */
+# include <nptl/descr.h>
+
+typedef struct
+{
+  dtv_t *dtv;
+  void *private;
+} tcbhead_t;
+
+/* This is the size of the initial TCB.  Because our TCB is before the thread
+   pointer, we don't need this.  */
+# define TLS_INIT_TCB_SIZE	0
+
+/* Alignment requirements for the initial TCB.  */
+# define TLS_INIT_TCB_ALIGN	__alignof__ (struct pthread)
+
+/* This is the size of the TCB.  Because our TCB is before the thread
+   pointer, we don't need this.  */
+# define TLS_TCB_SIZE		0
+
+/* Alignment requirements for the TCB.  */
+# define TLS_TCB_ALIGN		__alignof__ (struct pthread)
+
+/* This is the size we need before TCB - actually, it includes the TCB.  */
+# define TLS_PRE_TCB_SIZE \
+  (sizeof (struct pthread)						      \
+   + ((sizeof (tcbhead_t) + TLS_TCB_ALIGN - 1) & ~(TLS_TCB_ALIGN - 1)))
+
+/* The thread pointer tp points to the end of the TCB.
+   The pthread_descr structure is immediately in front of the TCB.  */
+# define TLS_TCB_OFFSET	0
+
+/* Install the dtv pointer.  The pointer passed is to the element with
+   index -1 which contain the length.  */
+# define INSTALL_DTV(tcbp, dtvp) \
+  (((tcbhead_t *) (tcbp))[-1].dtv = (dtvp) + 1)
+
+/* Install new dtv for current thread.  */
+# define INSTALL_NEW_DTV(dtv) \
+  (THREAD_DTV() = (dtv))
+
+/* Return dtv of given thread descriptor.  */
+# define GET_DTV(tcbp) \
+  (((tcbhead_t *) (tcbp))[-1].dtv)
+
+/* Code to initially initialize the thread pointer.  */
+# define TLS_INIT_TP(tcbp) \
+  ({ __thread_self = (char*)tcbp + TLS_TCB_OFFSET; NULL; })
+
+/* Return the address of the dtv for the current thread.  */
+# define THREAD_DTV() \
+  (((tcbhead_t *) (READ_THREAD_POINTER () - TLS_TCB_OFFSET))[-1].dtv)
+
+/* Return the thread descriptor for the current thread.  */
+# define THREAD_SELF \
+ ((struct pthread *) (READ_THREAD_POINTER ()			     \
+		      - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE))
+
+/* Value passed to 'clone' for initialization of the thread register.  */
+# define TLS_DEFINE_INIT_TP(tp, pd) \
+  void *tp = (void *) (pd) + TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE
+
+/* Magic for libthread_db to know how to do THREAD_SELF.  */
+# define DB_THREAD_SELF \
+  CONST_THREAD_AREA (32, TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE)
+
+/* Access to data in the thread descriptor is easy.  */
+# define THREAD_GETMEM(descr, member) \
+  descr->member
+# define THREAD_GETMEM_NC(descr, member, idx) \
+  descr->member[idx]
+# define THREAD_SETMEM(descr, member, value) \
+  descr->member = (value)
+# define THREAD_SETMEM_NC(descr, member, idx, value) \
+  descr->member[idx] = (value)
+
+/* l_tls_offset == 0 is perfectly valid, so we have to use some different
+   value to mean unset l_tls_offset.  */
+# define NO_TLS_OFFSET		-1
+
+/* Get and set the global scope generation counter in struct pthread.  */
+# define THREAD_GSCOPE_FLAG_UNUSED 0
+# define THREAD_GSCOPE_FLAG_USED   1
+# define THREAD_GSCOPE_FLAG_WAIT   2
+# define THREAD_GSCOPE_RESET_FLAG() \
+  do									     \
+    { int __res								     \
+	= atomic_exchange_rel (&THREAD_SELF->header.gscope_flag,	     \
+			       THREAD_GSCOPE_FLAG_UNUSED);		     \
+      if (__res == THREAD_GSCOPE_FLAG_WAIT)				     \
+	lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE);   \
+    }									     \
+  while (0)
+# define THREAD_GSCOPE_SET_FLAG() \
+  do									     \
+    {									     \
+      THREAD_SELF->header.gscope_flag = THREAD_GSCOPE_FLAG_USED;	     \
+      atomic_write_barrier ();						     \
+    }									     \
+  while (0)
+# define THREAD_GSCOPE_WAIT() \
+  GL(dl_wait_lookup_done) ()
+
+#endif /* __ASSEMBLER__ */
+
+#endif	/* tls.h */
diff --git a/sysdeps/riscv/stackinfo.h b/sysdeps/riscv/stackinfo.h
new file mode 100644
index 0000000000..5b4f91c6a1
--- /dev/null
+++ b/sysdeps/riscv/stackinfo.h
@@ -0,0 +1,33 @@
+/* Stack environment definitions for RISC-V.
+   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/>.  */
+
+/* This file contains a bit of information about the stack allocation
+   of the processor.  */
+
+#ifndef _STACKINFO_H
+#define _STACKINFO_H	1
+
+#include <elf.h>
+
+/* On RISC-V the stack grows down.  */
+#define _STACK_GROWS_DOWN	1
+
+/* Default to a non-executable stack.  */
+#define DEFAULT_STACK_PERMS (PF_R | PF_W)
+
+#endif	/* stackinfo.h */