diff mbox series

[v6,03/13] ARC: Thread Local Storage support

Message ID 20200423014126.10417-4-vgupta@synopsys.com
State Superseded
Headers show
Series glibc port to ARC processors | expand

Commit Message

Vineet Gupta April 23, 2020, 1:41 a.m. UTC
This includes all 4 TLS addressing models

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 sysdeps/arc/dl-tls.h             |  30 +++++++
 sysdeps/arc/libc-tls.c           |  27 ++++++
 sysdeps/arc/nptl/tcb-offsets.sym |  11 +++
 sysdeps/arc/nptl/tls.h           | 150 +++++++++++++++++++++++++++++++
 sysdeps/arc/stackinfo.h          |  33 +++++++
 5 files changed, 251 insertions(+)
 create mode 100644 sysdeps/arc/dl-tls.h
 create mode 100644 sysdeps/arc/libc-tls.c
 create mode 100644 sysdeps/arc/nptl/tcb-offsets.sym
 create mode 100644 sysdeps/arc/nptl/tls.h
 create mode 100644 sysdeps/arc/stackinfo.h

Comments

Adhemerval Zanella May 27, 2020, 7:17 p.m. UTC | #1
On 22/04/2020 22:41, Vineet Gupta via Libc-alpha wrote:
> This includes all 4 TLS addressing models
> 
> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

As prior patch we do not use DCO, but rather copyright assignment.

Looks ok in general, with some comments below.

> ---
>  sysdeps/arc/dl-tls.h             |  30 +++++++
>  sysdeps/arc/libc-tls.c           |  27 ++++++
>  sysdeps/arc/nptl/tcb-offsets.sym |  11 +++
>  sysdeps/arc/nptl/tls.h           | 150 +++++++++++++++++++++++++++++++
>  sysdeps/arc/stackinfo.h          |  33 +++++++
>  5 files changed, 251 insertions(+)
>  create mode 100644 sysdeps/arc/dl-tls.h
>  create mode 100644 sysdeps/arc/libc-tls.c
>  create mode 100644 sysdeps/arc/nptl/tcb-offsets.sym
>  create mode 100644 sysdeps/arc/nptl/tls.h
>  create mode 100644 sysdeps/arc/stackinfo.h
> 
> diff --git a/sysdeps/arc/dl-tls.h b/sysdeps/arc/dl-tls.h
> new file mode 100644
> index 000000000000..2269ac6c3daa
> --- /dev/null
> +++ b/sysdeps/arc/dl-tls.h
> @@ -0,0 +1,30 @@
> +/* Thread-local storage handling in the ELF dynamic linker.  ARC version.
> +   Copyright (C) 2012-2020 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
> +   <https://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;
> +
> +extern void *__tls_get_addr (tls_index *ti);
> +
> +/* Value used for dtv entries for which the allocation is delayed.  */
> +#define TLS_DTV_UNALLOCATED	((void *) -1l)

Ok.

> diff --git a/sysdeps/arc/libc-tls.c b/sysdeps/arc/libc-tls.c
> new file mode 100644
> index 000000000000..ec88282de60e
> --- /dev/null
> +++ b/sysdeps/arc/libc-tls.c
> @@ -0,0 +1,27 @@
> +/* Thread-local storage handling in the ELF dynamic linker.  ARC version.
> +   Copyright (C) 2005-2020 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
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <csu/libc-tls.c>
> +#include <dl-tls.h>
> +
> +void *
> +__tls_get_addr (tls_index *ti)
> +{
> +  dtv_t *dtv = THREAD_DTV ();
> +  return (char *) dtv[1].pointer.val + ti->ti_offset;
> +}

Ok.

> diff --git a/sysdeps/arc/nptl/tcb-offsets.sym b/sysdeps/arc/nptl/tcb-offsets.sym
> new file mode 100644
> index 000000000000..64c432c22e76
> --- /dev/null
> +++ b/sysdeps/arc/nptl/tcb-offsets.sym
> @@ -0,0 +1,11 @@
> +#include <sysdep.h>
> +#include <tls.h>
> +
> +-- Derive offsets relative to the thread register.
> +#define thread_offsetof(mem)	(long)(offsetof (struct pthread, mem) - sizeof (struct pthread))
> +
> +MULTIPLE_THREADS_OFFSET		offsetof (struct pthread, header.multiple_threads)
> +TLS_PRE_TCB_SIZE		sizeof (struct pthread)
> +TLS_TCB_SIZE            	sizeof (tcbhead_t)
> +
> +PTHREAD_TID			offsetof (struct pthread, tid)

Ok.

> diff --git a/sysdeps/arc/nptl/tls.h b/sysdeps/arc/nptl/tls.h
> new file mode 100644
> index 000000000000..a836af121a85
> --- /dev/null
> +++ b/sysdeps/arc/nptl/tls.h
> @@ -0,0 +1,150 @@
> +/* Definition for thread-local data handling.  NPTL/ARC version.
> +   Copyright (C) 2012-2020 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
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef _ARC_NPTL_TLS_H
> +#define _ARC_NPTL_TLS_H	1
> +
> +#include <dl-sysdep.h>
> +
> +#ifndef __ASSEMBLER__
> +# include <stdbool.h>
> +# include <stddef.h>
> +# include <stdint.h>
> +
> +#include <dl-dtv.h>
> +
> +/* Get system call information.  */
> +# include <sysdep.h>
> +
> +/* The TLS blocks start right after the TCB.  */
> +# 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;
> +  uintptr_t pointer_guard;
> +} tcbhead_t;
> +
> +register struct pthread *__thread_self __asm__("r25");

This is used on other ports, but I am not sure if this is a valid definition
for a global variable.  Usually the register specifier is used as an input 
for inline assembly.  Do we really need this global on ARC port? Couldn't
we replace it with __builtin_thread_pointer where applicable?

> +
> +/* This is the size of the initial TCB.  */
> +# define TLS_INIT_TCB_SIZE	sizeof (tcbhead_t)
> +
> +/* Alignment requirements for the initial TCB.  */
> +# define TLS_INIT_TCB_ALIGN	__alignof__ (struct pthread)
> +
> +/* This is the size of the TCB.  */
> +#ifndef TLS_TCB_SIZE
> +# define TLS_TCB_SIZE		sizeof (tcbhead_t)
> +#endif
> +
> +/* Alignment requirements for the TCB.  */
> +# define TLS_TCB_ALIGN		__alignof__ (struct pthread)
> +
> +/* This is the size we need before TCB.  */
> +# define TLS_PRE_TCB_SIZE	sizeof (struct pthread)
> +
> +/* 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))->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))->dtv)
> +
> +/* Code to initially initialize the thread pointer.  */
> +# define TLS_INIT_TP(tcbp)					\
> +  ({                                            		\
> +	long result_var;					\
> +	__builtin_set_thread_pointer (tcbp);     		\
> +	result_var = INTERNAL_SYSCALL (arc_settls, 1, (tcbp));	\
> +	INTERNAL_SYSCALL_ERROR_P (result_var)			\
> +	? "settls syscall error" : NULL;			\
> +   })
> +
> +/* Value passed to 'clone' for initialization of the thread register.  */
> +# define TLS_DEFINE_INIT_TP(tp, pd) void *tp = (pd) + 1
> +
> +/* Return the address of the dtv for the current thread.  */
> +# define THREAD_DTV() \
> +  (((tcbhead_t *) __builtin_thread_pointer ())->dtv)
> +
> +/* Return the thread descriptor for the current thread.  */
> +# define THREAD_SELF \
> + ((struct pthread *)__builtin_thread_pointer () - 1)
> +
> +/* Magic for libthread_db to know how to do THREAD_SELF.  */
> +# define DB_THREAD_SELF \
> +  CONST_THREAD_AREA (32, sizeof (struct pthread))
> +
> +/* 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)
> +
> +/* Get and set the global scope generation counter in struct pthread.  */
> +#define THREAD_GSCOPE_IN_TCB      1
> +#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) ()
> +
> +#else
> +
> +# include <tcb-offsets.h>
> +
> +# r25 is dedicated TLS register for ARC
> +.macro THREAD_SELF reg
> +	# struct pthread is just ahead of TCB
> +	sub     \reg, r25, TLS_PRE_TCB_SIZE
> +.endm
> +
> +#endif /* __ASSEMBLER__ */
> +
> +#endif	/* tls.h */

Ok.

> diff --git a/sysdeps/arc/stackinfo.h b/sysdeps/arc/stackinfo.h
> new file mode 100644
> index 000000000000..911efd928675
> --- /dev/null
> +++ b/sysdeps/arc/stackinfo.h
> @@ -0,0 +1,33 @@
> +/* Stack environment definitions for ARC.
> +   Copyright (C) 2012-2020 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
> +   <https://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 ARC 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 */
> 

Ok.
Vineet Gupta May 28, 2020, 1:36 a.m. UTC | #2
On 5/27/20 12:17 PM, Adhemerval Zanella via Libc-alpha wrote:
> 
> 
> On 22/04/2020 22:41, Vineet Gupta via Libc-alpha wrote:
>> This includes all 4 TLS addressing models
>>
>> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
> 
> As prior patch we do not use DCO, but rather copyright assignment.
> 
> Looks ok in general, with some comments below.

>> +
>> +register struct pthread *__thread_self __asm__("r25");
> 
> This is used on other ports, but I am not sure if this is a valid definition
> for a global variable. 

Not valid from gcc implementation POV ? The syntax seems to work alright in ARC
linux kernel where we use r25 to cache the current task pointer.

> Usually the register specifier is used as an input 
> for inline assembly.  Do we really need this global on ARC port? Couldn't
> we replace it with __builtin_thread_pointer where applicable?

We do use __builtin_thread_pointer and actually __thread_self is not used in ARC
port :-) so I can just drop it

Many thx for reviewing.
-Vineet
Adhemerval Zanella June 1, 2020, 6:53 p.m. UTC | #3
On 27/05/2020 22:36, Vineet Gupta wrote:
> On 5/27/20 12:17 PM, Adhemerval Zanella via Libc-alpha wrote:
>>
>>
>> On 22/04/2020 22:41, Vineet Gupta via Libc-alpha wrote:
>>> This includes all 4 TLS addressing models
>>>
>>> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
>>
>> As prior patch we do not use DCO, but rather copyright assignment.
>>
>> Looks ok in general, with some comments below.
> 
>>> +
>>> +register struct pthread *__thread_self __asm__("r25");
>>
>> This is used on other ports, but I am not sure if this is a valid definition
>> for a global variable. 
> 
> Not valid from gcc implementation POV ? The syntax seems to work alright in ARC
> linux kernel where we use r25 to cache the current task pointer.

The gcc documentation [1] does specify register global variables, but it
also states that 

"[...] it is recommended that you choose a register that is normally saved and 
restored by function calls on your machine, so that calls to library routines
will not clobber it."

So I see that the semantic of global register is kind fragile and since
it is usage is solely for asm inline argument I don't see a very compelling
reason to keep using it.

[1] https://gcc.gnu.org/onlinedocs/gcc/Local-Register-Variables.html

> 
>> Usually the register specifier is used as an input 
>> for inline assembly.  Do we really need this global on ARC port? Couldn't
>> we replace it with __builtin_thread_pointer where applicable?
> 
> We do use __builtin_thread_pointer and actually __thread_self is not used in ARC
> port :-) so I can just drop it

Ack.

> 
> Many thx for reviewing.
> -Vineet
>
diff mbox series

Patch

diff --git a/sysdeps/arc/dl-tls.h b/sysdeps/arc/dl-tls.h
new file mode 100644
index 000000000000..2269ac6c3daa
--- /dev/null
+++ b/sysdeps/arc/dl-tls.h
@@ -0,0 +1,30 @@ 
+/* Thread-local storage handling in the ELF dynamic linker.  ARC version.
+   Copyright (C) 2012-2020 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
+   <https://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;
+
+extern void *__tls_get_addr (tls_index *ti);
+
+/* Value used for dtv entries for which the allocation is delayed.  */
+#define TLS_DTV_UNALLOCATED	((void *) -1l)
diff --git a/sysdeps/arc/libc-tls.c b/sysdeps/arc/libc-tls.c
new file mode 100644
index 000000000000..ec88282de60e
--- /dev/null
+++ b/sysdeps/arc/libc-tls.c
@@ -0,0 +1,27 @@ 
+/* Thread-local storage handling in the ELF dynamic linker.  ARC version.
+   Copyright (C) 2005-2020 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <csu/libc-tls.c>
+#include <dl-tls.h>
+
+void *
+__tls_get_addr (tls_index *ti)
+{
+  dtv_t *dtv = THREAD_DTV ();
+  return (char *) dtv[1].pointer.val + ti->ti_offset;
+}
diff --git a/sysdeps/arc/nptl/tcb-offsets.sym b/sysdeps/arc/nptl/tcb-offsets.sym
new file mode 100644
index 000000000000..64c432c22e76
--- /dev/null
+++ b/sysdeps/arc/nptl/tcb-offsets.sym
@@ -0,0 +1,11 @@ 
+#include <sysdep.h>
+#include <tls.h>
+
+-- Derive offsets relative to the thread register.
+#define thread_offsetof(mem)	(long)(offsetof (struct pthread, mem) - sizeof (struct pthread))
+
+MULTIPLE_THREADS_OFFSET		offsetof (struct pthread, header.multiple_threads)
+TLS_PRE_TCB_SIZE		sizeof (struct pthread)
+TLS_TCB_SIZE            	sizeof (tcbhead_t)
+
+PTHREAD_TID			offsetof (struct pthread, tid)
diff --git a/sysdeps/arc/nptl/tls.h b/sysdeps/arc/nptl/tls.h
new file mode 100644
index 000000000000..a836af121a85
--- /dev/null
+++ b/sysdeps/arc/nptl/tls.h
@@ -0,0 +1,150 @@ 
+/* Definition for thread-local data handling.  NPTL/ARC version.
+   Copyright (C) 2012-2020 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
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _ARC_NPTL_TLS_H
+#define _ARC_NPTL_TLS_H	1
+
+#include <dl-sysdep.h>
+
+#ifndef __ASSEMBLER__
+# include <stdbool.h>
+# include <stddef.h>
+# include <stdint.h>
+
+#include <dl-dtv.h>
+
+/* Get system call information.  */
+# include <sysdep.h>
+
+/* The TLS blocks start right after the TCB.  */
+# 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;
+  uintptr_t pointer_guard;
+} tcbhead_t;
+
+register struct pthread *__thread_self __asm__("r25");
+
+/* This is the size of the initial TCB.  */
+# define TLS_INIT_TCB_SIZE	sizeof (tcbhead_t)
+
+/* Alignment requirements for the initial TCB.  */
+# define TLS_INIT_TCB_ALIGN	__alignof__ (struct pthread)
+
+/* This is the size of the TCB.  */
+#ifndef TLS_TCB_SIZE
+# define TLS_TCB_SIZE		sizeof (tcbhead_t)
+#endif
+
+/* Alignment requirements for the TCB.  */
+# define TLS_TCB_ALIGN		__alignof__ (struct pthread)
+
+/* This is the size we need before TCB.  */
+# define TLS_PRE_TCB_SIZE	sizeof (struct pthread)
+
+/* 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))->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))->dtv)
+
+/* Code to initially initialize the thread pointer.  */
+# define TLS_INIT_TP(tcbp)					\
+  ({                                            		\
+	long result_var;					\
+	__builtin_set_thread_pointer (tcbp);     		\
+	result_var = INTERNAL_SYSCALL (arc_settls, 1, (tcbp));	\
+	INTERNAL_SYSCALL_ERROR_P (result_var)			\
+	? "settls syscall error" : NULL;			\
+   })
+
+/* Value passed to 'clone' for initialization of the thread register.  */
+# define TLS_DEFINE_INIT_TP(tp, pd) void *tp = (pd) + 1
+
+/* Return the address of the dtv for the current thread.  */
+# define THREAD_DTV() \
+  (((tcbhead_t *) __builtin_thread_pointer ())->dtv)
+
+/* Return the thread descriptor for the current thread.  */
+# define THREAD_SELF \
+ ((struct pthread *)__builtin_thread_pointer () - 1)
+
+/* Magic for libthread_db to know how to do THREAD_SELF.  */
+# define DB_THREAD_SELF \
+  CONST_THREAD_AREA (32, sizeof (struct pthread))
+
+/* 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)
+
+/* Get and set the global scope generation counter in struct pthread.  */
+#define THREAD_GSCOPE_IN_TCB      1
+#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) ()
+
+#else
+
+# include <tcb-offsets.h>
+
+# r25 is dedicated TLS register for ARC
+.macro THREAD_SELF reg
+	# struct pthread is just ahead of TCB
+	sub     \reg, r25, TLS_PRE_TCB_SIZE
+.endm
+
+#endif /* __ASSEMBLER__ */
+
+#endif	/* tls.h */
diff --git a/sysdeps/arc/stackinfo.h b/sysdeps/arc/stackinfo.h
new file mode 100644
index 000000000000..911efd928675
--- /dev/null
+++ b/sysdeps/arc/stackinfo.h
@@ -0,0 +1,33 @@ 
+/* Stack environment definitions for ARC.
+   Copyright (C) 2012-2020 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
+   <https://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 ARC 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 */