ARC: Linux ABI

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

13 files changed, 600 insertions, 0 deletions

diff --git a/sysdeps/arc/nptl/pthreaddef.h b/sysdeps/arc/nptl/pthreaddef.h
new file mode 100644
index 0000000000..5c2b752bec
--- /dev/null
+++ b/sysdeps/arc/nptl/pthreaddef.h
@@ -0,0 +1,32 @@
+/* pthread machine parameter definitions, ARC version.
+   Copyright (C) 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/>.  */
+
+/* Default stack size.  */
+#define ARCH_STACK_DEFAULT_SIZE	(2 * 1024 * 1024)
+
+/* Required stack pointer alignment at beginning.  */
+#define STACK_ALIGN		4
+
+/* Minimal stack size after allocating thread descriptor and guard size.  */
+#define MINIMAL_REST_STACK	2048
+
+/* Alignment requirement for TCB.  */
+#define TCB_ALIGNMENT		4
+
+/* Location of current stack frame.  */
+#define CURRENT_STACK_FRAME	__builtin_frame_address (0)
diff --git a/sysdeps/unix/sysv/linux/arc/bits/procfs.h b/sysdeps/unix/sysv/linux/arc/bits/procfs.h
new file mode 100644
index 0000000000..9fabca2c47
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/bits/procfs.h
@@ -0,0 +1,35 @@
+/* Types for registers for sys/procfs.h.  ARC version.
+   Copyright (C) 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 _SYS_PROCFS_H
+# error "Never include <bits/procfs.h> directly; use <sys/procfs.h> instead."
+#endif
+
+#include <sys/ucontext.h>
+
+/* And the whole bunch of them.  We could have used `struct
+   user_regs' directly in the typedef, but tradition says that
+   the register set is an array, which does have some peculiar
+   semantics, so leave it that way.  */
+#define ELF_NGREG (sizeof (struct user_regs_struct) / sizeof (elf_greg_t))
+
+typedef unsigned long int elf_greg_t;
+typedef unsigned long int elf_gregset_t[ELF_NGREG];
+
+/* There's no seperate floating point reg file in ARCv2.  */
+typedef struct { } elf_fpregset_t;
diff --git a/sysdeps/unix/sysv/linux/arc/bits/types/__sigset_t.h b/sysdeps/unix/sysv/linux/arc/bits/types/__sigset_t.h
new file mode 100644
index 0000000000..795638a30b
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/bits/types/__sigset_t.h
@@ -0,0 +1,12 @@
+/* Architecture-specific __sigset_t definition.  ARC version.  */
+#ifndef ____sigset_t_defined
+#define ____sigset_t_defined
+
+/* Linux asm-generic syscall ABI expects sigset_t to hold 64 signals.  */
+#define _SIGSET_NWORDS (64 / (8 * sizeof (unsigned long int)))
+typedef struct
+{
+  unsigned long int __val[_SIGSET_NWORDS];
+} __sigset_t;
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/arc/getcontext.S b/sysdeps/unix/sysv/linux/arc/getcontext.S
new file mode 100644
index 0000000000..486cc622ef
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/getcontext.S
@@ -0,0 +1,64 @@
+/* Save current context for ARC.
+   Copyright (C) 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 "ucontext-macros.h"
+
+/* int getcontext (ucontext_t *ucp)
+   Save machine context in @ucp and return 0 on success, -1 on error
+    - saves callee saved registers only
+    - layout mandated by uncontext_t:uc_mcontext (hence different from setjmp).  */
+
+ENTRY (__getcontext)
+
+	/* Callee saved registers.  */
+	add r2, r0, UCONTEXT_MCONTEXT
+	STR (r13,   r2, 37)
+	STR (r14,   r2, 36)
+	STR (r15,   r2, 35)
+	STR (r16,   r2, 34)
+	STR (r17,   r2, 33)
+	STR (r18,   r2, 32)
+	STR (r19,   r2, 31)
+	STR (r20,   r2, 30)
+	STR (r21,   r2, 29)
+	STR (r22,   r2, 28)
+	STR (r23,   r2, 27)
+	STR (r24,   r2, 26)
+
+	STR (blink, r2,  7)
+	STR (fp,    r2,  8)
+	STR (gp,    r2,  9)
+	STR (sp,    r2, 23)
+
+	/* Save 0 in r0 placeholder to return 0 when this @ucp activated.  */
+	mov r9, 0
+	STR (r9,    r2, 22)
+
+	/* rt_sigprocmask (SIG_BLOCK, NULL, &ucp->uc_sigmask, _NSIG8).  */
+	mov r3, _NSIG8
+	add r2, r0, UCONTEXT_SIGMASK
+	mov r1, 0
+	mov r0, SIG_BLOCK
+	mov r8, __NR_rt_sigprocmask
+	ARC_TRAP_INSN
+	brhi    r0, -1024, L (call_syscall_err)
+	j.d	[blink]
+	mov r0, 0	/* Success, error handled in .Lcall_syscall_err.  */
+
+PSEUDO_END (__getcontext)
+weak_alias (__getcontext, getcontext)
diff --git a/sysdeps/unix/sysv/linux/arc/makecontext.c b/sysdeps/unix/sysv/linux/arc/makecontext.c
new file mode 100644
index 0000000000..5ded1ad3e2
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/makecontext.c
@@ -0,0 +1,73 @@
+/* Create new context for ARC.
+   Copyright (C) 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 <sysdep.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <sys/ucontext.h>
+
+void
+__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
+{
+  extern void __startcontext (void) attribute_hidden;
+  unsigned long int sp, *r;
+  va_list vl;
+  int i, reg_args, stack_args;
+
+  sp = ((unsigned long int) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) & ~7;
+
+  ucp->uc_mcontext.__sp = sp;
+  ucp->uc_mcontext.__fp = 0;
+
+  /* __startcontext is sort of trampoline to invoke @func
+     From setcontext pov, the resume address is __startcontext,
+     set it up in BLINK place holder.  */
+
+  ucp->uc_mcontext.__blink = (unsigned long int) &__startcontext;
+
+  /* __startcontext passed 2 types of args
+       - args to @func setup in canonical r0-r7
+       - @func and next function in r14,r15.   */
+
+  ucp->uc_mcontext.__r14 = (unsigned long int) func;
+  ucp->uc_mcontext.__r15 = (unsigned long int) ucp->uc_link;
+
+  r = &ucp->uc_mcontext.__r0;
+
+  va_start (vl, argc);
+
+  reg_args = argc > 8 ? 8 : argc;
+  for (i = 0; i < reg_args; i++)
+    *r-- = va_arg (vl, unsigned long int);
+
+  stack_args = argc - reg_args;
+
+  if (__glibc_unlikely (stack_args > 0))
+    {
+      sp -= stack_args * sizeof (unsigned long int);
+      ucp->uc_mcontext.__sp = sp;
+      r = (unsigned long int *) sp;
+
+      for (i = 0; i < stack_args; i++)
+        *r++ = va_arg (vl, unsigned long int);
+    }
+
+  va_end (vl);
+}
+
+weak_alias (__makecontext, makecontext)
diff --git a/sysdeps/unix/sysv/linux/arc/setcontext.S b/sysdeps/unix/sysv/linux/arc/setcontext.S
new file mode 100644
index 0000000000..56a362f837
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/setcontext.S
@@ -0,0 +1,93 @@
+/* Set current context for ARC.
+   Copyright (C) 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 "ucontext-macros.h"
+
+/* int setcontext (const ucontext_t *ucp)
+     - Restores the machine context in @ucp and resumes execution
+       (doesn't return to caller).  */
+
+ENTRY (__setcontext)
+
+	mov  r9, r0	/* Stash @ucp across syscall.  */
+
+	/* rt_sigprocmask (SIG_SETMASK, &ucp->uc_sigmask, NULL, _NSIG8).  */
+	mov  r3, _NSIG8
+	mov  r2, 0
+	add  r1, r0, UCONTEXT_SIGMASK
+	mov  r0, SIG_SETMASK
+	mov  r8, __NR_rt_sigprocmask
+	ARC_TRAP_INSN
+	brhi r0, -1024, L (call_syscall_err)
+
+	/* Restore scratch/arg regs for makecontext case.  */
+	add r9, r9, UCONTEXT_MCONTEXT
+	LDR (r0,    r9, 22)
+	LDR (r1,    r9, 21)
+	LDR (r2,    r9, 20)
+	LDR (r3,    r9, 19)
+	LDR (r4,    r9, 18)
+	LDR (r5,    r9, 17)
+	LDR (r6,    r9, 16)
+	LDR (r7,    r9, 15)
+
+	/* Restore callee saved registers.  */
+	LDR (r13,   r9, 37)
+	LDR (r14,   r9, 36)
+	LDR (r15,   r9, 35)
+	LDR (r16,   r9, 34)
+	LDR (r17,   r9, 33)
+	LDR (r18,   r9, 32)
+	LDR (r19,   r9, 31)
+	LDR (r20,   r9, 30)
+	LDR (r21,   r9, 29)
+	LDR (r22,   r9, 28)
+	LDR (r23,   r9, 27)
+	LDR (r24,   r9, 26)
+
+	LDR (blink, r9,  7)
+	LDR (fp,    r9,  8)
+	LDR (gp,    r9,  9)
+	LDR (sp,    r9, 23)
+
+	j    [blink]
+
+PSEUDO_END (__setcontext)
+weak_alias (__setcontext, setcontext)
+
+
+/* Helper for activating makecontext created context
+     - r14 has @func, r15 has uc_link.  */
+
+ENTRY (__startcontext)
+
+	.cfi_label .Ldummy
+	cfi_undefined (blink)
+
+	/* Call user @func, loaded in r14 by setcontext.  */
+	jl   [r14]
+
+	/* If uc_link (r15) call setcontext with that.  */
+	mov  r0, r15
+	breq r0, 0, 1f
+
+	bl   __setcontext
+1:
+	/* Exit with status 0.  */
+	b    HIDDEN_JUMPTARGET(exit)
+END (__startcontext)
diff --git a/sysdeps/unix/sysv/linux/arc/sigcontextinfo.h b/sysdeps/unix/sysv/linux/arc/sigcontextinfo.h
new file mode 100644
index 0000000000..c674da7b8f
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/sigcontextinfo.h
@@ -0,0 +1,28 @@
+/* ARC definitions for signal handling calling conventions.
+   Copyright (C) 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 _SIGCONTEXTINFO_H
+#define _SIGCONTEXTINFO_H
+
+static inline uintptr_t
+sigcontext_get_pc (const ucontext_t *ctx)
+{
+  return ctx->uc_mcontext.__ret;
+}
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/arc/swapcontext.S b/sysdeps/unix/sysv/linux/arc/swapcontext.S
new file mode 100644
index 0000000000..3da072da3d
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/swapcontext.S
@@ -0,0 +1,94 @@
+/* Save and set current context for ARC.
+   Copyright (C) 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 "ucontext-macros.h"
+
+/* int swapcontext (ucontext_t *oucp, const ucontext_t *ucp).  */
+
+ENTRY (__swapcontext)
+
+	/* Save context into @oucp pointed to by r0.  */
+
+	add r2, r0, UCONTEXT_MCONTEXT
+	STR (r13,   r2, 37)
+	STR (r14,   r2, 36)
+	STR (r15,   r2, 35)
+	STR (r16,   r2, 34)
+	STR (r17,   r2, 33)
+	STR (r18,   r2, 32)
+	STR (r19,   r2, 31)
+	STR (r20,   r2, 30)
+	STR (r21,   r2, 29)
+	STR (r22,   r2, 28)
+	STR (r23,   r2, 27)
+	STR (r24,   r2, 26)
+
+	STR (blink, r2,  7)
+	STR (fp,    r2,  8)
+	STR (gp,    r2,  9)
+	STR (sp,    r2, 23)
+
+	/* Save 0 in r0 placeholder to return 0 when @oucp activated.  */
+	mov r9, 0
+	STR (r9,    r2, 22)
+
+	/* Load context from @ucp.  */
+
+	mov r9, r1	/* Safekeep @ucp across syscall.  */
+
+	/* rt_sigprocmask (SIG_SETMASK, &ucp->uc_sigmask, &oucp->uc_sigmask, _NSIG8) */
+	mov r3, _NSIG8
+	add r2, r0, UCONTEXT_SIGMASK
+	add r1, r1, UCONTEXT_SIGMASK
+	mov r0, SIG_SETMASK
+	mov r8, __NR_rt_sigprocmask
+	ARC_TRAP_INSN
+	brhi r0, -1024, L (call_syscall_err)
+
+	add r9, r9, UCONTEXT_MCONTEXT
+	LDR (r0,    r9, 22)
+	LDR (r1,    r9, 21)
+	LDR (r2,    r9, 20)
+	LDR (r3,    r9, 19)
+	LDR (r4,    r9, 18)
+	LDR (r5,    r9, 17)
+	LDR (r6,    r9, 16)
+	LDR (r7,    r9, 15)
+
+	LDR (r13,   r9, 37)
+	LDR (r14,   r9, 36)
+	LDR (r15,   r9, 35)
+	LDR (r16,   r9, 34)
+	LDR (r17,   r9, 33)
+	LDR (r18,   r9, 32)
+	LDR (r19,   r9, 31)
+	LDR (r20,   r9, 30)
+	LDR (r21,   r9, 29)
+	LDR (r22,   r9, 28)
+	LDR (r23,   r9, 27)
+	LDR (r24,   r9, 26)
+
+	LDR (blink, r9,  7)
+	LDR (fp,    r9,  8)
+	LDR (gp,    r9,  9)
+	LDR (sp,    r9, 23)
+
+	j    [blink]
+
+PSEUDO_END (__swapcontext)
+weak_alias (__swapcontext, swapcontext)
diff --git a/sysdeps/unix/sysv/linux/arc/sys/cachectl.h b/sysdeps/unix/sysv/linux/arc/sys/cachectl.h
new file mode 100644
index 0000000000..dbed8d3af6
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/sys/cachectl.h
@@ -0,0 +1,35 @@
+/* cacheflush - flush contents of instruction and/or data cache.
+   Copyright (C) 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 _SYS_CACHECTL_H
+#define _SYS_CACHECTL_H 1
+
+#include <features.h>
+
+/* Get the kernel definition for the op bits.  */
+#include <asm/cachectl.h>
+
+__BEGIN_DECLS
+
+#ifdef __USE_MISC
+extern int cacheflush (void *__addr, int __nbytes, int __op) __THROW;
+#endif
+
+__END_DECLS
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/arc/sys/ucontext.h b/sysdeps/unix/sysv/linux/arc/sys/ucontext.h
new file mode 100644
index 0000000000..ca24e7ae85
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/sys/ucontext.h
@@ -0,0 +1,57 @@
+/* struct ucontext definition, ARC version.
+   Copyright (C) 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/>.  */
+
+/* System V/ARC ABI compliant context switching support.  */
+
+#ifndef _SYS_UCONTEXT_H
+#define _SYS_UCONTEXT_H	1
+
+#include <features.h>
+
+#include <bits/types/sigset_t.h>
+#include <bits/types/stack_t.h>
+
+typedef struct
+{
+  unsigned long int __pad;
+  unsigned long int __bta;
+  unsigned long int __lp_start, __lp_end, __lp_count;
+  unsigned long int __status32, __ret, __blink;
+  unsigned long int __fp, __gp;
+  unsigned long int __r12, __r11, __r10, __r9, __r8, __r7;
+  unsigned long int __r6, __r5, __r4, __r3, __r2, __r1, __r0;
+  unsigned long int __sp;
+  unsigned long int __r26;
+  unsigned long int __r25, __r24, __r23, __r22, __r21, __r20;
+  unsigned long int __r19, __r18, __r17, __r16, __r15, __r14, __r13;
+  unsigned long int __efa;
+  unsigned long int __stop_pc;
+  unsigned long int __r30, __r58, __r59;
+} mcontext_t;
+
+/* Userlevel context.  */
+typedef struct ucontext_t
+{
+  unsigned long int __uc_flags;
+  struct ucontext_t *uc_link;
+  stack_t uc_stack;
+  mcontext_t uc_mcontext;
+  sigset_t uc_sigmask;
+} ucontext_t;
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/arc/sys/user.h b/sysdeps/unix/sysv/linux/arc/sys/user.h
new file mode 100644
index 0000000000..2ad9f89e25
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/sys/user.h
@@ -0,0 +1,32 @@
+/* ptrace register data format definitions.
+   Copyright (C) 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 _SYS_USER_H
+#define _SYS_USER_H	1
+
+/* Struct user_regs_struct is exported by kernel header
+   However apps like strace also expect a struct user, so it's better to
+   have a dummy implementation.  */
+#include <asm/ptrace.h>
+
+struct user
+{
+  long int dummy;
+};
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/arc/ucontext-macros.h b/sysdeps/unix/sysv/linux/arc/ucontext-macros.h
new file mode 100644
index 0000000000..891a5e71f2
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/ucontext-macros.h
@@ -0,0 +1,25 @@
+/* Macros for ucontext routines, ARC version.
+   Copyright (C) 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 _LINUX_ARC_UCONTEXT_MACROS_H
+#define _LINUX_ARC_UCONTEXT_MACROS_H
+
+#include <sysdep.h>
+#include "ucontext_i.h"
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/arc/ucontext_i.sym b/sysdeps/unix/sysv/linux/arc/ucontext_i.sym
new file mode 100644
index 0000000000..d84e92f9f5
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/ucontext_i.sym
@@ -0,0 +1,20 @@
+#include <inttypes.h>
+#include <signal.h>
+#include <stddef.h>
+#include <sys/ucontext.h>
+
+SIG_BLOCK
+SIG_SETMASK
+
+-- sizeof(sigset_t) expected by kernel: see comment in ARC sigaction.c for details
+_NSIG8				(_NSIG / 8)
+
+-- Offsets of the fields in the ucontext_t structure.
+#define ucontext(member)	offsetof (ucontext_t, member)
+
+UCONTEXT_FLAGS			ucontext (__uc_flags)
+UCONTEXT_LINK			ucontext (uc_link)
+UCONTEXT_STACK			ucontext (uc_stack)
+UCONTEXT_MCONTEXT		ucontext (uc_mcontext)
+UCONTEXT_SIGMASK		ucontext (uc_sigmask)
+UCONTEXT_SIZE			sizeof (ucontext_t)