Re: [PATCH v3 09/13] or1k: Linux ABI

[Stafford Horne <shorne@gmail.com>]

On Tue, Dec 21, 2021 at 11:54:46PM +0900, Stafford Horne wrote:
> On Tue, Dec 21, 2021 at 10:41:17AM -0300, Adhemerval Zanella wrote:
> > Some comments below.
> > 
> > On 10/12/2021 20:34, Stafford Horne via Libc-alpha wrote:
> > > ---
> > >  sysdeps/or1k/nptl/bits/pthreadtypes-arch.h    |  48 ++++++++
> > >  sysdeps/or1k/nptl/pthreaddef.h                |  36 ++++++
> > >  sysdeps/unix/sysv/linux/or1k/bits/procfs.h    |  38 ++++++
> > >  sysdeps/unix/sysv/linux/or1k/getcontext.S     |  72 +++++++++++
> > >  sysdeps/unix/sysv/linux/or1k/makecontext.c    |  77 ++++++++++++
> > >  sysdeps/unix/sysv/linux/or1k/setcontext.S     | 108 ++++++++++++++++
> > >  sysdeps/unix/sysv/linux/or1k/sigcontextinfo.h |  28 +++++
> > >  sysdeps/unix/sysv/linux/or1k/swapcontext.S    | 116 ++++++++++++++++++
> > >  sysdeps/unix/sysv/linux/or1k/sys/ucontext.h   |  53 ++++++++
> > >  sysdeps/unix/sysv/linux/or1k/sys/user.h       |   1 +
> > >  sysdeps/unix/sysv/linux/or1k/ucontext_i.sym   |  26 ++++
> > >  11 files changed, 603 insertions(+)
> > >  create mode 100644 sysdeps/or1k/nptl/bits/pthreadtypes-arch.h
> > >  create mode 100644 sysdeps/or1k/nptl/pthreaddef.h
> > >  create mode 100644 sysdeps/unix/sysv/linux/or1k/bits/procfs.h
> > >  create mode 100644 sysdeps/unix/sysv/linux/or1k/getcontext.S
> > >  create mode 100644 sysdeps/unix/sysv/linux/or1k/makecontext.c
> > >  create mode 100644 sysdeps/unix/sysv/linux/or1k/setcontext.S
> > >  create mode 100644 sysdeps/unix/sysv/linux/or1k/sigcontextinfo.h
> > >  create mode 100644 sysdeps/unix/sysv/linux/or1k/swapcontext.S
> > >  create mode 100644 sysdeps/unix/sysv/linux/or1k/sys/ucontext.h
> > >  create mode 100644 sysdeps/unix/sysv/linux/or1k/sys/user.h
> > >  create mode 100644 sysdeps/unix/sysv/linux/or1k/ucontext_i.sym
> > > 
> > > diff --git a/sysdeps/or1k/nptl/bits/pthreadtypes-arch.h b/sysdeps/or1k/nptl/bits/pthreadtypes-arch.h
> > > new file mode 100644
> > > index 0000000000..56a62a7161
> > > --- /dev/null
> > > +++ b/sysdeps/or1k/nptl/bits/pthreadtypes-arch.h
> > > @@ -0,0 +1,48 @@
> > > +/* Machine-specific pthread type layouts.  OpenRISC version.
> > > +   Copyright (C) 2021 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 _BITS_PTHREADTYPES_H
> > > +#define _BITS_PTHREADTYPES_H	1
> > > +
> > > +#include <bits/wordsize.h>
> > > +
> > > +/* Opaque union sizes for:
> > > +     pthread_attr_t - internally pthread_attr
> > > +     pthread_mutex_t - internally __pthread_mutex_s
> > > +     pthread_mutexattr_t - internally pthread_mutexattr
> > > +     pthread_cond_t - internally __pthread_cond_s
> > > +     pthread_condattr_t - internally pthread_condattr
> > > +     pthread_rwlock_t - internally __pthread_rwlock_arch_t
> > > +     pthread_rwlockattr_t - internally pthread_rwlockattr
> > > +     pthread_barrier_t - internally pthread_barrier
> > > +     pthread_barrierattr_t - internally pthread_barrierattr  */
> > > +
> > > +#define __SIZEOF_PTHREAD_ATTR_T 32
> > > +#define __SIZEOF_PTHREAD_MUTEX_T 32
> > > +#define __SIZEOF_PTHREAD_MUTEXATTR_T 4
> > > +#define __SIZEOF_PTHREAD_COND_T 48
> > > +#define __SIZEOF_PTHREAD_CONDATTR_T 4
> > > +#define __SIZEOF_PTHREAD_RWLOCK_T 44
> > > +#define __SIZEOF_PTHREAD_RWLOCKATTR_T 8
> > > +#define __SIZEOF_PTHREAD_BARRIER_T 20
> > > +#define __SIZEOF_PTHREAD_BARRIERATTR_T 4
> > > +
> > > +#define __LOCK_ALIGNMENT
> > > +#define __ONCE_ALIGNMENT
> > > +
> > > +#endif	/* bits/pthreadtypes.h */
> > 
> > Why can't use the default values on sysdeps/nptl/bits/pthreadtypes-arch.h ?
> 
> I think it can, let me test.
> 
> > > diff --git a/sysdeps/or1k/nptl/pthreaddef.h b/sysdeps/or1k/nptl/pthreaddef.h
> > > new file mode 100644
> > > index 0000000000..d17918ea11
> > > --- /dev/null
> > > +++ b/sysdeps/or1k/nptl/pthreaddef.h
> > > @@ -0,0 +1,36 @@
> > > +/* pthread machine parameter definitions.  OpenRISC version.
> > > +   Copyright (C) 2021 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)
> > > +
> > > +/* Minimum guard size.  */
> > > +#define ARCH_MIN_GUARD_SIZE 0
> > > +
> > > +/* Required stack pointer alignment at beginning.  */
> > > +#define STACK_ALIGN 16
> > > +
> > > +/* Minimal stack size after allocating thread descriptor and guard size.  */
> > > +#define MINIMAL_REST_STACK 2048
> > > +
> > > +/* Alignment requirement for TCB.  Needs to be >= to STACK_ALIGN.  */
> > > +#define TCB_ALIGNMENT 32
> > > +
> > > +/* Location of current stack frame.  */
> > > +#define CURRENT_STACK_FRAME __builtin_frame_address (0)
> > 
> > Ok.  As a side note, maybe we could provide a default header with this exact
> > definitions. 
> > 
> > > diff --git a/sysdeps/unix/sysv/linux/or1k/bits/procfs.h b/sysdeps/unix/sysv/linux/or1k/bits/procfs.h
> > > new file mode 100644
> > > index 0000000000..b50c92efb1
> > > --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/or1k/bits/procfs.h
> > > @@ -0,0 +1,38 @@
> > > +/* Types for registers for sys/procfs.h.  OpenRISC version.
> > > +   Copyright (C) 2021 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>
> > > +
> > > +#define ELF_NGREG __NGREG
> > > +
> > > +/* Type for a general-purpose register.  */
> > > +typedef unsigned long int elf_greg_t;
> > > +
> > > +/* And the array of general-purpose registers.  We could have used `struct
> > > +   user_regs' directly, but tradition says that the register set is an array,
> > > +   which does have some peculiar semantics, so leave it that way.
> > > +   GDB uses this for prtrace GETREGSET, on OpenRISC the regset contains 32
> > > +   gprs the PC and the SR, 34 longs.  */
> > > +typedef elf_greg_t elf_gregset_t[34];
> > > +
> > > +/* Register set for the floating-point registers.  */
> > > +typedef elf_greg_t elf_fpregset_t[32];
> > 
> > It indicates that that or1k would only support float32, is that correct?
> 
> OpenRISC support 64-bit double's by using register pairs. i.e. r16,r17 +
> r18,r19.  The floating point and genral purpose registers actually are the
> same 32 registers.
> 
> > > diff --git a/sysdeps/unix/sysv/linux/or1k/getcontext.S b/sysdeps/unix/sysv/linux/or1k/getcontext.S
> > > new file mode 100644
> > > index 0000000000..4c2e64db7a
> > > --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/or1k/getcontext.S
> > > @@ -0,0 +1,72 @@
> > > +/* Save current context.  OpenRISC version.
> > > +   Copyright (C) 2021 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 "ucontext_i.h"
> > > +
> > > +/* int getcontext (ucontext_t *ucp)
> > > +
> > > +   Returns 0 on success -1 and errno on failure.
> > > + */
> > > +	.text
> > > +ENTRY(__getcontext)
> > > +	/* Store r1, the stack pointer.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT +  1*4)(r3), r1
> > > +	/* Store r2, the frame pointer.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT +  2*4)(r3), r2
> > > +	/* Store r9, the link register.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT +  9*4)(r3), r9
> > > +	/* Store r9 to reg[11] too, as we need two links for makecontext.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT + 11*4)(r3), r9
> > > +	/* Store r10, the TLS register.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT + 10*4)(r3), r10
> > > +	/* Store r14-r30 even, callee saved registers.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT + 14*4)(r3), r14
> > > +	l.sw	(UCONTEXT_MCONTEXT + 16*4)(r3), r16
> > > +	l.sw	(UCONTEXT_MCONTEXT + 18*4)(r3), r18
> > > +	l.sw	(UCONTEXT_MCONTEXT + 20*4)(r3), r20
> > > +	l.sw	(UCONTEXT_MCONTEXT + 22*4)(r3), r22
> > > +	l.sw	(UCONTEXT_MCONTEXT + 24*4)(r3), r24
> > > +	l.sw	(UCONTEXT_MCONTEXT + 26*4)(r3), r26
> > > +	l.sw	(UCONTEXT_MCONTEXT + 28*4)(r3), r28
> > > +	l.sw	(UCONTEXT_MCONTEXT + 30*4)(r3), r30
> > > +
> > > +	/* Get signal mask.  */
> > > +	/* rt_sigprocmask (SIG_BLOCK, NULL, &ucp->uc_sigmask, _NSIG8) */
> > > +	l.ori	r6, r0, _NSIG8
> > > +	l.addi	r5, r3, UCONTEXT_SIGMASK
> > > +	l.ori	r4, r0, 0
> > > +	l.ori	r3, r0, SIG_BLOCK
> > > +	l.ori	r11, r0, SYS_ify (rt_sigprocmask)
> > > +	/* Do the syscall.  */
> > > +	l.sys	1
> > > +	 l.nop
> > > +
> > > +	/* if -4096 < ret < 0 holds, it's an error */
> > > +	l.sfgeui r11, 0xf001
> > > +	l.bf	1f
> > > +	 l.nop
> > > +
> > > +	l.jr	r9
> > > +	 l.ori r11, r0, 0
> > > +
> > > +1:	l.j	__syscall_error
> > > +	 l.ori	r3, r11, 0
> > > +
> > > +END(__getcontext)
> > > +weak_alias(__getcontext, getcontext)
> > > diff --git a/sysdeps/unix/sysv/linux/or1k/makecontext.c b/sysdeps/unix/sysv/linux/or1k/makecontext.c
> > > new file mode 100644
> > > index 0000000000..3dd4134a6b
> > > --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/or1k/makecontext.c
> > > @@ -0,0 +1,77 @@
> > > +/* Create new context.  OpenRISC version.
> > > +   Copyright (C) 2021 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 <ucontext.h>
> > > +
> > > +/* makecontext sets up a stack and the registers for the
> > > +   user context.  The stack looks like this:
> > > +
> > > +		+-----------------------+
> > > +		| padding as required   |
> > > +		+-----------------------+
> > > +    sp ->       | parameters 7 to n     |
> > > +		+-----------------------+
> > > +
> > > +   The registers are set up like this:
> > > +     r3-r8  : parameters 1 to 6
> > > +     r14    : uc_link
> > > +     r1     : stack pointer
> > > +     r2     : frame pointer, set to NULL
> > > +*/
> > > +void
> > > +__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
> > > +{
> > > +  extern void __startcontext (void);
> > > +  unsigned long int *sp;
> > > +  va_list ap;
> > > +  int i;
> > > +
> > > +  sp = (unsigned long int *)
> > > +    ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
> > > +
> > > +  /* Allocate stack arguments.  */
> > > +  sp -= argc < 6 ? 0 : argc - 6;
> > > +
> > > +  /* Keep the stack aligned.  */
> > > +  sp = (unsigned long int *) (((uintptr_t) sp) & -4L);
> > 
> > Is stack required to be 4 or 16 (STACK_ALIGN from pthreaddef.h)?
> 
> Is STACK_ALIGN used for anything other than asserts now?
> 
> I cannot recall why the alignment was set to 16 bytes, it may be copy and paste
> or it may be due to our cache lines being either 16bytes or 32bytes (usually
> 32).
> 
> Do you see any issue changing STACK_ALIGN to 4 bytes?

Nevermind, this should be in the OpenRISC spec.  And it is, it specifies 4 byte
alignment.

Also, GCC and GDB define it as 4.

-Stafford

> -Stafford
> 
> > > +
> > > +  /* Keep uc_link in r14.  */
> > > +  ucp->uc_mcontext.__gprs[14] = (uintptr_t) ucp->uc_link;
> > > +  /* Return address points to function __startcontext.  */
> > > +  ucp->uc_mcontext.__gprs[9] = (uintptr_t) &__startcontext;
> > > +  /* Frame pointer is null.  */
> > > +  ucp->uc_mcontext.__gprs[2] = (uintptr_t) 0;
> > > +  /* Restart in user-space starting at 'func'.  */
> > > +  ucp->uc_mcontext.__gprs[11] = (uintptr_t) func;
> > > +  /* Set stack pointer.  */
> > > +  ucp->uc_mcontext.__gprs[1] = (uintptr_t) sp;
> > > +
> > > +  va_start (ap, argc);
> > > +  for (i = 0; i < argc; ++i)
> > > +    if (i < 6)
> > > +      ucp->uc_mcontext.__gprs[i + 3] = va_arg (ap, unsigned long int);
> > > +    else
> > > +      sp[i - 6] = va_arg (ap, unsigned long int);
> > > +
> > > +  va_end (ap);
> > > +}
> > > +
> > > +weak_alias (__makecontext, makecontext)
> > > diff --git a/sysdeps/unix/sysv/linux/or1k/setcontext.S b/sysdeps/unix/sysv/linux/or1k/setcontext.S
> > > new file mode 100644
> > > index 0000000000..b4808d5422
> > > --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/or1k/setcontext.S
> > > @@ -0,0 +1,108 @@
> > > +/* Set current context.  OpenRISC version.
> > > +   Copyright (C) 2021 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 "ucontext_i.h"
> > > +
> > > +/* int setcontext (const ucontext_t *ucp) */
> > > +	.text
> > > +ENTRY(__setcontext)
> > > +	l.ori	r30, r3, 0
> > > +
> > > +	/* Restore signal mask.  */
> > > +	/* rt_sigprocmask (SIG_SETMASK, &ucp->uc_sigmask, NULL, _NSIG8) */
> > > +	l.ori	r6, r0, _NSIG8
> > > +	l.ori	r5, r0, 0
> > > +	l.addi	r4, r3, UCONTEXT_SIGMASK
> > > +	l.ori	r3, r0, SIG_SETMASK
> > > +	l.ori	r11, r0, SYS_ify (rt_sigprocmask)
> > > +	/* Do the syscall.  */
> > > +	l.sys 1
> > > +	 l.nop
> > > +
> > > +	/* if -4096 < ret < 0 holds, it's an error */
> > > +	l.sfgeui r11, 0xf001
> > > +	l.bf	1f
> > > +	 l.nop
> > > +
> > > +	/* Restore argument registers, for the makecontext case.  */
> > > +	l.lwz	r3, (UCONTEXT_MCONTEXT +  3*4)(r30)
> > > +	l.lwz	r4, (UCONTEXT_MCONTEXT +  4*4)(r30)
> > > +	l.lwz	r5, (UCONTEXT_MCONTEXT +  5*4)(r30)
> > > +	l.lwz	r6, (UCONTEXT_MCONTEXT +  6*4)(r30)
> > > +	l.lwz	r7, (UCONTEXT_MCONTEXT +  7*4)(r30)
> > > +	l.lwz	r8, (UCONTEXT_MCONTEXT +  8*4)(r30)
> > > +
> > > +	/* Restore registers stored in getcontext.  */
> > > +	l.lwz	r1,  (UCONTEXT_MCONTEXT +  1*4)(r30)
> > > +	l.lwz	r2,  (UCONTEXT_MCONTEXT +  2*4)(r30)
> > > +	l.lwz	r9,  (UCONTEXT_MCONTEXT +  9*4)(r30)
> > > +	l.lwz	r10, (UCONTEXT_MCONTEXT + 10*4)(r30)
> > > +	l.lwz	r11, (UCONTEXT_MCONTEXT + 11*4)(r30)
> > > +	/* Restore r14-r30 even, callee saved registers.  */
> > > +	l.lwz	r14, (UCONTEXT_MCONTEXT + 14*4)(r30)
> > > +	l.lwz	r16, (UCONTEXT_MCONTEXT + 16*4)(r30)
> > > +	l.lwz	r18, (UCONTEXT_MCONTEXT + 18*4)(r30)
> > > +	l.lwz	r20, (UCONTEXT_MCONTEXT + 20*4)(r30)
> > > +	l.lwz	r22, (UCONTEXT_MCONTEXT + 22*4)(r30)
> > > +	l.lwz	r24, (UCONTEXT_MCONTEXT + 24*4)(r30)
> > > +	l.lwz	r26, (UCONTEXT_MCONTEXT + 26*4)(r30)
> > > +	l.lwz	r28, (UCONTEXT_MCONTEXT + 28*4)(r30)
> > > +	l.lwz	r30, (UCONTEXT_MCONTEXT + 30*4)(r30)
> > > +
> > > +	l.jr	r11
> > > +	 l.ori	r11, r0, 0
> > > +
> > > +1:	l.j	__syscall_error
> > > +	 l.ori	r3, r11, 0
> > > +
> > > +END (__setcontext)
> > > +weak_alias (__setcontext, setcontext)
> > > +
> > > +	/* We add a NOP here because when the unwinder is looking for the
> > > +	   enclosing function of the link register (r9) address FDE lookup will
> > > +	   use '$r9 - 1' finding setcontext which is wrong.  This is because in
> > > +	   makecontext we have set r9 to the start of &__startcontext.
> > > +
> > > +	   If this NOP did not exist the unwinder would repeatedly find
> > > +	   __setcontext's FDE in an infinite loop.  Modifiying/deleting the below
> > > +	   __startcontext's FDE has no help on this.  */
> > > +	l.nop
> > > +
> > > +ENTRY(__startcontext)
> > > +
> > > +	l.ori	r3, r14, 0
> > > +	l.sfeq	r3, r0
> > > +	/* If uc_link is not 0 resume there, otherwise exit.  */
> > > +	l.bnf	__setcontext
> > > +	 l.nop
> > > +
> > > +#ifdef SHARED
> > > +	/* Obtain a pointer to .got in r16 */
> > > +	l.jal	0x8
> > > +	 l.movhi r16, gotpchi(_GLOBAL_OFFSET_TABLE_-4)
> > > +	l.ori	r16, r16, gotpclo(_GLOBAL_OFFSET_TABLE_+0)
> > > +	l.add	r16, r16, r9
> > > +	l.lwz	r16, got(exit)(r16)
> > > +	l.jr	r16
> > > +#else
> > > +	l.j	exit
> > > +#endif
> > > +	 l.nop
> > > +
> > > +END(__startcontext)
> > > diff --git a/sysdeps/unix/sysv/linux/or1k/sigcontextinfo.h b/sysdeps/unix/sysv/linux/or1k/sigcontextinfo.h
> > > new file mode 100644
> > > index 0000000000..de94b59578
> > > --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/or1k/sigcontextinfo.h
> > > @@ -0,0 +1,28 @@
> > > +/* Profile counter helper to get PC from sigcontext.  OpenRISC version.
> > > +   Copyright (C) 2021 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.__pc;
> > > +}
> > > +
> > > +#endif /* _SIGCONTEXTINFO_H */
> > > diff --git a/sysdeps/unix/sysv/linux/or1k/swapcontext.S b/sysdeps/unix/sysv/linux/or1k/swapcontext.S
> > > new file mode 100644
> > > index 0000000000..2acdc6d9bd
> > > --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/or1k/swapcontext.S
> > > @@ -0,0 +1,116 @@
> > > +/* Swap two contexts.  OpenRISC version.
> > > +   Copyright (C) 2021 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 "ucontext_i.h"
> > > +
> > > +/* int swapcontext (ucontext_t *oucp, const ucontext_t *ucp) */
> > > +	.text
> > > +ENTRY(__swapcontext)
> > > +
> > > +	/* Same as getcontext.  */
> > > +	/* Store r1, the stack pointer.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT +  1*4)(r3), r1
> > > +	/* Store r2, the frame pointer.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT +  2*4)(r3), r2
> > > +	/* Store r9, the link register.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT +  9*4)(r3), r9
> > > +	/* Store r9 to reg[11] too, as we need two links for makecontext.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT + 11*4)(r3), r9
> > > +	/* Store r10, the TLS register.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT + 10*4)(r3), r10
> > > +	/* Store r14-r30 even, callee saved registers.  */
> > > +	l.sw	(UCONTEXT_MCONTEXT + 14*4)(r3), r14
> > > +	l.sw	(UCONTEXT_MCONTEXT + 16*4)(r3), r16
> > > +	l.sw	(UCONTEXT_MCONTEXT + 18*4)(r3), r18
> > > +	l.sw	(UCONTEXT_MCONTEXT + 20*4)(r3), r20
> > > +	l.sw	(UCONTEXT_MCONTEXT + 22*4)(r3), r22
> > > +	l.sw	(UCONTEXT_MCONTEXT + 24*4)(r3), r24
> > > +	l.sw	(UCONTEXT_MCONTEXT + 26*4)(r3), r26
> > > +	l.sw	(UCONTEXT_MCONTEXT + 28*4)(r3), r28
> > > +	l.sw	(UCONTEXT_MCONTEXT + 30*4)(r3), r30
> > > +
> > > +	/* Store ucp to non-argument syscall preserved register.  */
> > > +	l.ori	r30, r4, 0
> > > +
> > > +	/* Get signal mask.  */
> > > +	/* rt_sigprocmask (SIG_BLOCK, NULL, &ucp->uc_sigmask, _NSIG8) */
> > > +	l.ori	r6, r0, _NSIG8
> > > +	l.addi	r5, r3, UCONTEXT_SIGMASK
> > > +	l.ori	r4, r0, 0
> > > +	l.ori	r3, r0, SIG_BLOCK
> > > +	l.ori	r11, r0, SYS_ify (rt_sigprocmask)
> > > +	/* Do the syscall.  */
> > > +	l.sys	1
> > > +	 l.nop
> > > +
> > > +	/* if -4096 < ret < 0 holds, it's an error */
> > > +	l.sfgeui r11, 0xf001
> > > +	l.bf	1f
> > > +	 l.nop
> > > +
> > > +	/* Same as setcontext.  */
> > > +
> > > +	/* Restore signal mask.  */
> > > +	/* rt_sigprocmask (SIG_SETMASK, &ucp->uc_sigmask, NULL, _NSIG8) */
> > > +	l.ori	r6, r0, _NSIG8
> > > +	l.ori	r5, r0, 0
> > > +	l.addi	r4, r30, UCONTEXT_SIGMASK
> > > +	l.ori	r3, r0, SIG_SETMASK
> > > +	l.ori	r11, r0, SYS_ify (rt_sigprocmask)
> > > +	/* Do the syscall.  */
> > > +	l.sys 1
> > > +	 l.nop
> > > +
> > > +	/* if -4096 < ret < 0 holds, it's an error */
> > > +	l.sfgeui r11, 0xf001
> > > +	l.bf	1f
> > > +	 l.nop
> > > +
> > > +	/* Restore argument registers, for the makecontext case.  */
> > > +	l.lwz	r3, (UCONTEXT_MCONTEXT +  3*4)(r30)
> > > +	l.lwz	r4, (UCONTEXT_MCONTEXT +  4*4)(r30)
> > > +	l.lwz	r5, (UCONTEXT_MCONTEXT +  5*4)(r30)
> > > +	l.lwz	r6, (UCONTEXT_MCONTEXT +  6*4)(r30)
> > > +	l.lwz	r7, (UCONTEXT_MCONTEXT +  7*4)(r30)
> > > +	l.lwz	r8, (UCONTEXT_MCONTEXT +  8*4)(r30)
> > > +
> > > +	/* Restore registers stored in getcontext.  */
> > > +	l.lwz	r1,  (UCONTEXT_MCONTEXT +  1*4)(r30)
> > > +	l.lwz	r2,  (UCONTEXT_MCONTEXT +  2*4)(r30)
> > > +	l.lwz	r9,  (UCONTEXT_MCONTEXT +  9*4)(r30)
> > > +	l.lwz	r10, (UCONTEXT_MCONTEXT + 10*4)(r30)
> > > +	l.lwz	r11, (UCONTEXT_MCONTEXT + 11*4)(r30)
> > > +	l.lwz	r14, (UCONTEXT_MCONTEXT + 14*4)(r30)
> > > +	l.lwz	r16, (UCONTEXT_MCONTEXT + 16*4)(r30)
> > > +	l.lwz	r18, (UCONTEXT_MCONTEXT + 18*4)(r30)
> > > +	l.lwz	r20, (UCONTEXT_MCONTEXT + 20*4)(r30)
> > > +	l.lwz	r22, (UCONTEXT_MCONTEXT + 22*4)(r30)
> > > +	l.lwz	r24, (UCONTEXT_MCONTEXT + 24*4)(r30)
> > > +	l.lwz	r26, (UCONTEXT_MCONTEXT + 26*4)(r30)
> > > +	l.lwz	r28, (UCONTEXT_MCONTEXT + 28*4)(r30)
> > > +	l.lwz	r30, (UCONTEXT_MCONTEXT + 30*4)(r30)
> > > +
> > > +	l.jr	r11
> > > +	 l.ori	r11, r0, 0
> > > +
> > > +1:	l.j	__syscall_error
> > > +	 l.ori	r3, r11, 0
> > > +
> > > +END (__swapcontext)
> > > +weak_alias (__swapcontext, swapcontext)
> > > diff --git a/sysdeps/unix/sysv/linux/or1k/sys/ucontext.h b/sysdeps/unix/sysv/linux/or1k/sys/ucontext.h
> > > new file mode 100644
> > > index 0000000000..c4aead8f93
> > > --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/or1k/sys/ucontext.h
> > > @@ -0,0 +1,53 @@
> > > +/* ucontext_t definition, OpenRISC version.
> > > +   Copyright (C) 2021 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/OpenRISC 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>
> > > +
> > > +/* Number of general registers.  */
> > > +#define __NGREG	32
> > > +#ifdef __USE_MISC
> > > +# define NGREG	__NGREG
> > > +#endif
> > > +
> > > +/* Context to describe whole processor state.  */
> > > +typedef struct
> > > +  {
> > > +    unsigned long int __gprs[__NGREG];
> > > +    unsigned long int __pc;
> > > +    unsigned long int __sr;
> > > +  } 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 /* sys/ucontext.h */
> > > diff --git a/sysdeps/unix/sysv/linux/or1k/sys/user.h b/sysdeps/unix/sysv/linux/or1k/sys/user.h
> > > new file mode 100644
> > > index 0000000000..c871f1a03d
> > > --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/or1k/sys/user.h
> > > @@ -0,0 +1 @@
> > > +/* This file is not needed, but in practice gdb might try to include it.  */
> > > diff --git a/sysdeps/unix/sysv/linux/or1k/ucontext_i.sym b/sysdeps/unix/sysv/linux/or1k/ucontext_i.sym
> > > new file mode 100644
> > > index 0000000000..a8d4db080f
> > > --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/or1k/ucontext_i.sym
> > > @@ -0,0 +1,26 @@
> > > +#include <inttypes.h>
> > > +#include <signal.h>
> > > +#include <stddef.h>
> > > +#include <sys/ucontext.h>
> > > +
> > > +-- Constants used by the rt_sigprocmask call.
> > > +
> > > +SIG_BLOCK
> > > +SIG_SETMASK
> > > +
> > > +_NSIG8				(_NSIG / 8)
> > > +
> > > +-- Offsets of the fields in the ucontext_t structure.
> > > +#define ucontext(member)	offsetof (ucontext_t, member)
> > > +#define stack(member)		ucontext (uc_stack.member)
> > > +
> > > +UCONTEXT_LINK			ucontext (uc_link)
> > > +UCONTEXT_STACK			ucontext (uc_stack)
> > > +UCONTEXT_MCONTEXT		ucontext (uc_mcontext)
> > > +UCONTEXT_SIGMASK		ucontext (uc_sigmask)
> > > +
> > > +STACK_SP			stack (ss_sp)
> > > +STACK_SIZE			stack (ss_size)
> > > +STACK_FLAGS			stack (ss_flags)
> > > +
> > > +UCONTEXT_SIZE			sizeof (ucontext_t)