Patchwork riscv: Remove support for variable page sizes

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Submitter Florian Weimer
Date Sept. 30, 2019, 12:45 p.m.
Message ID <87r23y2br3.fsf@oldenburg2.str.redhat.com>
Download mbox | patch
Permalink /patch/34726/
State New
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Comments

Florian Weimer - Sept. 30, 2019, 12:45 p.m.
[NB: I could use some help with testing here.]

_dl_var_init is used to patch the read-only data section after
relocation.  Several architectures use this to update
GLRO(page_size) with the correct value for the static dlopen case,
where _rtld_global_ro has not been initialized by the dynamic
loader.

RISC-V does not need this.  The RISC-V Instruction Set Manual,
Volume II: Privileged Architecture, Document Version
20190608-Priv-MSU-Ratified says this:

    After much deliberation, we have settled on a conventional
    page size of 4 KiB for both RV32 and RV64. We expect this
    decision to ease the porting of low-level runtime software
    and device drivers. The TLB reach problem is ameliorated by
    transparent superpage support in modern operating systems
    [2]. Additionally, multi-level TLB hierarchies are quite
    inexpensive relative to the multi-level cache hierarchies
    whose address space they map.

    [2] Juan Navarro, Sitaram Iyer, Peter Druschel, and
      Alan Cox. Practical, transparent operating system support
      for superpages.  SIGOPS Oper. Syst. Rev., 36(SI):89–104,
      December 2002.

This means that the initialization of
_rtld_global_ro._dl_page_size in elf/rtld.c with EXEC_PAGESIZE
is sufficient for RISC-V.

2019-09-30  Florian Weimer  <fweimer@redhat.com>

	riscv: Remove support for variable page sizes.
	* sysdeps/unix/sysv/linux/riscv/Makefile [$(subdir) == elf]
	(sysdep_routines): Do not add dl-static.
	* sysdeps/unix/sysv/linux/riscv/dl-static.c: Remove file.
	* sysdeps/unix/sysv/linux/riscv/ldsodefs.h: Likewise.
Florian Weimer - Oct. 7, 2019, 4:21 p.m.
Ping.  I need a review of this glibc patch from a RISC-V architecture
maintainer:

  <https://sourceware.org/ml/libc-alpha/2019-09/msg00506.html>

I believe this is another artifact needlessly copied over from the MIPS
port of glibc, but this one we can fix easily.

Thanks,
Florian

* Florian Weimer:

> _dl_var_init is used to patch the read-only data section after
> relocation.  Several architectures use this to update
> GLRO(page_size) with the correct value for the static dlopen case,
> where _rtld_global_ro has not been initialized by the dynamic
> loader.
>
> RISC-V does not need this.  The RISC-V Instruction Set Manual,
> Volume II: Privileged Architecture, Document Version
> 20190608-Priv-MSU-Ratified says this:
>
>     After much deliberation, we have settled on a conventional
>     page size of 4 KiB for both RV32 and RV64. We expect this
>     decision to ease the porting of low-level runtime software
>     and device drivers. The TLB reach problem is ameliorated by
>     transparent superpage support in modern operating systems
>     [2]. Additionally, multi-level TLB hierarchies are quite
>     inexpensive relative to the multi-level cache hierarchies
>     whose address space they map.
>
>     [2] Juan Navarro, Sitaram Iyer, Peter Druschel, and
>       Alan Cox. Practical, transparent operating system support
>       for superpages.  SIGOPS Oper. Syst. Rev., 36(SI):89–104,
>       December 2002.
>
> This means that the initialization of
> _rtld_global_ro._dl_page_size in elf/rtld.c with EXEC_PAGESIZE
> is sufficient for RISC-V.
>
> 2019-09-30  Florian Weimer  <fweimer@redhat.com>
>
> 	riscv: Remove support for variable page sizes.
> 	* sysdeps/unix/sysv/linux/riscv/Makefile [$(subdir) == elf]
> 	(sysdep_routines): Do not add dl-static.
> 	* sysdeps/unix/sysv/linux/riscv/dl-static.c: Remove file.
> 	* sysdeps/unix/sysv/linux/riscv/ldsodefs.h: Likewise.
>
> diff --git a/sysdeps/unix/sysv/linux/riscv/Makefile b/sysdeps/unix/sysv/linux/riscv/Makefile
> index b47858769f..b7ad31885c 100644
> --- a/sysdeps/unix/sysv/linux/riscv/Makefile
> +++ b/sysdeps/unix/sysv/linux/riscv/Makefile
> @@ -1,9 +1,5 @@
>  ifeq ($(subdir),elf)
>  sysdep_routines	+= dl-vdso
> -ifeq ($(build-shared),yes)
> -# This is needed for DSO loading from static binaries.
> -sysdep-dl-routines += dl-static
> -endif
>  endif
>  
>  ifeq ($(subdir),misc)
> diff --git a/sysdeps/unix/sysv/linux/riscv/dl-static.c b/sysdeps/unix/sysv/linux/riscv/dl-static.c
> deleted file mode 100644
> index e52612a267..0000000000
> --- a/sysdeps/unix/sysv/linux/riscv/dl-static.c
> +++ /dev/null
> @@ -1,84 +0,0 @@
> -/* Variable initialization.  RISC-V version
> -   Copyright (C) 2001-2019 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 <ldsodefs.h>
> -
> -#ifdef SHARED
> -
> -void
> -_dl_var_init (void *array[])
> -{
> -  /* It has to match "variables" below.  */
> -  enum
> -    {
> -      DL_PAGESIZE = 0
> -    };
> -
> -  GLRO(dl_pagesize) = *((size_t *) array[DL_PAGESIZE]);
> -}
> -
> -#else
> -
> -static void *variables[] =
> -{
> -  &GLRO(dl_pagesize)
> -};
> -
> -static void
> -_dl_unprotect_relro (struct link_map *l)
> -{
> -  ElfW(Addr) start = ((l->l_addr + l->l_relro_addr)
> -		      & ~(GLRO(dl_pagesize) - 1));
> -  ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size)
> -		    & ~(GLRO(dl_pagesize) - 1));
> -
> -  if (start != end)
> -    __mprotect ((void *) start, end - start, PROT_READ | PROT_WRITE);
> -}
> -
> -void
> -_dl_static_init (struct link_map *l)
> -{
> -  struct link_map *rtld_map = l;
> -  struct r_scope_elem **scope;
> -  const ElfW(Sym) *ref = NULL;
> -  lookup_t loadbase;
> -  void (*f) (void *[]);
> -  size_t i;
> -
> -  loadbase = _dl_lookup_symbol_x ("_dl_var_init", l, &ref, l->l_local_scope,
> -				  NULL, 0, 1, NULL);
> -
> -  for (scope = l->l_local_scope; *scope != NULL; scope++)
> -    for (i = 0; i < (*scope)->r_nlist; i++)
> -      if ((*scope)->r_list[i] == loadbase)
> -	{
> -	  rtld_map = (*scope)->r_list[i];
> -	  break;
> -	}
> -
> -  if (ref != NULL)
> -    {
> -      f = (void (*) (void *[])) DL_SYMBOL_ADDRESS (loadbase, ref);
> -      _dl_unprotect_relro (rtld_map);
> -      f (variables);
> -      _dl_protect_relro (rtld_map);
> -    }
> -}
> -
> -#endif
> diff --git a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h b/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> deleted file mode 100644
> index a46e676752..0000000000
> --- a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> +++ /dev/null
> @@ -1,32 +0,0 @@
> -/* RISC-V dynamic linker data structures for loaded ELF shared objects.
> -   Copyright (C) 2001-2019 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	_LDSODEFS_H
> -
> -/* Get the real definitions.  */
> -#include_next <ldsodefs.h>
> -
> -/* Now define our stuff.  */
> -
> -/* We need special support to initialize DSO loaded for statically linked
> -   binaries.  */
> -extern void _dl_static_init (struct link_map *map);
> -#undef DL_STATIC_INIT
> -#define DL_STATIC_INIT(map) _dl_static_init (map)
> -
> -#endif /* ldsodefs.h */
Andrew Waterman - Oct. 7, 2019, 4:49 p.m.
LGTM; I believe you are right on both counts that this was borrowed
from MIPS and that we do not need this for RISC-V.

On Mon, Oct 7, 2019 at 6:21 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> Ping.  I need a review of this glibc patch from a RISC-V architecture
> maintainer:
>
>   <https://sourceware.org/ml/libc-alpha/2019-09/msg00506.html>
>
> I believe this is another artifact needlessly copied over from the MIPS
> port of glibc, but this one we can fix easily.
>
> Thanks,
> Florian
>
> * Florian Weimer:
>
> > _dl_var_init is used to patch the read-only data section after
> > relocation.  Several architectures use this to update
> > GLRO(page_size) with the correct value for the static dlopen case,
> > where _rtld_global_ro has not been initialized by the dynamic
> > loader.
> >
> > RISC-V does not need this.  The RISC-V Instruction Set Manual,
> > Volume II: Privileged Architecture, Document Version
> > 20190608-Priv-MSU-Ratified says this:
> >
> >     After much deliberation, we have settled on a conventional
> >     page size of 4 KiB for both RV32 and RV64. We expect this
> >     decision to ease the porting of low-level runtime software
> >     and device drivers. The TLB reach problem is ameliorated by
> >     transparent superpage support in modern operating systems
> >     [2]. Additionally, multi-level TLB hierarchies are quite
> >     inexpensive relative to the multi-level cache hierarchies
> >     whose address space they map.
> >
> >     [2] Juan Navarro, Sitaram Iyer, Peter Druschel, and
> >       Alan Cox. Practical, transparent operating system support
> >       for superpages.  SIGOPS Oper. Syst. Rev., 36(SI):89–104,
> >       December 2002.
> >
> > This means that the initialization of
> > _rtld_global_ro._dl_page_size in elf/rtld.c with EXEC_PAGESIZE
> > is sufficient for RISC-V.
> >
> > 2019-09-30  Florian Weimer  <fweimer@redhat.com>
> >
> >       riscv: Remove support for variable page sizes.
> >       * sysdeps/unix/sysv/linux/riscv/Makefile [$(subdir) == elf]
> >       (sysdep_routines): Do not add dl-static.
> >       * sysdeps/unix/sysv/linux/riscv/dl-static.c: Remove file.
> >       * sysdeps/unix/sysv/linux/riscv/ldsodefs.h: Likewise.
> >
> > diff --git a/sysdeps/unix/sysv/linux/riscv/Makefile b/sysdeps/unix/sysv/linux/riscv/Makefile
> > index b47858769f..b7ad31885c 100644
> > --- a/sysdeps/unix/sysv/linux/riscv/Makefile
> > +++ b/sysdeps/unix/sysv/linux/riscv/Makefile
> > @@ -1,9 +1,5 @@
> >  ifeq ($(subdir),elf)
> >  sysdep_routines      += dl-vdso
> > -ifeq ($(build-shared),yes)
> > -# This is needed for DSO loading from static binaries.
> > -sysdep-dl-routines += dl-static
> > -endif
> >  endif
> >
> >  ifeq ($(subdir),misc)
> > diff --git a/sysdeps/unix/sysv/linux/riscv/dl-static.c b/sysdeps/unix/sysv/linux/riscv/dl-static.c
> > deleted file mode 100644
> > index e52612a267..0000000000
> > --- a/sysdeps/unix/sysv/linux/riscv/dl-static.c
> > +++ /dev/null
> > @@ -1,84 +0,0 @@
> > -/* Variable initialization.  RISC-V version
> > -   Copyright (C) 2001-2019 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 <ldsodefs.h>
> > -
> > -#ifdef SHARED
> > -
> > -void
> > -_dl_var_init (void *array[])
> > -{
> > -  /* It has to match "variables" below.  */
> > -  enum
> > -    {
> > -      DL_PAGESIZE = 0
> > -    };
> > -
> > -  GLRO(dl_pagesize) = *((size_t *) array[DL_PAGESIZE]);
> > -}
> > -
> > -#else
> > -
> > -static void *variables[] =
> > -{
> > -  &GLRO(dl_pagesize)
> > -};
> > -
> > -static void
> > -_dl_unprotect_relro (struct link_map *l)
> > -{
> > -  ElfW(Addr) start = ((l->l_addr + l->l_relro_addr)
> > -                   & ~(GLRO(dl_pagesize) - 1));
> > -  ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size)
> > -                 & ~(GLRO(dl_pagesize) - 1));
> > -
> > -  if (start != end)
> > -    __mprotect ((void *) start, end - start, PROT_READ | PROT_WRITE);
> > -}
> > -
> > -void
> > -_dl_static_init (struct link_map *l)
> > -{
> > -  struct link_map *rtld_map = l;
> > -  struct r_scope_elem **scope;
> > -  const ElfW(Sym) *ref = NULL;
> > -  lookup_t loadbase;
> > -  void (*f) (void *[]);
> > -  size_t i;
> > -
> > -  loadbase = _dl_lookup_symbol_x ("_dl_var_init", l, &ref, l->l_local_scope,
> > -                               NULL, 0, 1, NULL);
> > -
> > -  for (scope = l->l_local_scope; *scope != NULL; scope++)
> > -    for (i = 0; i < (*scope)->r_nlist; i++)
> > -      if ((*scope)->r_list[i] == loadbase)
> > -     {
> > -       rtld_map = (*scope)->r_list[i];
> > -       break;
> > -     }
> > -
> > -  if (ref != NULL)
> > -    {
> > -      f = (void (*) (void *[])) DL_SYMBOL_ADDRESS (loadbase, ref);
> > -      _dl_unprotect_relro (rtld_map);
> > -      f (variables);
> > -      _dl_protect_relro (rtld_map);
> > -    }
> > -}
> > -
> > -#endif
> > diff --git a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h b/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> > deleted file mode 100644
> > index a46e676752..0000000000
> > --- a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> > +++ /dev/null
> > @@ -1,32 +0,0 @@
> > -/* RISC-V dynamic linker data structures for loaded ELF shared objects.
> > -   Copyright (C) 2001-2019 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      _LDSODEFS_H
> > -
> > -/* Get the real definitions.  */
> > -#include_next <ldsodefs.h>
> > -
> > -/* Now define our stuff.  */
> > -
> > -/* We need special support to initialize DSO loaded for statically linked
> > -   binaries.  */
> > -extern void _dl_static_init (struct link_map *map);
> > -#undef DL_STATIC_INIT
> > -#define DL_STATIC_INIT(map) _dl_static_init (map)
> > -
> > -#endif /* ldsodefs.h */
Alistair Francis - Oct. 7, 2019, 9:03 p.m.
On Mon, Sep 30, 2019 at 5:46 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> [NB: I could use some help with testing here.]
>
> _dl_var_init is used to patch the read-only data section after
> relocation.  Several architectures use this to update
> GLRO(page_size) with the correct value for the static dlopen case,
> where _rtld_global_ro has not been initialized by the dynamic
> loader.
>
> RISC-V does not need this.  The RISC-V Instruction Set Manual,
> Volume II: Privileged Architecture, Document Version
> 20190608-Priv-MSU-Ratified says this:
>
>     After much deliberation, we have settled on a conventional
>     page size of 4 KiB for both RV32 and RV64. We expect this
>     decision to ease the porting of low-level runtime software
>     and device drivers. The TLB reach problem is ameliorated by
>     transparent superpage support in modern operating systems
>     [2]. Additionally, multi-level TLB hierarchies are quite
>     inexpensive relative to the multi-level cache hierarchies
>     whose address space they map.
>
>     [2] Juan Navarro, Sitaram Iyer, Peter Druschel, and
>       Alan Cox. Practical, transparent operating system support
>       for superpages.  SIGOPS Oper. Syst. Rev., 36(SI):89–104,
>       December 2002.
>
> This means that the initialization of
> _rtld_global_ro._dl_page_size in elf/rtld.c with EXEC_PAGESIZE
> is sufficient for RISC-V.
>
> 2019-09-30  Florian Weimer  <fweimer@redhat.com>
>
>         riscv: Remove support for variable page sizes.
>         * sysdeps/unix/sysv/linux/riscv/Makefile [$(subdir) == elf]
>         (sysdep_routines): Do not add dl-static.
>         * sysdeps/unix/sysv/linux/riscv/dl-static.c: Remove file.
>         * sysdeps/unix/sysv/linux/riscv/ldsodefs.h: Likewise.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

>
> diff --git a/sysdeps/unix/sysv/linux/riscv/Makefile b/sysdeps/unix/sysv/linux/riscv/Makefile
> index b47858769f..b7ad31885c 100644
> --- a/sysdeps/unix/sysv/linux/riscv/Makefile
> +++ b/sysdeps/unix/sysv/linux/riscv/Makefile
> @@ -1,9 +1,5 @@
>  ifeq ($(subdir),elf)
>  sysdep_routines        += dl-vdso
> -ifeq ($(build-shared),yes)
> -# This is needed for DSO loading from static binaries.
> -sysdep-dl-routines += dl-static
> -endif
>  endif
>
>  ifeq ($(subdir),misc)
> diff --git a/sysdeps/unix/sysv/linux/riscv/dl-static.c b/sysdeps/unix/sysv/linux/riscv/dl-static.c
> deleted file mode 100644
> index e52612a267..0000000000
> --- a/sysdeps/unix/sysv/linux/riscv/dl-static.c
> +++ /dev/null
> @@ -1,84 +0,0 @@
> -/* Variable initialization.  RISC-V version
> -   Copyright (C) 2001-2019 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 <ldsodefs.h>
> -
> -#ifdef SHARED
> -
> -void
> -_dl_var_init (void *array[])
> -{
> -  /* It has to match "variables" below.  */
> -  enum
> -    {
> -      DL_PAGESIZE = 0
> -    };
> -
> -  GLRO(dl_pagesize) = *((size_t *) array[DL_PAGESIZE]);
> -}
> -
> -#else
> -
> -static void *variables[] =
> -{
> -  &GLRO(dl_pagesize)
> -};
> -
> -static void
> -_dl_unprotect_relro (struct link_map *l)
> -{
> -  ElfW(Addr) start = ((l->l_addr + l->l_relro_addr)
> -                     & ~(GLRO(dl_pagesize) - 1));
> -  ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size)
> -                   & ~(GLRO(dl_pagesize) - 1));
> -
> -  if (start != end)
> -    __mprotect ((void *) start, end - start, PROT_READ | PROT_WRITE);
> -}
> -
> -void
> -_dl_static_init (struct link_map *l)
> -{
> -  struct link_map *rtld_map = l;
> -  struct r_scope_elem **scope;
> -  const ElfW(Sym) *ref = NULL;
> -  lookup_t loadbase;
> -  void (*f) (void *[]);
> -  size_t i;
> -
> -  loadbase = _dl_lookup_symbol_x ("_dl_var_init", l, &ref, l->l_local_scope,
> -                                 NULL, 0, 1, NULL);
> -
> -  for (scope = l->l_local_scope; *scope != NULL; scope++)
> -    for (i = 0; i < (*scope)->r_nlist; i++)
> -      if ((*scope)->r_list[i] == loadbase)
> -       {
> -         rtld_map = (*scope)->r_list[i];
> -         break;
> -       }
> -
> -  if (ref != NULL)
> -    {
> -      f = (void (*) (void *[])) DL_SYMBOL_ADDRESS (loadbase, ref);
> -      _dl_unprotect_relro (rtld_map);
> -      f (variables);
> -      _dl_protect_relro (rtld_map);
> -    }
> -}
> -
> -#endif
> diff --git a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h b/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> deleted file mode 100644
> index a46e676752..0000000000
> --- a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> +++ /dev/null
> @@ -1,32 +0,0 @@
> -/* RISC-V dynamic linker data structures for loaded ELF shared objects.
> -   Copyright (C) 2001-2019 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        _LDSODEFS_H
> -
> -/* Get the real definitions.  */
> -#include_next <ldsodefs.h>
> -
> -/* Now define our stuff.  */
> -
> -/* We need special support to initialize DSO loaded for statically linked
> -   binaries.  */
> -extern void _dl_static_init (struct link_map *map);
> -#undef DL_STATIC_INIT
> -#define DL_STATIC_INIT(map) _dl_static_init (map)
> -
> -#endif /* ldsodefs.h */
Jim Wilson - Oct. 8, 2019, 10:47 p.m.
On Mon, Sep 30, 2019 at 5:45 AM Florian Weimer <fweimer@redhat.com> wrote:
> [NB: I could use some help with testing here.]

I was out sick most of last week, but I did a top of tree
riscv64-linux native binutils/gcc/glibc build this week which ended up
testing your patch.  I got 16 glibc failures which is what I expected.
6 of those are asin/acos ULP problems, so I think only 10 real
problems.  I did have to add -Wno-error=stringop-overflow to gccwarn
to complete the glibc build, but I believe that is a gcc bug, and I
see that there are already a number of stringop-overflow bugs that
have been reported, so it might be related to one of the existing bug
reports.

Jim
Florian Weimer - Oct. 9, 2019, 7:05 a.m.
* Jim Wilson:

> On Mon, Sep 30, 2019 at 5:45 AM Florian Weimer <fweimer@redhat.com> wrote:
>> [NB: I could use some help with testing here.]
>
> I was out sick most of last week, but I did a top of tree
> riscv64-linux native binutils/gcc/glibc build this week which ended up
> testing your patch.  I got 16 glibc failures which is what I expected.
> 6 of those are asin/acos ULP problems, so I think only 10 real
> problems.  I did have to add -Wno-error=stringop-overflow to gccwarn
> to complete the glibc build, but I believe that is a gcc bug, and I
> see that there are already a number of stringop-overflow bugs that
> have been reported, so it might be related to one of the existing bug
> reports.

Thanks for the additional testing.

Florian

Patch

diff --git a/sysdeps/unix/sysv/linux/riscv/Makefile b/sysdeps/unix/sysv/linux/riscv/Makefile
index b47858769f..b7ad31885c 100644
--- a/sysdeps/unix/sysv/linux/riscv/Makefile
+++ b/sysdeps/unix/sysv/linux/riscv/Makefile
@@ -1,9 +1,5 @@ 
 ifeq ($(subdir),elf)
 sysdep_routines	+= dl-vdso
-ifeq ($(build-shared),yes)
-# This is needed for DSO loading from static binaries.
-sysdep-dl-routines += dl-static
-endif
 endif
 
 ifeq ($(subdir),misc)
diff --git a/sysdeps/unix/sysv/linux/riscv/dl-static.c b/sysdeps/unix/sysv/linux/riscv/dl-static.c
deleted file mode 100644
index e52612a267..0000000000
--- a/sysdeps/unix/sysv/linux/riscv/dl-static.c
+++ /dev/null
@@ -1,84 +0,0 @@ 
-/* Variable initialization.  RISC-V version
-   Copyright (C) 2001-2019 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 <ldsodefs.h>
-
-#ifdef SHARED
-
-void
-_dl_var_init (void *array[])
-{
-  /* It has to match "variables" below.  */
-  enum
-    {
-      DL_PAGESIZE = 0
-    };
-
-  GLRO(dl_pagesize) = *((size_t *) array[DL_PAGESIZE]);
-}
-
-#else
-
-static void *variables[] =
-{
-  &GLRO(dl_pagesize)
-};
-
-static void
-_dl_unprotect_relro (struct link_map *l)
-{
-  ElfW(Addr) start = ((l->l_addr + l->l_relro_addr)
-		      & ~(GLRO(dl_pagesize) - 1));
-  ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size)
-		    & ~(GLRO(dl_pagesize) - 1));
-
-  if (start != end)
-    __mprotect ((void *) start, end - start, PROT_READ | PROT_WRITE);
-}
-
-void
-_dl_static_init (struct link_map *l)
-{
-  struct link_map *rtld_map = l;
-  struct r_scope_elem **scope;
-  const ElfW(Sym) *ref = NULL;
-  lookup_t loadbase;
-  void (*f) (void *[]);
-  size_t i;
-
-  loadbase = _dl_lookup_symbol_x ("_dl_var_init", l, &ref, l->l_local_scope,
-				  NULL, 0, 1, NULL);
-
-  for (scope = l->l_local_scope; *scope != NULL; scope++)
-    for (i = 0; i < (*scope)->r_nlist; i++)
-      if ((*scope)->r_list[i] == loadbase)
-	{
-	  rtld_map = (*scope)->r_list[i];
-	  break;
-	}
-
-  if (ref != NULL)
-    {
-      f = (void (*) (void *[])) DL_SYMBOL_ADDRESS (loadbase, ref);
-      _dl_unprotect_relro (rtld_map);
-      f (variables);
-      _dl_protect_relro (rtld_map);
-    }
-}
-
-#endif
diff --git a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h b/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
deleted file mode 100644
index a46e676752..0000000000
--- a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
+++ /dev/null
@@ -1,32 +0,0 @@ 
-/* RISC-V dynamic linker data structures for loaded ELF shared objects.
-   Copyright (C) 2001-2019 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	_LDSODEFS_H
-
-/* Get the real definitions.  */
-#include_next <ldsodefs.h>
-
-/* Now define our stuff.  */
-
-/* We need special support to initialize DSO loaded for statically linked
-   binaries.  */
-extern void _dl_static_init (struct link_map *map);
-#undef DL_STATIC_INIT
-#define DL_STATIC_INIT(map) _dl_static_init (map)
-
-#endif /* ldsodefs.h */