[PATCH v7 09/13] ARC: Linux Startup and Dynamic Loading

[Adhemerval Zanella]

On 15/06/2020 17:14, Vineet Gupta via Libc-alpha wrote:
> ---
>  sysdeps/unix/sysv/linux/arc/dl-static.c | 84 +++++++++++++++++++++++++
>  sysdeps/unix/sysv/linux/arc/ldsodefs.h  | 32 ++++++++++
>  2 files changed, 116 insertions(+)
>  create mode 100644 sysdeps/unix/sysv/linux/arc/dl-static.c
>  create mode 100644 sysdeps/unix/sysv/linux/arc/ldsodefs.h

LGTM, thanks.

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

> 
> diff --git a/sysdeps/unix/sysv/linux/arc/dl-static.c b/sysdeps/unix/sysv/linux/arc/dl-static.c
> new file mode 100644
> index 000000000000..30bcd899d42d
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/arc/dl-static.c
> @@ -0,0 +1,84 @@
> +/* Variable initialization.  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/>.  */
> +
> +#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

Ok and as a side note we need to refactor and consolidate to avoid
making each architecture with variable pagesize to duplicate this
code.

> diff --git a/sysdeps/unix/sysv/linux/arc/ldsodefs.h b/sysdeps/unix/sysv/linux/arc/ldsodefs.h
> new file mode 100644
> index 000000000000..204a0ff8946c
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/arc/ldsodefs.h
> @@ -0,0 +1,32 @@
> +/* Run-time dynamic linker data structures for loaded ELF shared objects. 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/>.  */
> +
> +#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 */
> 

Ok.