/* AArch64 BTI functions.
   Copyright (C) 2020 Free Software Foundation, Inc.

   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 <unistd.h>
#include <errno.h>
#include <libintl.h>
#include <ldsodefs.h>

static int
enable_bti (struct link_map *map, const char *program)
{
  const ElfW(Phdr) *phdr;
  unsigned prot;

  for (phdr = map->l_phdr; phdr < &map->l_phdr[map->l_phnum]; ++phdr)
    if (phdr->p_type == PT_LOAD && (phdr->p_flags & PF_X))
      {
	void *start = (void *) (phdr->p_vaddr + map->l_addr);
	size_t len = phdr->p_memsz;

	prot = PROT_EXEC | PROT_BTI;
	if (phdr->p_flags & PF_R)
	  prot |= PROT_READ;
	if (phdr->p_flags & PF_W)
	  prot |= PROT_WRITE;

	if (__mprotect (start, len, prot) < 0)
	  {
	    if (program)
	      _dl_fatal_printf ("%s: mprotect failed to turn on BTI\n",
				map->l_name);
	    else
	      _dl_signal_error (errno, map->l_name, "dlopen",
				N_("mprotect failed to turn on BTI"));
	  }
      }
  return 0;
}

/* Enable BTI for MAP and its dependencies.  */

void
_dl_bti_check (struct link_map *map, const char *program)
{
  if (!GLRO(dl_aarch64_cpu_features).bti)
    return;

  if (map->l_mach.bti)
    enable_bti (map, program);

  unsigned int i = map->l_searchlist.r_nlist;
  while (i-- > 0)
    {
      struct link_map *l = map->l_initfini[i];
      if (l->l_init_called)
	continue;
      if (l->l_mach.bti)
	enable_bti (l, program);
    }
}