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/* Support for GNU properties. x86 version.
Copyright (C) 2018-2021 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 _DL_PROP_H
#define _DL_PROP_H
#include <libintl.h>
extern void _dl_cet_check (struct link_map *, const char *)
attribute_hidden;
extern void _dl_cet_open_check (struct link_map *)
attribute_hidden;
static void
dl_isa_level_check (struct link_map *m, const char *program)
{
const struct cpu_features *cpu_features = __get_cpu_features ();
unsigned int i;
struct link_map *l;
i = m->l_searchlist.r_nlist;
while (i-- > 0)
{
/* Check each shared object to see if ISA level is compatible. */
l = m->l_initfini[i];
/* Skip ISA level check if functions have been executed. */
if (l->l_init_called)
continue;
#ifdef SHARED
/* Skip ISA level check for ld.so since ld.so won't run if its ISA
level is higher than CPU. */
if (l == &GL(dl_rtld_map) || l->l_real == &GL(dl_rtld_map))
continue;
#endif
if ((l->l_x86_isa_1_needed & cpu_features->isa_1)
!= l->l_x86_isa_1_needed)
{
if (program)
_dl_fatal_printf ("%s: CPU ISA level is lower than required\n",
*l->l_name != '\0' ? l->l_name : program);
else
_dl_signal_error (0, l->l_name, "dlopen",
N_("CPU ISA level is lower than required"));
}
}
}
static inline void __attribute__ ((always_inline))
_rtld_main_check (struct link_map *m, const char *program)
{
dl_isa_level_check (m, program);
#if CET_ENABLED
_dl_cet_check (m, program);
#endif
}
static inline void __attribute__ ((always_inline))
_dl_open_check (struct link_map *m)
{
dl_isa_level_check (m, NULL);
#if CET_ENABLED
_dl_cet_open_check (m);
#endif
}
static inline void __attribute__ ((unused))
_dl_process_property_note (struct link_map *l, const ElfW(Nhdr) *note,
const ElfW(Addr) size, const ElfW(Addr) align)
{
/* Skip if we have seen a NT_GNU_PROPERTY_TYPE_0 note before. */
if (l->l_property != lc_property_unknown)
return;
/* The NT_GNU_PROPERTY_TYPE_0 note must be aliged to 4 bytes in
32-bit objects and to 8 bytes in 64-bit objects. Skip notes
with incorrect alignment. */
if (align != (__ELF_NATIVE_CLASS / 8))
return;
const ElfW(Addr) start = (ElfW(Addr)) note;
unsigned int feature_1_and = 0;
unsigned int isa_1_needed = 0;
unsigned int last_type = 0;
while ((ElfW(Addr)) (note + 1) - start < size)
{
/* Find the NT_GNU_PROPERTY_TYPE_0 note. */
if (note->n_namesz == 4
&& note->n_type == NT_GNU_PROPERTY_TYPE_0
&& memcmp (note + 1, "GNU", 4) == 0)
{
/* Stop if we see more than one GNU property note which may
be generated by the older linker. */
if (l->l_property != lc_property_unknown)
return;
/* Check CET status and ISA levels now. */
l->l_property = lc_property_none;
/* Check for invalid property. */
if (note->n_descsz < 8
|| (note->n_descsz % sizeof (ElfW(Addr))) != 0)
return;
/* Start and end of property array. */
unsigned char *ptr = (unsigned char *) (note + 1) + 4;
unsigned char *ptr_end = ptr + note->n_descsz;
do
{
unsigned int type = *(unsigned int *) ptr;
unsigned int datasz = *(unsigned int *) (ptr + 4);
/* Property type must be in ascending order. */
if (type < last_type)
return;
ptr += 8;
if ((ptr + datasz) > ptr_end)
return;
last_type = type;
if (type == GNU_PROPERTY_X86_FEATURE_1_AND
|| type == GNU_PROPERTY_X86_ISA_1_NEEDED)
{
/* The sizes of types which we are searching for are
4 bytes. There is no point to continue if this
note is ill-formed. */
if (datasz != 4)
return;
/* NB: Stop the scan only after seeing all types which
we are searching for. */
_Static_assert ((GNU_PROPERTY_X86_ISA_1_NEEDED >
GNU_PROPERTY_X86_FEATURE_1_AND),
"GNU_PROPERTY_X86_ISA_1_NEEDED > "
"GNU_PROPERTY_X86_FEATURE_1_AND");
if (type == GNU_PROPERTY_X86_FEATURE_1_AND)
feature_1_and = *(unsigned int *) ptr;
else
{
isa_1_needed = *(unsigned int *) ptr;
/* Keep searching for the next GNU property note
generated by the older linker. */
break;
}
}
else if (type > GNU_PROPERTY_X86_ISA_1_NEEDED)
{
/* Stop the scan since property type is in ascending
order. */
break;
}
/* Check the next property item. */
ptr += ALIGN_UP (datasz, sizeof (ElfW(Addr)));
}
while ((ptr_end - ptr) >= 8);
}
/* NB: Note sections like .note.ABI-tag and .note.gnu.build-id are
aligned to 4 bytes in 64-bit ELF objects. */
note = ((const void *) note
+ ELF_NOTE_NEXT_OFFSET (note->n_namesz, note->n_descsz,
align));
}
/* We get here only if there is one or no GNU property note. */
if (isa_1_needed != 0 || feature_1_and != 0)
{
l->l_property = lc_property_valid;
l->l_x86_isa_1_needed = isa_1_needed;
l->l_x86_feature_1_and = feature_1_and;
}
else
l->l_property = lc_property_none;
}
static inline void __attribute__ ((unused))
_dl_process_pt_note (struct link_map *l, int fd, const ElfW(Phdr) *ph)
{
const ElfW(Nhdr) *note = (const void *) (ph->p_vaddr + l->l_addr);
_dl_process_property_note (l, note, ph->p_memsz, ph->p_align);
}
static inline int __attribute__ ((always_inline))
_dl_process_gnu_property (struct link_map *l, int fd, uint32_t type,
uint32_t datasz, void *data)
{
return 0;
}
#endif /* _DL_PROP_H */
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