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x86: Propery check PC16 reloc overflow in 16-bit mode instructions

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commit a7664973b24a242cd9ea17deb5eaf503065fc0bd
Author: Jan Beulich <jbeulich@suse.com>
Date:   Mon Apr 26 10:41:35 2021 +0200

    x86: correct overflow checking for 16-bit PC-relative relocs

caused linker failure when building 16-bit program in a 32-bit ELF
container.  Update GNU_PROPERTY_X86_FEATURE_2_USED with

 #define GNU_PROPERTY_X86_FEATURE_2_CODE16 (1U << 12)

to indicate that 16-bit mode instructions are used in the input object:

https://groups.google.com/g/x86-64-abi/c/UvvXWeHIGMA

to indicate that 16-bit mode instructions are used in the object to
allow linker to properly perform relocation overflow check for 16-bit
PC-relative relocations in 16-bit mode instructions.

1. Update x86 assembler to always generate the GNU property note with
GNU_PROPERTY_X86_FEATURE_2_CODE16 for .code16 in ELF object.
2. Update i386 and x86-64 linkers to use 16-bit PC16 relocations if
input object is marked with GNU_PROPERTY_X86_FEATURE_2_CODE16.

bfd/

	PR ld/27905
	* elf32-i386.c: Include "libiberty.h".
	(elf_howto_table): Add 16-bit R_386_PC16 entry.
	(elf_i386_rtype_to_howto): Add a BFD argument.  Use 16-bit
	R_386_PC16 if input has 16-bit mode instructions.
	(elf_i386_info_to_howto_rel): Update elf_i386_rtype_to_howto
	call.
	(elf_i386_tls_transition): Likewise.
	(elf_i386_relocate_section): Likewise.
	* elf64-x86-64.c (x86_64_elf_howto_table): Add 16-bit
	R_X86_64_PC16 entry.
	(elf_x86_64_rtype_to_howto): Use 16-bit R_X86_64_PC16 if input
	has 16-bit mode instructions.
	* elfxx-x86.c (_bfd_x86_elf_parse_gnu_properties): Set
	elf_x86_has_code16 if relocatable input is marked with
	GNU_PROPERTY_X86_FEATURE_2_CODE16.
	* elfxx-x86.h (elf_x86_obj_tdata): Add has_code16.
	(elf_x86_has_code16): New.

binutils/

	PR ld/27905
	* readelf.c (decode_x86_feature_2): Support
	GNU_PROPERTY_X86_FEATURE_2_CODE16.

gas/

	PR ld/27905
	* config/tc-i386.c (set_code_flag): Update x86_feature_2_used
	with GNU_PROPERTY_X86_FEATURE_2_CODE16 for .code16 in ELF
	object.
	(set_16bit_gcc_code_flag): Likewise.
	(x86_cleanup): Always generate the GNU property note if
	x86_feature_2_used isn't 0.
	* testsuite/gas/i386/code16-2.d: New file.
	* testsuite/gas/i386/code16-2.s: Likewise.
	* testsuite/gas/i386/x86-64-code16-2.d: Likewise.
	* testsuite/gas/i386/i386.exp: Run code16-2 and x86-64-code16-2.

include/

	PR ld/27905
	* elf/common.h (GNU_PROPERTY_X86_FEATURE_2_CODE16): New.

ld/

	PR ld/27905
	* testsuite/ld-i386/code16.d: New file.
	* testsuite/ld-i386/code16.t: Likewise.
	* testsuite/ld-x86-64/code16.d: Likewise.
	* testsuite/ld-x86-64/code16.t: Likewise.
	* testsuite/ld-i386/i386.exp: Run code16.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
This commit is contained in:
H.J. Lu
2021-05-26 12:13:13 -07:00
parent 11bb5c41eb
commit 50c95a739c
22 changed files with 223 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
bfd/ChangeLog
View File

@ -1,3 +1,24 @@
2021-05-26 H.J. Lu <hongjiu.lu@intel.com>
PR ld/27905
* elf32-i386.c: Include "libiberty.h".
(elf_howto_table): Add 16-bit R_386_PC16 entry.
(elf_i386_rtype_to_howto): Add a BFD argument. Use 16-bit
R_386_PC16 if input has 16-bit mode instructions.
(elf_i386_info_to_howto_rel): Update elf_i386_rtype_to_howto
call.
(elf_i386_tls_transition): Likewise.
(elf_i386_relocate_section): Likewise.
* elf64-x86-64.c (x86_64_elf_howto_table): Add 16-bit
R_X86_64_PC16 entry.
(elf_x86_64_rtype_to_howto): Use 16-bit R_X86_64_PC16 if input
has 16-bit mode instructions.
* elfxx-x86.c (_bfd_x86_elf_parse_gnu_properties): Set
elf_x86_has_code16 if relocatable input is marked with
GNU_PROPERTY_X86_FEATURE_2_CODE16.
* elfxx-x86.h (elf_x86_obj_tdata): Add has_code16.
(elf_x86_has_code16): New.
2021-05-26 Nelson Chu <nelson.chu@sifive.com>
* elfxx-riscv.h (check_unknown_prefixed_ext): New bool.

23
bfd/elf32-i386.c
View File

@ -22,6 +22,7 @@
#include "elf-vxworks.h"
#include "dwarf2.h"
#include "opcode/i386.h"
#include "libiberty.h"
/* 386 uses REL relocations instead of RELA. */
#define USE_REL 1
@ -175,10 +176,14 @@ static reloc_howto_type elf_howto_table[]=
false, /* partial_inplace */
0, /* src_mask */
0, /* dst_mask */
false) /* pcrel_offset */
false), /* pcrel_offset */
#define R_386_vt (R_386_GNU_VTENTRY + 1 - R_386_vt_offset)
/* Use complain_overflow_bitfield on R_386_PC16 for code16. */
HOWTO(R_386_PC16, 0, 1, 16, true, 0, complain_overflow_bitfield,
bfd_elf_generic_reloc, "R_386_PC16",
true, 0xffff, 0xffff, true)
};
#define X86_PCREL_TYPE_P(TYPE) ((TYPE) == R_386_PC32)
@ -369,7 +374,7 @@ elf_i386_reloc_name_lookup (bfd *abfd ATTRIBUTE_UNUSED,
}
static reloc_howto_type *
elf_i386_rtype_to_howto (unsigned r_type)
elf_i386_rtype_to_howto (bfd *abfd, unsigned r_type)
{
unsigned int indx;
@ -384,6 +389,11 @@ elf_i386_rtype_to_howto (unsigned r_type)
/* PR 17512: file: 0f67f69d. */
if (elf_howto_table [indx].type != r_type)
return NULL;
/* Use complain_overflow_bitfield on R_386_PC16 for code16. */
if (r_type == (unsigned int) R_386_PC16 && elf_x86_has_code16 (abfd))
indx = ARRAY_SIZE (elf_howto_table) - 1;
return &elf_howto_table[indx];
}
@ -394,7 +404,8 @@ elf_i386_info_to_howto_rel (bfd *abfd,
{
unsigned int r_type = ELF32_R_TYPE (dst->r_info);
if ((cache_ptr->howto = elf_i386_rtype_to_howto (r_type)) == NULL)
if ((cache_ptr->howto = elf_i386_rtype_to_howto (abfd, r_type))
== NULL)
{
/* xgettext:c-format */
_bfd_error_handler (_("%pB: unsupported relocation type %#x"),
@ -1142,8 +1153,8 @@ elf_i386_tls_transition (struct bfd_link_info *info, bfd *abfd,
reloc_howto_type *from, *to;
const char *name;
from = elf_i386_rtype_to_howto (from_type);
to = elf_i386_rtype_to_howto (to_type);
from = elf_i386_rtype_to_howto (abfd, from_type);
to = elf_i386_rtype_to_howto (abfd, to_type);
if (h)
name = h->root.root.string;
@ -2074,7 +2085,7 @@ elf_i386_relocate_section (bfd *output_bfd,
continue;
}
howto = elf_i386_rtype_to_howto (r_type);
howto = elf_i386_rtype_to_howto (input_bfd, r_type);
if (howto == NULL)
return _bfd_unrecognized_reloc (input_bfd, input_section, r_type);

12
bfd/elf64-x86-64.c
View File

@ -187,6 +187,10 @@ static reloc_howto_type x86_64_elf_howto_table[] =
_bfd_elf_rel_vtable_reloc_fn, "R_X86_64_GNU_VTENTRY", false, 0, 0,
false),
/* Use complain_overflow_bitfield on R_X86_64_PC16 for code16. */
HOWTO(R_X86_64_PC16, 0, 1, 16, true, 0, complain_overflow_bitfield,
bfd_elf_generic_reloc, "R_X86_64_PC16", false, 0, 0xffff, true),
/* Use complain_overflow_bitfield on R_X86_64_32 for x32. */
HOWTO(R_X86_64_32, 0, 2, 32, false, 0, complain_overflow_bitfield,
bfd_elf_generic_reloc, "R_X86_64_32", false, 0, 0xffffffff,
@ -270,6 +274,14 @@ elf_x86_64_rtype_to_howto (bfd *abfd, unsigned r_type)
else
i = ARRAY_SIZE (x86_64_elf_howto_table) - 1;
}
else if (r_type == (unsigned int) R_X86_64_PC16)
{
/* Use complain_overflow_bitfield on R_X86_64_PC16 for code16. */
if (elf_x86_has_code16 (abfd))
i = ARRAY_SIZE (x86_64_elf_howto_table) - 2;
else
i = r_type;
}
else if (r_type < (unsigned int) R_X86_64_GNU_VTINHERIT
|| r_type >= (unsigned int) R_X86_64_max)
{

9
bfd/elfxx-x86.c
View File

@ -2353,6 +2353,7 @@ _bfd_x86_elf_parse_gnu_properties (bfd *abfd, unsigned int type,
|| (type >= GNU_PROPERTY_X86_UINT32_OR_AND_LO
&& type <= GNU_PROPERTY_X86_UINT32_OR_AND_HI))
{
unsigned int number;
if (datasz != 4)
{
_bfd_error_handler
@ -2361,7 +2362,13 @@ _bfd_x86_elf_parse_gnu_properties (bfd *abfd, unsigned int type,
return property_corrupt;
}
prop = _bfd_elf_get_property (abfd, type, datasz);
prop->u.number |= bfd_h_get_32 (abfd, ptr);
number = bfd_h_get_32 (abfd, ptr);
if ((abfd->flags
& (DYNAMIC | BFD_LINKER_CREATED | BFD_PLUGIN)) == 0
&& type == GNU_PROPERTY_X86_FEATURE_2_USED
&& (number & GNU_PROPERTY_X86_FEATURE_2_CODE16) != 0)
elf_x86_has_code16 (abfd) = 1;
prop->u.number |= number;
prop->pr_kind = property_number;
return property_number;
}

6
bfd/elfxx-x86.h
View File

@ -549,6 +549,9 @@ struct elf_x86_obj_tdata
/* GOTPLT entries for TLS descriptors. */
bfd_vma *local_tlsdesc_gotent;
/* Set if the objec file has 16-bit code. */
unsigned int has_code16 : 1;
};
enum elf_x86_plt_type
@ -584,6 +587,9 @@ struct elf_x86_plt
#define elf_x86_local_tlsdesc_gotent(abfd) \
(elf_x86_tdata (abfd)->local_tlsdesc_gotent)
#define elf_x86_has_code16(abfd) \
(elf_x86_tdata (abfd)->has_code16)
#define elf_x86_compute_jump_table_size(htab) \
((htab)->elf.srelplt->reloc_count * (htab)->got_entry_size)

6
binutils/ChangeLog
View File

@ -1,3 +1,9 @@
2021-05-26 H.J. Lu <hongjiu.lu@intel.com>
PR ld/27905
* readelf.c (decode_x86_feature_2): Support
GNU_PROPERTY_X86_FEATURE_2_CODE16.
2021-05-23 Tiezhu Yang <yangtiezhu@loongson.cn>
* readelf.c (get_machine_name): Change Loongson Loongarch to

3
binutils/readelf.c
View File

@ -19140,6 +19140,9 @@ decode_x86_feature_2 (unsigned int bitmask)
case GNU_PROPERTY_X86_FEATURE_2_XSAVEC:
printf ("XSAVEC");
break;
case GNU_PROPERTY_X86_FEATURE_2_CODE16:
printf ("CODE16");
break;
default:
printf (_("<unknown: %x>"), bit);
break;

14
gas/ChangeLog
View File

@ -1,3 +1,17 @@
2021-05-26 H.J. Lu <hongjiu.lu@intel.com>
PR ld/27905
* config/tc-i386.c (set_code_flag): Update x86_feature_2_used
with GNU_PROPERTY_X86_FEATURE_2_CODE16 for .code16 in ELF
object.
(set_16bit_gcc_code_flag): Likewise.
(x86_cleanup): Always generate the GNU property note if
x86_feature_2_used isn't 0.
* testsuite/gas/i386/code16-2.d: New file.
* testsuite/gas/i386/code16-2.s: Likewise.
* testsuite/gas/i386/x86-64-code16-2.d: Likewise.
* testsuite/gas/i386/i386.exp: Run code16-2 and x86-64-code16-2.
2021-05-26 Sebastien Villemot <sebastien@debian.org>
PR gas/27906

55
gas/config/tc-i386.c
View File

@ -2695,6 +2695,10 @@ static void
set_code_flag (int value)
{
update_code_flag (value, 0);
#if defined (OBJ_ELF) || defined (OBJ_MAYBE_ELF)
if (value == CODE_16BIT)
x86_feature_2_used |= GNU_PROPERTY_X86_FEATURE_2_CODE16;
#endif
}
static void
@ -2706,6 +2710,10 @@ set_16bit_gcc_code_flag (int new_code_flag)
cpu_arch_flags.bitfield.cpu64 = 0;
cpu_arch_flags.bitfield.cpuno64 = 1;
stackop_size = LONG_MNEM_SUFFIX;
#if defined (OBJ_ELF) || defined (OBJ_MAYBE_ELF)
if (new_code_flag == CODE_16BIT)
x86_feature_2_used |= GNU_PROPERTY_X86_FEATURE_2_CODE16;
#endif
}
static void
@ -9032,7 +9040,7 @@ x86_cleanup (void)
unsigned int isa_1_descsz_raw, feature_2_descsz_raw;
unsigned int padding;
if (!IS_ELF || !x86_used_note)
if (!IS_ELF || (!x86_used_note && !x86_feature_2_used))
return;
x86_feature_2_used |= GNU_PROPERTY_X86_FEATURE_2_X86;
@ -9072,15 +9080,23 @@ x86_cleanup (void)
bfd_set_section_alignment (sec, alignment);
elf_section_type (sec) = SHT_NOTE;
/* GNU_PROPERTY_X86_ISA_1_USED: 4-byte type + 4-byte data size
+ 4-byte data */
isa_1_descsz_raw = 4 + 4 + 4;
/* Align GNU_PROPERTY_X86_ISA_1_USED. */
isa_1_descsz = (isa_1_descsz_raw + align_size_1) & ~align_size_1;
if (x86_used_note)
{
/* GNU_PROPERTY_X86_ISA_1_USED: 4-byte type + 4-byte data size
+ 4-byte data */
isa_1_descsz_raw = 4 + 4 + 4;
/* Align GNU_PROPERTY_X86_ISA_1_USED. */
isa_1_descsz = (isa_1_descsz_raw + align_size_1) & ~align_size_1;
}
else
{
isa_1_descsz_raw = 0;
isa_1_descsz = 0;
}
feature_2_descsz_raw = isa_1_descsz;
/* GNU_PROPERTY_X86_FEATURE_2_USED: 4-byte type + 4-byte data size
+ 4-byte data */
+ 4-byte data */
feature_2_descsz_raw += 4 + 4 + 4;
/* Align GNU_PROPERTY_X86_FEATURE_2_USED. */
feature_2_descsz = ((feature_2_descsz_raw + align_size_1)
@ -9102,20 +9118,23 @@ x86_cleanup (void)
/* Write n_name. */
memcpy (p + 4 * 3, "GNU", 4);
/* Write 4-byte type. */
md_number_to_chars (p + 4 * 4,
(valueT) GNU_PROPERTY_X86_ISA_1_USED, 4);
if (isa_1_descsz != 0)
{
/* Write 4-byte type. */
md_number_to_chars (p + 4 * 4,
(valueT) GNU_PROPERTY_X86_ISA_1_USED, 4);
/* Write 4-byte data size. */
md_number_to_chars (p + 4 * 5, (valueT) 4, 4);
/* Write 4-byte data size. */
md_number_to_chars (p + 4 * 5, (valueT) 4, 4);
/* Write 4-byte data. */
md_number_to_chars (p + 4 * 6, (valueT) x86_isa_1_used, 4);
/* Write 4-byte data. */
md_number_to_chars (p + 4 * 6, (valueT) x86_isa_1_used, 4);
/* Zero out paddings. */
padding = isa_1_descsz - isa_1_descsz_raw;
if (padding)
memset (p + 4 * 7, 0, padding);
/* Zero out paddings. */
padding = isa_1_descsz - isa_1_descsz_raw;
if (padding)
memset (p + 4 * 7, 0, padding);
}
/* Write 4-byte type. */
md_number_to_chars (p + isa_1_descsz + 4 * 4,

8
gas/testsuite/gas/i386/code16-2.d Normal file
View File

@ -0,0 +1,8 @@
#name: i386 code16 2
#as: -mx86-used-note=no --generate-missing-build-notes=no
#readelf: -n
Displaying notes found in: .note.gnu.property
[ ]+Owner[ ]+Data size[ ]+Description
GNU 0x[0-9a-f]+ NT_GNU_PROPERTY_TYPE_0
Properties: x86 feature used: x86, CODE16

10
gas/testsuite/gas/i386/code16-2.s Normal file
View File

@ -0,0 +1,10 @@
.code16gcc
.text
.section .text.default_process_op.isra.0,"ax",@progbits
.type default_process_op.isra.0, @function
default_process_op.isra.0:
ret
.section .text.mpt_scsi_process_op,"ax",@progbits
.type mpt_scsi_process_op, @function
mpt_scsi_process_op:
jmp default_process_op.isra.0

2
gas/testsuite/gas/i386/i386.exp
View File

@ -734,6 +734,7 @@ if {[is_elf_format] || [istarget "*-*-vxworks*"]} then {
run_dump_test "property-ldmxcsr"
run_dump_test "property-vldmxcsr"
run_dump_test "property-vzeroall"
run_dump_test "code16-2"
if {![istarget "*-*-dragonfly*"]
&& ![istarget "*-*-gnu*"]
@ -1298,6 +1299,7 @@ if [gas_64_check] then {
run_dump_test "x86-64-property-8"
run_dump_test "x86-64-property-9"
run_dump_test "x86-64-property-14"
run_dump_test "x86-64-code16-2"
if {[istarget "*-*-linux*"]} then {
run_dump_test "x86-64-align-branch-3"

9
gas/testsuite/gas/i386/x86-64-code16-2.d Normal file
View File

@ -0,0 +1,9 @@
#source: code16-2.s
#name: x86-64 code16 2
#as: -mx86-used-note=no --generate-missing-build-notes=no
#readelf: -n
Displaying notes found in: .note.gnu.property
[ ]+Owner[ ]+Data size[ ]+Description
GNU 0x[0-9a-f]+ NT_GNU_PROPERTY_TYPE_0
Properties: x86 feature used: x86, CODE16

5
include/ChangeLog
View File

@ -1,3 +1,8 @@
2021-05-26 H.J. Lu <hongjiu.lu@intel.com>
PR ld/27905
* elf/common.h (GNU_PROPERTY_X86_FEATURE_2_CODE16): New.
2021-05-23 Tiezhu Yang <yangtiezhu@loongson.cn>
* elf/common.h (EM_LOONGARCH): Change Loongson Loongarch to

1
include/elf/common.h
View File

@ -872,6 +872,7 @@
#define GNU_PROPERTY_X86_FEATURE_2_XSAVEC (1U << 9)
#define GNU_PROPERTY_X86_FEATURE_2_TMM (1U << 10)
#define GNU_PROPERTY_X86_FEATURE_2_MASK (1U << 11)
#define GNU_PROPERTY_X86_FEATURE_2_CODE16 (1U << 12)
#define GNU_PROPERTY_X86_COMPAT_2_ISA_1_NEEDED \
(GNU_PROPERTY_X86_UINT32_OR_LO + 0)

10
ld/ChangeLog
View File

@ -1,3 +1,13 @@
2021-05-26 H.J. Lu <hongjiu.lu@intel.com>
PR ld/27905
* testsuite/ld-i386/code16.d: New file.
* testsuite/ld-i386/code16.t: Likewise.
* testsuite/ld-x86-64/code16.d: Likewise.
* testsuite/ld-x86-64/code16.t: Likewise.
* testsuite/ld-i386/i386.exp: Run code16.
* testsuite/ld-x86-64/x86-64.exp: Likewise.
2021-05-26 H.J. Lu <hongjiu.lu@intel.com>
* testsuite/ld-x86-64/ilp32-12.d: New file.

19
ld/testsuite/ld-i386/code16.d Normal file
View File

@ -0,0 +1,19 @@
#name: i386 R_386_PC16 reloc in 16-bit mode
#as: --32 -mx86-used-note=no --generate-missing-build-notes=no
#source: ${srcdir}/../../../gas/testsuite/gas/i386/code16-2.s
#ld: -T code16.t
#objdump: -dw -Mi8086
.*: +file format .*
Disassembly of section .text.default_process_op.isra.0:
0+737c <default_process_op.isra.0>:
+[a-f0-9]+: 66 c3 retl
Disassembly of section .text.mpt_scsi_process_op:
0+f869 <mpt_scsi_process_op>:
+[a-f0-9]+: e9 10 7b jmp 737c <default_process_op.isra.0>
#pass

7
ld/testsuite/ld-i386/code16.t Normal file
View File

@ -0,0 +1,7 @@
OUTPUT_FORMAT("elf32-i386")
OUTPUT_ARCH("i386")
SECTIONS
{
.text.default_process_op.isra.0 0x737c : { *(.text.default_process_op.isra.0) }
.text.mpt_scsi_process_op 0xf869 : { *(.text.mpt_scsi_process_op) }
}

1
ld/testsuite/ld-i386/i386.exp
View File

@ -492,6 +492,7 @@ run_dump_test "property-x86-isa2"
run_dump_test "property-x86-isa3"
run_dump_test "property-x86-isa4"
run_dump_test "pr26869"
run_dump_test "code16"
if { !([istarget "i?86-*-linux*"]
|| [istarget "i?86-*-gnu*"]

19
ld/testsuite/ld-x86-64/code16.d Normal file
View File

@ -0,0 +1,19 @@
#name: x86-64 R_X86_64_PC16 reloc in 16-bit mode
#as: --64 -mx86-used-note=no --generate-missing-build-notes=no
#source: ${srcdir}/../../../gas/testsuite/gas/i386/code16-2.s
#ld: -T code16.t
#objdump: -dw -Mi8086
.*: +file format .*
Disassembly of section .text.default_process_op.isra.0:
0+737c <default_process_op.isra.0>:
+[a-f0-9]+: 66 c3 retl
Disassembly of section .text.mpt_scsi_process_op:
0+f869 <mpt_scsi_process_op>:
+[a-f0-9]+: e9 10 7b jmp 737c <default_process_op.isra.0>
#pass

7
ld/testsuite/ld-x86-64/code16.t Normal file
View File

@ -0,0 +1,7 @@
OUTPUT_FORMAT("elf64-x86-64")
OUTPUT_ARCH("i386:x86-64")
SECTIONS
{
.text.default_process_op.isra.0 0x737c : { *(.text.default_process_op.isra.0) }
.text.mpt_scsi_process_op 0xf869 : { *(.text.mpt_scsi_process_op) }
}

1
ld/testsuite/ld-x86-64/x86-64.exp
View File

@ -474,6 +474,7 @@ run_dump_test "property-x86-isa3"
run_dump_test "property-x86-isa3-x32"
run_dump_test "property-x86-isa4"
run_dump_test "property-x86-isa4-x32"
run_dump_test "code16"
if ![istarget "x86_64-*-linux*"] {
return