* [PATCH v2] x86-64: Add -z mark-plt and -z nomark-plt
@ 2023-09-27 17:19 H.J. Lu
2023-09-28 6:00 ` Jan Beulich
2023-09-28 6:07 ` Jan Beulich
0 siblings, 2 replies; 6+ messages in thread
From: H.J. Lu @ 2023-09-27 17:19 UTC (permalink / raw)
To: binutils
The PLT entry in executables and shared libraries contains an indirect
branch, like
jmp *foo@GOTPCREL(%rip)
push $index_foo
jmp .PLT0
or
endbr64
jmp *foo@GOTPCREL(%rip)
NOP padding
which is used to branch to the function, foo, defined in another object.
Each R_X86_64_JUMP_SLOT relocation has a corresponding PLT entry.
The dynamic tags have been added to the x86-64 psABI to mark such PLT
entries:
https://gitlab.com/x86-psABIs/x86-64-ABI/-/commit/6d824a52a42d173eb838b879616c1be5870b593e
Add an x86-64 linker option, -z mark-plt, to mark PLT entries with
#define DT_X86_64_PLT (DT_LOPROC + 0)
#define DT_X86_64_PLTSZ (DT_LOPROC + 1)
#define DT_X86_64_PLTENT (DT_LOPROC + 3)
1. DT_X86_64_PLT: The address of the procedure linkage table.
2. DT_X86_64_PLTSZ: The total size, in bytes, of the procedure linkage
table.
3. DT_X86_64_PLTENT: The size, in bytes, of a procedure linkage table
entry.
and set the r_addend field of the R_X86_64_JUMP_SLOT relocation to the
memory offset of the indirect branch instruction. The dynamic linker
can use these tags to update the PLT section to direct branch.
bfd/
* elf-linker-x86.h (elf_linker_x86_params): Add mark_plt.
* elf64-x86-64.c (elf_x86_64_finish_dynamic_symbol): Set the
r_addend of R_X86_64_JUMP_SLOT to the indirect branch offset
in PLT entry for -z mark-plt.
* elfxx-x86.c (_bfd_x86_elf_size_dynamic_sections): Add
DT_X86_64_PLT, DT_X86_64_PLTSZ and DT_X86_64_PLTENT for
-z mark-plt.
(_bfd_x86_elf_finish_dynamic_sections): Set DT_X86_64_PLT,
DT_X86_64_PLTSZ and DT_X86_64_PLTENT.
(_bfd_x86_elf_get_synthetic_symtab): Ignore addend for
JUMP_SLOT relocation.
(_bfd_x86_elf_link_setup_gnu_properties): Set
plt_indirect_branch_offset.
* elfxx-x86.h (elf_x86_plt_layout): Add plt_indirect_branch_offset.
binutils/
* readelf.c (get_x86_64_dynamic_type): New function.
(get_dynamic_type): Call get_x86_64_dynamic_type.
include/
* elf/x86-64.h (DT_X86_64_PLT): New.
(DT_X86_64_PLTSZ): Likewise.
(DT_X86_64_PLTENT): Likewise.
ld/
* ld.texi: Document -z mark-plt and -z nomark-plt.
* emulparams/elf32_x86_64.sh: Source x86-64-plt.sh.
* emulparams/elf_x86_64.sh: Likewise.
* emulparams/x86-64-plt.sh: New file.
* testsuite/ld-x86-64/mark-plt-1.s: Likewise.
* testsuite/ld-x86-64/mark-plt-1a-x32.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1a.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1b-x32.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1b.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1c-x32.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1c.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1d-x32.d: Likewise.
* testsuite/ld-x86-64/mark-plt-1d.d: Likewise.
* testsuite/ld-x86-64/x86-64.exp: Run -z mark-plt tests.
---
bfd/elf-linker-x86.h | 3 ++
bfd/elf64-x86-64.c | 7 +++-
bfd/elfxx-x86.c | 47 +++++++++++++++++++++++-
bfd/elfxx-x86.h | 3 ++
binutils/readelf.c | 19 ++++++++++
include/elf/x86-64.h | 5 +++
ld/emulparams/elf32_x86_64.sh | 1 +
ld/emulparams/elf_x86_64.sh | 1 +
ld/emulparams/x86-64-plt.sh | 14 +++++++
ld/ld.texi | 5 +++
ld/testsuite/ld-x86-64/mark-plt-1.s | 7 ++++
ld/testsuite/ld-x86-64/mark-plt-1a-x32.d | 12 ++++++
ld/testsuite/ld-x86-64/mark-plt-1a.d | 12 ++++++
ld/testsuite/ld-x86-64/mark-plt-1b-x32.d | 16 ++++++++
ld/testsuite/ld-x86-64/mark-plt-1b.d | 16 ++++++++
ld/testsuite/ld-x86-64/mark-plt-1c-x32.d | 12 ++++++
ld/testsuite/ld-x86-64/mark-plt-1c.d | 12 ++++++
ld/testsuite/ld-x86-64/mark-plt-1d-x32.d | 16 ++++++++
ld/testsuite/ld-x86-64/mark-plt-1d.d | 16 ++++++++
ld/testsuite/ld-x86-64/x86-64.exp | 8 ++++
20 files changed, 230 insertions(+), 2 deletions(-)
create mode 100644 ld/emulparams/x86-64-plt.sh
create mode 100644 ld/testsuite/ld-x86-64/mark-plt-1.s
create mode 100644 ld/testsuite/ld-x86-64/mark-plt-1a-x32.d
create mode 100644 ld/testsuite/ld-x86-64/mark-plt-1a.d
create mode 100644 ld/testsuite/ld-x86-64/mark-plt-1b-x32.d
create mode 100644 ld/testsuite/ld-x86-64/mark-plt-1b.d
create mode 100644 ld/testsuite/ld-x86-64/mark-plt-1c-x32.d
create mode 100644 ld/testsuite/ld-x86-64/mark-plt-1c.d
create mode 100644 ld/testsuite/ld-x86-64/mark-plt-1d-x32.d
create mode 100644 ld/testsuite/ld-x86-64/mark-plt-1d.d
diff --git a/bfd/elf-linker-x86.h b/bfd/elf-linker-x86.h
index e39dbf21a4f..1e6ecb1bd3b 100644
--- a/bfd/elf-linker-x86.h
+++ b/bfd/elf-linker-x86.h
@@ -61,6 +61,9 @@ struct elf_linker_x86_params
/* Report relative relocations. */
unsigned int report_relative_reloc : 1;
+ /* Mark PLT with dynamic tags. */
+ unsigned int mark_plt : 1;
+
/* X86-64 ISA level needed. */
unsigned int isa_level;
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index e7a0a9166f5..3b7a8aeee11 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -4455,7 +4455,12 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
else
{
rela.r_info = htab->r_info (h->dynindx, R_X86_64_JUMP_SLOT);
- rela.r_addend = 0;
+ if (htab->params->mark_plt)
+ rela.r_addend = (resolved_plt->output_section->vma
+ + plt_offset
+ + htab->plt.plt_indirect_branch_offset);
+ else
+ rela.r_addend = 0;
plt_index = htab->next_jump_slot_index++;
}
diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index 103559d77ec..58bd76dc6fc 100644
--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -2525,6 +2525,19 @@ _bfd_x86_elf_size_dynamic_sections (bfd *output_bfd,
}
}
+ asection *resolved_plt = NULL;
+
+ if (htab->params->mark_plt && htab->elf.dynamic_sections_created)
+ {
+ if (htab->plt_second != NULL)
+ resolved_plt = htab->plt_second;
+ else
+ resolved_plt = htab->elf.splt;
+
+ if (resolved_plt != NULL && resolved_plt->size == 0)
+ resolved_plt = NULL;
+ }
+
/* We now have determined the sizes of the various dynamic sections.
Allocate memory for them. */
relocs = false;
@@ -2673,6 +2686,12 @@ _bfd_x86_elf_size_dynamic_sections (bfd *output_bfd,
_bfd_x86_elf_write_sframe_plt (output_bfd, info, SFRAME_PLT_SEC);
}
+ if (resolved_plt != NULL
+ && (!_bfd_elf_add_dynamic_entry (info, DT_X86_64_PLT, 0)
+ || !_bfd_elf_add_dynamic_entry (info, DT_X86_64_PLTSZ, 0)
+ || !_bfd_elf_add_dynamic_entry (info, DT_X86_64_PLTENT, 0)))
+ return false;
+
return _bfd_elf_maybe_vxworks_add_dynamic_tags (output_bfd, info,
relocs);
}
@@ -2747,6 +2766,12 @@ _bfd_x86_elf_finish_dynamic_sections (bfd *output_bfd,
if (sdyn == NULL || htab->elf.sgot == NULL)
abort ();
+ asection *resolved_plt;
+ if (htab->plt_second != NULL)
+ resolved_plt = htab->plt_second;
+ else
+ resolved_plt = htab->elf.splt;
+
sizeof_dyn = bed->s->sizeof_dyn;
dyncon = sdyn->contents;
dynconend = sdyn->contents + sdyn->size;
@@ -2791,6 +2816,19 @@ _bfd_x86_elf_finish_dynamic_sections (bfd *output_bfd,
dyn.d_un.d_ptr = s->output_section->vma + s->output_offset
+ htab->elf.tlsdesc_got;
break;
+
+ case DT_X86_64_PLT:
+ s = resolved_plt->output_section;
+ dyn.d_un.d_ptr = s->output_section->vma + s->output_offset;
+ break;
+
+ case DT_X86_64_PLTSZ:
+ dyn.d_un.d_val = resolved_plt->size;
+ break;
+
+ case DT_X86_64_PLTENT:
+ dyn.d_un.d_ptr = htab->plt.plt_entry_size;
+ break;
}
(*bed->s->swap_dyn_out) (output_bfd, &dyn, dyncon);
@@ -3561,6 +3599,7 @@ _bfd_x86_elf_get_synthetic_symtab (bfd *abfd,
bfd_vma (*get_plt_got_vma) (struct elf_x86_plt *, bfd_vma, bfd_vma,
bfd_vma);
bool (*valid_plt_reloc_p) (unsigned int);
+ unsigned int jump_slot_reloc;
dynrelbuf = NULL;
if (count == 0)
@@ -3601,11 +3640,13 @@ _bfd_x86_elf_get_synthetic_symtab (bfd *abfd,
{
get_plt_got_vma = elf_x86_64_get_plt_got_vma;
valid_plt_reloc_p = elf_x86_64_valid_plt_reloc_p;
+ jump_slot_reloc = R_X86_64_JUMP_SLOT;
}
else
{
get_plt_got_vma = elf_i386_get_plt_got_vma;
valid_plt_reloc_p = elf_i386_valid_plt_reloc_p;
+ jump_slot_reloc = R_386_JUMP_SLOT;
if (got_addr)
{
/* Check .got.plt and then .got to get the _GLOBAL_OFFSET_TABLE_
@@ -3710,7 +3751,9 @@ _bfd_x86_elf_get_synthetic_symtab (bfd *abfd,
len = strlen ((*p->sym_ptr_ptr)->name);
memcpy (names, (*p->sym_ptr_ptr)->name, len);
names += len;
- if (p->addend != 0)
+ /* There may be JUMP_SLOT and IRELATIVE relocations.
+ JUMP_SLOT r_addend should be ignored. */
+ if (p->addend != 0 && p->howto->type != jump_slot_reloc)
{
char buf[30], *a;
@@ -4275,6 +4318,7 @@ _bfd_x86_elf_link_setup_gnu_properties
still be used with LD_AUDIT or LD_PROFILE if PLT entry is used for
canonical function address. */
htab->plt.has_plt0 = 1;
+ htab->plt.plt_indirect_branch_offset = 0;
normal_target = htab->elf.target_os == is_normal;
if (normal_target)
@@ -4283,6 +4327,7 @@ _bfd_x86_elf_link_setup_gnu_properties
{
htab->lazy_plt = init_table->lazy_ibt_plt;
htab->non_lazy_plt = init_table->non_lazy_ibt_plt;
+ htab->plt.plt_indirect_branch_offset = 4;
}
else
{
diff --git a/bfd/elfxx-x86.h b/bfd/elfxx-x86.h
index 3b4644ca478..0bc966b1274 100644
--- a/bfd/elfxx-x86.h
+++ b/bfd/elfxx-x86.h
@@ -502,6 +502,9 @@ struct elf_x86_plt_layout
/* 1 has PLT0. */
unsigned int has_plt0;
+ /* Offset of indirect branch in plt_entry. */
+ unsigned int plt_indirect_branch_offset;
+
/* Offsets into plt_entry that are to be replaced with... */
unsigned int plt_got_offset; /* ... address of this symbol in .got. */
diff --git a/binutils/readelf.c b/binutils/readelf.c
index e9935c010cf..34ac6b62443 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -2522,6 +2522,22 @@ get_riscv_dynamic_type (unsigned long type)
}
}
+static const char *
+get_x86_64_dynamic_type (unsigned long type)
+{
+ switch (type)
+ {
+ case DT_X86_64_PLT:
+ return "DT_X86_64_PLT";
+ case DT_X86_64_PLTSZ:
+ return "DT_X86_64_PLTSZ";
+ case DT_X86_64_PLTENT:
+ return "DT_X86_64_PLTENT";
+ default:
+ return NULL;
+ }
+}
+
static const char *
get_dynamic_type (Filedata * filedata, unsigned long type)
{
@@ -2650,6 +2666,9 @@ get_dynamic_type (Filedata * filedata, unsigned long type)
case EM_RISCV:
result = get_riscv_dynamic_type (type);
break;
+ case EM_X86_64:
+ result = get_x86_64_dynamic_type (type);
+ break;
default:
if (filedata->file_header.e_ident[EI_OSABI] == ELFOSABI_SOLARIS)
result = get_solaris_dynamic_type (type);
diff --git a/include/elf/x86-64.h b/include/elf/x86-64.h
index 60b3c2ad10e..1b87beef41a 100644
--- a/include/elf/x86-64.h
+++ b/include/elf/x86-64.h
@@ -95,4 +95,9 @@ END_RELOC_NUMBERS (R_X86_64_max)
#define SHN_X86_64_LCOMMON (SHN_LORESERVE + 2)
#define SHF_X86_64_LARGE 0x10000000
+
+#define DT_X86_64_PLT (DT_LOPROC + 0)
+#define DT_X86_64_PLTSZ (DT_LOPROC + 1)
+#define DT_X86_64_PLTENT (DT_LOPROC + 3)
+
#endif
diff --git a/ld/emulparams/elf32_x86_64.sh b/ld/emulparams/elf32_x86_64.sh
index 4bff41287c1..f6c6de9cc9e 100644
--- a/ld/emulparams/elf32_x86_64.sh
+++ b/ld/emulparams/elf32_x86_64.sh
@@ -6,6 +6,7 @@ source_sh ${srcdir}/emulparams/call_nop.sh
source_sh ${srcdir}/emulparams/cet.sh
source_sh ${srcdir}/emulparams/x86-report-relative.sh
source_sh ${srcdir}/emulparams/x86-64-level.sh
+source_sh ${srcdir}/emulparams/x86-64-plt.sh
source_sh ${srcdir}/emulparams/static.sh
source_sh ${srcdir}/emulparams/dt-relr.sh
SCRIPT_NAME=elf
diff --git a/ld/emulparams/elf_x86_64.sh b/ld/emulparams/elf_x86_64.sh
index a689a7b6dc4..466da2c48ca 100644
--- a/ld/emulparams/elf_x86_64.sh
+++ b/ld/emulparams/elf_x86_64.sh
@@ -7,6 +7,7 @@ source_sh ${srcdir}/emulparams/cet.sh
source_sh ${srcdir}/emulparams/x86-report-relative.sh
source_sh ${srcdir}/emulparams/x86-64-level.sh
source_sh ${srcdir}/emulparams/x86-64-lam.sh
+source_sh ${srcdir}/emulparams/x86-64-plt.sh
source_sh ${srcdir}/emulparams/static.sh
source_sh ${srcdir}/emulparams/dt-relr.sh
SCRIPT_NAME=elf
diff --git a/ld/emulparams/x86-64-plt.sh b/ld/emulparams/x86-64-plt.sh
new file mode 100644
index 00000000000..92732401dc7
--- /dev/null
+++ b/ld/emulparams/x86-64-plt.sh
@@ -0,0 +1,14 @@
+PARSE_AND_LIST_OPTIONS_X86_64_PLT='
+ fprintf (file, _("\
+ -z mark-plt Mark PLT with dynamic tags\n\
+ -z nomark-plt Do not mark PLT with dynamic tags (default)\n"));
+'
+PARSE_AND_LIST_ARGS_CASE_Z_X86_64_PLT='
+ else if (strcmp (optarg, "mark-plt") == 0)
+ params.mark_plt = 1;
+ else if (strcmp (optarg, "nomark-plt") == 0)
+ params.mark_plt = 0;
+'
+
+PARSE_AND_LIST_OPTIONS="$PARSE_AND_LIST_OPTIONS $PARSE_AND_LIST_OPTIONS_X86_64_PLT"
+PARSE_AND_LIST_ARGS_CASE_Z="$PARSE_AND_LIST_ARGS_CASE_Z $PARSE_AND_LIST_ARGS_CASE_Z_X86_64_PLT"
diff --git a/ld/ld.texi b/ld/ld.texi
index 24e9debfb5f..15e4ae34dbf 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -1475,6 +1475,11 @@ Specify that the object's filters be processed immediately at runtime.
@item max-page-size=@var{value}
Set the maximum memory page size supported to @var{value}.
+@item mark-plt
+@itemx nomark-plt
+Mark PLT entries with dynamic tags, DT_X86_64_PLT, DT_X86_64_PLTSZ and
+DT_X86_64_PLTENT. Supported for x86_64.
+
@item muldefs
Allow multiple definitions.
diff --git a/ld/testsuite/ld-x86-64/mark-plt-1.s b/ld/testsuite/ld-x86-64/mark-plt-1.s
new file mode 100644
index 00000000000..e3f03c89b51
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1.s
@@ -0,0 +1,7 @@
+ .text
+ .globl foo
+ .type foo, @function
+foo:
+ call bar@PLT
+ ret
+ .section .note.GNU-stack,"",@progbits
diff --git a/ld/testsuite/ld-x86-64/mark-plt-1a-x32.d b/ld/testsuite/ld-x86-64/mark-plt-1a-x32.d
new file mode 100644
index 00000000000..2051356be73
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1a-x32.d
@@ -0,0 +1,12 @@
+#source: mark-plt-1.s
+#as: --x32
+#ld: -melf32_x86_64 -shared -z mark-plt
+#readelf: -drW
+
+#...
+ 0x70000000 \(DT_X86_64_PLT\) 0x1000
+ 0x70000001 \(DT_X86_64_PLTSZ\) 0x20
+ 0x70000003 \(DT_X86_64_PLTENT\) 0x10
+#...
+[0-9a-f ]+R_X86_64_JUMP_SLOT +0+ +bar \+ 1010
+#pass
diff --git a/ld/testsuite/ld-x86-64/mark-plt-1a.d b/ld/testsuite/ld-x86-64/mark-plt-1a.d
new file mode 100644
index 00000000000..a252e95e759
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1a.d
@@ -0,0 +1,12 @@
+#source: mark-plt-1.s
+#as: --64
+#ld: -melf_x86_64 -shared -z mark-plt
+#readelf: -drW
+
+#...
+ 0x0000000070000000 \(DT_X86_64_PLT\) 0x1000
+ 0x0000000070000001 \(DT_X86_64_PLTSZ\) 0x20
+ 0x0000000070000003 \(DT_X86_64_PLTENT\) 0x10
+#...
+[0-9a-f ]+R_X86_64_JUMP_SLOT +0+ +bar \+ 1010
+#pass
diff --git a/ld/testsuite/ld-x86-64/mark-plt-1b-x32.d b/ld/testsuite/ld-x86-64/mark-plt-1b-x32.d
new file mode 100644
index 00000000000..74306a0d8d7
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1b-x32.d
@@ -0,0 +1,16 @@
+#source: mark-plt-1.s
+#as: --x32
+#ld: -melf32_x86_64 -shared -z mark-plt
+#objdump: -dw
+
+#...
+0+1010 <bar@plt>:
+ +1010: ff 25 9a 10 00 00 jmp \*0x109a\(%rip\) # 20b0 <bar>
+ +1016: 68 00 00 00 00 push \$0x0
+ +101b: e9 e0 ff ff ff jmp 1000 <bar@plt-0x10>
+
+Disassembly of section .text:
+
+0+1020 <foo>:
+ +1020: e8 eb ff ff ff call 1010 <bar@plt>
+#pass
diff --git a/ld/testsuite/ld-x86-64/mark-plt-1b.d b/ld/testsuite/ld-x86-64/mark-plt-1b.d
new file mode 100644
index 00000000000..dc046c031eb
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1b.d
@@ -0,0 +1,16 @@
+#source: mark-plt-1.s
+#as: --64
+#ld: -melf_x86_64 -shared -z mark-plt
+#objdump: -dw
+
+#...
+0+1010 <bar@plt>:
+ +1010: ff 25 32 11 00 00 jmp \*0x1132\(%rip\) # 2148 <bar>
+ +1016: 68 00 00 00 00 push \$0x0
+ +101b: e9 e0 ff ff ff jmp 1000 <bar@plt-0x10>
+
+Disassembly of section .text:
+
+0+1020 <foo>:
+ +1020: e8 eb ff ff ff call 1010 <bar@plt>
+#pass
diff --git a/ld/testsuite/ld-x86-64/mark-plt-1c-x32.d b/ld/testsuite/ld-x86-64/mark-plt-1c-x32.d
new file mode 100644
index 00000000000..6354dc3bd95
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1c-x32.d
@@ -0,0 +1,12 @@
+#source: mark-plt-1.s
+#as: --x32
+#ld: -melf32_x86_64 -shared -z mark-plt -z ibtplt
+#readelf: -drW
+
+#...
+ 0x70000000 \(DT_X86_64_PLT\) 0x1020
+ 0x70000001 \(DT_X86_64_PLTSZ\) 0x10
+ 0x70000003 \(DT_X86_64_PLTENT\) 0x10
+#...
+[0-9a-f ]+R_X86_64_JUMP_SLOT +0+ +bar \+ 1024
+#pass
diff --git a/ld/testsuite/ld-x86-64/mark-plt-1c.d b/ld/testsuite/ld-x86-64/mark-plt-1c.d
new file mode 100644
index 00000000000..e11e0b7a758
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1c.d
@@ -0,0 +1,12 @@
+#source: mark-plt-1.s
+#as: --64
+#ld: -melf_x86_64 -shared -z mark-plt -z ibtplt
+#readelf: -drW
+
+#...
+ 0x0000000070000000 \(DT_X86_64_PLT\) 0x1020
+ 0x0000000070000001 \(DT_X86_64_PLTSZ\) 0x10
+ 0x0000000070000003 \(DT_X86_64_PLTENT\) 0x10
+#...
+[0-9a-f ]+R_X86_64_JUMP_SLOT +0+ +bar \+ 1024
+#pass
diff --git a/ld/testsuite/ld-x86-64/mark-plt-1d-x32.d b/ld/testsuite/ld-x86-64/mark-plt-1d-x32.d
new file mode 100644
index 00000000000..318ca1f0931
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1d-x32.d
@@ -0,0 +1,16 @@
+#source: mark-plt-1.s
+#as: --x32
+#ld: -melf32_x86_64 -shared -z mark-plt -z ibtplt
+#objdump: -dw
+
+#...
+0+1020 <bar@plt>:
+ +1020: f3 0f 1e fa endbr64
+ +1024: ff 25 86 10 00 00 jmp \*0x1086\(%rip\) # 20b0 <bar>
+ +102a: 66 0f 1f 44 00 00 nopw 0x0\(%rax,%rax,1\)
+
+Disassembly of section .text:
+
+0+1030 <foo>:
+ +1030: e8 eb ff ff ff call 1020 <bar@plt>
+#pass
diff --git a/ld/testsuite/ld-x86-64/mark-plt-1d.d b/ld/testsuite/ld-x86-64/mark-plt-1d.d
new file mode 100644
index 00000000000..2dd63bc10b7
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1d.d
@@ -0,0 +1,16 @@
+#source: mark-plt-1.s
+#as: --64
+#ld: -melf_x86_64 -shared -z mark-plt -z ibtplt
+#objdump: -dw
+
+#...
+0+1020 <bar@plt>:
+ +1020: f3 0f 1e fa endbr64
+ +1024: ff 25 1e 11 00 00 jmp \*0x111e\(%rip\) # 2148 <bar>
+ +102a: 66 0f 1f 44 00 00 nopw 0x0\(%rax,%rax,1\)
+
+Disassembly of section .text:
+
+0+1030 <foo>:
+ +1030: e8 eb ff ff ff call 1020 <bar@plt>
+#pass
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index f94284b079c..3dc8cb47192 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -2228,5 +2228,13 @@ run_dump_test "ibt-plt-3a-x32"
run_dump_test "ibt-plt-3b-x32"
run_dump_test "ibt-plt-3c-x32"
run_dump_test "ibt-plt-3d-x32"
+run_dump_test "mark-plt-1a"
+run_dump_test "mark-plt-1b"
+run_dump_test "mark-plt-1c"
+run_dump_test "mark-plt-1d"
+run_dump_test "mark-plt-1a-x32"
+run_dump_test "mark-plt-1b-x32"
+run_dump_test "mark-plt-1c-x32"
+run_dump_test "mark-plt-1d-x32"
set ASFLAGS "$saved_ASFLAGS"
--
2.41.0
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] x86-64: Add -z mark-plt and -z nomark-plt
2023-09-27 17:19 [PATCH v2] x86-64: Add -z mark-plt and -z nomark-plt H.J. Lu
@ 2023-09-28 6:00 ` Jan Beulich
2023-09-28 6:07 ` Jan Beulich
1 sibling, 0 replies; 6+ messages in thread
From: Jan Beulich @ 2023-09-28 6:00 UTC (permalink / raw)
To: H.J. Lu
On 27.09.2023 19:19, H.J. Lu via Binutils wrote:
> --- a/ld/ld.texi
> +++ b/ld/ld.texi
> @@ -1475,6 +1475,11 @@ Specify that the object's filters be processed immediately at runtime.
> @item max-page-size=@var{value}
> Set the maximum memory page size supported to @var{value}.
>
> +@item mark-plt
> +@itemx nomark-plt
> +Mark PLT entries with dynamic tags, DT_X86_64_PLT, DT_X86_64_PLTSZ and
> +DT_X86_64_PLTENT. Supported for x86_64.
Hmm, you use backwards compatibility issues as justification for not having
a configure time way to default the new behavior to enabled, and then you
don't mention the backwards compatibility aspect here?
Jan
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] x86-64: Add -z mark-plt and -z nomark-plt
2023-09-27 17:19 [PATCH v2] x86-64: Add -z mark-plt and -z nomark-plt H.J. Lu
2023-09-28 6:00 ` Jan Beulich
@ 2023-09-28 6:07 ` Jan Beulich
2023-09-28 7:02 ` Fangrui Song
2023-09-28 14:52 ` H.J. Lu
1 sibling, 2 replies; 6+ messages in thread
From: Jan Beulich @ 2023-09-28 6:07 UTC (permalink / raw)
To: H.J. Lu; +Cc: binutils
On 27.09.2023 19:19, H.J. Lu via Binutils wrote:
> --- a/ld/ld.texi
> +++ b/ld/ld.texi
> @@ -1475,6 +1475,11 @@ Specify that the object's filters be processed immediately at runtime.
> @item max-page-size=@var{value}
> Set the maximum memory page size supported to @var{value}.
>
> +@item mark-plt
> +@itemx nomark-plt
> +Mark PLT entries with dynamic tags, DT_X86_64_PLT, DT_X86_64_PLTSZ and
> +DT_X86_64_PLTENT. Supported for x86_64.
Hmm, you use backwards compatibility issues as justification for not having
a configure time way to default the new behavior to enabled, and then you
don't mention the backwards compatibility aspect here?
Jan
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] x86-64: Add -z mark-plt and -z nomark-plt
2023-09-28 6:07 ` Jan Beulich
@ 2023-09-28 7:02 ` Fangrui Song
2023-09-28 14:52 ` H.J. Lu
1 sibling, 0 replies; 6+ messages in thread
From: Fangrui Song @ 2023-09-28 7:02 UTC (permalink / raw)
To: Jan Beulich; +Cc: H.J. Lu, binutils
On Wed, Sep 27, 2023 at 11:07 PM Jan Beulich via Binutils
<binutils@sourceware.org> wrote:
>
> On 27.09.2023 19:19, H.J. Lu via Binutils wrote:
> > --- a/ld/ld.texi
> > +++ b/ld/ld.texi
> > @@ -1475,6 +1475,11 @@ Specify that the object's filters be processed immediately at runtime.
> > @item max-page-size=@var{value}
> > Set the maximum memory page size supported to @var{value}.
> >
> > +@item mark-plt
> > +@itemx nomark-plt
> > +Mark PLT entries with dynamic tags, DT_X86_64_PLT, DT_X86_64_PLTSZ and
> > +DT_X86_64_PLTENT. Supported for x86_64.
>
> Hmm, you use backwards compatibility issues as justification for not having
> a configure time way to default the new behavior to enabled, and then you
> don't mention the backwards compatibility aspect here?
>
> Jan
For linker defaults, they can be performed either on the linker side
or on the compiler driver side.
If GCC specifies an extra option to ld (like -z relro -z now), I think
it is fine for ld not to have a configure-time option.
(I understand that someone may argue that patching ld has a greater
coverage... I typically refute such arguments. This mark-plt is for a
rtld optimization that unlikely applies to the programs that directly
use ld anyway.)
At least for LLD that I maintain, we prefer not to have
target-specific differences and prefer that the compiler drivers pass
relevant options to the linker.
Linker not having to deal with too many defaults allows testing more
address-related properties in the output, which I find valuable to
catch many bugs without doing distribution testing.
(https://sourceware.org/bugzilla/show_bug.cgi?id=28602)
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] x86-64: Add -z mark-plt and -z nomark-plt
2023-09-28 6:07 ` Jan Beulich
2023-09-28 7:02 ` Fangrui Song
@ 2023-09-28 14:52 ` H.J. Lu
2023-09-28 14:54 ` Jan Beulich
1 sibling, 1 reply; 6+ messages in thread
From: H.J. Lu @ 2023-09-28 14:52 UTC (permalink / raw)
To: Jan Beulich; +Cc: binutils
On Wed, Sep 27, 2023 at 11:07 PM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 27.09.2023 19:19, H.J. Lu via Binutils wrote:
> > --- a/ld/ld.texi
> > +++ b/ld/ld.texi
> > @@ -1475,6 +1475,11 @@ Specify that the object's filters be processed immediately at runtime.
> > @item max-page-size=@var{value}
> > Set the maximum memory page size supported to @var{value}.
> >
> > +@item mark-plt
> > +@itemx nomark-plt
> > +Mark PLT entries with dynamic tags, DT_X86_64_PLT, DT_X86_64_PLTSZ and
> > +DT_X86_64_PLTENT. Supported for x86_64.
>
> Hmm, you use backwards compatibility issues as justification for not having
> a configure time way to default the new behavior to enabled, and then you
> don't mention the backwards compatibility aspect here?
>
How about this:
@item mark-plt
@itemx nomark-plt
Mark PLT entries with dynamic tags, DT_X86_64_PLT, DT_X86_64_PLTSZ and
DT_X86_64_PLTENT. Since this option stores a non-zero value in the
r_addend field of R_X86_64_JUMP_SLOT relocations, the resulting
executables and shared libraries are incompatible with dynamic linkers,
such as those in older versions of glibc without the change to ignore
r_addend in R_X86_64_GLOB_DAT and R_X86_64_JUMP_SLOT relocations, which
don't ignore the r_addend field of R_X86_64_JUMP_SLOT relocations.
Supported for x86_64.
--
H.J.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] x86-64: Add -z mark-plt and -z nomark-plt
2023-09-28 14:52 ` H.J. Lu
@ 2023-09-28 14:54 ` Jan Beulich
0 siblings, 0 replies; 6+ messages in thread
From: Jan Beulich @ 2023-09-28 14:54 UTC (permalink / raw)
To: H.J. Lu; +Cc: binutils
On 28.09.2023 16:52, H.J. Lu wrote:
> On Wed, Sep 27, 2023 at 11:07 PM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 27.09.2023 19:19, H.J. Lu via Binutils wrote:
>>> --- a/ld/ld.texi
>>> +++ b/ld/ld.texi
>>> @@ -1475,6 +1475,11 @@ Specify that the object's filters be processed immediately at runtime.
>>> @item max-page-size=@var{value}
>>> Set the maximum memory page size supported to @var{value}.
>>>
>>> +@item mark-plt
>>> +@itemx nomark-plt
>>> +Mark PLT entries with dynamic tags, DT_X86_64_PLT, DT_X86_64_PLTSZ and
>>> +DT_X86_64_PLTENT. Supported for x86_64.
>>
>> Hmm, you use backwards compatibility issues as justification for not having
>> a configure time way to default the new behavior to enabled, and then you
>> don't mention the backwards compatibility aspect here?
>>
>
> How about this:
>
> @item mark-plt
> @itemx nomark-plt
> Mark PLT entries with dynamic tags, DT_X86_64_PLT, DT_X86_64_PLTSZ and
> DT_X86_64_PLTENT. Since this option stores a non-zero value in the
> r_addend field of R_X86_64_JUMP_SLOT relocations, the resulting
> executables and shared libraries are incompatible with dynamic linkers,
> such as those in older versions of glibc without the change to ignore
> r_addend in R_X86_64_GLOB_DAT and R_X86_64_JUMP_SLOT relocations, which
> don't ignore the r_addend field of R_X86_64_JUMP_SLOT relocations.
> Supported for x86_64.
Reads okay to me, thanks.
Jan
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-09-28 14:54 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-09-27 17:19 [PATCH v2] x86-64: Add -z mark-plt and -z nomark-plt H.J. Lu
2023-09-28 6:00 ` Jan Beulich
2023-09-28 6:07 ` Jan Beulich
2023-09-28 7:02 ` Fangrui Song
2023-09-28 14:52 ` H.J. Lu
2023-09-28 14:54 ` Jan Beulich
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