diff mbox series

[10/10] ld: Add glibc dependency for DT_RELR

Message ID 20220107190631.309790-11-hjl.tools@gmail.com
State Superseded
Headers show
Series ld: Implement DT_RELR for x86 | expand

Checks

Context Check Description
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Commit Message

H.J. Lu Jan. 7, 2022, 7:06 p.m. UTC
When DT_RELR is enabled, to avoid random run-time crash with older glibc
binaries without DT_RELR support, add a GLIBC_ABI_DT_RELR symbol version,
which is provided by glibc with DT_RELR support, dependency on the shared
C library if it provides a GLIBC_2.XX symbol version.

bfd/

	* elflink.c (elf_link_add_dt_relr_dependency): New function.
	(bfd_elf_size_dynamic_sections): Call
	elf_link_add_dt_relr_dependency if DT_RELR is enabled.

ld/

	* ld.texi: Mention GLIBC_ABI_DT_RELR in -z pack-relative-relocs
	entry.
	* testsuite/ld-elf/dt-relr-glibc-1.c: New file.
	* testsuite/ld-elf/dt-relr-glibc-1a.rd: Likewise.
	* testsuite/ld-elf/dt-relr-glibc-1b.rd: Likewise.
	* testsuite/ld-elf/dt-relr.exp: Likewise.
---
 bfd/elflink.c                           | 86 +++++++++++++++++++++++++
 ld/ld.texi                              |  4 +-
 ld/testsuite/ld-elf/dt-relr-glibc-1.c   | 11 ++++
 ld/testsuite/ld-elf/dt-relr-glibc-1a.rd |  4 ++
 ld/testsuite/ld-elf/dt-relr-glibc-1b.rd |  7 ++
 ld/testsuite/ld-elf/dt-relr.exp         | 44 +++++++++++++
 6 files changed, 155 insertions(+), 1 deletion(-)
 create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1.c
 create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
 create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
 create mode 100644 ld/testsuite/ld-elf/dt-relr.exp

Comments

Fangrui Song Jan. 8, 2022, 4:43 a.m. UTC | #1
On 2022-01-07, H.J. Lu via Binutils wrote:
>When DT_RELR is enabled, to avoid random run-time crash with older glibc
>binaries without DT_RELR support, add a GLIBC_ABI_DT_RELR symbol version,
>which is provided by glibc with DT_RELR support, dependency on the shared
>C library if it provides a GLIBC_2.XX symbol version.
>
>bfd/
>
>	* elflink.c (elf_link_add_dt_relr_dependency): New function.
>	(bfd_elf_size_dynamic_sections): Call
>	elf_link_add_dt_relr_dependency if DT_RELR is enabled.
>
>ld/
>
>	* ld.texi: Mention GLIBC_ABI_DT_RELR in -z pack-relative-relocs
>	entry.
>	* testsuite/ld-elf/dt-relr-glibc-1.c: New file.
>	* testsuite/ld-elf/dt-relr-glibc-1a.rd: Likewise.
>	* testsuite/ld-elf/dt-relr-glibc-1b.rd: Likewise.
>	* testsuite/ld-elf/dt-relr.exp: Likewise.
>---
> bfd/elflink.c                           | 86 +++++++++++++++++++++++++
> ld/ld.texi                              |  4 +-
> ld/testsuite/ld-elf/dt-relr-glibc-1.c   | 11 ++++
> ld/testsuite/ld-elf/dt-relr-glibc-1a.rd |  4 ++
> ld/testsuite/ld-elf/dt-relr-glibc-1b.rd |  7 ++
> ld/testsuite/ld-elf/dt-relr.exp         | 44 +++++++++++++
> 6 files changed, 155 insertions(+), 1 deletion(-)
> create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1.c
> create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
> create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
> create mode 100644 ld/testsuite/ld-elf/dt-relr.exp
>
>diff --git a/bfd/elflink.c b/bfd/elflink.c
>index 31b13f5df7a..05ac1cb7a63 100644
>--- a/bfd/elflink.c
>+++ b/bfd/elflink.c
>@@ -2213,6 +2213,85 @@ _bfd_elf_export_symbol (struct elf_link_hash_entry *h, void *data)
>   return true;
> }
> 
>+/* Return true if GLIBC_ABI_DT_RELR is added to the list of version
>+   dependencies successfully.  GLIBC_ABI_DT_RELR will be put into the
>+   .gnu.version_r section.  */
>+
>+static bool
>+elf_link_add_dt_relr_dependency (struct elf_find_verdep_info *rinfo)
>+{
>+  bfd *glibc_bfd = NULL;
>+  Elf_Internal_Verneed *t;
>+  Elf_Internal_Vernaux *a;
>+  size_t amt;
>+  const char *relr = "GLIBC_ABI_DT_RELR";
>+
>+  /* See if we already know about GLIBC_PRIVATE_DT_RELR.  */
>+  for (t = elf_tdata (rinfo->info->output_bfd)->verref;
>+       t != NULL;
>+       t = t->vn_nextref)
>+    {
>+      const char *soname = bfd_elf_get_dt_soname (t->vn_bfd);
>+      /* Skip the shared library if it isn't libc.so.  */
>+      if (!soname || !startswith (soname, "libc.so."))
>+	continue;

Having the dependency on ld.so is better.
(The linker knows the --dynamic-linker value.)
libc.so does not need to know whether DT_RELR is used.

It's also easier on glibc side.
Defining  __glibc_abi_dt_relr@@GLIBC_ABI_DT_RELR in elf/Versions is
simpler than defining it in libc.so and updating every libc.abilist.

>+      for (a = t->vn_auxptr; a != NULL; a = a->vna_nextptr)
>+	{
>+	  /* Return if GLIBC_PRIVATE_DT_RELR dependency has been
>+	     added.  */
>+	  if (a->vna_nodename == relr
>+	      || strcmp (a->vna_nodename, relr) == 0)
>+	    return true;
>+
>+	  /* Check if libc.so provides GLIBC_2.XX version.  */
>+	  if (!glibc_bfd && startswith (a->vna_nodename, "GLIBC_2."))
>+	    glibc_bfd = t->vn_bfd;
>+	}
>+
>+      break;
>+    }
>+
>+  /* Skip if it isn't linked against glibc.  */
>+  if (glibc_bfd == NULL)
>+    return true;
>+
>+  /* This is a new version.  Add it to tree we are building.  */
>+  if (t == NULL)
>+    {
>+      amt = sizeof *t;
>+      t = (Elf_Internal_Verneed *) bfd_zalloc (rinfo->info->output_bfd,
>+					       amt);
>+      if (t == NULL)
>+	{
>+	  rinfo->failed = true;
>+	  return false;
>+	}
>+
>+      t->vn_bfd = glibc_bfd;
>+      t->vn_nextref = elf_tdata (rinfo->info->output_bfd)->verref;
>+      elf_tdata (rinfo->info->output_bfd)->verref = t;
>+    }
>+
>+  amt = sizeof *a;
>+  a = (Elf_Internal_Vernaux *) bfd_zalloc (rinfo->info->output_bfd, amt);
>+  if (a == NULL)
>+    {
>+      rinfo->failed = true;
>+      return false;
>+    }
>+
>+  a->vna_nodename = relr;
>+  a->vna_flags = 0;
>+  a->vna_nextptr = t->vn_auxptr;
>+  a->vna_other = rinfo->vers + 1;
>+  ++rinfo->vers;
>+
>+  t->vn_auxptr = a;
>+
>+  return true;
>+}
>+
> /* Look through the symbols which are defined in other shared
>    libraries and referenced here.  Update the list of version
>    dependencies.  This will be put into the .gnu.version_r section.
>@@ -6940,6 +7019,13 @@ bfd_elf_size_dynamic_sections (bfd *output_bfd,
>       if (sinfo.failed)
> 	return false;
>
>+      if (info->enable_dt_relr)
>+	{
>+	  elf_link_add_dt_relr_dependency (&sinfo);
>+	  if (sinfo.failed)
>+	    return false;
>+	}
>+
>       if (elf_tdata (output_bfd)->verref == NULL)
> 	s->flags |= SEC_EXCLUDE;
>       else
>diff --git a/ld/ld.texi b/ld/ld.texi
>index 457089ec06a..a16657ddb45 100644
>--- a/ld/ld.texi
>+++ b/ld/ld.texi
>@@ -1439,7 +1439,9 @@ and shared library.  It adds @code{DT_RELR}, @code{DT_RELRSZ} and
> building position-dependent executable and relocatable output.  This
> option also implies @option{combreloc} and @option{--relax}.
> @option{nopack-relative-relocs} is the default, which disables
>-compact relative relocation.  Supported for i386 and x86-64.
>+compact relative relocation.  When linked against the GNU C Library,
>+a GLIBC_ABI_DT_RELR symbol version dependency on the shared C Library
>+is added to the output.  Supported for i386 and x86-64.

> @item relro
> @itemx norelro
>diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1.c b/ld/testsuite/ld-elf/dt-relr-glibc-1.c
>new file mode 100644
>index 00000000000..beacffe29e7
>--- /dev/null
>+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1.c
>@@ -0,0 +1,11 @@
>+#define REL(n) \
>+  static int data##n; \
>+  void *p##n = &data##n;
>+
>+REL(1)
>+REL(2)
>+REL(3)
>+REL(4)
>+REL(5)
>+REL(6)
>+REL(7)
>diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd b/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
>new file mode 100644
>index 00000000000..51bda5d70a1
>--- /dev/null
>+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
>@@ -0,0 +1,4 @@
>+#failif
>+#...
>+  0x[a-f0-9]+:   Name: GLIBC_ABI_DT_RELR  Flags: none  Version: [0-9]+
>+#...
>diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd b/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
>new file mode 100644
>index 00000000000..6556a6d939e
>--- /dev/null
>+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
>@@ -0,0 +1,7 @@
>+#...
>+Version needs section '.gnu.version_r' contains 1 entry:
>+ Addr: 0x[0-9a-f]+ +Offset: 0x[0-9a-f]+ +Link: +[0-9]+ +\(.dynstr\)
>+ +0+: Version: 1 +File: libc\.so\.6(|\.1) +Cnt: +[0-9]+
>+#...
>+  0x[a-f0-9]+:   Name: GLIBC_ABI_DT_RELR  Flags: none  Version: [0-9]+
>+#pass
>diff --git a/ld/testsuite/ld-elf/dt-relr.exp b/ld/testsuite/ld-elf/dt-relr.exp
>new file mode 100644
>index 00000000000..51d21e400ab
>--- /dev/null
>+++ b/ld/testsuite/ld-elf/dt-relr.exp
>@@ -0,0 +1,44 @@
>+# Expect script for DT_RELR.
>+#   Copyright (C) 2022 Free Software Foundation, Inc.
>+#
>+# This file is part of the GNU Binutils.
>+#
>+# This program is free software; you can redistribute it and/or modify
>+# it under the terms of the GNU General Public License as published by
>+# the Free Software Foundation; either version 3 of the License, or
>+# (at your option) any later version.
>+#
>+# This program 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 General Public License for more details.
>+#
>+# You should have received a copy of the GNU General Public License
>+# along with this program; if not, write to the Free Software
>+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
>+# MA 02110-1301, USA.
>+#
>+
>+# Linux tests.
>+if { ![istarget "*-*-linux*"] } {
>+    return
>+}
>+
>+run_cc_link_tests [list \
>+    [list \
>+	"Build dt-relr-glibc-1a.so" \
>+	"-shared $NO_DT_RELR_CC_LDFLAGS" \
>+	"-fPIC" \
>+	{ dt-relr-glibc-1.c } \
>+	{{readelf {--version-info} dt-relr-glibc-1a.rd}} \
>+	"glibc-relr-1a.so" \
>+    ] \
>+    [list \
>+	"Build dt-relr-glibc-1b.so" \
>+	"-shared $DT_RELR_CC_LDFLAGS" \
>+	"-fPIC" \
>+	{ dt-relr-glibc-1.c } \
>+	{{readelf {-W --version-info} dt-relr-glibc-1b.rd}} \
>+	"dt-relr-glibc-1b.so" \
>+    ] \
>+]
>-- 
>2.33.1
>
H.J. Lu Jan. 8, 2022, 4:51 a.m. UTC | #2
On Fri, Jan 7, 2022 at 8:43 PM Fangrui Song <i@maskray.me> wrote:
>
> On 2022-01-07, H.J. Lu via Binutils wrote:
> >When DT_RELR is enabled, to avoid random run-time crash with older glibc
> >binaries without DT_RELR support, add a GLIBC_ABI_DT_RELR symbol version,
> >which is provided by glibc with DT_RELR support, dependency on the shared
> >C library if it provides a GLIBC_2.XX symbol version.
> >
> >bfd/
> >
> >       * elflink.c (elf_link_add_dt_relr_dependency): New function.
> >       (bfd_elf_size_dynamic_sections): Call
> >       elf_link_add_dt_relr_dependency if DT_RELR is enabled.
> >
> >ld/
> >
> >       * ld.texi: Mention GLIBC_ABI_DT_RELR in -z pack-relative-relocs
> >       entry.
> >       * testsuite/ld-elf/dt-relr-glibc-1.c: New file.
> >       * testsuite/ld-elf/dt-relr-glibc-1a.rd: Likewise.
> >       * testsuite/ld-elf/dt-relr-glibc-1b.rd: Likewise.
> >       * testsuite/ld-elf/dt-relr.exp: Likewise.
> >---
> > bfd/elflink.c                           | 86 +++++++++++++++++++++++++
> > ld/ld.texi                              |  4 +-
> > ld/testsuite/ld-elf/dt-relr-glibc-1.c   | 11 ++++
> > ld/testsuite/ld-elf/dt-relr-glibc-1a.rd |  4 ++
> > ld/testsuite/ld-elf/dt-relr-glibc-1b.rd |  7 ++
> > ld/testsuite/ld-elf/dt-relr.exp         | 44 +++++++++++++
> > 6 files changed, 155 insertions(+), 1 deletion(-)
> > create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1.c
> > create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
> > create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
> > create mode 100644 ld/testsuite/ld-elf/dt-relr.exp
> >
> >diff --git a/bfd/elflink.c b/bfd/elflink.c
> >index 31b13f5df7a..05ac1cb7a63 100644
> >--- a/bfd/elflink.c
> >+++ b/bfd/elflink.c
> >@@ -2213,6 +2213,85 @@ _bfd_elf_export_symbol (struct elf_link_hash_entry *h, void *data)
> >   return true;
> > }
> >
> >+/* Return true if GLIBC_ABI_DT_RELR is added to the list of version
> >+   dependencies successfully.  GLIBC_ABI_DT_RELR will be put into the
> >+   .gnu.version_r section.  */
> >+
> >+static bool
> >+elf_link_add_dt_relr_dependency (struct elf_find_verdep_info *rinfo)
> >+{
> >+  bfd *glibc_bfd = NULL;
> >+  Elf_Internal_Verneed *t;
> >+  Elf_Internal_Vernaux *a;
> >+  size_t amt;
> >+  const char *relr = "GLIBC_ABI_DT_RELR";
> >+
> >+  /* See if we already know about GLIBC_PRIVATE_DT_RELR.  */
> >+  for (t = elf_tdata (rinfo->info->output_bfd)->verref;
> >+       t != NULL;
> >+       t = t->vn_nextref)
> >+    {
> >+      const char *soname = bfd_elf_get_dt_soname (t->vn_bfd);
> >+      /* Skip the shared library if it isn't libc.so.  */
> >+      if (!soname || !startswith (soname, "libc.so."))
> >+      continue;
>
> Having the dependency on ld.so is better.
> (The linker knows the --dynamic-linker value.)
> libc.so does not need to know whether DT_RELR is used.
>
> It's also easier on glibc side.
> Defining  __glibc_abi_dt_relr@@GLIBC_ABI_DT_RELR in elf/Versions is
> simpler than defining it in libc.so and updating every libc.abilist.

I chose libc.so instead of ld.so since shared libraries may
not be linked against ld.so.  The glibc change can be simple:

https://patchwork.sourceware.org/project/glibc/patch/20211123223053.3334224-1-hjl.tools@gmail.com/

Please replace GLIBC_ABI_VERSION_GEN2 with
GLIBC_ABI_DT_RELR.

or like

https://gitlab.com/x86-glibc/glibc/-/commit/3bc53baa5304855b5105dabd7726b23d454605fb

I can go either way.




> >+      for (a = t->vn_auxptr; a != NULL; a = a->vna_nextptr)
> >+      {
> >+        /* Return if GLIBC_PRIVATE_DT_RELR dependency has been
> >+           added.  */
> >+        if (a->vna_nodename == relr
> >+            || strcmp (a->vna_nodename, relr) == 0)
> >+          return true;
> >+
> >+        /* Check if libc.so provides GLIBC_2.XX version.  */
> >+        if (!glibc_bfd && startswith (a->vna_nodename, "GLIBC_2."))
> >+          glibc_bfd = t->vn_bfd;
> >+      }
> >+
> >+      break;
> >+    }
> >+
> >+  /* Skip if it isn't linked against glibc.  */
> >+  if (glibc_bfd == NULL)
> >+    return true;
> >+
> >+  /* This is a new version.  Add it to tree we are building.  */
> >+  if (t == NULL)
> >+    {
> >+      amt = sizeof *t;
> >+      t = (Elf_Internal_Verneed *) bfd_zalloc (rinfo->info->output_bfd,
> >+                                             amt);
> >+      if (t == NULL)
> >+      {
> >+        rinfo->failed = true;
> >+        return false;
> >+      }
> >+
> >+      t->vn_bfd = glibc_bfd;
> >+      t->vn_nextref = elf_tdata (rinfo->info->output_bfd)->verref;
> >+      elf_tdata (rinfo->info->output_bfd)->verref = t;
> >+    }
> >+
> >+  amt = sizeof *a;
> >+  a = (Elf_Internal_Vernaux *) bfd_zalloc (rinfo->info->output_bfd, amt);
> >+  if (a == NULL)
> >+    {
> >+      rinfo->failed = true;
> >+      return false;
> >+    }
> >+
> >+  a->vna_nodename = relr;
> >+  a->vna_flags = 0;
> >+  a->vna_nextptr = t->vn_auxptr;
> >+  a->vna_other = rinfo->vers + 1;
> >+  ++rinfo->vers;
> >+
> >+  t->vn_auxptr = a;
> >+
> >+  return true;
> >+}
> >+
> > /* Look through the symbols which are defined in other shared
> >    libraries and referenced here.  Update the list of version
> >    dependencies.  This will be put into the .gnu.version_r section.
> >@@ -6940,6 +7019,13 @@ bfd_elf_size_dynamic_sections (bfd *output_bfd,
> >       if (sinfo.failed)
> >       return false;
> >
> >+      if (info->enable_dt_relr)
> >+      {
> >+        elf_link_add_dt_relr_dependency (&sinfo);
> >+        if (sinfo.failed)
> >+          return false;
> >+      }
> >+
> >       if (elf_tdata (output_bfd)->verref == NULL)
> >       s->flags |= SEC_EXCLUDE;
> >       else
> >diff --git a/ld/ld.texi b/ld/ld.texi
> >index 457089ec06a..a16657ddb45 100644
> >--- a/ld/ld.texi
> >+++ b/ld/ld.texi
> >@@ -1439,7 +1439,9 @@ and shared library.  It adds @code{DT_RELR}, @code{DT_RELRSZ} and
> > building position-dependent executable and relocatable output.  This
> > option also implies @option{combreloc} and @option{--relax}.
> > @option{nopack-relative-relocs} is the default, which disables
> >-compact relative relocation.  Supported for i386 and x86-64.
> >+compact relative relocation.  When linked against the GNU C Library,
> >+a GLIBC_ABI_DT_RELR symbol version dependency on the shared C Library
> >+is added to the output.  Supported for i386 and x86-64.
>
> > @item relro
> > @itemx norelro
> >diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1.c b/ld/testsuite/ld-elf/dt-relr-glibc-1.c
> >new file mode 100644
> >index 00000000000..beacffe29e7
> >--- /dev/null
> >+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1.c
> >@@ -0,0 +1,11 @@
> >+#define REL(n) \
> >+  static int data##n; \
> >+  void *p##n = &data##n;
> >+
> >+REL(1)
> >+REL(2)
> >+REL(3)
> >+REL(4)
> >+REL(5)
> >+REL(6)
> >+REL(7)
> >diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd b/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
> >new file mode 100644
> >index 00000000000..51bda5d70a1
> >--- /dev/null
> >+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
> >@@ -0,0 +1,4 @@
> >+#failif
> >+#...
> >+  0x[a-f0-9]+:   Name: GLIBC_ABI_DT_RELR  Flags: none  Version: [0-9]+
> >+#...
> >diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd b/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
> >new file mode 100644
> >index 00000000000..6556a6d939e
> >--- /dev/null
> >+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
> >@@ -0,0 +1,7 @@
> >+#...
> >+Version needs section '.gnu.version_r' contains 1 entry:
> >+ Addr: 0x[0-9a-f]+ +Offset: 0x[0-9a-f]+ +Link: +[0-9]+ +\(.dynstr\)
> >+ +0+: Version: 1 +File: libc\.so\.6(|\.1) +Cnt: +[0-9]+
> >+#...
> >+  0x[a-f0-9]+:   Name: GLIBC_ABI_DT_RELR  Flags: none  Version: [0-9]+
> >+#pass
> >diff --git a/ld/testsuite/ld-elf/dt-relr.exp b/ld/testsuite/ld-elf/dt-relr.exp
> >new file mode 100644
> >index 00000000000..51d21e400ab
> >--- /dev/null
> >+++ b/ld/testsuite/ld-elf/dt-relr.exp
> >@@ -0,0 +1,44 @@
> >+# Expect script for DT_RELR.
> >+#   Copyright (C) 2022 Free Software Foundation, Inc.
> >+#
> >+# This file is part of the GNU Binutils.
> >+#
> >+# This program is free software; you can redistribute it and/or modify
> >+# it under the terms of the GNU General Public License as published by
> >+# the Free Software Foundation; either version 3 of the License, or
> >+# (at your option) any later version.
> >+#
> >+# This program 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 General Public License for more details.
> >+#
> >+# You should have received a copy of the GNU General Public License
> >+# along with this program; if not, write to the Free Software
> >+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
> >+# MA 02110-1301, USA.
> >+#
> >+
> >+# Linux tests.
> >+if { ![istarget "*-*-linux*"] } {
> >+    return
> >+}
> >+
> >+run_cc_link_tests [list \
> >+    [list \
> >+      "Build dt-relr-glibc-1a.so" \
> >+      "-shared $NO_DT_RELR_CC_LDFLAGS" \
> >+      "-fPIC" \
> >+      { dt-relr-glibc-1.c } \
> >+      {{readelf {--version-info} dt-relr-glibc-1a.rd}} \
> >+      "glibc-relr-1a.so" \
> >+    ] \
> >+    [list \
> >+      "Build dt-relr-glibc-1b.so" \
> >+      "-shared $DT_RELR_CC_LDFLAGS" \
> >+      "-fPIC" \
> >+      { dt-relr-glibc-1.c } \
> >+      {{readelf {-W --version-info} dt-relr-glibc-1b.rd}} \
> >+      "dt-relr-glibc-1b.so" \
> >+    ] \
> >+]
> >--
> >2.33.1
> >



--
H.J.
Fangrui Song Jan. 8, 2022, 8:19 a.m. UTC | #3
On 2022-01-07, H.J. Lu wrote:
>On Fri, Jan 7, 2022 at 8:43 PM Fangrui Song <i@maskray.me> wrote:
>>
>> On 2022-01-07, H.J. Lu via Binutils wrote:
>> >When DT_RELR is enabled, to avoid random run-time crash with older glibc
>> >binaries without DT_RELR support, add a GLIBC_ABI_DT_RELR symbol version,
>> >which is provided by glibc with DT_RELR support, dependency on the shared
>> >C library if it provides a GLIBC_2.XX symbol version.
>> >
>> >bfd/
>> >
>> >       * elflink.c (elf_link_add_dt_relr_dependency): New function.
>> >       (bfd_elf_size_dynamic_sections): Call
>> >       elf_link_add_dt_relr_dependency if DT_RELR is enabled.
>> >
>> >ld/
>> >
>> >       * ld.texi: Mention GLIBC_ABI_DT_RELR in -z pack-relative-relocs
>> >       entry.
>> >       * testsuite/ld-elf/dt-relr-glibc-1.c: New file.
>> >       * testsuite/ld-elf/dt-relr-glibc-1a.rd: Likewise.
>> >       * testsuite/ld-elf/dt-relr-glibc-1b.rd: Likewise.
>> >       * testsuite/ld-elf/dt-relr.exp: Likewise.
>> >---
>> > bfd/elflink.c                           | 86 +++++++++++++++++++++++++
>> > ld/ld.texi                              |  4 +-
>> > ld/testsuite/ld-elf/dt-relr-glibc-1.c   | 11 ++++
>> > ld/testsuite/ld-elf/dt-relr-glibc-1a.rd |  4 ++
>> > ld/testsuite/ld-elf/dt-relr-glibc-1b.rd |  7 ++
>> > ld/testsuite/ld-elf/dt-relr.exp         | 44 +++++++++++++
>> > 6 files changed, 155 insertions(+), 1 deletion(-)
>> > create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1.c
>> > create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
>> > create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
>> > create mode 100644 ld/testsuite/ld-elf/dt-relr.exp
>> >
>> >diff --git a/bfd/elflink.c b/bfd/elflink.c
>> >index 31b13f5df7a..05ac1cb7a63 100644
>> >--- a/bfd/elflink.c
>> >+++ b/bfd/elflink.c
>> >@@ -2213,6 +2213,85 @@ _bfd_elf_export_symbol (struct elf_link_hash_entry *h, void *data)
>> >   return true;
>> > }
>> >
>> >+/* Return true if GLIBC_ABI_DT_RELR is added to the list of version
>> >+   dependencies successfully.  GLIBC_ABI_DT_RELR will be put into the
>> >+   .gnu.version_r section.  */
>> >+
>> >+static bool
>> >+elf_link_add_dt_relr_dependency (struct elf_find_verdep_info *rinfo)
>> >+{
>> >+  bfd *glibc_bfd = NULL;
>> >+  Elf_Internal_Verneed *t;
>> >+  Elf_Internal_Vernaux *a;
>> >+  size_t amt;
>> >+  const char *relr = "GLIBC_ABI_DT_RELR";
>> >+
>> >+  /* See if we already know about GLIBC_PRIVATE_DT_RELR.  */
>> >+  for (t = elf_tdata (rinfo->info->output_bfd)->verref;
>> >+       t != NULL;
>> >+       t = t->vn_nextref)
>> >+    {
>> >+      const char *soname = bfd_elf_get_dt_soname (t->vn_bfd);
>> >+      /* Skip the shared library if it isn't libc.so.  */
>> >+      if (!soname || !startswith (soname, "libc.so."))
>> >+      continue;
>>
>> Having the dependency on ld.so is better.
>> (The linker knows the --dynamic-linker value.)
>> libc.so does not need to know whether DT_RELR is used.
>>
>> It's also easier on glibc side.
>> Defining  __glibc_abi_dt_relr@@GLIBC_ABI_DT_RELR in elf/Versions is
>> simpler than defining it in libc.so and updating every libc.abilist.
>
>I chose libc.so instead of ld.so since shared libraries may
>not be linked against ld.so.  The glibc change can be simple:
>
>https://patchwork.sourceware.org/project/glibc/patch/20211123223053.3334224-1-hjl.tools@gmail.com/
>
>Please replace GLIBC_ABI_VERSION_GEN2 with
>GLIBC_ABI_DT_RELR.
>
>or like
>
>https://gitlab.com/x86-glibc/glibc/-/commit/3bc53baa5304855b5105dabd7726b23d454605fb
>
>I can go either way.

OK... I picked the first way:
https://sourceware.org/git/?p=glibc.git;a=shortlog;h=refs/heads/maskray/relr

>
>
>
>> >+      for (a = t->vn_auxptr; a != NULL; a = a->vna_nextptr)
>> >+      {
>> >+        /* Return if GLIBC_PRIVATE_DT_RELR dependency has been
>> >+           added.  */
>> >+        if (a->vna_nodename == relr
>> >+            || strcmp (a->vna_nodename, relr) == 0)
>> >+          return true;
>> >+
>> >+        /* Check if libc.so provides GLIBC_2.XX version.  */
>> >+        if (!glibc_bfd && startswith (a->vna_nodename, "GLIBC_2."))
>> >+          glibc_bfd = t->vn_bfd;
>> >+      }
>> >+
>> >+      break;
>> >+    }
>> >+
>> >+  /* Skip if it isn't linked against glibc.  */
>> >+  if (glibc_bfd == NULL)
>> >+    return true;
>> >+
>> >+  /* This is a new version.  Add it to tree we are building.  */
>> >+  if (t == NULL)
>> >+    {
>> >+      amt = sizeof *t;
>> >+      t = (Elf_Internal_Verneed *) bfd_zalloc (rinfo->info->output_bfd,
>> >+                                             amt);
>> >+      if (t == NULL)
>> >+      {
>> >+        rinfo->failed = true;
>> >+        return false;
>> >+      }
>> >+
>> >+      t->vn_bfd = glibc_bfd;
>> >+      t->vn_nextref = elf_tdata (rinfo->info->output_bfd)->verref;
>> >+      elf_tdata (rinfo->info->output_bfd)->verref = t;
>> >+    }
>> >+
>> >+  amt = sizeof *a;
>> >+  a = (Elf_Internal_Vernaux *) bfd_zalloc (rinfo->info->output_bfd, amt);
>> >+  if (a == NULL)
>> >+    {
>> >+      rinfo->failed = true;
>> >+      return false;
>> >+    }
>> >+
>> >+  a->vna_nodename = relr;
>> >+  a->vna_flags = 0;
>> >+  a->vna_nextptr = t->vn_auxptr;
>> >+  a->vna_other = rinfo->vers + 1;
>> >+  ++rinfo->vers;
>> >+
>> >+  t->vn_auxptr = a;
>> >+
>> >+  return true;
>> >+}
>> >+
>> > /* Look through the symbols which are defined in other shared
>> >    libraries and referenced here.  Update the list of version
>> >    dependencies.  This will be put into the .gnu.version_r section.
>> >@@ -6940,6 +7019,13 @@ bfd_elf_size_dynamic_sections (bfd *output_bfd,
>> >       if (sinfo.failed)
>> >       return false;
>> >
>> >+      if (info->enable_dt_relr)
>> >+      {
>> >+        elf_link_add_dt_relr_dependency (&sinfo);
>> >+        if (sinfo.failed)
>> >+          return false;
>> >+      }
>> >+
>> >       if (elf_tdata (output_bfd)->verref == NULL)
>> >       s->flags |= SEC_EXCLUDE;
>> >       else
>> >diff --git a/ld/ld.texi b/ld/ld.texi
>> >index 457089ec06a..a16657ddb45 100644
>> >--- a/ld/ld.texi
>> >+++ b/ld/ld.texi
>> >@@ -1439,7 +1439,9 @@ and shared library.  It adds @code{DT_RELR}, @code{DT_RELRSZ} and
>> > building position-dependent executable and relocatable output.  This
>> > option also implies @option{combreloc} and @option{--relax}.
>> > @option{nopack-relative-relocs} is the default, which disables
>> >-compact relative relocation.  Supported for i386 and x86-64.
>> >+compact relative relocation.  When linked against the GNU C Library,
>> >+a GLIBC_ABI_DT_RELR symbol version dependency on the shared C Library
>> >+is added to the output.  Supported for i386 and x86-64.
>>
>> > @item relro
>> > @itemx norelro
>> >diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1.c b/ld/testsuite/ld-elf/dt-relr-glibc-1.c
>> >new file mode 100644
>> >index 00000000000..beacffe29e7
>> >--- /dev/null
>> >+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1.c
>> >@@ -0,0 +1,11 @@
>> >+#define REL(n) \
>> >+  static int data##n; \
>> >+  void *p##n = &data##n;
>> >+
>> >+REL(1)
>> >+REL(2)
>> >+REL(3)
>> >+REL(4)
>> >+REL(5)
>> >+REL(6)
>> >+REL(7)
>> >diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd b/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
>> >new file mode 100644
>> >index 00000000000..51bda5d70a1
>> >--- /dev/null
>> >+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
>> >@@ -0,0 +1,4 @@
>> >+#failif
>> >+#...
>> >+  0x[a-f0-9]+:   Name: GLIBC_ABI_DT_RELR  Flags: none  Version: [0-9]+
>> >+#...
>> >diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd b/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
>> >new file mode 100644
>> >index 00000000000..6556a6d939e
>> >--- /dev/null
>> >+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
>> >@@ -0,0 +1,7 @@
>> >+#...
>> >+Version needs section '.gnu.version_r' contains 1 entry:
>> >+ Addr: 0x[0-9a-f]+ +Offset: 0x[0-9a-f]+ +Link: +[0-9]+ +\(.dynstr\)
>> >+ +0+: Version: 1 +File: libc\.so\.6(|\.1) +Cnt: +[0-9]+
>> >+#...
>> >+  0x[a-f0-9]+:   Name: GLIBC_ABI_DT_RELR  Flags: none  Version: [0-9]+
>> >+#pass
>> >diff --git a/ld/testsuite/ld-elf/dt-relr.exp b/ld/testsuite/ld-elf/dt-relr.exp
>> >new file mode 100644
>> >index 00000000000..51d21e400ab
>> >--- /dev/null
>> >+++ b/ld/testsuite/ld-elf/dt-relr.exp
>> >@@ -0,0 +1,44 @@
>> >+# Expect script for DT_RELR.
>> >+#   Copyright (C) 2022 Free Software Foundation, Inc.
>> >+#
>> >+# This file is part of the GNU Binutils.
>> >+#
>> >+# This program is free software; you can redistribute it and/or modify
>> >+# it under the terms of the GNU General Public License as published by
>> >+# the Free Software Foundation; either version 3 of the License, or
>> >+# (at your option) any later version.
>> >+#
>> >+# This program 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 General Public License for more details.
>> >+#
>> >+# You should have received a copy of the GNU General Public License
>> >+# along with this program; if not, write to the Free Software
>> >+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
>> >+# MA 02110-1301, USA.
>> >+#
>> >+
>> >+# Linux tests.
>> >+if { ![istarget "*-*-linux*"] } {
>> >+    return
>> >+}
>> >+
>> >+run_cc_link_tests [list \
>> >+    [list \
>> >+      "Build dt-relr-glibc-1a.so" \
>> >+      "-shared $NO_DT_RELR_CC_LDFLAGS" \
>> >+      "-fPIC" \
>> >+      { dt-relr-glibc-1.c } \
>> >+      {{readelf {--version-info} dt-relr-glibc-1a.rd}} \
>> >+      "glibc-relr-1a.so" \
>> >+    ] \
>> >+    [list \
>> >+      "Build dt-relr-glibc-1b.so" \
>> >+      "-shared $DT_RELR_CC_LDFLAGS" \
>> >+      "-fPIC" \
>> >+      { dt-relr-glibc-1.c } \
>> >+      {{readelf {-W --version-info} dt-relr-glibc-1b.rd}} \
>> >+      "dt-relr-glibc-1b.so" \
>> >+    ] \
>> >+]
>> >--
>> >2.33.1
>> >
>
>
>
>--
>H.J.
H.J. Lu Jan. 8, 2022, 6:37 p.m. UTC | #4
On Sat, Jan 8, 2022 at 12:19 AM Fangrui Song <i@maskray.me> wrote:
>
> On 2022-01-07, H.J. Lu wrote:
> >On Fri, Jan 7, 2022 at 8:43 PM Fangrui Song <i@maskray.me> wrote:
> >>
> >> On 2022-01-07, H.J. Lu via Binutils wrote:
> >> >When DT_RELR is enabled, to avoid random run-time crash with older glibc
> >> >binaries without DT_RELR support, add a GLIBC_ABI_DT_RELR symbol version,
> >> >which is provided by glibc with DT_RELR support, dependency on the shared
> >> >C library if it provides a GLIBC_2.XX symbol version.
> >> >
> >> >bfd/
> >> >
> >> >       * elflink.c (elf_link_add_dt_relr_dependency): New function.
> >> >       (bfd_elf_size_dynamic_sections): Call
> >> >       elf_link_add_dt_relr_dependency if DT_RELR is enabled.
> >> >
> >> >ld/
> >> >
> >> >       * ld.texi: Mention GLIBC_ABI_DT_RELR in -z pack-relative-relocs
> >> >       entry.
> >> >       * testsuite/ld-elf/dt-relr-glibc-1.c: New file.
> >> >       * testsuite/ld-elf/dt-relr-glibc-1a.rd: Likewise.
> >> >       * testsuite/ld-elf/dt-relr-glibc-1b.rd: Likewise.
> >> >       * testsuite/ld-elf/dt-relr.exp: Likewise.
> >> >---
> >> > bfd/elflink.c                           | 86 +++++++++++++++++++++++++
> >> > ld/ld.texi                              |  4 +-
> >> > ld/testsuite/ld-elf/dt-relr-glibc-1.c   | 11 ++++
> >> > ld/testsuite/ld-elf/dt-relr-glibc-1a.rd |  4 ++
> >> > ld/testsuite/ld-elf/dt-relr-glibc-1b.rd |  7 ++
> >> > ld/testsuite/ld-elf/dt-relr.exp         | 44 +++++++++++++
> >> > 6 files changed, 155 insertions(+), 1 deletion(-)
> >> > create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1.c
> >> > create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
> >> > create mode 100644 ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
> >> > create mode 100644 ld/testsuite/ld-elf/dt-relr.exp
> >> >
> >> >diff --git a/bfd/elflink.c b/bfd/elflink.c
> >> >index 31b13f5df7a..05ac1cb7a63 100644
> >> >--- a/bfd/elflink.c
> >> >+++ b/bfd/elflink.c
> >> >@@ -2213,6 +2213,85 @@ _bfd_elf_export_symbol (struct elf_link_hash_entry *h, void *data)
> >> >   return true;
> >> > }
> >> >
> >> >+/* Return true if GLIBC_ABI_DT_RELR is added to the list of version
> >> >+   dependencies successfully.  GLIBC_ABI_DT_RELR will be put into the
> >> >+   .gnu.version_r section.  */
> >> >+
> >> >+static bool
> >> >+elf_link_add_dt_relr_dependency (struct elf_find_verdep_info *rinfo)
> >> >+{
> >> >+  bfd *glibc_bfd = NULL;
> >> >+  Elf_Internal_Verneed *t;
> >> >+  Elf_Internal_Vernaux *a;
> >> >+  size_t amt;
> >> >+  const char *relr = "GLIBC_ABI_DT_RELR";
> >> >+
> >> >+  /* See if we already know about GLIBC_PRIVATE_DT_RELR.  */
> >> >+  for (t = elf_tdata (rinfo->info->output_bfd)->verref;
> >> >+       t != NULL;
> >> >+       t = t->vn_nextref)
> >> >+    {
> >> >+      const char *soname = bfd_elf_get_dt_soname (t->vn_bfd);
> >> >+      /* Skip the shared library if it isn't libc.so.  */
> >> >+      if (!soname || !startswith (soname, "libc.so."))
> >> >+      continue;
> >>
> >> Having the dependency on ld.so is better.
> >> (The linker knows the --dynamic-linker value.)
> >> libc.so does not need to know whether DT_RELR is used.
> >>
> >> It's also easier on glibc side.
> >> Defining  __glibc_abi_dt_relr@@GLIBC_ABI_DT_RELR in elf/Versions is
> >> simpler than defining it in libc.so and updating every libc.abilist.
> >
> >I chose libc.so instead of ld.so since shared libraries may
> >not be linked against ld.so.  The glibc change can be simple:
> >
> >https://patchwork.sourceware.org/project/glibc/patch/20211123223053.3334224-1-hjl.tools@gmail.com/
> >
> >Please replace GLIBC_ABI_VERSION_GEN2 with
> >GLIBC_ABI_DT_RELR.
> >
> >or like
> >
> >https://gitlab.com/x86-glibc/glibc/-/commit/3bc53baa5304855b5105dabd7726b23d454605fb
> >
> >I can go either way.
>
> OK... I picked the first way:
> https://sourceware.org/git/?p=glibc.git;a=shortlog;h=refs/heads/maskray/relr

Here it is:

https://gitlab.com/x86-glibc/glibc/-/commit/0cef25a4c61f39355224c13ae4f5c15f036659f7

--
H.J.
diff mbox series

Patch

diff --git a/bfd/elflink.c b/bfd/elflink.c
index 31b13f5df7a..05ac1cb7a63 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -2213,6 +2213,85 @@  _bfd_elf_export_symbol (struct elf_link_hash_entry *h, void *data)
   return true;
 }
 
+/* Return true if GLIBC_ABI_DT_RELR is added to the list of version
+   dependencies successfully.  GLIBC_ABI_DT_RELR will be put into the
+   .gnu.version_r section.  */
+
+static bool
+elf_link_add_dt_relr_dependency (struct elf_find_verdep_info *rinfo)
+{
+  bfd *glibc_bfd = NULL;
+  Elf_Internal_Verneed *t;
+  Elf_Internal_Vernaux *a;
+  size_t amt;
+  const char *relr = "GLIBC_ABI_DT_RELR";
+
+  /* See if we already know about GLIBC_PRIVATE_DT_RELR.  */
+  for (t = elf_tdata (rinfo->info->output_bfd)->verref;
+       t != NULL;
+       t = t->vn_nextref)
+    {
+      const char *soname = bfd_elf_get_dt_soname (t->vn_bfd);
+      /* Skip the shared library if it isn't libc.so.  */
+      if (!soname || !startswith (soname, "libc.so."))
+	continue;
+
+      for (a = t->vn_auxptr; a != NULL; a = a->vna_nextptr)
+	{
+	  /* Return if GLIBC_PRIVATE_DT_RELR dependency has been
+	     added.  */
+	  if (a->vna_nodename == relr
+	      || strcmp (a->vna_nodename, relr) == 0)
+	    return true;
+
+	  /* Check if libc.so provides GLIBC_2.XX version.  */
+	  if (!glibc_bfd && startswith (a->vna_nodename, "GLIBC_2."))
+	    glibc_bfd = t->vn_bfd;
+	}
+
+      break;
+    }
+
+  /* Skip if it isn't linked against glibc.  */
+  if (glibc_bfd == NULL)
+    return true;
+
+  /* This is a new version.  Add it to tree we are building.  */
+  if (t == NULL)
+    {
+      amt = sizeof *t;
+      t = (Elf_Internal_Verneed *) bfd_zalloc (rinfo->info->output_bfd,
+					       amt);
+      if (t == NULL)
+	{
+	  rinfo->failed = true;
+	  return false;
+	}
+
+      t->vn_bfd = glibc_bfd;
+      t->vn_nextref = elf_tdata (rinfo->info->output_bfd)->verref;
+      elf_tdata (rinfo->info->output_bfd)->verref = t;
+    }
+
+  amt = sizeof *a;
+  a = (Elf_Internal_Vernaux *) bfd_zalloc (rinfo->info->output_bfd, amt);
+  if (a == NULL)
+    {
+      rinfo->failed = true;
+      return false;
+    }
+
+  a->vna_nodename = relr;
+  a->vna_flags = 0;
+  a->vna_nextptr = t->vn_auxptr;
+  a->vna_other = rinfo->vers + 1;
+  ++rinfo->vers;
+
+  t->vn_auxptr = a;
+
+  return true;
+}
+
 /* Look through the symbols which are defined in other shared
    libraries and referenced here.  Update the list of version
    dependencies.  This will be put into the .gnu.version_r section.
@@ -6940,6 +7019,13 @@  bfd_elf_size_dynamic_sections (bfd *output_bfd,
       if (sinfo.failed)
 	return false;
 
+      if (info->enable_dt_relr)
+	{
+	  elf_link_add_dt_relr_dependency (&sinfo);
+	  if (sinfo.failed)
+	    return false;
+	}
+
       if (elf_tdata (output_bfd)->verref == NULL)
 	s->flags |= SEC_EXCLUDE;
       else
diff --git a/ld/ld.texi b/ld/ld.texi
index 457089ec06a..a16657ddb45 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -1439,7 +1439,9 @@  and shared library.  It adds @code{DT_RELR}, @code{DT_RELRSZ} and
 building position-dependent executable and relocatable output.  This
 option also implies @option{combreloc} and @option{--relax}.
 @option{nopack-relative-relocs} is the default, which disables
-compact relative relocation.  Supported for i386 and x86-64.
+compact relative relocation.  When linked against the GNU C Library,
+a GLIBC_ABI_DT_RELR symbol version dependency on the shared C Library
+is added to the output.  Supported for i386 and x86-64.
 
 @item relro
 @itemx norelro
diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1.c b/ld/testsuite/ld-elf/dt-relr-glibc-1.c
new file mode 100644
index 00000000000..beacffe29e7
--- /dev/null
+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1.c
@@ -0,0 +1,11 @@ 
+#define REL(n) \
+  static int data##n; \
+  void *p##n = &data##n;
+
+REL(1)
+REL(2)
+REL(3)
+REL(4)
+REL(5)
+REL(6)
+REL(7)
diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd b/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
new file mode 100644
index 00000000000..51bda5d70a1
--- /dev/null
+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1a.rd
@@ -0,0 +1,4 @@ 
+#failif
+#...
+  0x[a-f0-9]+:   Name: GLIBC_ABI_DT_RELR  Flags: none  Version: [0-9]+
+#...
diff --git a/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd b/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
new file mode 100644
index 00000000000..6556a6d939e
--- /dev/null
+++ b/ld/testsuite/ld-elf/dt-relr-glibc-1b.rd
@@ -0,0 +1,7 @@ 
+#...
+Version needs section '.gnu.version_r' contains 1 entry:
+ Addr: 0x[0-9a-f]+ +Offset: 0x[0-9a-f]+ +Link: +[0-9]+ +\(.dynstr\)
+ +0+: Version: 1 +File: libc\.so\.6(|\.1) +Cnt: +[0-9]+
+#...
+  0x[a-f0-9]+:   Name: GLIBC_ABI_DT_RELR  Flags: none  Version: [0-9]+
+#pass
diff --git a/ld/testsuite/ld-elf/dt-relr.exp b/ld/testsuite/ld-elf/dt-relr.exp
new file mode 100644
index 00000000000..51d21e400ab
--- /dev/null
+++ b/ld/testsuite/ld-elf/dt-relr.exp
@@ -0,0 +1,44 @@ 
+# Expect script for DT_RELR.
+#   Copyright (C) 2022 Free Software Foundation, Inc.
+#
+# This file is part of the GNU Binutils.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+# MA 02110-1301, USA.
+#
+
+# Linux tests.
+if { ![istarget "*-*-linux*"] } {
+    return
+}
+
+run_cc_link_tests [list \
+    [list \
+	"Build dt-relr-glibc-1a.so" \
+	"-shared $NO_DT_RELR_CC_LDFLAGS" \
+	"-fPIC" \
+	{ dt-relr-glibc-1.c } \
+	{{readelf {--version-info} dt-relr-glibc-1a.rd}} \
+	"glibc-relr-1a.so" \
+    ] \
+    [list \
+	"Build dt-relr-glibc-1b.so" \
+	"-shared $DT_RELR_CC_LDFLAGS" \
+	"-fPIC" \
+	{ dt-relr-glibc-1.c } \
+	{{readelf {-W --version-info} dt-relr-glibc-1b.rd}} \
+	"dt-relr-glibc-1b.so" \
+    ] \
+]