[10/10] ld: Add glibc dependency for DT_RELR
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Commit Message
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
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
>
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.
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.
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.
@@ -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
@@ -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
new file mode 100644
@@ -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)
new file mode 100644
@@ -0,0 +1,4 @@
+#failif
+#...
+ 0x[a-f0-9]+: Name: GLIBC_ABI_DT_RELR Flags: none Version: [0-9]+
+#...
new file mode 100644
@@ -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
new file mode 100644
@@ -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" \
+ ] \
+]