gnu: glibc: Update to 2.27.

* gnu/packages/base.scm (glibc/linux): Update to 2.27.
[source](patches): Add 'glibc-hidden-visibility-ldconfig.patch' and
'glibc-2.27-git-fixes.patch'.
[native-inputs]: Add BISON.
[arguments]: Remove deprecated "--enable-add-ons" from #:configure-flags.
Also remove unneeded "libc_cv_ssp=no" and "libcv_ssp_strong=no".
(glibc-2.26): New public variable.
* gnu/packages/commencement.scm (glibc-final-with-bootstrap-bash)[native-inputs]:
Add BISON-BOOT0.
* gnu/packages/patches/glibc-2.27-git-fixes.patch,
gnu/packages/patches/glibc-hidden-visibility-ldconfig.patch: New files.
* gnu/local.mk (dist_patch_DATA): Register them.

4 files changed, 594 insertions, 21 deletions

diff --git a/gnu/packages/base.scm b/gnu/packages/base.scm
index 7265a46199..06f41284ef 100644
--- a/gnu/packages/base.scm
+++ b/gnu/packages/base.scm
@@ -36,6 +36,7 @@
   #:use-module (gnu packages)
   #:use-module (gnu packages acl)
   #:use-module (gnu packages bash)
+  #:use-module (gnu packages bison)
   #:use-module (gnu packages ed)
   #:use-module (gnu packages guile)
   #:use-module (gnu packages multiprecision)
@@ -538,26 +539,15 @@ store.")
 (define-public glibc/linux
   (package
    (name "glibc")
-   ;; Glibc has stable branches that continuously pick fixes for each supported
-   ;; release.  Unfortunately they do not do point-releases, so we are stuck
-   ;; with copying almost all patches, or use a snapshot of the release branch.
-   ;;
-   ;; This version number corresponds to the output of `git describe` and the
-   ;; archive can be generated by checking out the commit ID and running:
-   ;;  git archive --prefix=$(git describe)/ HEAD | xz > $(git describe).tar.xz
-   ;; See <https://bugs.gnu.org/29406> for details.
-   ;;
    ;; Note: Always use a dot after the minor version since various places rely
    ;; on "version-major+minor" to determine where locales are found.
-   (version "2.26.105-g0890d5379c")
+   (version "2.27")
    (source (origin
             (method url-fetch)
-            (uri (string-append "https://alpha.gnu.org/gnu/guix/mirror/"
-                                "glibc-" (version-major+minor version) "-"
-                                (caddr (string-split version #\.)) ".tar.xz"))
+            (uri (string-append "mirror://gnu/glibc/glibc-" version ".tar.xz"))
             (sha256
              (base32
-              "1jck0c1i248sn02rvsfjykk77qncma34bjq89dyy2irwm50d7s3g"))
+              "0wpwq7gsm7sd6ysidv0z575ckqdg13cr2njyfgrbgh4f65adwwji"))
             (snippet
              ;; Disable 'ldconfig' and /etc/ld.so.cache.  The latter is
              ;; required on LFS distros to avoid loading the distro's libc.so
@@ -569,6 +559,8 @@ store.")
                 #t))
             (modules '((guix build utils)))
             (patches (search-patches "glibc-ldd-x86_64.patch"
+                                     "glibc-2.27-git-fixes.patch"
+                                     "glibc-hidden-visibility-ldconfig.patch"
                                      "glibc-versioned-locpath.patch"
                                      "glibc-allow-kernel-2.6.32.patch"))))
    (build-system gnu-build-system)
@@ -595,8 +587,7 @@ store.")
                  (guix build gnu-build-system))
 
       #:configure-flags
-      (list "--enable-add-ons"
-            "--sysconfdir=/etc"
+      (list "--sysconfdir=/etc"
 
             ;; Installing a locale archive with all the locales is to
             ;; expensive (~100 MiB), so we rely on users to install the
@@ -631,10 +622,7 @@ store.")
             ;; Use our Bash instead of /bin/sh.
             (string-append "BASH_SHELL="
                            (assoc-ref %build-inputs "bash")
-                           "/bin/bash")
-
-            ;; XXX: Work around "undefined reference to `__stack_chk_guard'".
-            "libc_cv_ssp=no" "libc_cv_ssp_strong=no")
+                           "/bin/bash"))
 
       #:tests? #f                                 ; XXX
       #:phases (modify-phases %standard-phases
@@ -745,6 +733,7 @@ store.")
    ;; install the message catalogs, with 'msgfmt'.
    (native-inputs `(("texinfo" ,texinfo)
                     ("perl" ,perl)
+                    ("bison" ,bison)
                     ("gettext" ,gettext-minimal)))
 
    (native-search-paths
@@ -853,6 +842,26 @@ GLIBC/HURD for a Hurd host"
 ;; Below are old libc versions, which we use mostly to build locale data in
 ;; the old format (which the new libc cannot cope with.)
 
+(define-public glibc-2.26
+  (package
+    (inherit glibc)
+    ;; This version number corresponds to the output of `git describe` and the
+    ;; archive can be generated by checking out the commit ID and running:
+    ;;  git archive --prefix=$(git describe)/ HEAD | xz > $(git describe).tar.xz
+    ;; See <https://bugs.gnu.org/29406> for why this was necessary.
+    (version "2.26.105-g0890d5379c")
+    (source (origin
+              (inherit (package-source glibc))
+              (uri (string-append "https://alpha.gnu.org/gnu/guix/mirror/"
+                                  "glibc-" (version-major+minor version) "-"
+                                  (caddr (string-split version #\.)) ".tar.xz"))
+              (sha256
+               (base32
+                "1jck0c1i248sn02rvsfjykk77qncma34bjq89dyy2irwm50d7s3g"))
+              (patches (search-patches "glibc-ldd-x86_64.patch"
+                                       "glibc-versioned-locpath.patch"
+                                       "glibc-allow-kernel-2.6.32.patch"))))))
+
 (define-public glibc-2.25
   (package
     (inherit glibc)
diff --git a/gnu/packages/commencement.scm b/gnu/packages/commencement.scm
index 92766de6e7..3a7555b074 100644
--- a/gnu/packages/commencement.scm
+++ b/gnu/packages/commencement.scm
@@ -522,7 +522,8 @@ the bootstrap environment."
                     #t)))))))
      (propagated-inputs `(("kernel-headers" ,(kernel-headers-boot0))))
      (native-inputs
-      `(("texinfo" ,texinfo-boot0)
+      `(("bison" ,bison-boot0)
+        ("texinfo" ,texinfo-boot0)
         ("perl" ,perl-boot0)))
      (inputs
       `(;; The boot inputs.  That includes the bootstrap libc.  We don't want
diff --git a/gnu/packages/patches/glibc-2.27-git-fixes.patch b/gnu/packages/patches/glibc-2.27-git-fixes.patch
new file mode 100644
index 0000000000..c28bac222a
--- /dev/null
+++ b/gnu/packages/patches/glibc-2.27-git-fixes.patch
@@ -0,0 +1,547 @@
+These commits are cherry-picked from the "release/2.27/master" branch.
+
+https://sourceware.org/git/?p=glibc.git;a=shortlog;h=refs/heads/release/2.27/master
+
+Currently, we have the following (with NEWS and ChangeLog entries omitted).
+
+56170e064e2b21ce204f0817733e92f1730541ea
+516fa6080481a1433c173320b1c1432868e1e38a
+f36553bf6a4f69070f99badbdab5802b43e6e211
+7c6304182b9f422b782ace1cdd3efbde056aec36
+78a90c2f74a2012dd3eff302189e47ff6779a757
+1e52d8e65a58c49a48549053a1b89c06240e0c6c
+
+From 56170e064e2b21ce204f0817733e92f1730541ea Mon Sep 17 00:00:00 2001
+From: Igor Gnatenko <ignatenko@redhat.com>
+Date: Wed, 7 Feb 2018 13:53:10 +0100
+Subject: [PATCH] Linux: use reserved name __key in pkey_get [BZ #22797]
+
+_key is not reserved name and we should avoid using that. It seems that
+it was simple typo when pkey_* was implemented.
+
+(cherry picked from commit 388ff7bd0d57d7061fdd39a2f26f65687e8058da)
+
+diff --git a/sysdeps/unix/sysv/linux/bits/mman-shared.h b/sysdeps/unix/sysv/linux/bits/mman-shared.h
+index 7715e680ca..d15ba95c9d 100644
+--- a/sysdeps/unix/sysv/linux/bits/mman-shared.h
++++ b/sysdeps/unix/sysv/linux/bits/mman-shared.h
+@@ -61,7 +61,7 @@ int pkey_set (int __key, unsigned int __access_rights) __THROW;
+ 
+ /* Return the access rights for the current thread for KEY, which must
+    have been allocated using pkey_alloc.  */
+-int pkey_get (int _key) __THROW;
++int pkey_get (int __key) __THROW;
+ 
+ /* Free an allocated protection key, which must have been allocated
+    using pkey_alloc.  */
+
+From 516fa6080481a1433c173320b1c1432868e1e38a Mon Sep 17 00:00:00 2001
+From: "Dmitry V. Levin" <ldv@altlinux.org>
+Date: Fri, 29 Dec 2017 23:19:32 +0000
+Subject: [PATCH] linux/aarch64: sync sys/ptrace.h with Linux 4.15 [BZ #22433]
+
+Remove compat-specific constants that were never exported by kernel
+headers under these names.  Before linux commit v3.7-rc1~16^2~1 they
+were exported with COMPAT_ prefix, and since that commit they are not
+exported at all.
+
+* sysdeps/unix/sysv/linux/aarch64/sys/ptrace.h (__ptrace_request):
+Remove arm-specific PTRACE_GET_THREAD_AREA, PTRACE_GETHBPREGS,
+and PTRACE_SETHBPREGS.
+
+(cherry picked from commit 2fd4bbaa1446f1be700e10c526cf585a796c4991)
+
+diff --git a/sysdeps/unix/sysv/linux/aarch64/sys/ptrace.h b/sysdeps/unix/sysv/linux/aarch64/sys/ptrace.h
+index 4be45b95ff..444edbb702 100644
+--- a/sysdeps/unix/sysv/linux/aarch64/sys/ptrace.h
++++ b/sysdeps/unix/sysv/linux/aarch64/sys/ptrace.h
+@@ -78,18 +78,10 @@ enum __ptrace_request
+   PTRACE_DETACH = 17,
+ #define PT_DETACH PTRACE_DETACH
+ 
+-  PTRACE_GET_THREAD_AREA = 22,
+-
+   /* Continue and stop at the next entry to or return from syscall.  */
+   PTRACE_SYSCALL = 24,
+ #define PT_SYSCALL PTRACE_SYSCALL
+ 
+-  /* Get all hardware breakpoint registers.  */
+-  PTRACE_GETHBPREGS = 29,
+-
+-  /* Set all hardware breakpoint registers.  */
+-  PTRACE_SETHBPREGS = 30,
+-
+   /* Set ptrace filter options.  */
+   PTRACE_SETOPTIONS = 0x4200,
+ #define PT_SETOPTIONS PTRACE_SETOPTIONS
+
+From f36553bf6a4f69070f99badbdab5802b43e6e211 Mon Sep 17 00:00:00 2001
+From: Mike FABIAN <mfabian@redhat.com>
+Date: Mon, 19 Feb 2018 21:59:30 +0100
+Subject: [PATCH] =?UTF-8?q?Add=20missing=20=E2=80=9Creorder-end=E2=80=9D?=
+ =?UTF-8?q?=20in=20LC=5FCOLLATE=20of=20et=5FEE=20[BZ=20#22517]?=
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+	[BZ #22517]
+	* localedata/locales/et_EE (LC_COLLATE): add missing “reorder-end”
+
+(cherry picked from commit 7ec5f9465e732e668d0dc94ac078ba68056d6d0a)
+
+diff --git a/localedata/locales/et_EE b/localedata/locales/et_EE
+index 9cb55b568f..bab7493c98 100644
+--- a/localedata/locales/et_EE
++++ b/localedata/locales/et_EE
+@@ -103,6 +103,8 @@ reorder-after <w>
+ <U00FC> <u-diaresis>;<BAS>;<MIN>;IGNORE % ü
+ <U00DC> <u-diaresis>;<BAS>;<CAP>;IGNORE % Ü
+ 
++reorder-end
++
+ END LC_COLLATE
+ 
+ LC_CTYPE
+
+From 7c6304182b9f422b782ace1cdd3efbde056aec36 Mon Sep 17 00:00:00 2001
+From: DJ Delorie <dj@redhat.com>
+Date: Thu, 1 Mar 2018 23:20:45 -0500
+Subject: [PATCH] [BZ #22342] Fix netgroup cache keys.
+
+Unlike other nscd caches, the netgroup cache contains two types of
+records - those for "iterate through a netgroup" (i.e. setnetgrent())
+and those for "is this user in this netgroup" (i.e. innetgr()),
+i.e. full and partial records.  The timeout code assumes these records
+have the same key for the group name, so that the collection of records
+that is "this netgroup" can be expired as a unit.
+
+However, the keys are not the same, as the in-netgroup key is generated
+by nscd rather than being passed to it from elsewhere, and is generated
+without the trailing NUL.  All other keys have the trailing NUL, and as
+noted in the linked BZ, debug statements confirm that two keys for the
+same netgroup are added to the cache with two different lengths.
+
+The result of this is that as records in the cache expire, the purge
+code only cleans out one of the two types of entries, resulting in
+stale, possibly incorrect, and possibly inconsistent cache data.
+
+The patch simply includes the existing NUL in the computation for the
+key length ('key' points to the char after the NUL, and 'group' to the
+first char of the group, so 'key-group' includes the first char to the
+NUL, inclusive).
+
+	[BZ #22342]
+	* nscd/netgroupcache.c (addinnetgrX): Include trailing NUL in
+	key value.
+
+Reviewed-by: Carlos O'Donell <carlos@redhat.com>
+(cherry picked from commit 1c81d55fc4b07b51adf68558ba74ce975153e580)
+
+diff --git a/nscd/netgroupcache.c b/nscd/netgroupcache.c
+index b832c9315f..2f187b208c 100644
+--- a/nscd/netgroupcache.c
++++ b/nscd/netgroupcache.c
+@@ -480,7 +480,7 @@ addinnetgrX (struct database_dyn *db, int fd, request_header *req,
+ {
+   const char *group = key;
+   key = (char *) rawmemchr (key, '\0') + 1;
+-  size_t group_len = key - group - 1;
++  size_t group_len = key - group;
+   const char *host = *key++ ? key : NULL;
+   if (host != NULL)
+     key = (char *) rawmemchr (key, '\0') + 1;
+
+From 78a90c2f74a2012dd3eff302189e47ff6779a757 Mon Sep 17 00:00:00 2001
+From: Andreas Schwab <schwab@linux-m68k.org>
+Date: Fri, 2 Mar 2018 23:07:14 +0100
+Subject: [PATCH] Fix multiple definitions of __nss_*_database (bug 22918)
+
+(cherry picked from commit eaf6753f8aac33a36deb98c1031d1bad7b593d2d)
+
+diff --git a/nscd/gai.c b/nscd/gai.c
+index d081747797..576fd0045b 100644
+--- a/nscd/gai.c
++++ b/nscd/gai.c
+@@ -45,3 +45,6 @@
+ #ifdef HAVE_LIBIDN
+ # include <libidn/idn-stub.c>
+ #endif
++
++/* Some variables normally defined in libc.  */
++service_user *__nss_hosts_database attribute_hidden;
+diff --git a/nss/nsswitch.c b/nss/nsswitch.c
+index d5e655974f..b0f0c11a3e 100644
+--- a/nss/nsswitch.c
++++ b/nss/nsswitch.c
+@@ -62,7 +62,7 @@ static service_library *nss_new_service (name_database *database,
+ 
+ /* Declare external database variables.  */
+ #define DEFINE_DATABASE(name)						      \
+-  extern service_user *__nss_##name##_database attribute_hidden;	      \
++  service_user *__nss_##name##_database attribute_hidden;		      \
+   weak_extern (__nss_##name##_database)
+ #include "databases.def"
+ #undef DEFINE_DATABASE
+diff --git a/nss/nsswitch.h b/nss/nsswitch.h
+index eccb535ef5..63573b9ebc 100644
+--- a/nss/nsswitch.h
++++ b/nss/nsswitch.h
+@@ -226,10 +226,10 @@ libc_hidden_proto (__nss_hostname_digits_dots)
+ #define MAX_NR_ADDRS    48
+ 
+ /* Prototypes for __nss_*_lookup2 functions.  */
+-#define DEFINE_DATABASE(arg)				    \
+-  service_user *__nss_##arg##_database attribute_hidden;    \
+-  int __nss_##arg##_lookup2 (service_user **, const char *, \
+-			     const char *, void **);	    \
++#define DEFINE_DATABASE(arg)						      \
++  extern service_user *__nss_##arg##_database attribute_hidden;		      \
++  int __nss_##arg##_lookup2 (service_user **, const char *,		      \
++			     const char *, void **);			      \
+   libc_hidden_proto (__nss_##arg##_lookup2)
+ #include "databases.def"
+ #undef DEFINE_DATABASE
+diff --git a/posix/tst-rfc3484-2.c b/posix/tst-rfc3484-2.c
+index f509534ca9..8c64ac59ff 100644
+--- a/posix/tst-rfc3484-2.c
++++ b/posix/tst-rfc3484-2.c
+@@ -58,6 +58,7 @@ _res_hconf_init (void)
+ #undef	USE_NSCD
+ #include "../sysdeps/posix/getaddrinfo.c"
+ 
++service_user *__nss_hosts_database attribute_hidden;
+ 
+ /* This is the beginning of the real test code.  The above defines
+    (among other things) the function rfc3484_sort.  */
+diff --git a/posix/tst-rfc3484-3.c b/posix/tst-rfc3484-3.c
+index ae44087a10..1c61aaf844 100644
+--- a/posix/tst-rfc3484-3.c
++++ b/posix/tst-rfc3484-3.c
+@@ -58,6 +58,7 @@ _res_hconf_init (void)
+ #undef	USE_NSCD
+ #include "../sysdeps/posix/getaddrinfo.c"
+ 
++service_user *__nss_hosts_database attribute_hidden;
+ 
+ /* This is the beginning of the real test code.  The above defines
+    (among other things) the function rfc3484_sort.  */
+diff --git a/posix/tst-rfc3484.c b/posix/tst-rfc3484.c
+index 7f191abbbc..8f45848e44 100644
+--- a/posix/tst-rfc3484.c
++++ b/posix/tst-rfc3484.c
+@@ -58,6 +58,7 @@ _res_hconf_init (void)
+ #undef	USE_NSCD
+ #include "../sysdeps/posix/getaddrinfo.c"
+ 
++service_user *__nss_hosts_database attribute_hidden;
+ 
+ /* This is the beginning of the real test code.  The above defines
+    (among other things) the function rfc3484_sort.  */
+
+From 1e52d8e65a58c49a48549053a1b89c06240e0c6c Mon Sep 17 00:00:00 2001
+From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
+Date: Fri, 17 Nov 2017 16:04:29 -0200
+Subject: [PATCH] i386: Fix i386 sigaction sa_restorer initialization
+ (BZ#21269)
+
+This patch fixes the i386 sa_restorer field initialization for sigaction
+syscall for kernel with vDSO.  As described in bug report, i386 Linux
+(and compat on x86_64) interprets SA_RESTORER clear with nonzero
+sa_restorer as a request for stack switching if the SS segment is 'funny'.
+This means that anything that tries to mix glibc's signal handling with
+segmentation (for instance through modify_ldt syscall) is randomly broken
+depending on what values lands in sa_restorer.
+
+The testcase added  is based on Linux test tools/testing/selftests/x86/ldt_gdt.c,
+more specifically in do_multicpu_tests function.  The main changes are:
+
+  - C11 atomics instead of plain access.
+
+  - Remove x86_64 support which simplifies the syscall handling and fallbacks.
+
+  - Replicate only the test required to trigger the issue.
+
+Checked on i686-linux-gnu.
+
+	[BZ #21269]
+	* sysdeps/unix/sysv/linux/i386/Makefile (tests): Add tst-bz21269.
+	* sysdeps/unix/sysv/linux/i386/sigaction.c (SET_SA_RESTORER): Clear
+	sa_restorer for vDSO case.
+	* sysdeps/unix/sysv/linux/i386/tst-bz21269.c: New file.
+
+(cherry picked from commit 68448be208ee06e76665918b37b0a57e3e00c8b4)
+
+diff --git a/sysdeps/unix/sysv/linux/i386/Makefile b/sysdeps/unix/sysv/linux/i386/Makefile
+index 4080b8c966..da716e2c1b 100644
+--- a/sysdeps/unix/sysv/linux/i386/Makefile
++++ b/sysdeps/unix/sysv/linux/i386/Makefile
+@@ -3,6 +3,9 @@ default-abi := 32
+ 
+ ifeq ($(subdir),misc)
+ sysdep_routines += ioperm iopl vm86
++
++tests += tst-bz21269
++$(objpfx)tst-bz21269: $(shared-thread-library)
+ endif
+ 
+ ifeq ($(subdir),elf)
+diff --git a/sysdeps/unix/sysv/linux/i386/sigaction.c b/sysdeps/unix/sysv/linux/i386/sigaction.c
+index a5eb9e0d3e..177ff60ee6 100644
+--- a/sysdeps/unix/sysv/linux/i386/sigaction.c
++++ b/sysdeps/unix/sysv/linux/i386/sigaction.c
+@@ -42,7 +42,6 @@ extern void restore_rt (void) asm ("__restore_rt") attribute_hidden;
+ #endif
+ extern void restore (void) asm ("__restore") attribute_hidden;
+ 
+-
+ /* If ACT is not NULL, change the action for SIG to *ACT.
+    If OACT is not NULL, put the old action for SIG in *OACT.  */
+ int
+@@ -65,6 +64,8 @@ __libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
+ 	  kact.sa_restorer = ((act->sa_flags & SA_SIGINFO)
+ 			      ? &restore_rt : &restore);
+ 	}
++      else
++	kact.sa_restorer = NULL;
+     }
+ 
+   /* XXX The size argument hopefully will have to be changed to the
+diff --git a/sysdeps/unix/sysv/linux/i386/tst-bz21269.c b/sysdeps/unix/sysv/linux/i386/tst-bz21269.c
+new file mode 100644
+index 0000000000..353e36507d
+--- /dev/null
++++ b/sysdeps/unix/sysv/linux/i386/tst-bz21269.c
+@@ -0,0 +1,233 @@
++/* Test for i386 sigaction sa_restorer handling (BZ#21269)
++   Copyright (C) 2017 Free Software Foundation, Inc.
++   This file is part of the GNU C Library.
++
++   The GNU C Library is free software; you can redistribute it and/or
++   modify it under the terms of the GNU Lesser General Public
++   License as published by the Free Software Foundation; either
++   version 2.1 of the License, or (at your option) any later version.
++
++   The GNU C Library is distributed in the hope that it will be useful,
++   but WITHOUT ANY WARRANTY; without even the implied warranty of
++   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
++   Lesser General Public License for more details.
++
++   You should have received a copy of the GNU Lesser General Public
++   License along with the GNU C Library; if not, see
++   <http://www.gnu.org/licenses/>.  */
++
++/* This is based on Linux test tools/testing/selftests/x86/ldt_gdt.c,
++   more specifically in do_multicpu_tests function.  The main changes
++   are:
++
++   - C11 atomics instead of plain access.
++   - Remove x86_64 support which simplifies the syscall handling
++     and fallbacks.
++   - Replicate only the test required to trigger the issue for the
++     BZ#21269.  */
++
++#include <stdatomic.h>
++
++#include <asm/ldt.h>
++#include <linux/futex.h>
++
++#include <setjmp.h>
++#include <signal.h>
++#include <errno.h>
++#include <sys/syscall.h>
++#include <sys/mman.h>
++
++#include <support/xunistd.h>
++#include <support/check.h>
++#include <support/xthread.h>
++
++static int
++xset_thread_area (struct user_desc *u_info)
++{
++  long ret = syscall (SYS_set_thread_area, u_info);
++  TEST_VERIFY_EXIT (ret == 0);
++  return ret;
++}
++
++static void
++xmodify_ldt (int func, const void *ptr, unsigned long bytecount)
++{
++  TEST_VERIFY_EXIT (syscall (SYS_modify_ldt, 1, ptr, bytecount) == 0);
++}
++
++static int
++futex (int *uaddr, int futex_op, int val, void *timeout, int *uaddr2,
++	int val3)
++{
++  return syscall (SYS_futex, uaddr, futex_op, val, timeout, uaddr2, val3);
++}
++
++static void
++xsethandler (int sig, void (*handler)(int, siginfo_t *, void *), int flags)
++{
++  struct sigaction sa = { 0 };
++  sa.sa_sigaction = handler;
++  sa.sa_flags = SA_SIGINFO | flags;
++  TEST_VERIFY_EXIT (sigemptyset (&sa.sa_mask) == 0);
++  TEST_VERIFY_EXIT (sigaction (sig, &sa, 0) == 0);
++}
++
++static jmp_buf jmpbuf;
++
++static void
++sigsegv_handler (int sig, siginfo_t *info, void *ctx_void)
++{
++  siglongjmp (jmpbuf, 1);
++}
++
++/* Points to an array of 1024 ints, each holding its own index.  */
++static const unsigned int *counter_page;
++static struct user_desc *low_user_desc;
++static struct user_desc *low_user_desc_clear; /* Used to delete GDT entry.  */
++static int gdt_entry_num;
++
++static void
++setup_counter_page (void)
++{
++  long page_size = sysconf (_SC_PAGE_SIZE);
++  TEST_VERIFY_EXIT (page_size > 0);
++  unsigned int *page = xmmap (NULL, page_size, PROT_READ | PROT_WRITE,
++			      MAP_ANONYMOUS | MAP_PRIVATE | MAP_32BIT, -1);
++  for (int i = 0; i < (page_size / sizeof (unsigned int)); i++)
++    page[i] = i;
++  counter_page = page;
++}
++
++static void
++setup_low_user_desc (void)
++{
++  low_user_desc = xmmap (NULL, 2 * sizeof (struct user_desc),
++			 PROT_READ | PROT_WRITE,
++			 MAP_ANONYMOUS | MAP_PRIVATE | MAP_32BIT, -1);
++
++  low_user_desc->entry_number    = -1;
++  low_user_desc->base_addr       = (unsigned long) &counter_page[1];
++  low_user_desc->limit           = 0xffff;
++  low_user_desc->seg_32bit       = 1;
++  low_user_desc->contents        = 0;
++  low_user_desc->read_exec_only  = 0;
++  low_user_desc->limit_in_pages  = 1;
++  low_user_desc->seg_not_present = 0;
++  low_user_desc->useable         = 0;
++
++  xset_thread_area (low_user_desc);
++
++  low_user_desc_clear = low_user_desc + 1;
++  low_user_desc_clear->entry_number = gdt_entry_num;
++  low_user_desc_clear->read_exec_only = 1;
++  low_user_desc_clear->seg_not_present = 1;
++}
++
++/* Possible values of futex:
++   0: thread is idle.
++   1: thread armed.
++   2: thread should clear LDT entry 0.
++   3: thread should exit.  */
++static atomic_uint ftx;
++
++static void *
++threadproc (void *ctx)
++{
++  while (1)
++    {
++      futex ((int *) &ftx, FUTEX_WAIT, 1, NULL, NULL, 0);
++      while (atomic_load (&ftx) != 2)
++	{
++	  if (atomic_load (&ftx) >= 3)
++	    return NULL;
++	}
++
++      /* clear LDT entry 0.  */
++      const struct user_desc desc = { 0 };
++      xmodify_ldt (1, &desc, sizeof (desc));
++
++      /* If ftx == 2, set it to zero,  If ftx == 100, quit.  */
++      if (atomic_fetch_add (&ftx, -2) != 2)
++	return NULL;
++    }
++}
++
++
++/* As described in testcase, for historical reasons x86_32 Linux (and compat
++   on x86_64) interprets SA_RESTORER clear with nonzero sa_restorer as a
++   request for stack switching if the SS segment is 'funny' (this is default
++   scenario for vDSO system).  This means that anything that tries to mix
++   signal handling with segmentation should explicit clear the sa_restorer.
++
++   This testcase check if sigaction in fact does it by changing the local
++   descriptor table (LDT) through the modify_ldt syscall and triggering
++   a synchronous segfault on iret fault by trying to install an invalid
++   segment.  With a correct zeroed sa_restorer it should not trigger an
++   'real' SEGSEGV and allows the siglongjmp in signal handler.  */
++
++static int
++do_test (void)
++{
++  setup_counter_page ();
++  setup_low_user_desc ();
++
++  pthread_t thread;
++  unsigned short orig_ss;
++
++  xsethandler (SIGSEGV, sigsegv_handler, 0);
++  /* 32-bit kernels send SIGILL instead of SIGSEGV on IRET faults.  */
++  xsethandler (SIGILL, sigsegv_handler, 0);
++
++  thread = xpthread_create (0, threadproc, 0);
++
++  asm volatile ("mov %%ss, %0" : "=rm" (orig_ss));
++
++  for (int i = 0; i < 5; i++)
++    {
++      if (sigsetjmp (jmpbuf, 1) != 0)
++	continue;
++
++      /* Make sure the thread is ready after the last test. */
++      while (atomic_load (&ftx) != 0)
++	;
++
++      struct user_desc desc = {
++	.entry_number       = 0,
++	.base_addr          = 0,
++	.limit              = 0xffff,
++	.seg_32bit          = 1,
++	.contents           = 0,
++	.read_exec_only     = 0,
++	.limit_in_pages     = 1,
++	.seg_not_present    = 0,
++	.useable            = 0
++      };
++
++      xmodify_ldt (0x11, &desc, sizeof (desc));
++
++      /* Arm the thread.  */
++      ftx = 1;
++      futex ((int*) &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
++
++      asm volatile ("mov %0, %%ss" : : "r" (0x7));
++
++      /* Fire up thread modify_ldt call.  */
++      atomic_store (&ftx, 2);
++
++      while (atomic_load (&ftx) != 0)
++	;
++
++      /* On success, modify_ldt will segfault us synchronously and we will
++	 escape via siglongjmp.  */
++      support_record_failure ();
++    }
++
++  atomic_store (&ftx, 100);
++  futex ((int*) &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
++
++  xpthread_join (thread);
++
++  return 0;
++}
++
++#include <support/test-driver.c>
diff --git a/gnu/packages/patches/glibc-hidden-visibility-ldconfig.patch b/gnu/packages/patches/glibc-hidden-visibility-ldconfig.patch
new file mode 100644
index 0000000000..c796946d7e
--- /dev/null
+++ b/gnu/packages/patches/glibc-hidden-visibility-ldconfig.patch
@@ -0,0 +1,16 @@
+Fix a regression in glibc 2.27 when built without ldconfig.  See
+<https://sourceware.org/bugzilla/show_bug.cgi?id=22977> for details.
+
+diff --git a/include/libc-symbols.h b/include/libc-symbols.h
+index 6137304b0b..7d630f36d8 100644
+--- a/include/libc-symbols.h
++++ b/include/libc-symbols.h
+@@ -508,7 +508,7 @@ for linking")
+ # ifndef __ASSEMBLER__
+ #  if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \
+       && (!defined PIC || !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE) \
+-      && !defined NO_HIDDEN
++      && !defined NO_HIDDEN && defined USE_LDCONFIG
+ #   define __hidden_proto_hiddenattr(attrs...) \
+   __attribute__ ((visibility ("hidden"), ##attrs))
+ #   define hidden_proto(name, attrs...) \