s390x: Implement preliminary check for z14 support (#1945473)

Resolves: #1945473

glibc-rh1945473.patch

@@ -0,0 +1,28 @@
+Add diagnostics for missing z14 support.  Not yet upstream.  Discussion
+is here:
+
+  s390x: Diagnose missing VXE at run time if required at build time
+  <https://sourceware.org/pipermail/libc-alpha/2021-April/124834.html>
+
+The approach implemented by upstream will likely be slightly different
+(if upstream takes the patch at all).  dl_platform_init does not work
+for POWER because POWER9 instructions are used in __tunables_init,
+which is called before DL_PLATFORM_INIT/dl_platform_init.
+
+diff --git a/sysdeps/s390/s390-64/dl-machine.h b/sysdeps/s390/s390-64/dl-machine.h
+index 543361c83637c071..deaf37951206fb7c 100644
+--- a/sysdeps/s390/s390-64/dl-machine.h
++++ b/sysdeps/s390/s390-64/dl-machine.h
+@@ -235,6 +235,12 @@ _dl_start_user:\n\
+ static inline void __attribute__ ((unused))
+ dl_platform_init (void)
+ {
++#ifdef __LONG_DOUBLE_VX__
++  if (!(GLRO(dl_hwcap) & HWCAP_S390_VXE))
++    _dl_fatal_printf ("\
++Fatal glibc error: CPU lacks VXE support (z14 or later required)\n");
++#endif
++
+   if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
+     /* Avoid an empty string which would disturb us.  */
+     GLRO(dl_platform) = NULL;

glibc.spec

@@ -89,7 +89,7 @@
 Summary: The GNU libc libraries
 Name: glibc
 Version: %{glibcversion}
-Release: 7%{?dist}
+Release: 8%{?dist}
 
 # In general, GPLv2+ is used by programs, LGPLv2+ is used for
 # libraries.
@@ -167,6 +167,7 @@ Patch47: glibc-upstream-2.33-16.patch
 Patch48: glibc-upstream-2.33-17.patch
 Patch49: glibc-upstream-2.33-18.patch
 Patch50: glibc-upstream-2.33-19.patch
+Patch51: glibc-rh1945473.patch
 
 ##############################################################################
 # Continued list of core "glibc" package information:
@@ -2288,6 +2289,9 @@ fi
 %files -f compat-libpthread-nonshared.filelist -n compat-libpthread-nonshared
 
 %changelog
+* Fri Apr  9 2021 Florian Weimer <fweimer@redhat.com> - 2.33-8
+- s390x: Implement preliminary check for z14 support (#1945473)
+
 * Fri Apr  9 2021 Florian Weimer <fweimer@redhat.com> - 2.33-7
 - Inherit additional build flags from redhat-rpm-config (#1947895)