From: H.J. Lu <hjl.tools@gmail.com>
Date: Wed, 23 Jun 2021 21:27:58 +0000 (-0700)
Subject: x86: Copy IBT and SHSTK usable only if CET is enabled
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5cb6edb6cd193d4b0462c718f4b6071f8b84ff90;p=thirdparty%2Fglibc.git

x86: Copy IBT and SHSTK usable only if CET is enabled

IBT and SHSTK usable bits are copied from CPUID feature bits and later
cleared if kernel doesn't support CET.  Copy IBT and SHSTK usable only
if CET is enabled so that they aren't set on CET capable processors
with non-CET enabled glibc.

(cherry picked from commit ea26ff03227d7cacef5de6036df57734373449b4)
---

diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index dfad82f14ca..7a524dbae61 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -75,7 +75,6 @@ update_usable (struct cpu_features *cpu_features)
   CPU_FEATURE_SET_USABLE (cpu_features, PREFETCHWT1);
   CPU_FEATURE_SET_USABLE (cpu_features, OSPKE);
   CPU_FEATURE_SET_USABLE (cpu_features, WAITPKG);
-  CPU_FEATURE_SET_USABLE (cpu_features, SHSTK);
   CPU_FEATURE_SET_USABLE (cpu_features, GFNI);
   CPU_FEATURE_SET_USABLE (cpu_features, RDPID);
   CPU_FEATURE_SET_USABLE (cpu_features, RDRAND);
@@ -85,7 +84,6 @@ update_usable (struct cpu_features *cpu_features)
   CPU_FEATURE_SET_USABLE (cpu_features, FSRM);
   CPU_FEATURE_SET_USABLE (cpu_features, SERIALIZE);
   CPU_FEATURE_SET_USABLE (cpu_features, TSXLDTRK);
-  CPU_FEATURE_SET_USABLE (cpu_features, IBT);
   CPU_FEATURE_SET_USABLE (cpu_features, LAHF64_SAHF64);
   CPU_FEATURE_SET_USABLE (cpu_features, LZCNT);
   CPU_FEATURE_SET_USABLE (cpu_features, SSE4A);
@@ -97,6 +95,11 @@ update_usable (struct cpu_features *cpu_features)
   CPU_FEATURE_SET_USABLE (cpu_features, FSRS);
   CPU_FEATURE_SET_USABLE (cpu_features, FSRCS);
 
+#if CET_ENABLED
+  CPU_FEATURE_SET_USABLE (cpu_features, IBT);
+  CPU_FEATURE_SET_USABLE (cpu_features, SHSTK);
+#endif
+
   /* Can we call xgetbv?  */
   if (CPU_FEATURES_CPU_P (cpu_features, OSXSAVE))
     {