[glibc/release/2.33/master] x86: Copy IBT and SHSTK usable only if CET is enabled

[glibc/release/2.33/master] x86: Copy IBT and SHSTK usable only if CET is enabled

[H.J. Lu]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5cb6edb6cd193d4b0462c718f4b6071f8b84ff90

commit 5cb6edb6cd193d4b0462c718f4b6071f8b84ff90
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Jun 23 14:27:58 2021 -0700

    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:
---
 sysdeps/x86/cpu-features.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index dfad82f14c..7a524dbae6 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))
     {