[2.33 and older][PATCH] x86: Copy IBT and SHSTK usable only if CET is enabled

["H.J. Lu" <hjl.tools@gmail.com>]

I am backporting this to 2.33 and older branches.


H.J.
---
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)
---
 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))
     {
-- 
2.34.1