x86/cet: Don't assume that SHSTK implies IBT

Since shadow stack (SHSTK) is enabled in the Linux kernel without
enabling indirect branch tracking (IBT), don't assume that SHSTK
implies IBT.  Use "CPU_FEATURE_ACTIVE (IBT)" to check if IBT is active
and "CPU_FEATURE_ACTIVE (SHSTK)" to check if SHSTK is active.

diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
index 5631a59a26709af0d5e3dc4a38f1ce03839cb5d0..3d936ed53749314c63bbfe333072e8d84714b9da 100644 (file)
--- a/sysdeps/x86/Makefile
+++ b/sysdeps/x86/Makefile
@@ -209,7 +209,6 @@ CFLAGS-tst-cet-legacy-mod-6a.c += -fcf-protection=branch
 CFLAGS-tst-cet-legacy-mod-6b.c += -fcf-protection
 CFLAGS-tst-cet-legacy-mod-6c.c += -fcf-protection
 CFLAGS-tst-cet-legacy-7.c += -fcf-protection=none
-CFLAGS-tst-cet-legacy-8.c += -mshstk
 CFLAGS-tst-cet-legacy-10.c += -mshstk
 CFLAGS-tst-cet-legacy-10-static.c += -mshstk
 

diff --git a/sysdeps/x86/tst-cet-legacy-10.c b/sysdeps/x86/tst-cet-legacy-10.c
index a85cdc3171b1cb366978124677166ee8268f5235..ae2c34de3e8a033b696e34ecad8c22f872f478bc 100644 (file)
--- a/sysdeps/x86/tst-cet-legacy-10.c
+++ b/sysdeps/x86/tst-cet-legacy-10.c
@@ -21,19 +21,19 @@
 #include <support/test-driver.h>
 #include <support/xunistd.h>
 
-/* Check that CPU_FEATURE_ACTIVE on IBT and SHSTK matches _get_ssp.  */
+/* Check that CPU_FEATURE_ACTIVE on SHSTK matches _get_ssp.  */
 
 static int
 do_test (void)
 {
   if (_get_ssp () != 0)
     {
-      if (CPU_FEATURE_ACTIVE (IBT) && CPU_FEATURE_ACTIVE (SHSTK))
+      if (CPU_FEATURE_ACTIVE (SHSTK))
        return EXIT_SUCCESS;
     }
   else
     {
-      if (!CPU_FEATURE_ACTIVE (IBT) && !CPU_FEATURE_ACTIVE (SHSTK))
+      if (!CPU_FEATURE_ACTIVE (SHSTK))
        return EXIT_SUCCESS;
     }
 

diff --git a/sysdeps/x86/tst-cet-legacy-8.c b/sysdeps/x86/tst-cet-legacy-8.c
index 5d8d9ba7dcd65da3e58afd477a07bc92626ec207..77d77a540837c413b6c533caa48d084bb8dad308 100644 (file)
--- a/sysdeps/x86/tst-cet-legacy-8.c
+++ b/sysdeps/x86/tst-cet-legacy-8.c
@@ -18,7 +18,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-#include <x86intrin.h>
+#include <sys/platform/x86.h>
 #include <sys/mman.h>
 #include <support/test-driver.h>
 #include <support/xsignal.h>
@@ -29,11 +29,6 @@
 static int
 do_test (void)
 {
-  /* NB: This test should trigger SIGSEGV on CET platforms.  If SHSTK
-     is disabled, assuming IBT is also disabled.  */
-  if (_get_ssp () == 0)
-    return EXIT_UNSUPPORTED;
-
   void (*funcp) (void);
   funcp = xmmap (NULL, 0x1000, PROT_EXEC | PROT_READ | PROT_WRITE,
                 MAP_ANONYMOUS | MAP_PRIVATE, -1);
@@ -41,8 +36,14 @@ do_test (void)
   /* Write RET instruction.  */
   *(char *) funcp = 0xc3;
   funcp ();
+
+  /* NB: This test should trigger SIGSEGV when IBT is active.  We should
+     reach here if IBT isn't active.  */
+  if (!CPU_FEATURE_ACTIVE (IBT))
+    return EXIT_UNSUPPORTED;
+
   return EXIT_FAILURE;
 }
 
-#define EXPECTED_SIGNAL (_get_ssp () == 0 ? 0 : SIGSEGV)
+#define EXPECTED_SIGNAL (CPU_FEATURE_ACTIVE (IBT) ? SIGSEGV : 0)
 #include <support/test-driver.c>