[tip:x86/asm] selftests/x86/ldt_gdt: Run most existing LDT test cases against the GDT as well

[tip-bot for Andy Lutomirski]

Commit-ID:  adedf2893c192dd09b1cc2f2dcfdd7cad99ec49d
Gitweb:     https://git.kernel.org/tip/adedf2893c192dd09b1cc2f2dcfdd7cad99ec49d
Author:     Andy Lutomirski <luto@xxxxxxxxxx>
AuthorDate: Sat, 4 Nov 2017 04:19:51 -0700
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 7 Nov 2017 11:13:43 +0100

selftests/x86/ldt_gdt: Run most existing LDT test cases against the GDT as well

Now that the main test infrastructure supports the GDT, run tests
that will pass the kernel's GDT permission tests against the GDT.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bpetkov@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/686a1eda63414da38fcecc2412db8dba1ae40581.1509794321.git.luto@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 tools/testing/selftests/x86/ldt_gdt.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/x86/ldt_gdt.c b/tools/testing/selftests/x86/ldt_gdt.c
index 45f3024..3bb42ff 100644
--- a/tools/testing/selftests/x86/ldt_gdt.c
+++ b/tools/testing/selftests/x86/ldt_gdt.c
@@ -189,7 +189,15 @@ static bool install_valid_mode(const struct user_desc *d, uint32_t ar,
 
 static bool install_valid(const struct user_desc *desc, uint32_t ar)
 {
-	return install_valid_mode(desc, ar, false, true);
+	bool ret = install_valid_mode(desc, ar, false, true);
+
+	if (desc->contents <= 1 && desc->seg_32bit &&
+	    !desc->seg_not_present) {
+		/* Should work in the GDT, too. */
+		install_valid_mode(desc, ar, false, false);
+	}
+
+	return ret;
 }
 
 static void install_invalid(const struct user_desc *desc, bool oldmode)