selftests/x86/ldt_gdt: Add infrastructure to test set_thread_area()

commit d744dcad39094c9187075e274d1cdef79c57c8b5 upstream.

Much of the test design could apply to set_thread_area() (i.e. GDT),
not just modify_ldt().  Add set_thread_area() to the
install_valid_mode() helper.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/02c23f8fba5547007f741dc24c3926e5284ede02.1509794321.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/testing/selftests/x86/ldt_gdt.c b/tools/testing/selftests/x86/ldt_gdt.c
index 2afc41a3730fb4a277a55db60541036c7943d35c..4e9add7bf8a93a0f8f0260213f99819a679ff4cf 100644 (file)
--- a/tools/testing/selftests/x86/ldt_gdt.c
+++ b/tools/testing/selftests/x86/ldt_gdt.c
@@ -137,30 +137,51 @@ static void check_valid_segment(uint16_t index, int ldt,
        }
 }
 
-static bool install_valid_mode(const struct user_desc *desc, uint32_t ar,
-                              bool oldmode)
+static bool install_valid_mode(const struct user_desc *d, uint32_t ar,
+                              bool oldmode, bool ldt)
 {
-       int ret = syscall(SYS_modify_ldt, oldmode ? 1 : 0x11,
-                         desc, sizeof(*desc));
-       if (ret < -1)
-               errno = -ret;
+       struct user_desc desc = *d;
+       int ret;
+
+       if (!ldt) {
+#ifndef __i386__
+               /* No point testing set_thread_area in a 64-bit build */
+               return false;
+#endif
+               if (!gdt_entry_num)
+                       return false;
+               desc.entry_number = gdt_entry_num;
+
+               ret = syscall(SYS_set_thread_area, &desc);
+       } else {
+               ret = syscall(SYS_modify_ldt, oldmode ? 1 : 0x11,
+                             &desc, sizeof(desc));
+
+               if (ret < -1)
+                       errno = -ret;
+
+               if (ret != 0 && errno == ENOSYS) {
+                       printf("[OK]\tmodify_ldt returned -ENOSYS\n");
+                       return false;
+               }
+       }
+
        if (ret == 0) {
-               uint32_t limit = desc->limit;
-               if (desc->limit_in_pages)
+               uint32_t limit = desc.limit;
+               if (desc.limit_in_pages)
                        limit = (limit << 12) + 4095;
-               check_valid_segment(desc->entry_number, 1, ar, limit, true);
+               check_valid_segment(desc.entry_number, ldt, ar, limit, true);
                return true;
-       } else if (errno == ENOSYS) {
-               printf("[OK]\tmodify_ldt returned -ENOSYS\n");
-               return false;
        } else {
-               if (desc->seg_32bit) {
-                       printf("[FAIL]\tUnexpected modify_ldt failure %d\n",
+               if (desc.seg_32bit) {
+                       printf("[FAIL]\tUnexpected %s failure %d\n",
+                              ldt ? "modify_ldt" : "set_thread_area",
                               errno);
                        nerrs++;
                        return false;
                } else {
-                       printf("[OK]\tmodify_ldt rejected 16 bit segment\n");
+                       printf("[OK]\t%s rejected 16 bit segment\n",
+                              ldt ? "modify_ldt" : "set_thread_area");
                        return false;
                }
        }
@@ -168,7 +189,7 @@ static bool install_valid_mode(const struct user_desc *desc, uint32_t ar,
 
 static bool install_valid(const struct user_desc *desc, uint32_t ar)
 {
-       return install_valid_mode(desc, ar, false);
+       return install_valid_mode(desc, ar, false, true);
 }
 
 static void install_invalid(const struct user_desc *desc, bool oldmode)