[PATCH 4.14 061/159] selftests/x86/ldt_gdt: Add infrastructure to test set_thread_area()

Greg Kroah-Hartman
2017-12-22T09:48:50Z

From: Andy Lutomirski <luto@kernel.org>

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>

---
tools/testing/selftests/x86/ldt_gdt.c | 53 +++++++++++++++++++++++-----------
1 file changed, 37 insertions(+), 16 deletions(-)

--- 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
}
}

-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 str

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)