x86/pkeys/selftests: Give better unexpected fault error messages

do_not_expect_pk_fault() is a helper that we call when we do not expect
a PK fault to have occurred.  But, it is a function, which means that
it obscures the line numbers from pkey_assert().  It also gives no
details.

Replace it with an implementation that gives nice line numbers and
also lets callers pass in a more descriptive message about what
happened that caused the unexpected fault.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellermen <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180509171338.55D13B64@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/tools/testing/selftests/x86/protection_keys.c b/tools/testing/selftests/x86/protection_keys.c
index bbe80a5..a0f0a73 100644 (file)
--- a/tools/testing/selftests/x86/protection_keys.c
+++ b/tools/testing/selftests/x86/protection_keys.c
@@ -954,10 +954,11 @@ void expected_pk_fault(int pkey)
        last_si_pkey = -1;
 }
 
-void do_not_expect_pk_fault(void)
-{
-       pkey_assert(last_pkru_faults == pkru_faults);
-}
+#define do_not_expect_pk_fault(msg)    do {                    \
+       if (last_pkru_faults != pkru_faults)                    \
+               dprintf0("unexpected PK fault: %s\n", msg);     \
+       pkey_assert(last_pkru_faults == pkru_faults);           \
+} while (0)
 
 int test_fds[10] = { -1 };
 int nr_test_fds;
@@ -1243,7 +1244,7 @@ void test_ptrace_of_child(int *ptr, u16 pkey)
        pkey_assert(ret != -1);
        /* Now access from the current task, and expect NO exception: */
        peek_result = read_ptr(plain_ptr);
-       do_not_expect_pk_fault();
+       do_not_expect_pk_fault("read plain pointer after ptrace");
 
        ret = ptrace(PTRACE_DETACH, child_pid, ignored, 0);
        pkey_assert(ret != -1);
@@ -1287,7 +1288,7 @@ void test_executing_on_unreadable_memory(int *ptr, u16 pkey)
         */
        madvise(p1, PAGE_SIZE, MADV_DONTNEED);
        lots_o_noops_around_write(&scratch);
-       do_not_expect_pk_fault();
+       do_not_expect_pk_fault("executing on PROT_EXEC memory");
        ptr_contents = read_ptr(p1);
        dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
        expected_pk_fault(pkey);