[MSan] Mark dtls_test expected failure for MIPS

[mohit.bhakkad]

Summary

This test is failing with following report:

==4793==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0xfff51d13e0 in Thread1 llvm/projects/compiler-rt/test/msan/dtls_test.c:22:7
    #1 0xfff5149114 in MsanThreadStartFunc(void*) llvm/projects/compiler-rt/lib/msan/msan_interceptors.cc:1238
    #2 0xfff50a4cf4 in start_thread /build/glibc-g99ldr/glibc-2.19/nptl/pthread_create.c:311

Is it a known issue? I am unable to visit issue #44 because of transition of google code.

[eugenis]

Issue 44 is here: https://github.com/google/sanitizers/issues/547
And this failure shows that zero-initialized globals (.tbss) are not considered initialized by MSan, which is a bug somewhere in MSan TLS handling. See MsanThread::ClearShadowForThreadStackAndTLS.

test/msan/dtls_test.c

10

it's in dtls_test.c:22:7, isn't it?

[mohit.bhakkad]

Thanks,

I will update the link with a commit.
Looks like it was due to wrong kDtvOffset value for MIPS, corrected it in D17703.

test/msan/dtls_test.c

 /* RUN: %clang_msan -g %s -o %t
    RUN: %clang_msan -g %s -DBUILD_SO -fPIC -o %t-so.so -shared
    RUN: %run %t 2>&1
 
    Regression test for a bug in msan/glibc integration,
    see https://sourceware.org/bugzilla/show_bug.cgi?id=16291
    and https://code.google.com/p/memory-sanitizer/issues/detail?id=44
 */
+// MIPS64 shows fails with uninitialized value in
+// nptl/pthread_create.c:311 (glibc 2.19)
+// XFAIL: mips64
 
 #ifndef BUILD_SO
 #include <assert.h>
 #include <dlfcn.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <pthread.h>