[compiler-rt][FlexFat] Fix runtime overflow handling#5
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Running gcc test c-c++-common/tsan/tls_race.c on s390 we get: ThreadSanitizer: CHECK failed: tsan_platform_linux.cpp:618 "((thr_beg)) >= ((tls_addr))" (0x3ffaa35e140, 0x3ffaa35e250) (tid=2419930) #0 __tsan::CheckUnwind() /devel/src/libsanitizer/tsan/tsan_rtl.cpp:696 (libtsan.so.2+0x91b57) #1 __sanitizer::CheckFailed(char const*, int, char const*, unsigned long long, unsigned long long) /devel/src/libsanitizer/sanitizer_common/sanitizer_termination.cpp:86 (libtsan.so.2+0xd211b) #2 __tsan::ImitateTlsWrite(__tsan::ThreadState*, unsigned long, unsigned long) /devel/src/libsanitizer/tsan/tsan_platform_linux.cpp:618 (libtsan.so.2+0x8faa3) #3 __tsan::ThreadStart(__tsan::ThreadState*, unsigned int, unsigned long long, __sanitizer::ThreadType) /devel/src/libsanitizer/tsan/tsan_rtl_thread.cpp:225 (libtsan.so.2+0xaadb5) #4 __tsan_thread_start_func /devel/src/libsanitizer/tsan/tsan_interceptors_posix.cpp:1065 (libtsan.so.2+0x3d34d) #5 start_thread <null> (libc.so.6+0xae70d) (BuildId: d3b08de1b543c2d15d419bf861b3c2e4c01ac75b) llvm#6 thread_start <null> (libc.so.6+0x12d2ff) (BuildId: d3b08de1b543c2d15d419bf861b3c2e4c01ac75b) In order to determine the static TLS blocks in GetStaticTlsBoundary we iterate over the modules and try to find the largest range without a gap. Here we might have that modules are spaced exactly by the alignment. For example, for the failing test we have: (gdb) p/x ranges.data_[0] $1 = {begin = 0x3fff7f9e6b8, end = 0x3fff7f9e740, align = 0x8, tls_modid = 0x3} (gdb) p/x ranges.data_[1] $2 = {begin = 0x3fff7f9e740, end = 0x3fff7f9eed0, align = 0x40, tls_modid = 0x2} (gdb) p/x ranges.data_[2] $3 = {begin = 0x3fff7f9eed8, end = 0x3fff7f9eef8, align = 0x8, tls_modid = 0x4} (gdb) p/x ranges.data_[3] $4 = {begin = 0x3fff7f9eefc, end = 0x3fff7f9ef00, align = 0x4, tls_modid = 0x1} where ranges[3].begin == ranges[2].end + ranges[3].align holds. Since in the loop a strict inequality test is used we compute the wrong address (gdb) p/x *addr $5 = 0x3fff7f9eefc whereas 0x3fff7f9e6b8 is expected which is why we bail out in the subsequent.
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