libunwind & static+no-pie binaries

[Martin Pieuchot]

Test program below, provided by robert@ blows up when compiled with
"-static" and "-no-pie":

  $ c++ -no-pie -static e.cc && ./a.out 
  Segmentation fault (core dumped)

  #0  libunwind::EHHeaderParser<libunwind::LocalAddressSpace>::decodeEHHdr 
(addressSpace=..., ehHdrStart=4211204, ehHdrEnd=4876, ehHdrInfo=...)
    at /usr/src/lib/libcxxabi/../libunwind/src/EHHeaderParser.hpp:60
  #1  libunwind::LocalAddressSpace::findUnwindSections(unsigned long, 
libunwind::UnwindInfoSections&)::{lambda(dl_phdr_info*, unsigned long, 
void*)#1}::operator()(dl_phdr_info*, unsigned long, void*) const 
(this=<optimized out>, pinfo=0x24a058 <_static_phdr_info>, data=<optimized out>)
      at /usr/src/lib/libcxxabi/../libunwind/src/AddressSpace.hpp:598
  #2  0x00000000002110c4 in libunwind::LocalAddressSpace::findUnwindSections 
(this=<optimized out>, targetAddr=<optimized out>, info=...)
      at /usr/src/lib/libcxxabi/../libunwind/src/AddressSpace.hpp:538
  #3  libunwind::UnwindCursor<libunwind::LocalAddressSpace, 
libunwind::Registers_x86_64>::setInfoBasedOnIPRegister (this=0x7f7fffff8a08, 
isReturnAddress=<optimized out>)
      at /usr/src/lib/libcxxabi/../libunwind/src/UnwindCursor.hpp:1827
  #4  0x00000000002103ee in unw_init_local (cursor=0x7f7fffff8a08, 
context=<optimized out>) at 
/usr/src/lib/libcxxabi/../libunwind/src/libunwind.cpp:82
  #5  0x000000000020fd8c in unwind_phase1 (uc=0x20f600 
<__cxxabiv1::exception_cleanup_func(_Unwind_Reason_Code, _Unwind_Exception*)>, 
      cursor=0x247f88 <vtable for 
libunwind::UnwindCursor<libunwind::LocalAddressSpace, 
libunwind::Registers_x86_64>+16>, exception_object=0x2749dfe60)
      at /usr/src/lib/libcxxabi/../libunwind/src/UnwindLevel1.c:39
  #6  _Unwind_RaiseException (exception_object=0x2749dfe60) at 
/usr/src/lib/libcxxabi/../libunwind/src/UnwindLevel1.c:357
  #7  0x000000000020f5f3 in __cxa_throw (thrown_object=0x2749dfe80, 
tinfo=0x2475c8 <typeinfo for char const*>, dest=<optimized out>)
      at /usr/src/lib/libcxxabi/src/cxa_exception.cpp:281
  #8  0x000000000020c38f in division(int, int) ()
  #9  0x000000000020c410 in main ()

That means it's currently impossible to profile C++ binaries on OpenBSD,
which is what we need :o)


#include <iostream>
using namespace std;

double division(int a, int b) {
  if (b == 0) {
    throw "Division by zero condition!";
  }
  return (a/b);
}

int main () {
  int x = 50;
  int y = 0;
  double z = 0;

  for (uint64_t n = 40; n > 0; n--) {
    try {
      z = division(x, y);
    } catch (const char* msg) {
    }
  }

  return 0;
}