http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55521
--- Comment #6 from Jack Howarth <howarth at nitro dot med.uc.edu> 2012-11-29
21:25:07 UTC ---
Opened radr://12777299 so that the darwin linker maintainer could look at this
issue. His analysis of the failing test case so far is...
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I debugged this a bit and it seems the mach_override patching of __cxa_throw is
bogus. The start of that function is patched to jump to garbage.
Breakpoint 1, 0x0000000100001c19 in main ()
(gdb) display/i $pc
2: x/i $pc 0x100001c19 <main+318>: callq 0x100016386
<dyld_stub___cxa_throw>
(gdb) si
0x0000000100016386 in dyld_stub___cxa_throw ()
2: x/i $pc 0x100016386 <dyld_stub___cxa_throw>: jmpq *0xae1c(%rip)
# 0x1000211a8
(gdb)
0x0000000102244870 in __cxa_throw ()
2: x/i $pc 0x102244870 <__cxa_throw>: jmpq 0xffd27000
(gdb) # the above its __cxa_throw in gcc's libstdc++.6.dylib. The first
instruction has been patch to jump to a garbage address.
(gdb) x/8i 0x102244870-8
0x102244868
<_ZL23__gxx_exception_cleanup19_Unwind_Reason_CodeP17_Unwind_Exception+56>: std
0x102244869
<_ZL23__gxx_exception_cleanup19_Unwind_Reason_CodeP17_Unwind_Exception+57>:
(bad)
0x10224486a
<_ZL23__gxx_exception_cleanup19_Unwind_Reason_CodeP17_Unwind_Exception+58>:
decl (%rdi)
0x10224486c
<_ZL23__gxx_exception_cleanup19_Unwind_Reason_CodeP17_Unwind_Exception+60>:
(bad)
0x10224486d
<_ZL23__gxx_exception_cleanup19_Unwind_Reason_CodeP17_Unwind_Exception+61>: add
%r8b,(%rax)
0x102244870 <__cxa_throw>: jmpq 0xffd27000
0x102244875 <__cxa_throw+5>: or (%rax),%eax
0x102244877 <__cxa_throw+7>: push %rbx
(gdb)
(gdb) watch *0x102244870
Hardware watchpoint 2: *4330899568
(gdb) r
Old value = -788165304
New value = -1373139991
0x0000000100016203 in __asan_mach_override_ptr_custom ()
(gdb) bt
#0 0x0000000100016203 in __asan_mach_override_ptr_custom ()
#1 0x0000000100015a9e in __interception::OverrideFunction ()
#2 0x00007fff5fc13378 in ImageLoaderMachO::doModInitFunctions ()
#3 0x00007fff5fc13762 in ImageLoaderMachO::doInitialization ()
#4 0x00007fff5fc1006e in ImageLoader::recursiveInitialization ()
#5 0x00007fff5fc0feba in ImageLoader::runInitializers ()
#6 0x00007fff5fc01fc0 in dyld::initializeMainExecutable ()
#7 0x00007fff5fc05b04 in dyld::_main ()
#8 0x00007fff5fc01397 in dyldbootstrap::start ()
#9 0x00007fff5fc0105e in _dyld_start ()
(gdb) x/8i 0x102244870
0x102244870 <__cxa_throw>: jmpq 0xffd27000
0x102244875 <__cxa_throw+5>: or (%rax),%eax
0x102244877 <__cxa_throw+7>: push %rbx
0x102244878 <__cxa_throw+8>: lea -0x20(%rdi),%rbx
0x10224487c <__cxa_throw+12>: mov %rsi,-0x70(%rdi)
# Here is where the patching is being done
