On Thursday, 14 April 2022 14:52:42 PDT Henry Skoglund wrote: > Indeed it looks weird (it's pointing into 2TB territory) but I believe > it's just an effect of Microsoft's Control Flow Guard (tm) being active > for that .exe.
It's possible. I've read about that Windows feature, but have not yet experimented with it. Anyway, the absolute value of a pointer is completely irrelevant and could be anything. On Linux, for example, they start from both the top and bottom: $ gdb -batch -ex start libexec/moc | grep main Temporary breakpoint 1 at 0x429415: file /home/tjmaciei/src/qt/qt6/qtbase/src/ tools/moc/main.cpp, line 679. Temporary breakpoint 1, main (_argc=1, _argv=0x7fffffffd548) at /home/ tjmaciei/src/qt/qt6/qtbase/src/tools/moc/main.cpp:679 That pointer value of 0x7fffffffd548 is near 2^47, which is 128 TB. Meanwhile, the address of main is just above 4 MB. There's also a case of "starting from the middle" for position-independent executables: $ gdb -batch -ex start -ex 'p &main' /bin/ls | tail -1 $1 = (int (*)(int, char **)) 0x555555558700 <main> I don't know why they chose that bit pattern. On macOS, all 64-bit pointers are above 4 GB, to aid in catching accidental assignments to 32-bit integer variables. $ lldb --batch --one-line 'p &main' libexec/moc | tail -1 (int (*)(int, char **)) $0 = 0x00000001000301c0 -- Thiago Macieira - thiago.macieira (AT) intel.com Software Architect - Intel DPG Cloud Engineering _______________________________________________ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
