https://sourceware.org/bugzilla/show_bug.cgi?id=31795
--- Comment #38 from mintsuki <mintsuki at protonmail dot com> --- (In reply to Fangrui Song from comment #37) > I agree with mintsuki . The "-pie -Ttext-segment=non-zero => ET_EXEC" hack > should not be needed. > > From https://sourceware.org/pipermail/binutils/2013-December/083381.html > > > Linker sets e_type in ELF header to ET_DYN for -pie -Ttext-segment=0xXXX. > > When I added -Ttext-segment=0xXXX, one goal was to load > > small model executable above 4GB on Linux/x86-64, which > > was done with -pie -Ttext-segment=0xXXX. But -pie sets > > e_type in ELF header to ET_DYN and kernel may ignore > > p_vaddr in ELF header to load ET_DYN binary at a random > > address. This patch changes ld to set e_type in ELF header > > to ET_EXEC if the first PT_LOAD segment has non-zero > > p_vaddr. If this is unacceptable as generic ELF change, > > I can make it specific to x86. > > Was the intention for the following command to load the text segment at an > address >= 0x600000000000 ? > > ``` > % cat a.c > #include <stdio.h> > int main() { printf("%p\n", main); } > % gcc -pie -Wl,-no-pie a.c -fuse-ld=bfd > -Wl,--no-relax,-Ttext-segment=0x600000000000 -o a > % ./a > 0x600000001139 > % ./a > 0x600000001139 # no ASLR > ``` > > Changing ET_DYN to ET_EXEC fulfills the address requirement but disables > ASLR. > Is it intentional? > > I added `--no-pie` to GNU ld in 2021: > https://sourceware.org/cgit/binutils-gdb/commit/ > ?id=e8f6c2a5bab10b039a12b69a30a8248c91161e11 , with which we can do the > following instead. (GNU ld also needs `--no-relax` while lld doesn't). > > ``` > % gcc -pie a.c -fuse-ld=bfd > -Wl,--no-pie,--no-relax,-Ttext-segment=0x600000000000 -o a > % ./a > 0x600000001139 > % ./a > 0x600000001139 > ``` Thanks for agreeing with me and reopening this bug report. I appreciate that someone else sees this for the bug that it is, rather than trying to hand wave the issue away. I hope it will get addressed. -- You are receiving this mail because: You are on the CC list for the bug.
