Hi Ben, > Don't we lose randomization ? Or do we randomize the whole mem map > nowadays ?
The start of the top down mmap region is randomized, so the VDSO will be in a different position each time. A quick example: run 1: fffb01f6000-fffb01f9000 r-xp 00000000 00:00 0 [vdso] fffb01f9000-fffb01fa000 r--p 00027000 08:06 4333852 /lib64/ld-2.9.so fffb01fa000-fffb01fd000 rw-p 00028000 08:06 4333852 /lib64/ld-2.9.so fffb01fd000-fffb01fe000 rw-p 00000000 00:00 0 ffff7c6f000-ffff7c84000 rw-p 00000000 00:00 0 [stack] run 2: fff9a094000-fff9a097000 r-xp 00000000 00:00 0 [vdso] fff9a097000-fff9a098000 r--p 00027000 08:06 4333852 /lib64/ld-2.9.so fff9a098000-fff9a09b000 rw-p 00028000 08:06 4333852 /lib64/ld-2.9.so fff9a09b000-fff9a09c000 rw-p 00000000 00:00 0 fffea0a6000-fffea0bb000 rw-p 00000000 00:00 0 [stack] You will notice we aren't randomising each mmap, so the relative offset between ld.so and the vdso will be consistent. I just checked and it looks like x86 does the same. It might make sense to add a small amount of randomness between mmaps on both x86 and PowerPC, at least for 64bit applications where we have enough address space. Anton _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
