On Wed, Nov 5, 2014 at 9:09 AM, Jan Beulich <jbeul...@suse.com> wrote: >>>> Andy Lutomirski <l...@amacapital.net> 11/04/14 8:33 PM >>> >>On 11/04/2014 12:49 AM, Jan Beulich wrote: >>> Observing that per-CPU data (in the SMP case) is reachable by >>> exploiting 64-bit address wraparound, these two patches >>> arrange for using the one byte shorter RIP-relative addressing >>> forms for the majority of per-CPU accesses. >>> >>> 1: handle PC-relative relocations on per-CPU data >>> 2: use RIP-relative addressing for most per-CPU accesses >>> >>> Signed-off-by: Jan Beulich <jbeul...@suse.com> >>> >> >>I'm lost here. Can you give an example of a physical and virtual >>address of an instruction, the address within the gs segment, and why >>the relocations are backwards? > > When an instruction using RIP relative addressing gets moved up in > address space, the distance to the target address decreases. I.e. it's the > opposite of a normal, non-PC-relative base relocation (where the target > address increases together with the instruction getting moved up). >
Duh. Thanks :) --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
