On Thu, May 7, 2015 at 9:21 AM, H.J. Lu <[email protected]> wrote: > On Thu, May 7, 2015 at 4:52 AM, Jan Beulich <[email protected]> wrote: >>>>> On 07.05.15 at 08:02, <[email protected]> wrote: >>> AFAICT gas will produce relocations for jumps to global labels in the >>> same file. This doesn't seem directly harmful to me, except that, on >>> x86, it forces five-byte jumps instead of two-byte jumps. >>> >>> This seems especially unfortunate, since even hidden and protected >>> symbols have this problem. >>> >>> Given that many users don't want interposition support (especially the >>> kernel and anyone using .hidden or .protected), it would be nice to >>> have a command-line option to turn this off and probably also to turn >>> it off by default for hidden and protected symbols. Can gas do this? >> >> I've been running with the below changes (taken off of a bigger set >> of changes, so the line numbers may look a little odd) for the last >> couple of years. I never tried to submit this change because so far >> I couldn't find the time to check whether this would have any >> unwanted side effects on cases I don't normally use. >> > > This is the patch I checked in. > > Thanks. > > -- > H.J. > --- > Branches to global non-weak symbols defined in the same segment with > non-default visibility can be optimized the same way as branches to > local symbols.
Would it make sense to also add a command line option along the lines of gcc's -fno-semantic-interposition or some way to override the default visibility? AFAICS this patch helps but only if asm code gets liberally sprinkled with .hidden or .protected directives. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
