Sure... but now you have to wrap things in stac/clac. I'm not sure I see the point since the code is already pretty much optimal.
On July 27, 2015 4:49:46 PM PDT, Andy Lutomirski <[email protected]> wrote: >On Mon, Jul 27, 2015 at 4:46 PM, H. Peter Anvin <[email protected]> wrote: >> Sure, but that is different than getting rid of the _ex forms. >> > >If we did that and got rid of the _ex forms, though, then the code >that matters (the no-fault case) would just be a bunch of movs, right? > That's basically the same as the current _ex code. > >--Andy > >> On July 27, 2015 4:36:26 PM PDT, Andy Lutomirski ><[email protected]> >> wrote: >>> >>> On Mon, Jul 27, 2015 at 4:22 PM, H. Peter Anvin <[email protected]> >wrote: >>>> >>>> For that to work, gcc would have to know about the extable. >>> >>> >>> It could, I think: >>> >>> asm goto ( >>> "1: mov ...\n\t" >>> _ASM_EXTABLE(1b, %l2) /* or whatever index it is */ >>> : ... : ... : ... : efault); >>> >>> return 0; >>> >>> efault: >>> return -EFAULT; >>> >>> I think that wrmsr_safe could get this treatment with current GCC. >>> put_user plausibly could, too, if we were willing to mark it >volatile >>> and accept that we're lying a little bit about the lack of an output >>> constraint. get_user would need GCC to understand output >constraints >>> for real. >>> >>> --Andy >> >> >> -- >> Sent from my Android device with K-9 Mail. Please excuse my brevity. -- Sent from my Android device with K-9 Mail. Please excuse my brevity. -- 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/
