On 09/03/09 14:15, H. Peter Anvin wrote: > On 09/03/2009 01:45 PM, Jeremy Fitzhardinge wrote: > >> Two problems: >> >> * gcc generates %gs: references for stack-protector, but we use %fs >> for percpu data (because restoring %fs is faster if it's a null >> selector; TLS uses %gs). I guess we could use %fs if >> !CONFIG_CC_STACKPROTECTOR, or %gs if we are using it (though that >> has some fiddly ramifications for things like ptrace). >> > Well, by touching two segments we're getting the worst of both worlds, > so at least assuming some significant number of real-world deployments > use CC_STACKPROTECTOR, we really don't want to pessimize that case too much. > I'm assuming that stack-protector has fairly serious performance impact anyway, so a bit of extra entry/exit cost is acceptable. But I agree that there's no point in making it gratuitously bad. J -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html