PIE on 64bit
john.r.moser at gmail.com
Thu Apr 18 18:25:31 UTC 2013
Meant to go to list
On Apr 18, 2013 2:15 PM, "John Moser" <john.r.moser at gmail.com> wrote:
> On Apr 18, 2013 2:07 PM, "Insanity Bit" <colintrexob at gmail.com> wrote:
> > On 64bit multiple services (pulseaudio, rsyslogd, many others) are
> shipping without Position Independent Code. On 32bit there is a potential
> performance hit for startup time... but there shouldn't be any performance
> hit (or negligible) on 64bit.
> There is a continuous performance hit of under 1% without
> -fomit-frame-pointer and under 6% with -fomit-frame-pointer on IA-32. The
> impact is statistically insignificant (i got 0.002% +/- 0.5%) on x86-64.
> The performance hit on IA-32 only applies to main executable code because
> library code is PIC already. This accounts for under 2% runtime, except in
> X where it used to be 5%. That makes the overall impact 2% of 6% or
> 0.12%--which is non-existent if your CPU is ever at less than 99.88% load
> because you would swiftly catch up.
> In other words: there is NO PERFORMANCE HIT for PIE in any
> non-laboratory, non-theoretical situation. (Theo de Raadt argued this with
> me once, using the term "very expensive" a lot. I built two identical
> Gentoo boxes and profiled them both extensively with oprofile. It is
> exactly a theoretical cost, and the performance concerns come from people
> who have no clue what the execution flow of modern software looks like)
> > "PIE on x86_64 does not have the same penalties, and will eventually be
> made the default, but more testing is required."
> > - https://wiki.ubuntu.com/Security/Features#pie
> > Is there an open bug for testing? A way for users to test and give
> feedback without recompiling massive projects like pulseaudio?
> > 13.04 still doesn't ship PIE. I would expect this would be something
> you'd want to put in *before* an LTS release?
> > --
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