Messages in this thread | | | Date | Sun, 2 Sep 2007 13:28:47 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] i386 and x86_64: randomize brk() |
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> On Sat, 01 Sep 2007 22:19:01 +0200 Franck Bui-Huu <vagabon.xyz@gmail.com> wrote: > Hello Andrew, > > Andrew Morton wrote: > > On Thu, 30 Aug 2007 17:10:03 +0200 (CEST) Jiri Kosina <jkosina@suse.cz> wrote: > >> Andrew, do you still strongly oppose to having ARCH_HAS_RANDOMIZE_BRK > >> macro instead please? > >> > > > > Not strongly, but the general opinion seems to be that ARCH_HAS_FOO is > > sucky. It should at least be done in Kconfig rather than in .h, but even > > better is just to implement the thing for all architectures. > > > > Sorry for asking again but the initial poster haven't taken time to > answer to my feedbacks... > > What about using a weak function in that case ? It actually gives a > default implementation in _one_ place and can be changed easily from > a nop to something more complex later.
Yeah, weak functions are by far the cleanest way of doing this - they're most elegant. But they do add the overhead of an empty call/return, so some thought needs to go into the tradeoff.
> Another point is that the current prototype of arch_randomize_brk() > could be slightly improved IMHO. > > The proposed prototype is: > > void arch_randomize_brk(void) > > and I think it could be: > > unsigned long randomize_brk(unsigned long brk) > > Because the current code of exec syscall is rather.. hmm "tricky", > _hiding_ "current" global usage inside this function is error prone: > if this function is moved later, its use of "current->mm" could > reference the old mm process and it's hard to notice/fix.
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