Messages in this thread | | | Date | Wed, 19 Feb 2014 17:31:35 -0500 | From | Dave Jones <> | Subject | Re: [PATCH] Set bounds on what /proc/self/make-it-fail accepts. |
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On Wed, Feb 19, 2014 at 02:00:21PM -0800, Andrew Morton wrote:
> > I toyed with the idea of changing task_struct.make_it_fail to unsigned too, > > but only realized I missed that after I'd sent out the diff. > > If we're touching the task_struct we could make it a bool. > > Or just a single bit(field). task_struct already has a bunch of > bitfields in it (strangely, they aren't contiguous).
afaics, asides from brk_randomized, they're contiguous, and gcc dtrt..
unsigned int in_execve:1; /* 768:31 4 */ unsigned int in_iowait:1; /* 768:30 4 */ unsigned int no_new_privs:1; /* 768:29 4 */ unsigned int sched_reset_on_fork:1; /* 768:28 4 */ unsigned int sched_contributes_to_load:1; /* 768:27 4 */
So we could move the COMPAT_BRK ifdef and save 4 bytes for all the people still using libc5. (Or those who are for some reason averse to heap randomization).
It's not really worth doing unless you're moving a bunch of other stuff around in task_struct though, because as it is now, that struct has a bunch of alignment padding & holes, so you're not going to save anything.
The other tricky part with reorganizing that struct is that so much of it is configurable.
Dave
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