Re: [PATCH v1 1/2] Add the initify gcc plugin

Kees Cook
2016-06-29T14:50:28Z

On Tue, Jun 28, 2016 at 2:05 PM, Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
> On Tue, Jun 28 2016, Emese Revfy <re.emese@gmail.com> wrote:
>
>> The kernel already has a mechanism to free up code and data memory that
>> is only used during kernel or module initialization.
>> This plugin will teach the compiler to find more such code and data that
>> can be freed after initialization.
>> It has two passes. The first one tries to find all functions that
>> can be become __init/__exit. The second one moves string constants
>> (local variables and function string arguments marked by
>> the nocapture attribute) only referenced in __init/__exit functions
>> to the __initconst/__exitconst sections.
>> It reduces memory usage. This plugin can be useful for embedded systems.
>
> May I suggest, as a followup patch, a debug option/plugin parameter to
> put the strings in a section which will not be reaped after init, but
> just marked inaccessible, with graceful handling of bad accesses (print
> a big fat warning, make the page(s) readable, continue)?

Is there a clean way to do this that isn't arch-specific?

-Kees

--
Kees Cook
Chrome OS & Brillo Security