[cfe-dev] increase size of function pointer?

[Reid Kleckner]

What's your overall goal?  If you want to be able to use page
protection to detect calls through function pointers, it seems like a
dynamic instrumentation tool like Pin or DynamoRIO would be a better
way to go.  Just find all indirect call instructions and instrument
them.

Reid

On Wed, Jun 1, 2011 at 11:50 PM, ret val <retval386 at gmail.com> wrote:
> I  mean pointers to functions unfortunately. I guess this will be more
> interesting that I thought. Any specific advice?
> Thank again
> On Wed, Jun 1, 2011 at 5:55 PM, John McCall <rjmccall at apple.com> wrote:
>>
>> On Jun 1, 2011, at 12:48 PM, ret val wrote:
>> > I would like to be able to increase the size allocated for normal
>> > function pointers so they each fill a entire (virtual memory) page.
>>
>> Do you mean that you want each *function* to occupy its own
>> VM page, or do you really mean that you want function *pointers*
>> to grow from 4-8 bytes apiece to 4KB?
>>
>> The best way of doing the former is to specify a huge alignment for
>> the function.  The latter is likely to break a lot of code that assumes
>> (yes, technically contrary to the standards) that function pointers
>> can be losslessly cast to, say, void*.
>>
>> John.
>
>
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