Re: Progress! was: Re: Yet more VM writable swap-cached pages
Linus Torvalds (torvalds@transmeta.com)
Mon, 20 Jul 1998 10:01:43 -0700 (PDT)
On Mon, 20 Jul 1998, Richard Henderson wrote:
> On Thu, Jul 09, 1998 at 05:54:21PM -0700, Linus Torvalds wrote:
> > It also explains why so few people saw this - PROT_NONE is not something
> > that is normally used.
>
> Actually, the glibc ld.so will create PROT_NONE regions if there is
> a hole between a shared library's text and data space. E.g.
>
> 20000110000-200001d6000 r-xp 00000000000 08:02 29407 /lib/libc-2.0.7.so
> 200001d6000-200002d0000 ---p 000000c6000 08:02 29407 /lib/libc-2.0.7.so
> 200002d0000-200002e6000 rwxp 000000c0000 08:02 29407 /lib/libc-2.0.7.so
Yes, but you won't have any actualy _pages_ mapped there.
The only way to get the pages there is to first map it with something else
than prot_none, touch some of the pages, and then do a mprotect() to make
them invisible again. I doubt glibc does that ;)
Linus
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