[Bug dynamic-link/31076] Extra struct vm_area_struct with ---p created when PAGE_SIZE < max-page-size

["fweimer at redhat dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=31076

--- Comment #18 from Florian Weimer <fweimer at redhat dot com> ---
(In reply to Kalesh Singh from comment #15)
> AIUI if the runtime-page-size equals the max-page-size, the holes are also
> mapped in as part of the segment mapping and share the same permissions.
> Does this mean that on such systems, any protection it offers becomes void?

That's my understanding. The current behavior gives programmers the *option* to
avoid mapping extra code on small-page systems, while maintaining compatibility
with large-page systems. The proposed change to over-map to the next
load-segment, to fill the gap, would take away that option. Unmapping (to
create a gap) has compatibility implications.

Just to clarify, I'm opposed to a glibc change here mainly because it's not
necessary to enable the desired behavior (fewer VMAs), and it removes
functionality that people might find useful. The link editor merely needs to
over-map in the generated LOAD segments, then there won't be any gaps for the
loader to process.

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