[Bug c/82411] New: const is not always read-only

[kees at outflux dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82411

            Bug ID: 82411
           Summary: const is not always read-only
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kees at outflux dot net
  Target Milestone: ---

On powerpc, a const variable may end up in the .sdata section, which is
writable. This means authors cannot depend on the "const" marking to mean
"read-only", as is required for sane Linux kernel memory protection security.

Thread here:
https://lkml.org/lkml/2017/10/2/488

At the very least, there should be a way to request never putting a const
variable into a writable section.