Thanks, I think I understand the challenge. Maybe I should have realized when I saw the external bug I linked. For as much as my opinion is worth, I guess I would also agree that ALIGN_UP on the start would at least be consistent. Coupled with an explanation such as "// Protect pages that are entirely within the relro region. Since the runtime page size can vary, we can not trust linkers to get this right and must be conservative." I would not have sent my email (though I would have continued being sad). Right now it looks like a worst of both worlds scenario. Joel On Tue, Jan 17, 2023 at 7:49 AM H.J. Lu wrote: > On Tue, Jan 17, 2023 at 6:30 AM Adhemerval Zanella Netto > wrote: > > > > > > > > On 17/01/23 11:16, Florian Weimer wrote: > > > * Adhemerval Zanella Netto: > > > > > >> On 17/01/23 04:57, Florian Weimer via Libc-help wrote: > > >>> * Joel Molin via Libc-help: > > >>> > > >>>> Since mprotect will protect entire pages anyway, wouldn't it make a > lot > > >>>> more sense here to say `end = ALIGN_UP(...)`? Apart from feeling > more > > >>>> intuitive, it also seems like it would avoid page size > inconsistencies > > >>>> between runtime and link editing like the one above. > > >>> > > >>> ALIGN_UP might make memory read-only that should not be. > > >>> > > >>> There's some discussion about the alignment here: > > >>> > > >>> PT_GNU_RELRO is somewhat broken > > >>> > > >>> > > >>> I still think this is fairly broken, but there does not seem to be > much > > >>> desire to fix it. > > >> > > >> It was not clear to me from that discussion what you think it is still > > >> broken with PT_GNU_RELRO. > > > > > > Using ALIGN_DOWN for the start address can't be right. > > > > > > > Do we have a bug report for this? Because H.J explanation [1] only > describes > > ld support for the end of the RO segment. > > > > [1] https://sourceware.org/pipermail/libc-alpha/2022-May/138642.html > > If the end of the PT_GNU_RELRO segment isn't page aligned, > ALIGN_UP may change the executable page to read-only. > > -- > H.J. >