On Fri, Jan 5, 2018 at 1:14 PM, Jiri Kosina <jikos@xxxxxxxxxx> wrote: > On Fri, 5 Jan 2018, Dave Hansen wrote: > >> >>> --- a/arch/x86/platform/efi/efi_64.c >> >>> +++ b/arch/x86/platform/efi/efi_64.c >> >>> @@ -95,6 +95,12 @@ pgd_t * __init efi_call_phys_prolog(void >> >>> save_pgd[pgd] = *pgd_offset_k(pgd * PGDIR_SIZE); >> >>> vaddress = (unsigned long)__va(pgd * PGDIR_SIZE); >> >>> set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), *pgd_offset_k(vaddress)); >> >>> + /* >> >>> + * pgprot API doesn't clear it for PGD >> >>> + * >> >>> + * Will be brought back automatically in _epilog() >> >>> + */ >> >>> + pgd_offset_k(pgd * PGDIR_SIZE)->pgd &= ~_PAGE_NX; >> >>> } >> >>> __flush_tlb_all(); >> >> >> >> Wait a sec... Where does the _PAGE_USER come from? Shouldn't we see >> >> the &init_mm in there and *not* set _PAGE_USER? >> > >> > That's because pgd_populate() uses _PAGE_TABLE and not _KERNPG_TABLE for >> > reasons that are behind me. Oh, I completely missed that; and then the issue would have got hidden by one of my later per-process-kaiser patches. >> > >> > I did put this on my TODO list, but for later. >> > >> > (and yes, I tried clearing _PAGE_USER from init_mm's PGD, and no obvious >> > breakages appeared, but I wanted to give it more thought later). >> >> Feel free to add my Ack on this. And mine - thanks a lot for dealing with this Jiri. > > Thanks. I'll extract the patch out of this thread and submit it > separately, so that it doesn't get lost buried here. > >> I'd personally much rather muck with random relatively unused bits of >> the efi code than touch the core PGD code. > > Exactly. Especially at this point. Indeed. > >> We need to go look at it again in the 4.16 timeframe, probably. > > Agreed. On my TODO list already. > > Thanks, > > -- > Jiri Kosina > SUSE Labs > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
