On 17 April 2018 at 23:13, Dave Hansen <[email protected]> wrote: > > These are _very_ lightly tested. I'm throwing them out there for > folks are looking for a fix. > > --- > > From: Dave Hansen <[email protected]> > > pageattr.c is not friendly when it encounters empty (zero) PTEs. The > kernel linear map is exempt from these checks, but kernel text is not. > This patch adds the code to also exempt kernel text from these checks. > The proximate cause of these warnings was most likely an __init area > that spanned a 2MB page boundary that resulted in a "zero" PMD. > > Signed-off-by: Dave Hansen <[email protected]> > Fixes: 39114b7a7 (x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel > image) > Reported-by: Mariusz Ceier <[email protected]> > Reported-by: Aaro Koskinen <[email protected]> > Cc: Andrea Arcangeli <[email protected]> > Cc: Andy Lutomirski <[email protected]> > Cc: Arjan van de Ven <[email protected]> > Cc: Borislav Petkov <[email protected]> > Cc: Dan Williams <[email protected]> > Cc: David Woodhouse <[email protected]> > Cc: Greg Kroah-Hartman <[email protected]> > Cc: Hugh Dickins <[email protected]> > Cc: Josh Poimboeuf <[email protected]> > Cc: Juergen Gross <[email protected]> > Cc: Kees Cook <[email protected]> > Cc: Linus Torvalds <[email protected]> > Cc: Nadav Amit <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: [email protected] > --- > > b/arch/x86/mm/pageattr.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff -puN arch/x86/mm/pageattr.c~pti-glb-warning-inpageattr > arch/x86/mm/pageattr.c > --- a/arch/x86/mm/pageattr.c~pti-glb-warning-inpageattr 2018-04-17 > 14:10:22.695395554 -0700 > +++ b/arch/x86/mm/pageattr.c 2018-04-17 14:10:22.721395554 -0700 > @@ -1151,6 +1151,16 @@ static int populate_pgd(struct cpa_data > return 0; > } > > +bool __cpa_pfn_in_highmap(unsigned long pfn) > +{ > + /* > + * Kernel text has an alias mapping at a high address, known > + * here as "highmap". > + */ > + return within_inclusive(pfn, highmap_start_pfn(), > + highmap_end_pfn()); > +} > + > static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr, > int primary) > { > @@ -1183,6 +1193,10 @@ static int __cpa_process_fault(struct cp > cpa->numpages = 1; > cpa->pfn = __pa(vaddr) >> PAGE_SHIFT; > return 0; > + > + } else if (__cpa_pfn_in_highmap(cpa->pfn)) { > + /* Faults in the highmap are OK, so do not warn: */ > + return -EFAULT; > } else { > WARN(1, KERN_WARNING "CPA: called for zero pte. " > "vaddr = %lx cpa->vaddr = %lx\n", vaddr, > @@ -1335,8 +1349,7 @@ static int cpa_process_alias(struct cpa_ > * to touch the high mapped kernel as well: > */ > if (!within(vaddr, (unsigned long)_text, _brk_end) && > - within_inclusive(cpa->pfn, highmap_start_pfn(), > - highmap_end_pfn())) { > + __cpa_pfn_in_highmap(cpa->pfn)) { > unsigned long temp_cpa_vaddr = (cpa->pfn << PAGE_SHIFT) + > __START_KERNEL_map - phys_base; > alias_cpa = *cpa; > _
I confirm that these 2 patches fix the BUG for me in kernel 4.17.0-rc1. Thanks
