On Feb 7, 2010, at 10:21 PM, Benjamin Herrenschmidt wrote: > On Fri, 2010-02-05 at 00:53 +0800, Li Yang wrote: >> We can't just clear the user read permission in book3e pte, because >> that will also clear supervisor read permission. This surely isn't >> desired. Fix the problem by adding the supervisor read back. >> >> Signed-off-by: Li Yang <le...@freescale.com> >> --- >> arch/powerpc/mm/pgtable_32.c | 5 +++++ >> 1 files changed, 5 insertions(+), 0 deletions(-) >> >> diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c >> index cb96cb2..aff7c04 100644 >> --- a/arch/powerpc/mm/pgtable_32.c >> +++ b/arch/powerpc/mm/pgtable_32.c >> @@ -144,6 +144,11 @@ ioremap_flags(phys_addr_t addr, unsigned long size, >> unsigned long flags) >> /* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */ >> flags &= ~(_PAGE_USER | _PAGE_EXEC); >> >> +#if defined(CONFIG_FSL_BOOKE) && defined(CONFIG_PTE_64BIT) >> + /* supervisor read permission has just been cleared, add back */ >> + flags |= _PAGE_BAP_SR; >> +#endif >> + > > So this is a bit fishy indeed. pgtable_64.c seems to have the same > problem in fact. > > It boils down to the "hack" I have in the new PTE format which consists > of having _SR be part of _PAGE_USER. I wonder if I should change that > instead. Kumar, what do you reckon ? > > _Maybe_ an option is to have _PAGE_NO_USER that defaults to be > ~_PAGE_USER in pte-common.h and can be set in pte-book3e.h to > only strip out UR and UW ?
We never closed on this. I think lets add _PAGE_NO_USER - k _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev