Excerpts from Aneesh Kumar K.V's message of 2016-03-27 03:23:13 -0500: > _PAGE_PRIVILEGED means the page can be accessed only by kernel. This is done > to keep pte bits similar to PowerISA 3.0 radix PTE format. User > pages are now makred by clearing _PAGE_PRIVILEGED bit. > > Previously we allowed kernel to have a privileged page > in the lower address range(USER_REGION). With this patch such access > is denied.
Copying in cxlflash folks - as the only in-kernel user of the cxl driver can you do some testing and make sure that the driver still works with this change? Copying in Andrew Donnellan since he has a patch to fix the kernel test that hasn't been merged yet that might be impacted by this. > We also prevent a kernel access to a non-privileged page in > higher address range (ie, REGION_ID != 0). Both the above access > scenario should never happen. > > Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> Acked-by: Ian Munsie <imun...@au1.ibm.com> > diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c > index a3d5e1e16c21..33bd0ee30edd 100644 > --- a/drivers/misc/cxl/fault.c > +++ b/drivers/misc/cxl/fault.c > @@ -152,8 +152,10 @@ static void cxl_handle_page_fault(struct cxl_context > *ctx, > access = _PAGE_PRESENT | _PAGE_READ; > if (dsisr & CXL_PSL_DSISR_An_S) > access |= _PAGE_WRITE; > + > + access |= _PAGE_PRIVILEGED; > if ((!ctx->kernel) || ~(dar & (1ULL << 63))) > - access |= _PAGE_USER; > + access &= ~_PAGE_PRIVILEGED; > > if (dsisr & DSISR_NOHPTE) > inv_flags |= HPTE_NOHPTE_UPDATE; _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
