Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933970AbcKOMJH (ORCPT ); Tue, 15 Nov 2016 07:09:07 -0500 Received: from mail-ua0-f193.google.com ([209.85.217.193]:34256 "EHLO mail-ua0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932643AbcKOMJE (ORCPT ); Tue, 15 Nov 2016 07:09:04 -0500 MIME-Version: 1.0 X-Originating-IP: [2a02:fe0:c130:1430:7e7a:91ff:fe0e:3e2c] In-Reply-To: <20161115120158.15388-2-dh.herrmann@gmail.com> References: <20161115120158.15388-1-dh.herrmann@gmail.com> <20161115120158.15388-2-dh.herrmann@gmail.com> From: Tom Gundersen Date: Tue, 15 Nov 2016 13:08:42 +0100 Message-ID: Subject: Re: [PATCH 1/2] x86/sysfb: add support for 64bit EFI lfb_base To: David Herrmann Cc: LKML , Matt Fleming , Ingo Molnar , "the arch/x86 maintainers" , "H. Peter Anvin" , Thomas Gleixner Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2602 Lines: 66 On Tue, Nov 15, 2016 at 1:01 PM, David Herrmann wrote: > The screen_info object was extended to support 64bit lfb_base addresses > in: > > commit ae2ee627dc87a70910de91b791b3cd0e9c6facdd > Author: Matt Fleming > Date: Tue Aug 25 16:32:55 2015 +0100 > > efifb: Add support for 64-bit frame buffer addresses > > However, the x86 simple-framebuffer setup code never made use of it. Fix > it to properly assemble and verify the lfb_base before advertising > simple-framebuffer devices. > > In particular, this means if VIDEO_CAPABILITY_64BIT_BASE is set, the > screen_info->ext_lfb_base field will contain the upper 32bit of the > actual lfb_base. Make sure the address is not 0 (i.e., unset), as well as > does not overflow the physical address type. > > Signed-off-by: David Herrmann Reviewed-by: Tom Gundersen > --- > arch/x86/kernel/sysfb_simplefb.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/sysfb_simplefb.c b/arch/x86/kernel/sysfb_simplefb.c > index 764a29f..35b8641 100644 > --- a/arch/x86/kernel/sysfb_simplefb.c > +++ b/arch/x86/kernel/sysfb_simplefb.c > @@ -67,6 +67,20 @@ __init int create_simplefb(const struct screen_info *si, > struct platform_device *pd; > struct resource res; > unsigned long len; > + u64 base; > + > + /* > + * If the 64BIT_BASE capability is set, ext_lfb_base will contain the > + * upper half of the base address. Assemble the address, then make sure > + * it is valid and we can actually access it. > + */ > + base = si->lfb_base; > + if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE) > + base |= (u64)si->ext_lfb_base << 32; > + if (!base || (u64)(resource_size_t)base != base) { > + printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n"); > + return -EINVAL; > + } > > /* don't use lfb_size as it may contain the whole VMEM instead of only > * the part that is occupied by the framebuffer */ > @@ -81,8 +95,8 @@ __init int create_simplefb(const struct screen_info *si, > memset(&res, 0, sizeof(res)); > res.flags = IORESOURCE_MEM | IORESOURCE_BUSY; > res.name = simplefb_resname; > - res.start = si->lfb_base; > - res.end = si->lfb_base + len - 1; > + res.start = base; > + res.end = res.start + len - 1; > if (res.end <= res.start) > return -EINVAL; > > -- > 2.10.2 >