From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752548AbbJWIhu (ORCPT ); Fri, 23 Oct 2015 04:37:50 -0400 Received: from mail-ig0-f178.google.com ([209.85.213.178]:37126 "EHLO mail-ig0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751768AbbJWIhr (ORCPT ); Fri, 23 Oct 2015 04:37:47 -0400 MIME-Version: 1.0 In-Reply-To: <1445593826-4578-1-git-send-email-izumi.taku@jp.fujitsu.com> References: <1445593826-4578-1-git-send-email-izumi.taku@jp.fujitsu.com> Date: Fri, 23 Oct 2015 10:37:46 +0200 Message-ID: Subject: Re: [PATCH v2] efi: Fix warning of int-to-pointer-cast on x86 32-bit builds From: Ard Biesheuvel To: Taku Izumi , Matt Fleming , Ingo Molnar Cc: "linux-kernel@vger.kernel.org" , kamezawa.hiroyu@jp.fujitsu.com, "linux-efi@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23 October 2015 at 11:50, Taku Izumi wrote: > commit-0f96a99 introduces the following warning message: > > drivers/firmware/efi/fake_mem.c:186:20: warning: cast to pointer > from integer of different size [-Wint-to-pointer-cast] > > new_memmap_phy was defined as a u64 value and casted to void*. > This causes a warning of int-to-pointer-cast on x86 32-bit > environment. > > This patch changes the type of "new_memmap_phy" variable > from "u64" into "ulong" to avoid it. > > v1 -> v2: > - change the type of "new_memmap_phy" from phys_addr_t > into ulong according to Ard's comment > > Reported-by: Ingo Molnar > Signed-off-by: Taku Izumi > --- > drivers/firmware/efi/fake_mem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/firmware/efi/fake_mem.c b/drivers/firmware/efi/fake_mem.c > index 32bcb14..1f483b4 100644 > --- a/drivers/firmware/efi/fake_mem.c > +++ b/drivers/firmware/efi/fake_mem.c > @@ -59,7 +59,7 @@ void __init efi_fake_memmap(void) > u64 start, end, m_start, m_end, m_attr; > int new_nr_map = memmap.nr_map; > efi_memory_desc_t *md; > - u64 new_memmap_phy; > + ulong new_memmap_phy; > void *new_memmap; > void *old, *new; > int i; After looking at the original (already merged) patch 11/11 again, I realize this is still not right: the problem is that efi_memory_map's phys_map member uses a void* type to hold a physical address, which happens to be correct in the normal case even when phys_addr_t is larger than void* (like on ARM with LPAE enabled) since the address it holds is the address of an allocation performed by the firmware, which only uses 1:1 addressable memory. However, overwriting memmap.phys_map with a value produced my memblock_alloc() is problematic, since the allocation may be above 4 GB on 32-bit (L)PAE platforms. So the correct way to do this would be to set the memblock limit to 4GB before memblock_alloc() on 32-bit platforms, and restore it afterwards. This is a bit of a kludge, though, and it would be more correct to change the type of efi_memory_map::phys_map to phys_addr_t, although I don't know what the potential fallout of that change is. Matt? So that means your v1 of this patch is correct after all, and the warning spotted by Ingo uncovered a problem with the original series that requires an additional fix. Regards, Ard.