Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752900AbcKYGsP (ORCPT ); Fri, 25 Nov 2016 01:48:15 -0500 Received: from terminus.zytor.com ([198.137.202.10]:59970 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752220AbcKYGsH (ORCPT ); Fri, 25 Nov 2016 01:48:07 -0500 Date: Thu, 24 Nov 2016 22:47:15 -0800 From: tip-bot for Ard Biesheuvel Message-ID: Cc: tglx@linutronix.de, peterz@infradead.org, mingo@kernel.org, arnd@arndb.de, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, matt@codeblueprint.co.uk, ard.biesheuvel@linaro.org, hpa@zytor.com Reply-To: tglx@linutronix.de, peterz@infradead.org, arnd@arndb.de, mingo@kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, matt@codeblueprint.co.uk, hpa@zytor.com, ard.biesheuvel@linaro.org In-Reply-To: <1480010543-25709-2-git-send-email-ard.biesheuvel@linaro.org> References: <1480010543-25709-2-git-send-email-ard.biesheuvel@linaro.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:efi/core] efi/libstub: Make efi_random_alloc() allocate below 4 GB on 32-bit Git-Commit-ID: 018edcfac4c3b140366ad51b0907f3becb5bb624 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2878 Lines: 73 Commit-ID: 018edcfac4c3b140366ad51b0907f3becb5bb624 Gitweb: http://git.kernel.org/tip/018edcfac4c3b140366ad51b0907f3becb5bb624 Author: Ard Biesheuvel AuthorDate: Thu, 24 Nov 2016 18:02:23 +0000 Committer: Ingo Molnar CommitDate: Fri, 25 Nov 2016 07:15:23 +0100 efi/libstub: Make efi_random_alloc() allocate below 4 GB on 32-bit The UEFI stub executes in the context of the firmware, which identity maps the available system RAM, which implies that only memory below 4 GB can be used for allocations on 32-bit architectures, even on [L]PAE capable hardware. So ignore any reported memory above 4 GB in efi_random_alloc(). This also fixes a reported build problem on ARM under -Os, where the 64-bit logical shift relies on a software routine that the ARM decompressor does not provide. A second [minor] issue is also fixed, where the '+ 1' is moved out of the shift, where it belongs: the reason for its presence is that a memory region where start == end should count as a single slot, given that 'end' takes the desired size and alignment of the allocation into account. To clarify the code in this regard, rename start/end to 'first_slot' and 'last_slot', respectively, and introduce 'region_end' to describe the last usable address of the current region. Reported-by: Arnd Bergmann Signed-off-by: Ard Biesheuvel Cc: Linus Torvalds Cc: Matt Fleming Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1480010543-25709-2-git-send-email-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar --- drivers/firmware/efi/libstub/random.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c index 3a3feac..7e72954 100644 --- a/drivers/firmware/efi/libstub/random.c +++ b/drivers/firmware/efi/libstub/random.c @@ -45,19 +45,20 @@ static unsigned long get_entry_num_slots(efi_memory_desc_t *md, unsigned long align_shift) { unsigned long align = 1UL << align_shift; - u64 start, end; + u64 first_slot, last_slot, region_end; if (md->type != EFI_CONVENTIONAL_MEMORY) return 0; - start = round_up(md->phys_addr, align); - end = round_down(md->phys_addr + md->num_pages * EFI_PAGE_SIZE - size, - align); + region_end = min((u64)ULONG_MAX, md->phys_addr + md->num_pages*EFI_PAGE_SIZE - 1); - if (start > end) + first_slot = round_up(md->phys_addr, align); + last_slot = round_down(region_end - size + 1, align); + + if (first_slot > last_slot) return 0; - return (end - start + 1) >> align_shift; + return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1; } /*