From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S943207AbcJ1WHW (ORCPT ); Fri, 28 Oct 2016 18:07:22 -0400 Received: from mail-qk0-f171.google.com ([209.85.220.171]:34439 "EHLO mail-qk0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S942601AbcJ1WHT (ORCPT ); Fri, 28 Oct 2016 18:07:19 -0400 Subject: Re: [RFC][PATCH] arm64: Add support for CONFIG_DEBUG_VIRTUAL To: Mark Rutland References: <1477613892-26076-1-git-send-email-labbott@redhat.com> <20161028144951.GI5806@leverpostej> <4911a788-602f-6ad0-b8e7-53f9de9fa8c5@redhat.com> Cc: Ard Biesheuvel , Will Deacon , Catalin Marinas , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org From: Laura Abbott Message-ID: <6a76edf2-3f80-fb18-4fc1-2e0b1f085d20@redhat.com> Date: Fri, 28 Oct 2016 15:07:14 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <4911a788-602f-6ad0-b8e7-53f9de9fa8c5@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> diff --git a/arch/arm64/mm/physaddr.c b/arch/arm64/mm/physaddr.c >>> new file mode 100644 >>> index 0000000..6c271e2 >>> --- /dev/null >>> +++ b/arch/arm64/mm/physaddr.c >>> @@ -0,0 +1,17 @@ >>> +#include >>> + >>> +#include >>> + >>> +unsigned long __virt_to_phys(unsigned long x) >>> +{ >>> + phys_addr_t __x = (phys_addr_t)x; >>> + >>> + if (__x & BIT(VA_BITS - 1)) { >>> + /* The bit check ensures this is the right range */ >>> + return (__x & ~PAGE_OFFSET) + PHYS_OFFSET; >>> + } else { >>> + VIRTUAL_BUG_ON(x < kimage_vaddr || x > (unsigned long)_end); >> >> IIUC, in (3) you were asking if the last check should be '>' or '>='? >> >> To match high_memory, I suspect the latter, as _end doesn't fall within >> the mapped virtual address space. >> > > I was actually concerned about if _end would be correct with KASLR. > Ard confirmed that it gets fixed up to be correct. I'll change the > check to check for >=. > While testing this, I found two places with __pa(_end) to get bounds, one in arm64 code and one in memblock code. x86 gets away with this because memblock is actually __pa_symbol and x86 does image placement different and can check against the maximum image size. I think including _end in __pa_symbol but excluding it from the generic __virt_to_phys makes sense. It's a bit nicer than doing _end - 1 + 1 everywhere. Thanks, Laura