From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f198.google.com (mail-qk0-f198.google.com [209.85.220.198]) by kanga.kvack.org (Postfix) with ESMTP id 806C76B0069 for ; Wed, 30 Nov 2016 23:27:19 -0500 (EST) Received: by mail-qk0-f198.google.com with SMTP id i34so171386264qkh.1 for ; Wed, 30 Nov 2016 20:27:19 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id x7si32048011qta.127.2016.11.30.20.27.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 30 Nov 2016 20:27:18 -0800 (PST) Date: Thu, 1 Dec 2016 12:27:03 +0800 From: Dave Young Subject: Re: [PATCHv4 07/10] kexec: Switch to __pa_symbol Message-ID: <20161201042703.GA13113@dhcp-128-65.nay.redhat.com> References: <1480445729-27130-1-git-send-email-labbott@redhat.com> <1480445729-27130-8-git-send-email-labbott@redhat.com> <20161201024103.GA32438@dhcp-128-65.nay.redhat.com> <87polc7357.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87polc7357.fsf@xmission.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Eric W. Biederman" Cc: Laura Abbott , Mark Rutland , Ard Biesheuvel , Will Deacon , Catalin Marinas , x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ingo Molnar , "H. Peter Anvin" , Joonsoo Kim , Thomas Gleixner , Andrew Morton , linux-arm-kernel@lists.infradead.org, Marek Szyprowski On 11/30/16 at 09:13pm, Eric W. Biederman wrote: > Dave Young writes: > > > Hi, Laura > > On 11/29/16 at 10:55am, Laura Abbott wrote: > >> > >> __pa_symbol is the correct api to get the physical address of kernel > >> symbols. Switch to it to allow for better debug checking. > >> > > > > I assume __pa_symbol is faster than __pa, but it still need some testing > > on all arches which support kexec. > > > > But seems long long ago there is a commit e3ebadd95cb in the commit log > > I see below from: > > "we should deprecate __pa_symbol(), and preferably __pa() too - and > > just use "virt_to_phys()" instead, which is is more readable and has > > nicer semantics." > > > > But maybe in modern code __pa_symbol is prefered I may miss background. > > virt_to_phys still sounds more readable now for me though. > > There has been a lot of history with the various definitions. > __pa_symbol used to be x86 specific. > > Now what we have is that __pa_symbol is just __pa(RELOC_HIDE(x)); > > Now arguably that whole reloc hide thing should happen by architectures > having a non-inline version of __pa as was done in the commit you > mention. But at this point there appears to be nothing wrong with > changing a __pa to a __pa_symbol it might make things a tad more > reliable depending on the implementation of __pa. Then it is safe and reasonable, thanks for the clarification. > > Acked-by: "Eric W. Biederman" > > > Eric > > >> Signed-off-by: Laura Abbott > >> --- > >> Found during review of the kernel. Untested. > >> --- > >> kernel/kexec_core.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c > >> index 5616755..e1b625e 100644 > >> --- a/kernel/kexec_core.c > >> +++ b/kernel/kexec_core.c > >> @@ -1397,7 +1397,7 @@ void __weak arch_crash_save_vmcoreinfo(void) > >> > >> phys_addr_t __weak paddr_vmcoreinfo_note(void) > >> { > >> - return __pa((unsigned long)(char *)&vmcoreinfo_note); > >> + return __pa_symbol((unsigned long)(char *)&vmcoreinfo_note); > >> } > >> > >> static int __init crash_save_vmcoreinfo_init(void) > >> -- > >> 2.7.4 > >> > >> > >> _______________________________________________ > >> kexec mailing list > >> kexec@lists.infradead.org > >> http://lists.infradead.org/mailman/listinfo/kexec > > > > Thanks > > Dave -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org