From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id C7D186B0253 for ; Wed, 30 Nov 2016 22:16:22 -0500 (EST) Received: by mail-pf0-f200.google.com with SMTP id 17so334634452pfy.2 for ; Wed, 30 Nov 2016 19:16:22 -0800 (PST) Received: from out01.mta.xmission.com (out01.mta.xmission.com. [166.70.13.231]) by mx.google.com with ESMTPS id 31si38515968pli.203.2016.11.30.19.16.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 30 Nov 2016 19:16:21 -0800 (PST) From: ebiederm@xmission.com (Eric W. Biederman) 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> Date: Wed, 30 Nov 2016 21:13:24 -0600 In-Reply-To: <20161201024103.GA32438@dhcp-128-65.nay.redhat.com> (Dave Young's message of "Thu, 1 Dec 2016 10:41:03 +0800") Message-ID: <87polc7357.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [PATCHv4 07/10] kexec: Switch to __pa_symbol Sender: owner-linux-mm@kvack.org List-ID: To: Dave Young 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 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. 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