From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WzUZl-0005Ei-GF for kexec@lists.infradead.org; Tue, 24 Jun 2014 17:32:10 +0000 Date: Tue, 24 Jun 2014 13:31:25 -0400 From: Vivek Goyal Subject: Re: [PATCH 11/13] kexec-bzImage: Support for loading bzImage using 64bit entry Message-ID: <20140624173125.GA18045@redhat.com> References: <1401800822-27425-1-git-send-email-vgoyal@redhat.com> <1401800822-27425-12-git-send-email-vgoyal@redhat.com> <20140615163515.GA17016@pd.tnic> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20140615163515.GA17016@pd.tnic> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Borislav Petkov Cc: mjg59@srcf.ucam.org, gong.chen@linux.intel.com, bhe@redhat.com, jkosina@suse.cz, greg@kroah.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, ebiederm@xmission.com, hpa@zytor.com, akpm@linux-foundation.org, dyoung@redhat.com, chaowang@redhat.com T24gU3VuLCBKdW4gMTUsIDIwMTQgYXQgMDY6MzU6MTVQTSArMDIwMCwgQm9yaXNsYXYgUGV0a292 IHdyb3RlOgoKWy4uXQo+ID4gK2ludCBrZXhlY19zZXR1cF9pbml0cmQoc3RydWN0IGJvb3RfcGFy YW1zICpwYXJhbXMsCj4gPiArCQl1bnNpZ25lZCBsb25nIGluaXRyZF9sb2FkX2FkZHIsIHVuc2ln bmVkIGxvbmcgaW5pdHJkX2xlbikKPiA+ICt7Cj4gPiArCXBhcmFtcy0+aGRyLnJhbWRpc2tfaW1h Z2UgPSBpbml0cmRfbG9hZF9hZGRyICYgMHhmZmZmZmZmZlVMOwo+ID4gKwlwYXJhbXMtPmhkci5y YW1kaXNrX3NpemUgPSBpbml0cmRfbGVuICYgMHhmZmZmZmZmZlVMOwo+IAo+IFdlIGhhdmUgbW9y ZSByZWFkYWJsZSBHRU5NQVNLKiBtYWNyb3MgZm9yIGNvbnRpZ3VvdXMgbWFza3MuIFRoaXMgb25l Cj4gd2lsbCB0aGVuIGxvb2sgbGlrZToKPiAKPiAJcGFyYW1zLT5oZHIucmFtZGlza19pbWFnZSA9 IGluaXRyZF9sb2FkX2FkZHIgJiBHRU5NQVNLKDMxLCAwKTsKPiAJcGFyYW1zLT5oZHIucmFtZGlz a19zaXplID0gaW5pdHJkX2xlbiAmIEdFTk1BU0soMzEsIDApOwo+IAo+IGFuZCB0aGlzIHdheSB3 ZSBrbm93IGV4YWN0bHkgYWJvdXQgd2hpY2ggYml0cyBhcmUgd2UgdGFsa2luZyBhYm91dC4gOikK ClsgQ0MgZ29uZy5jaGVuQGxpbnV4LmludGVsLmNvbSBdCgpHRU5NQVNLKDMxLDApIG91dHB1dHMg Y29tcGlsYXRpb24gd2FybmluZy4KCmFyY2gveDg2L2tlcm5lbC9tYWNoaW5lX2tleGVjLmM6IElu IGZ1bmN0aW9uIOKAmGtleGVjX3NldHVwX2luaXRyZOKAmToKYXJjaC94ODYva2VybmVsL21hY2hp bmVfa2V4ZWMuYzozMDoyOiB3YXJuaW5nOiBsZWZ0IHNoaWZ0IGNvdW50ID49IHdpZHRoCm9mIHR5 cGUgW2VuYWJsZWQgYnkgZGVmYXVsdF0KICBwYXJhbXMtPmhkci5yYW1kaXNrX2ltYWdlID0gaW5p dHJkX2xvYWRfYWRkciAmIEdFTk1BU0soMzEsIDApOwogIF4KYXJjaC94ODYva2VybmVsL21hY2hp bmVfa2V4ZWMuYzozMToyOiB3YXJuaW5nOiBsZWZ0IHNoaWZ0IGNvdW50ID49IHdpZHRoCm9mIHR5 cGUgW2VuYWJsZWQgYnkgZGVmYXVsdF0KICBwYXJhbXMtPmhkci5yYW1kaXNrX3NpemUgPSBpbml0 cmRfbGVuICYgR0VOTUFTSygzMSwgMCk7CiAgXgphcmNoL3g4Ni9rZXJuZWwvbWFjaGluZV9rZXhl Yy5jOiBJbiBmdW5jdGlvbiDigJhrZXhlY19zZXR1cF9jbWRsaW5l4oCZOgphcmNoL3g4Ni9rZXJu ZWwvbWFjaGluZV9rZXhlYy5jOjUyOjI6IHdhcm5pbmc6IGxlZnQgc2hpZnQgY291bnQgPj0gd2lk dGgKb2YgdHlwZSBbZW5hYmxlZCBieSBkZWZhdWx0XQogIGNtZGxpbmVfbG93XzMyID0gY21kbGlu ZV9wdHJfcGh5cyAmIEdFTk1BU0soMzEsIDApOwoKSSB0aGluayBwcm9ibGVtIGlzIHRoYXQgd2Ug c2hpZnQgMSBieSAzMiBiaXRzIGluIHRoaXMgY2FzZSAoMzEgLSAwICsgMSkgYW5kCnRoYXQgb3Zl cmZsb3dzIHRoZSBzaXplIG9mIHVuc2lnbmVkLiBTbyB0aGVyZSBpcyB0aGlzIGNvcm5lciBjYXNl IHdoZXJlIAppdCBkb2VzIG5vdCBzZWVtIHRvIHdvcmsgKG9yIGF0bGVhc3Qgb3V0cHV0cyB3YXJu aW5nKS4KClRoYW5rcwpWaXZlawoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX18Ka2V4ZWMgbWFpbGluZyBsaXN0CmtleGVjQGxpc3RzLmluZnJhZGVhZC5vcmcK aHR0cDovL2xpc3RzLmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5mby9rZXhlYwo= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755874AbaFXRcQ (ORCPT ); Tue, 24 Jun 2014 13:32:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2949 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755759AbaFXRcP (ORCPT ); Tue, 24 Jun 2014 13:32:15 -0400 Date: Tue, 24 Jun 2014 13:31:25 -0400 From: Vivek Goyal To: Borislav Petkov Cc: linux-kernel@vger.kernel.org, kexec@lists.infradead.org, ebiederm@xmission.com, hpa@zytor.com, mjg59@srcf.ucam.org, greg@kroah.com, jkosina@suse.cz, dyoung@redhat.com, chaowang@redhat.com, bhe@redhat.com, akpm@linux-foundation.org, gong.chen@linux.intel.com Subject: Re: [PATCH 11/13] kexec-bzImage: Support for loading bzImage using 64bit entry Message-ID: <20140624173125.GA18045@redhat.com> References: <1401800822-27425-1-git-send-email-vgoyal@redhat.com> <1401800822-27425-12-git-send-email-vgoyal@redhat.com> <20140615163515.GA17016@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20140615163515.GA17016@pd.tnic> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jun 15, 2014 at 06:35:15PM +0200, Borislav Petkov wrote: [..] > > +int kexec_setup_initrd(struct boot_params *params, > > + unsigned long initrd_load_addr, unsigned long initrd_len) > > +{ > > + params->hdr.ramdisk_image = initrd_load_addr & 0xffffffffUL; > > + params->hdr.ramdisk_size = initrd_len & 0xffffffffUL; > > We have more readable GENMASK* macros for contiguous masks. This one > will then look like: > > params->hdr.ramdisk_image = initrd_load_addr & GENMASK(31, 0); > params->hdr.ramdisk_size = initrd_len & GENMASK(31, 0); > > and this way we know exactly about which bits are we talking about. :) [ CC gong.chen@linux.intel.com ] GENMASK(31,0) outputs compilation warning. arch/x86/kernel/machine_kexec.c: In function ‘kexec_setup_initrd’: arch/x86/kernel/machine_kexec.c:30:2: warning: left shift count >= width of type [enabled by default] params->hdr.ramdisk_image = initrd_load_addr & GENMASK(31, 0); ^ arch/x86/kernel/machine_kexec.c:31:2: warning: left shift count >= width of type [enabled by default] params->hdr.ramdisk_size = initrd_len & GENMASK(31, 0); ^ arch/x86/kernel/machine_kexec.c: In function ‘kexec_setup_cmdline’: arch/x86/kernel/machine_kexec.c:52:2: warning: left shift count >= width of type [enabled by default] cmdline_low_32 = cmdline_ptr_phys & GENMASK(31, 0); I think problem is that we shift 1 by 32 bits in this case (31 - 0 + 1) and that overflows the size of unsigned. So there is this corner case where it does not seem to work (or atleast outputs warning). Thanks Vivek