[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAJcbSZE0rVuzi0tQj6_vUu47GBKnHQM1N-Mom9PZHTG88z-noA@mail.gmail.com>
Date: Wed, 19 Jul 2017 16:25:56 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: Herbert Xu <herbert@...dor.apana.org.au>, "David S . Miller" <davem@...emloft.net>,
Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...hat.com>,
Arnd Bergmann <arnd@...db.de>, Matthias Kaehlcke <mka@...omium.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>, Juergen Gross <jgross@...e.com>,
Paolo Bonzini <pbonzini@...hat.com>, Radim Krčmář <rkrcmar@...hat.com>,
Joerg Roedel <joro@...tes.org>, Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...en8.de>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>, Brian Gerst <brgerst@...il.com>,
Borislav Petkov <bp@...e.de>, Christian Borntraeger <borntraeger@...ibm.com>,
"Rafael J . Wysocki" <rjw@...ysocki.net>, Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>, Kees Cook <keescook@...omium.org>,
Paul Gortmaker <paul.gortmaker@...driver.com>, Chris Metcalf <cmetcalf@...lanox.com>,
"Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>, Andrew Morton <akpm@...ux-foundation.org>,
Christopher Li <sparse@...isli.org>, Dou Liyang <douly.fnst@...fujitsu.com>,
Masahiro Yamada <yamada.masahiro@...ionext.com>, Daniel Borkmann <daniel@...earbox.net>,
Markus Trippelsdorf <markus@...ppelsdorf.de>, Peter Foley <pefoley2@...oley.com>,
Steven Rostedt <rostedt@...dmis.org>, Tim Chen <tim.c.chen@...ux.intel.com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>, Catalin Marinas <catalin.marinas@....com>,
Matthew Wilcox <mawilcox@...rosoft.com>, Michal Hocko <mhocko@...e.com>, Rob Landley <rob@...dley.net>,
Jiri Kosina <jkosina@...e.cz>, "H . J . Lu" <hjl.tools@...il.com>, Paul Bolle <pebolle@...cali.nl>,
Baoquan He <bhe@...hat.com>, Daniel Micay <danielmicay@...il.com>,
"the arch/x86 maintainers" <x86@...nel.org>, linux-crypto@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>, xen-devel@...ts.xenproject.org,
kvm list <kvm@...r.kernel.org>, Linux PM list <linux-pm@...r.kernel.org>,
linux-arch <linux-arch@...r.kernel.org>, linux-sparse@...r.kernel.org,
Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [RFC 20/22] x86/relocs: Add option to generate 64-bit relocations
On Wed, Jul 19, 2017 at 4:08 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 07/19/17 15:47, Thomas Garnier wrote:
>> On Wed, Jul 19, 2017 at 3:33 PM, H. Peter Anvin <hpa@...or.com> wrote:
>>> On 07/18/17 15:33, Thomas Garnier wrote:
>>>> The x86 relocation tool generates a list of 32-bit signed integers. There
>>>> was no need to use 64-bit integers because all addresses where above the 2G
>>>> top of the memory.
>>>>
>>>> This change add a large-reloc option to generate 64-bit unsigned integers.
>>>> It can be used when the kernel plan to go below the top 2G and 32-bit
>>>> integers are not enough.
>>>
>>> Why on Earth? This would only be necessary if the *kernel itself* was
>>> more than 2G, which isn't going to happen for the forseeable future.
>>
>> Because the relocation integer is an absolute address, not an offset
>> in the binary. Next iteration, I can try using a 32-bit offset for
>> everyone.
>
> It is an absolute address *as the kernel was originally linked*, for
> obvious reasons.
Sure when the kernel was just above 0xffffffff80000000, it doesn't
work when it goes down to 0xffffffff00000000. That's why using an
offset might make more sense in general.
>
> -hpa
>
--
Thomas.
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
