From: Thomas Garnier <thgarnie@google.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Brian Gerst" <brgerst@gmail.com>,
"Herbert Xu" <herbert@gondor.apana.org.au>,
"David S . Miller" <davem@davemloft.net>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Josh Poimboeuf" <jpoimboe@redhat.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"Matthias Kaehlcke" <mka@chromium.org>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Juergen Gross" <jgross@suse.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Joerg Roedel" <joro@8bytes.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Borislav Petkov" <bp@alien8.de>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
"Borislav Petkov" <bp@suse.de>,
"Christian Borntraeger" <borntraeger@de.ibm.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
"Len Brown" <len.brown@intel.com>, "Pavel Machek" <pavel@ucw.cz>,
"Tejun Heo" <tj@kernel.org>
Subject: Re: [RFC 06/22] kvm: Adapt assembly for PIE support
Date: Wed, 19 Jul 2017 15:44:48 -0700 [thread overview]
Message-ID: <CAJcbSZFjiqPoOUDFSU_WhneEJCEhrAe6nV4tRGOpRg7hsOk1-A@mail.gmail.com> (raw)
In-Reply-To: <0cdd02e1-8bf2-41cd-f085-c338c2fd8e25@zytor.com>
On Wed, Jul 19, 2017 at 3:27 PM, H. Peter Anvin <hpa@zytor.com> wrote:
> On 07/19/17 08:40, Thomas Garnier wrote:
>>>
>>> This doesn't look right. It's accessing a per-cpu variable. The
>>> per-cpu section is an absolute, zero-based section and not subject to
>>> relocation.
>>
>> PIE does not respect the zero-based section, it tries to have
>> everything relative. Patch 16/22 also adapt per-cpu to work with PIE
>> (while keeping the zero absolute design by default).
>>
>
> This is silly. The right thing is for PIE is to be explicitly absolute,
> without (%rip). The use of (%rip) memory references for percpu is just
> an optimization.
I agree that it is odd but that's how the compiler generates code. I
will re-explore PIC options with mcmodel=small or medium, as mentioned
on other threads.
>
> -hpa
>
--
Thomas
next prev parent reply other threads:[~2017-07-19 22:44 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-18 22:33 x86: PIE support and option to extend KASLR randomization Thomas Garnier
2017-07-18 22:33 ` [RFC 01/22] x86/crypto: Adapt assembly for PIE support Thomas Garnier
2017-07-18 22:33 ` [RFC 02/22] x86: Use symbol name on bug table " Thomas Garnier
2017-07-18 22:33 ` [RFC 03/22] x86: Use symbol name in jump " Thomas Garnier
2017-07-18 22:33 ` [RFC 04/22] x86: Add macro to get symbol address " Thomas Garnier
2017-07-18 22:33 ` [RFC 05/22] xen: Adapt assembly " Thomas Garnier
2017-07-18 22:33 ` [RFC 06/22] kvm: " Thomas Garnier
2017-07-19 2:49 ` Brian Gerst
2017-07-19 15:40 ` Thomas Garnier
2017-07-19 22:27 ` H. Peter Anvin
2017-07-19 22:44 ` Thomas Garnier [this message]
2017-07-19 22:58 ` Ard Biesheuvel
2017-07-19 23:47 ` H. Peter Anvin
2017-07-19 23:47 ` H. Peter Anvin
2017-07-18 22:33 ` [RFC 07/22] x86: relocate_kernel - " Thomas Garnier
2017-07-19 22:58 ` H. Peter Anvin
2017-07-19 23:23 ` Thomas Garnier
2017-07-18 22:33 ` [RFC 08/22] x86/entry/64: " Thomas Garnier
2017-07-18 22:33 ` [RFC 09/22] x86: pm-trace - " Thomas Garnier
2017-07-18 22:33 ` [RFC 10/22] x86/CPU: " Thomas Garnier
2017-07-18 22:33 ` [RFC 11/22] x86/acpi: " Thomas Garnier
2017-07-18 22:33 ` [RFC 12/22] x86/boot/64: " Thomas Garnier
2017-07-18 22:33 ` [RFC 13/22] x86/power/64: " Thomas Garnier
2017-07-19 18:41 ` Pavel Machek
2017-07-18 22:33 ` [RFC 14/22] x86/paravirt: " Thomas Garnier
2017-07-18 22:33 ` [RFC 15/22] x86/boot/64: Use _text in a global " Thomas Garnier
2017-07-18 22:33 ` [RFC 16/22] x86/percpu: Adapt percpu " Thomas Garnier
2017-07-19 3:08 ` Brian Gerst
2017-07-19 18:26 ` Thomas Garnier
2017-07-19 23:33 ` H. Peter Anvin
2017-07-20 2:21 ` H. Peter Anvin
2017-07-20 3:03 ` H. Peter Anvin
2017-07-20 14:26 ` Thomas Garnier
2017-08-02 16:42 ` Thomas Garnier
2017-08-02 16:56 ` Kees Cook
2017-08-02 18:05 ` Thomas Garnier
2017-07-18 22:33 ` [RFC 17/22] compiler: Option to default to hidden symbols Thomas Garnier
2017-07-18 22:33 ` [RFC 18/22] x86/relocs: Handle DYN relocations for PIE support Thomas Garnier
2017-07-18 22:33 ` [RFC 19/22] x86/pie: Add option to build the kernel as PIE for x86_64 Thomas Garnier
2017-07-18 22:33 ` [RFC 20/22] x86/relocs: Add option to generate 64-bit relocations Thomas Garnier
2017-07-19 22:33 ` H. Peter Anvin
2017-07-19 22:47 ` Thomas Garnier
2017-07-19 23:08 ` H. Peter Anvin
2017-07-19 23:25 ` Thomas Garnier
2017-07-19 23:45 ` H. Peter Anvin
2017-07-19 23:45 ` H. Peter Anvin
2017-07-18 22:33 ` [RFC 21/22] x86/module: Add support for mcmodel large and PLTs Thomas Garnier
2017-07-19 1:35 ` H. Peter Anvin
2017-07-19 3:59 ` Brian Gerst
2017-07-19 15:58 ` Thomas Garnier
2017-07-19 17:34 ` Brian Gerst
2017-07-24 16:32 ` Thomas Garnier
2017-07-18 22:33 ` [RFC 22/22] x86/kaslr: Add option to extend KASLR range from 1GB to 3GB Thomas Garnier
2017-07-19 12:10 ` Baoquan He
2017-07-19 13:49 ` Baoquan He
2017-07-19 14:08 ` x86: PIE support and option to extend KASLR randomization Christopher Lameter
2017-07-19 19:21 ` Kees Cook
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