From: Thomas Garnier <thgarnie@chromium.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>,
Kristen Carlson Accardi <kristen@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v10 04/11] x86/entry/64: Adapt assembly for PIE support
Date: Fri, 6 Dec 2019 08:35:09 -0800 [thread overview]
Message-ID: <CAJcbSZHLcSN4BK=N7M3Kv9q-hkPe6dDxbHaRCG9v2JVwhSZxfw@mail.gmail.com> (raw)
In-Reply-To: <20191206102649.GC2844@hirez.programming.kicks-ass.net>
On Fri, Dec 6, 2019 at 2:27 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Thu, Dec 05, 2019 at 09:01:50AM -0800, Thomas Garnier wrote:
> > On Thu, Dec 5, 2019 at 1:04 AM Peter Zijlstra <peterz@infradead.org> wrote:
> > > On Wed, Dec 04, 2019 at 04:09:41PM -0800, Thomas Garnier wrote:
> > >
> > > > @@ -1625,7 +1627,11 @@ first_nmi:
> > > > addq $8, (%rsp) /* Fix up RSP */
> > > > pushfq /* RFLAGS */
> > > > pushq $__KERNEL_CS /* CS */
> > > > - pushq $1f /* RIP */
> > > > + pushq $0 /* Future return address */
> > >
> > > We're building an IRET frame, the IRET frame does not have a 'future
> > > return address' field.
> >
> > I assumed that's the target RIP after iretq.
>
> It is. But it's still the (R)IP field of the IRET frame. Calling it
> anything else is just confusing. The frame is 5 words: SS, (R)SP, (R)FLAGS,
> CS, (R)IP.
>
> > > > + pushq %rdx /* Save RAX */
> > > > + leaq 1f(%rip), %rdx /* RIP */
> > >
> > > nonsensical comment
> >
> > That was the same comment from the push $1f that I changed.
>
> Yes, but there it made sense since the PUSH actually created that field
> of the frame, here it is nonsensical. What this instruction does is put
> the address of the '1f' label into RDX, which is then stuck into the
> (R)IP field on the next instruction.
Got it, make sense. Thanks.
>
> > > > + movq %rdx, 8(%rsp) /* Put 1f on return address */
> > > > + popq %rdx /* Restore RAX */
next prev parent reply other threads:[~2019-12-06 16:35 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-05 0:09 [PATCH v10 00/11] x86: PIE support to extend KASLR randomization Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 01/11] x86/crypto: Adapt assembly for PIE support Thomas Garnier
2019-12-18 12:46 ` Borislav Petkov
2019-12-18 16:35 ` Thomas Garnier
2019-12-18 16:45 ` Borislav Petkov
2019-12-05 0:09 ` [PATCH v10 02/11] x86: Add macro to get symbol address " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 03/11] x86: relocate_kernel - Adapt assembly " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 04/11] x86/entry/64: " Thomas Garnier
2019-12-05 9:03 ` Peter Zijlstra
2019-12-05 17:01 ` Thomas Garnier
2019-12-06 10:26 ` Peter Zijlstra
2019-12-06 16:35 ` Thomas Garnier [this message]
2019-12-20 16:05 ` Borislav Petkov
2019-12-05 0:09 ` [PATCH v10 05/11] x86: pm-trace - " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 06/11] x86/CPU: " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 07/11] x86/acpi: " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 08/11] x86/boot/64: " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 09/11] x86/power/64: " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 10/11] x86/paravirt: " Thomas Garnier
2019-12-23 17:23 ` Borislav Petkov
2019-12-24 10:04 ` Borislav Petkov
2019-12-05 0:09 ` [PATCH v10 11/11] x86/alternatives: " Thomas Garnier
2019-12-19 13:34 ` [PATCH v10 00/11] x86: PIE support to extend KASLR randomization Peter Zijlstra
2019-12-19 16:35 ` Thomas Garnier
2019-12-24 13:03 ` Borislav Petkov
2019-12-30 18:52 ` Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAJcbSZHLcSN4BK=N7M3Kv9q-hkPe6dDxbHaRCG9v2JVwhSZxfw@mail.gmail.com' \
--to=thgarnie@chromium.org \
--cc=bp@alien8.de \
--cc=hpa@zytor.com \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=kristen@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).