Linux Virtualization - May 2018 - [PATCH v3 09/27] x86/acpi: Adapt assembly for PIE support

On Thu 2018-05-24 09:35:42, Thomas Garnier wrote:
> On Thu, May 24, 2018 at 4:03 AM Pavel Machek <pavel at ucw.cz> wrote:
> 
> > On Wed 2018-05-23 12:54:03, Thomas Garnier wrote:
> > > Change the assembly code to use only relative references of
symbols for
> the
> > > kernel to be PIE compatible.
> > >
> > > Position Independent Executable (PIE) support will allow to
extended the
> > > KASLR randomization range below the -2G memory limit.
> 
> > What testing did this get?
> 
> Tested boot, hibernation and performance on qemu and dedicated machine.
Well, this is suspend, not hibernation code.

So "sudo pm-suspend" or "echo mem > /sys/power/state"
would be good
way to test this.

Thanks,
							Pavel
> > > diff --git a/arch/x86/kernel/acpi/wakeup_64.S
> b/arch/x86/kernel/acpi/wakeup_64.S
> > > index 50b8ed0317a3..472659c0f811 100644
> > > --- a/arch/x86/kernel/acpi/wakeup_64.S
> > > +++ b/arch/x86/kernel/acpi/wakeup_64.S
> > > @@ -14,7 +14,7 @@
> > >        * Hooray, we are in Long 64-bit mode (but still running in
low
> memory)
> > >        */
> > >  ENTRY(wakeup_long64)
> > > -     movq    saved_magic, %rax
> > > +     movq    saved_magic(%rip), %rax
> > >       movq    $0x123456789abcdef0, %rdx
> > >       cmpq    %rdx, %rax
> > >       jne     bogus_64_magic
> 
> > Because, as comment says, this is rather tricky code.
> 
> I agree, I think maintainers feedback is very important for this patchset.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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On Fri, May 25, 2018 at 2:14 AM Pavel Machek <pavel at ucw.cz> wrote:
> On Thu 2018-05-24 09:35:42, Thomas Garnier wrote:
> > On Thu, May 24, 2018 at 4:03 AM Pavel Machek <pavel at ucw.cz>
wrote:
> >
> > > On Wed 2018-05-23 12:54:03, Thomas Garnier wrote:
> > > > Change the assembly code to use only relative references of
symbols
for
> > the
> > > > kernel to be PIE compatible.
> > > >
> > > > Position Independent Executable (PIE) support will allow to
extended the
> > > > KASLR randomization range below the -2G memory limit.
> >
> > > What testing did this get?
> >
> > Tested boot, hibernation and performance on qemu and dedicated
machine.
> Well, this is suspend, not hibernation code.
> So "sudo pm-suspend" or "echo mem >
/sys/power/state" would be good
> way to test this.
Thanks, it worked. I added this to the testsuite I use for KASLR.

> Thanks,
>                                                          Pavel
> > > > diff --git a/arch/x86/kernel/acpi/wakeup_64.S
> > b/arch/x86/kernel/acpi/wakeup_64.S
> > > > index 50b8ed0317a3..472659c0f811 100644
> > > > --- a/arch/x86/kernel/acpi/wakeup_64.S
> > > > +++ b/arch/x86/kernel/acpi/wakeup_64.S
> > > > @@ -14,7 +14,7 @@
> > > >        * Hooray, we are in Long 64-bit mode (but still
running in
low
> > memory)
> > > >        */
> > > >  ENTRY(wakeup_long64)
> > > > -     movq    saved_magic, %rax
> > > > +     movq    saved_magic(%rip), %rax
> > > >       movq    $0x123456789abcdef0, %rdx
> > > >       cmpq    %rdx, %rax
> > > >       jne     bogus_64_magic
> >
> > > Because, as comment says, this is rather tricky code.
> >
> > I agree, I think maintainers feedback is very important for this
patchset.

> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html



-- 
Thomas

On Fri 2018-05-25 10:00:04, Thomas Garnier wrote:
> On Fri, May 25, 2018 at 2:14 AM Pavel Machek <pavel at ucw.cz> wrote:
> 
> > On Thu 2018-05-24 09:35:42, Thomas Garnier wrote:
> > > On Thu, May 24, 2018 at 4:03 AM Pavel Machek <pavel at
ucw.cz> wrote:
> > >
> > > > On Wed 2018-05-23 12:54:03, Thomas Garnier wrote:
> > > > > Change the assembly code to use only relative
references of symbols
> for
> > > the
> > > > > kernel to be PIE compatible.
> > > > >
> > > > > Position Independent Executable (PIE) support will
allow to
> extended the
> > > > > KASLR randomization range below the -2G memory limit.
> > >
> > > > What testing did this get?
> > >
> > > Tested boot, hibernation and performance on qemu and dedicated
machine.
> 
> > Well, this is suspend, not hibernation code.
> 
> > So "sudo pm-suspend" or "echo mem >
/sys/power/state" would be good
> > way to test this.
> 
> Thanks, it worked. I added this to the testsuite I use for KASLR.
Thanks!

You can add my Acked-by:.

								Pavel
								
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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