Re: [PATCH v3 09/27] x86/acpi: Adapt assembly for PIE support

Pavel Machek
2018-05-25T09:14:47Z

[-- Attachment #1: Type: text/plain, Size: 1606 bytes --]

On Thu 2018-05-24 09:35:42, Thomas Garnier wrote:
> On Thu, May 24, 2018 at 4:03 AM Pavel Machek <pavel@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

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]