Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread Florian Weimer
* H. J. Lu via Gcc: > On Tue, Apr 28, 2020 at 10:24 AM David Woodhouse wrote: >> Sure, there is work to do to enable CET. But Andy's point is that >> we deliberately fixed up retpoline to be register-based >> *specifically* for the purpose of being CET-compatible, so it's >> somewhat daft for GCC

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread Andy Lutomirski
> On Apr 28, 2020, at 10:44 AM, H.J. Lu wrote: > > On Tue, Apr 28, 2020 at 10:24 AM David Woodhouse wrote: >> >> >> >>> On 28 April 2020 17:14:49 BST, Peter Zijlstra wrote: >>> On Tue, Apr 28, 2020 at 02:41:33PM +0100, Andrew Cooper wrote: Its fine to focus on userspace first, but t

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread H.J. Lu via Gcc
On Tue, Apr 28, 2020 at 10:24 AM David Woodhouse wrote: > > > > On 28 April 2020 17:14:49 BST, Peter Zijlstra wrote: > >On Tue, Apr 28, 2020 at 02:41:33PM +0100, Andrew Cooper wrote: > >> Its fine to focus on userspace first, but the kernel is far more > >simple. > >> > >> Looking at that present

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread David Woodhouse
On 28 April 2020 17:14:49 BST, Peter Zijlstra wrote: >On Tue, Apr 28, 2020 at 02:41:33PM +0100, Andrew Cooper wrote: >> Its fine to focus on userspace first, but the kernel is far more >simple. >> >> Looking at that presentation, the only thing missing for kernel is >the >> notrack thunks, in

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread H.J. Lu via Gcc
On Tue, Apr 28, 2020 at 9:33 AM Andy Lutomirski wrote: > > > > > > On Apr 28, 2020, at 9:14 AM, Peter Zijlstra wrote: > > > > On Tue, Apr 28, 2020 at 02:41:33PM +0100, Andrew Cooper wrote: > >> Its fine to focus on userspace first, but the kernel is far more simple. > >> > >> Looking at that pre

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread Andy Lutomirski
> On Apr 28, 2020, at 9:14 AM, Peter Zijlstra wrote: > > On Tue, Apr 28, 2020 at 02:41:33PM +0100, Andrew Cooper wrote: >> Its fine to focus on userspace first, but the kernel is far more simple. >> >> Looking at that presentation, the only thing missing for kernel is the >> notrack thunks,

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread Peter Zijlstra
On Tue, Apr 28, 2020 at 02:41:33PM +0100, Andrew Cooper wrote: > Its fine to focus on userspace first, but the kernel is far more simple. > > Looking at that presentation, the only thing missing for kernel is the > notrack thunks, in the unlikely case that such code would be tolerated > (Frankly,

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread Andrew Cooper via Gcc
On 28/04/2020 16:09, H.J. Lu wrote: > On Tue, Apr 28, 2020 at 8:06 AM Jan Beulich wrote: >> On 28.04.2020 17:00, H.J. Lu wrote: >>> On Tue, Apr 28, 2020 at 6:41 AM Andrew Cooper >>> wrote: On 28/04/2020 14:00, H.J. Lu wrote: > On Tue, Apr 28, 2020 at 5:43 AM Andrew Cooper > wrote:

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread H.J. Lu via Gcc
On Tue, Apr 28, 2020 at 8:06 AM Jan Beulich wrote: > > On 28.04.2020 17:00, H.J. Lu wrote: > > On Tue, Apr 28, 2020 at 6:41 AM Andrew Cooper > > wrote: > >> > >> On 28/04/2020 14:00, H.J. Lu wrote: > >>> On Tue, Apr 28, 2020 at 5:43 AM Andrew Cooper > >>> wrote: > Hello, > > I r

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread Jan Beulich
On 28.04.2020 17:00, H.J. Lu wrote: > On Tue, Apr 28, 2020 at 6:41 AM Andrew Cooper > wrote: >> >> On 28/04/2020 14:00, H.J. Lu wrote: >>> On Tue, Apr 28, 2020 at 5:43 AM Andrew Cooper >>> wrote: Hello, I raised https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 but it has h

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread H.J. Lu via Gcc
On Tue, Apr 28, 2020 at 6:41 AM Andrew Cooper wrote: > > On 28/04/2020 14:00, H.J. Lu wrote: > > On Tue, Apr 28, 2020 at 5:43 AM Andrew Cooper > > wrote: > >> Hello, > >> > >> I raised https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 but it has > >> had nothing but tumbleweeds in months, and i

Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread Andrew Cooper via Gcc
On 28/04/2020 14:00, H.J. Lu wrote: > On Tue, Apr 28, 2020 at 5:43 AM Andrew Cooper > wrote: >> Hello, >> >> I raised https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 but it has >> had nothing but tumbleweeds in months, and it is continuing to cause >> problems for Xen. >> >> During the Spectre

Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

2020-04-28 Thread Andrew Cooper via Gcc
Hello, I raised https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 but it has had nothing but tumbleweeds in months, and it is continuing to cause problems for Xen. During the Spectre embargo period, it was specifically identified that kernels would need to be able to compile one single binary, w