[CRIU] [PATCH 1/4] pie/x86_64: syscall clobbers rcx and r11

[Tycho Andersen]

On Tue, Jun 16, 2015 at 10:29:00PM +0300, Cyrill Gorcunov wrote:
> On Tue, Jun 16, 2015 at 10:10:53PM +0300, Cyrill Gorcunov wrote:
> > On Tue, Jun 16, 2015 at 07:34:55AM -0600, Tycho Andersen wrote:
> > > On Tue, Jun 16, 2015 at 04:31:50PM +0300, Cyrill Gorcunov wrote:
> > > > On Tue, Jun 16, 2015 at 07:20:56AM -0600, Tycho Andersen wrote:
> > > > > 
> > > > > Ok, I just added rcx because the above link said it could be clobbered
> > > > > too, but I can send a patch to remove it if you want.
> > > > 
> > > > no need to, i'm fine with as is.
> > > 
> > > Ok. I think the reason we've never seen a seg fault here is that the
> > > code path hasn't changed in a while (and neither has gcc's register
> > > allocator apparently, yay reaload.c). When I changed it for this
> > > patchset, gcc decided to use r11 for something (viz. the dissasembly
> > > in the commit message), which is what caused the fault.
> > 
> > I still wonder why it's happened ;) Look, the kernel saves all the data
> > it going to modify inside syscall
> 
> Not needed. The patch is correct, thanks for fixin!

Ah, what were you missing? Your assembly output looked right to me :)

Tycho