Re: [PATCHv8 1/2] x86/vdso: add mremap hook to vm_special_mapping

[Dmitry Safonov]

On 05/05/2016 02:52 PM, Ingo Molnar wrote:
> * Dmitry Safonov <dsafonov@xxxxxxxxxxxxx> wrote:
>
> > On 04/26/2016 12:38 AM, Andy Lutomirski wrote:
> > > On Mon, Apr 25, 2016 at 4:37 AM, Dmitry Safonov <dsafonov@xxxxxxxxxxxxx> wrote:
> > > > Add possibility for userspace 32-bit applications to move
> > > > vdso mapping. Previously, when userspace app called
> > > > mremap for vdso, in return path it would land on previous
> > > > address of vdso page, resulting in segmentation violation.
> > > > Now it lands fine and returns to userspace with remapped vdso.
> > > > This will also fix context.vdso pointer for 64-bit, which does not
> > > > affect the user of vdso after mremap by now, but this may change.
> > > >
> > > > As suggested by Andy, return EINVAL for mremap that splits vdso image.
> > > >
> > > > Renamed and moved text_mapping structure declaration inside
> > > > map_vdso, as it used only there and now it complement
> > > > vvar_mapping variable.
> > > >
> > > > There is still problem for remapping vdso in glibc applications:
> > > > linker relocates addresses for syscalls on vdso page, so
> > > > you need to relink with the new addresses. Or the next syscall
> > > > through glibc may fail:
> > > >   Program received signal SIGSEGV, Segmentation fault.
> > > >   #0  0xf7fd9b80 in __kernel_vsyscall ()
> > > >   #1  0xf7ec8238 in _exit () from /usr/lib32/libc.so.6
> > > Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>
> > >
> > > Ingo, can you apply this?
> >
> > Hm, so I'm not sure - should I resend those two?
> > Or just ping?
>
> Please send a clean series with updated Acked-by's, etc.


Thanks, Ingo, will do.
Sorry for html in the last email - mail agent got an
update and I overlooked html composing become turned on.

--
Regards,
Dmitry Safonov