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

[Ingo Molnar]

* 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