On Fri, Sep 11, 2015 at 06:36:05PM +0100, Julien Grall wrote: > On 11/09/15 18:32, Julien Grall wrote: > > On 11/09/15 18:00, Russell King - ARM Linux wrote: > >> On Fri, Sep 11, 2015 at 05:25:59PM +0100, Julien Grall wrote: > >>> + /* > >>> + * Privcmd calls are issued by the userspace. We need to allow the > >>> + * kernel to access the userspace memory before issuing the hypercall. > >>> + */ > >>> + uaccess_enable r4 > >>> + > >>> + /* r4 is loaded now as we use it as scratch register before */ > >>> ldr r4, [sp, #4] > >> > >> As I mentioned in one of my previous mails, "ip" should be safe to use > >> here - it's a caller-corrupted register, just like r0-r3 and lr. So, > >> you could do: > >> > >> ldr r4, [sp, #4] > >> + uaccess_enable ip > > > > The register ip (aka r12) is used to store the hypercall number. So we > > can't reuse it as scratch register. > > > > The easiest one is r4. > > > >> > >> which fractionally tightens the window. > >> > >> However, there's nothing actually wrong with your version - there's no > >> way we could've got this far with sp pointing at userspace. > >> > >> I'm happy with either version, so: > >> > >> Acked-by: Russell King <rmk+ker...@arm.linux.org.uk> > >> > >> How do you want to handle the patch? I already have some other uaccess > >> fixes queued up to send to Linus before the merge window closes. > > Forgot to answer to this bits. I was thinking to ask Stefano carrying > the patch in xentip. Although it won't go until rc1. > > I don't mind if it's going earlier in Linux/master.
Thanks, I've applied your patch as-is now. -- FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
