Re: [PATCH v8 13/30] powerpc: Add a probe_user_read_inst() function

[Jordan Niethe]

On Wed, May 13, 2020 at 10:52 PM Michael Ellerman <m...@ellerman.id.au> wrote:
>
> Jordan Niethe <jniet...@gmail.com> writes:
> > diff --git a/arch/powerpc/lib/inst.c b/arch/powerpc/lib/inst.c
> > new file mode 100644
> > index 000000000000..eaf786afad2b
> > --- /dev/null
> > +++ b/arch/powerpc/lib/inst.c
> > @@ -0,0 +1,18 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + *  Copyright 2020, IBM Corporation.
> > + */
> > +
> > +#include <linux/uaccess.h>
> > +#include <asm/inst.h>
> > +
> > +int probe_user_read_inst(struct ppc_inst *inst,
> > +                      struct ppc_inst *nip)
> > +{
> > +     unsigned int val;
> > +     int err;
> > +
> > +     err = probe_user_read(&val, nip, sizeof(val));
> > +     *inst = ppc_inst(val);
>
> We shouldn't be storing to *inst if the read failed?
Good point.
>
> I changed it to:
>
> +       if (!err)
> +               *inst = ppc_inst(val);
> +
>
> Similarly for probe_kernel_read_inst().
Thanks.
>
> cheers