On Tue, Jun 19, 2018 at 03:55:42PM +0100, Catalin Marinas wrote:
> On Tue, Jun 19, 2018 at 03:48:45PM +0100, Mark Rutland wrote:
> > On Tue, Jun 19, 2018 at 03:21:25PM +0100, Catalin Marinas wrote:
> > > On Mon, Jun 18, 2018 at 01:02:59PM +0100, Mark Rutland wrote:
> > > > diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
> > > > new file mode 100644
> > > > index 000000000000..b463b962d597
> > > > --- /dev/null
> > > > +++ b/arch/arm64/kernel/syscall.c
> > > > @@ -0,0 +1,30 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +
> > > > +#include <linux/nospec.h>
> > > > +#include <linux/ptrace.h>
> > > > +
> > > > +long do_ni_syscall(struct pt_regs *regs);
> > > > +
> > > > +typedef long (*syscall_fn_t)(unsigned long, unsigned long,
> > > > + unsigned long, unsigned long,
> > > > + unsigned long, unsigned long);
> > > > +
> > > > +static void __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn)
> > > > +{
> > > > + regs->regs[0] = syscall_fn(regs->regs[0], regs->regs[1],
> > > > + regs->regs[2], regs->regs[3],
> > > > + regs->regs[4], regs->regs[5]);
> > > > +}
> > > > +
> > > > +asmlinkage void invoke_syscall(struct pt_regs *regs, unsigned int scno,
> > > > + unsigned int sc_nr,
> > > > + syscall_fn_t syscall_table[])
> > > > +{
> > > > + if (scno < sc_nr) {
> > > > + syscall_fn_t syscall_fn;
> > > > + syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)];
> > > > + __invoke_syscall(regs, syscall_fn);
> > > > + } else {
> > > > + regs->regs[0] = do_ni_syscall(regs);
> > > > + }
> > > > +}
> > >
> > > While reviewing the subsequent patch, it crossed my mind that we no
> > > longer have any callers to do_ni_syscall() outside this file. Can we not
> > > more it here and have a similar implementation to __invoke_syscall() for
> > > consistency, i.e. set regs->regs[0].
> >
> > I think so, though it complicates the logic in do_ni_syscall(), since
> > there are two places we may return a value.
> >
> > Would you be happy if instead I made __invoke_syscall() return the
> > result, and have invoke_syscall() place the result in regs->regs[0] in
> > either case, e.g. as below?
>
> It looks fine. Feel free to keep the original reviewed-by tag.
Will do; cheers!
Mark.
