Re: [PATCH v3] LoongArch: Fixup do_ri csr_era

[Jun Yi]

do_ri is porting from mips, mipsr6 use do_ri to emulate some fp 
instructions, but Loongarch do not need to emulate these instructions.

And the regs->csr_era be always recovered to ths old_era = 
regs->csr_era, so the compute_return_era is useless.

On 9/27/22 07:41, Guo Ren wrote:
> On Mon, Sep 26, 2022 at 8:27 PM Jun Yi <yijun@xxxxxxxxxxx> wrote:
> > csr_era of pt_regs in do_ri should not add 4 to point to the
> > next instruction.
> The comment does not make sense. I think it wants to skip some
> instructions, but your patch broke that.
>
> > Signed-off-by: Jun Yi <yijun@xxxxxxxxxxx>
> > ---
> >   arch/loongarch/kernel/traps.c | 2 --
> >   1 file changed, 2 deletions(-)
> >
> > diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
> > index aa1c95aaf595..ec888eda3d45 100644
> > --- a/arch/loongarch/kernel/traps.c
> > +++ b/arch/loongarch/kernel/traps.c
> > @@ -477,8 +477,6 @@ asmlinkage void noinstr do_ri(struct pt_regs *regs)
> >
> >          die_if_kernel("Reserved instruction in kernel code", regs);
> >
> > -       compute_return_era(regs);
> > -
> >          if (unlikely(get_user(opcode, era) < 0)) {
> >                  status = SIGSEGV;
> >                  current->thread.error_code = 1;
> > --
> > 2.31.1