Re: [PATCH] riscv: keep interrupts disabled for BREAKPOINT exception
From: Masami Hiramatsu
Date: Wed Mar 31 2021 - 20:31:59 EST
Hi,
On Wed, 31 Mar 2021 22:22:44 +0800
Jisheng Zhang <jszhang3@xxxxxxxxxxxxxxxx> wrote:
> On Tue, 30 Mar 2021 18:33:16 +0900
> Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
>
> > Hi Jisheng,
>
> Hi Masami,
>
> >
> > On Tue, 30 Mar 2021 02:16:24 +0800
> > Jisheng Zhang <jszhang3@xxxxxxxxxxxxxxxx> wrote:
> >
> > > From: Jisheng Zhang <jszhang@xxxxxxxxxx>
> > >
> > > Current riscv's kprobe handlers are run with both preemption and
> > > interrupt enabled, this violates kprobe requirements. Fix this issue
> > > by keeping interrupts disabled for BREAKPOINT exception.
> >
> > Not only while the breakpoint exception but also until the end of
> > the single step (maybe you are using __BUG_INSN_32 ??) need to be
> > disable interrupts. Can this do that?
> >
>
> interrupt is disabled during "single step" by kprobes_save_local_irqflag()
> and kprobes_restore_local_irqflag(). The code flow looks like:
>
> do_trap_break() // for bp
> kprobe_breakpoint_handler()
> setup_singlestep()
> kprobes_restore_local_irqflag()
>
> do_trap_break() // for ss
> kprobe_single_step_handler()
> kprobes_restore_local_irqflag()
OK, thanks for the confirmation!
Reviewed-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Thanks,
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>