Re: [PATCH] riscv: keep interrupts disabled for BREAKPOINT exception

[Masami Hiramatsu]

Hi Jisheng,

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?

Thank you,

> 
> Fixes: c22b0bcb1dd0 ("riscv: Add kprobes supported")
> Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx>
> ---
>  arch/riscv/kernel/entry.S | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
> index 744f3209c48d..4114b65698ec 100644
> --- a/arch/riscv/kernel/entry.S
> +++ b/arch/riscv/kernel/entry.S
> @@ -130,6 +130,8 @@ skip_context_tracking:
>  	 */
>  	andi t0, s1, SR_PIE
>  	beqz t0, 1f
> +	li t0, EXC_BREAKPOINT
> +	beq s4, t0, 1f
>  #ifdef CONFIG_TRACE_IRQFLAGS
>  	call trace_hardirqs_on
>  #endif
> -- 
> 2.31.0
> 
> 


-- 
Masami Hiramatsu <mhiramat@xxxxxxxxxx>