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Message-Id: <20210330183316.942215efe8e6e8455ad14113@kernel.org>
Date: Tue, 30 Mar 2021 18:33:16 +0900
From: Masami Hiramatsu <mhiramat@...nel.org>
To: Jisheng Zhang <jszhang3@...l.ustc.edu.cn>
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Guo Ren <guoren@...ux.alibaba.com>,
linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv: keep interrupts disabled for BREAKPOINT
exception
Hi Jisheng,
On Tue, 30 Mar 2021 02:16:24 +0800
Jisheng Zhang <jszhang3@...l.ustc.edu.cn> wrote:
> From: Jisheng Zhang <jszhang@...nel.org>
>
> 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@...nel.org>
> ---
> 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@...nel.org>
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