[PATCH] riscv: keep interrupts disabled for BREAKPOINT exception
liaochang1 at huawei.com
Thu Apr 1 09:49:47 BST 2021
在 2021/3/31 22:22, Jisheng Zhang 写道:
> On Tue, 30 Mar 2021 18:33:16 +0900
> Masami Hiramatsu <mhiramat at kernel.org> wrote:
>> Hi Jisheng,
> Hi Masami,
>> On Tue, 30 Mar 2021 02:16:24 +0800
>> Jisheng Zhang <jszhang3 at mail.ustc.edu.cn> wrote:
>>> From: Jisheng Zhang <jszhang at kernel.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?
> 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
> do_trap_break() // for ss
Recently, kernel hit BUG_ON() on QEMU after I install a probe at "sys_read" via kprobe,
accoriding to my debugging and analysis it looks like caused by the "irq disable" operation for single-stepping.
I present a detailed description about this problem in the mail with title "[PATCH] riscv/kprobe: fix kernel panic when invoking sys_read traced by kprobe".
Looking forward to some feedback,Thanks.
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