lkml.org 
[lkml]   [2021]   [Mar]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] riscv: keep interrupts disabled for BREAKPOINT exception
On Tue, 30 Mar 2021 18:33:16 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> Hi Jisheng,

Hi Masami,

>
> On Tue, 30 Mar 2021 02:16:24 +0800
> Jisheng Zhang <jszhang3@mail.ustc.edu.cn> wrote:
>
> > From: Jisheng Zhang <jszhang@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
kprobe_breakpoint_handler()
setup_singlestep()
kprobes_restore_local_irqflag()

do_trap_break() // for ss
kprobe_single_step_handler()
kprobes_restore_local_irqflag()

Thanks

\
 
 \ /
  Last update: 2021-03-31 16:30    [W:0.084 / U:1.856 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site