linux-kernel - Re: [PATCH] xmon: Clear all breakpoints when xmon is disabled via debugfs

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Message-ID: <CAKTCnznOU=8W2up5PQFRQHbmCZvht_8Vmt5F_gb1yaZEKQDTWw@mail.gmail.com>
Date:   Mon, 5 Mar 2018 08:27:52 +1100
From:   Balbir Singh <bsingharora@...il.com>
To:     Vaibhav Jain <vaibhav@...ux.vnet.ibm.com>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Frederic Barrat <fbarrat@...ux.vnet.ibm.com>,
        "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" 
        <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Douglas Miller <dougmill@...ux.vnet.ibm.com>
Subject: Re: [PATCH] xmon: Clear all breakpoints when xmon is disabled via debugfs

On Mon, Mar 5, 2018 at 4:31 AM, Vaibhav Jain <vaibhav@...ux.vnet.ibm.com> wrote:
> Presently when xmon is disabled by debugfs any existing
> instruction/data-access breakpoints set are not disabled. This may
> lead to kernel oops when those breakpoints are hit as the necessary
> debugger hooks aren't installed.
>
> Hence this patch introduces a new function named clear_all_bpt()
> which is called when xmon is disabled via debugfs. The function will
> unpatch/clear all the trap and ciabr/dab based breakpoints.
>
> Signed-off-by: Vaibhav Jain <vaibhav@...ux.vnet.ibm.com>
> ---

Reviewed-by: Balbir Singh <bsingharora@...il.com>

Balbir