linux-kernel - Re: [v2] xmon: Setup xmon debugger hooks when first break-point is set

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Message-Id: <401RHQ2TS9z9s2R@ozlabs.org>
Date:   Wed, 14 Mar 2018 20:28:31 +1100 (AEDT)
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     Vaibhav Jain <vaibhav@...ux.vnet.ibm.com>,
        Balbir Singh <bsingharora@...il.com>
Cc:     Vaibhav Jain <vaibhav@...ux.vnet.ibm.com>,
        Frederic Barrat <fbarrat@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, Paul Mackerras <paulus@...ba.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Douglas Miller <dougmill@...ux.vnet.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [v2] xmon: Setup xmon debugger hooks when first break-point is set

On Sun, 2018-03-04 at 17:30:25 UTC, Vaibhav Jain wrote:
> Presently sysrq key for xmon('x') is registered during kernel init
> irrespective of the value of kernel param 'xmon'. Thus xmon is enabled
> even if 'xmon=off' is passed on the kernel command line. However this
> doesn't enable the kernel debugger hooks needed for instruction or data
> breakpoints. Thus when a break-point is hit with xmon=off a kernel oops
> of the form below is reported:
> 
> Oops: Exception in kernel mode, sig: 5 [#1]
> < snip >
> Trace/breakpoint trap
> 
> To fix this the patch checks and enables debugger hooks when an
> instruction or data break-point is set via xmon console.
> 
> Signed-off-by: Vaibhav Jain <vaibhav@...ux.vnet.ibm.com>
> Reviewed-by: Balbir Singh <bsingharora@...il.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/e1368d0c9edbc366e45216e7295fd6

cheers