linux-kernel - Re: [PATCH 14/15] powerpc/watchpoint/xmon: Don't allow breakpoint overwriting

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Message-ID: <b6892b22-c521-207e-e5fd-ca66c774b314@c-s.fr>
Date:   Tue, 17 Mar 2020 12:10:39 +0100
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Ravi Bangoria <ravi.bangoria@...ux.ibm.com>, mpe@...erman.id.au,
        mikey@...ling.org
Cc:     apopple@...ux.ibm.com, paulus@...ba.org, npiggin@...il.com,
        naveen.n.rao@...ux.vnet.ibm.com, peterz@...radead.org,
        jolsa@...nel.org, oleg@...hat.com, fweisbec@...il.com,
        mingo@...nel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 14/15] powerpc/watchpoint/xmon: Don't allow breakpoint
 overwriting



Le 09/03/2020 à 09:58, Ravi Bangoria a écrit :
> Xmon allows overwriting breakpoints because it's supported by only
> one dawr. But with multiple dawrs, overwriting becomes ambiguous
> or unnecessary complicated. So let's not allow it.

Could we drop this completely (I mean the functionnality, not the patch).

Christophe

> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
> ---
>   arch/powerpc/xmon/xmon.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index 0ca0d29f99c6..ac18fe3e4295 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -1381,6 +1381,10 @@ bpt_cmds(void)
>   			printf("Hardware data breakpoint not supported on this cpu\n");
>   			break;
>   		}
> +		if (dabr.enabled) {
> +			printf("Couldn't find free breakpoint register\n");
> +			break;
> +		}
>   		mode = 7;
>   		cmd = inchar();
>   		if (cmd == 'r')
>