linux-kernel - Re: [PATCH 3/5] Powerpc/hw-breakpoint: Refactor set

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Message-ID: <36044d6d-d46f-8c7b-c597-0e5d156fd9db@c-s.fr>
Date:   Tue, 18 Jun 2019 08:24:53 +0200
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Ravi Bangoria <ravi.bangoria@...ux.ibm.com>, mpe@...erman.id.au
Cc:     benh@...nel.crashing.org, paulus@...ba.org, mikey@...ling.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        npiggin@...il.com, naveen.n.rao@...ux.vnet.ibm.com
Subject: Re: [PATCH 3/5] Powerpc/hw-breakpoint: Refactor set_dawr()



Le 18/06/2019 à 06:27, Ravi Bangoria a écrit :
> Remove unnecessary comments. Code itself is self explanatory.
> And, ISA already talks about MRD field. I Don't think we need
> to re-describe it.

In an RFC patch you may "don't think".
But in the final patch you need to make a decision and write it as such.

Ie, you should write: "We don't need to re-describe it."


> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
> ---
>   arch/powerpc/kernel/process.c | 17 +++++------------
>   1 file changed, 5 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index f0fbbf6a6a1f..f002d2ffff86 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -799,18 +799,11 @@ int set_dawr(struct arch_hw_breakpoint *brk)
>   
>   	dawr = brk->address;
>   
> -	dawrx  = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE)) \
> -		                   << (63 - 58); //* read/write bits */
> -	dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) \
> -		                   << (63 - 59); //* translate */
> -	dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) \
> -		                   >> 3; //* PRIM bits */
> -	/* dawr length is stored in field MDR bits 48:53.  Matches range in
> -	   doublewords (64 bits) baised by -1 eg. 0b000000=1DW and
> -	   0b111111=64DW.
> -	   brk->len is in bytes.
> -	   This aligns up to double word size, shifts and does the bias.
> -	*/
> +	dawrx  = (brk->type & HW_BRK_TYPE_RDWR) << (63 - 58);
> +	dawrx |= ((brk->type & HW_BRK_TYPE_TRANSLATE) >> 2) << (63 - 59);
> +	dawrx |= (brk->type & HW_BRK_TYPE_PRIV_ALL) >> 3;
> +
> +	/* brk->len is in bytes. */
>   	mrd = ((brk->len + 7) >> 3) - 1;
>   	dawrx |= (mrd & 0x3f) << (63 - 53);
>   
>