linux-kernel - Re: [PATCH v2 05/16] powerpc/watchpoint: Provide DAWR number to set

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Message-ID: <2e7ac5a6-744e-0962-bc84-3005bda229d1@c-s.fr>
Date:   Wed, 1 Apr 2020 09:03:03 +0200
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 v2 05/16] powerpc/watchpoint: Provide DAWR number to
 set_dawr



Le 01/04/2020 à 08:12, Ravi Bangoria a écrit :
> Introduce new parameter 'nr' to set_dawr() which indicates which DAWR
> should be programed.
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
> ---
>   arch/powerpc/include/asm/hw_breakpoint.h |  4 ++--
>   arch/powerpc/kernel/dawr.c               | 15 ++++++++++-----
>   arch/powerpc/kernel/process.c            |  2 +-
>   3 files changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
> index 518b41eef924..62549007c87a 100644
> --- a/arch/powerpc/include/asm/hw_breakpoint.h
> +++ b/arch/powerpc/include/asm/hw_breakpoint.h
> @@ -104,10 +104,10 @@ static inline bool dawr_enabled(void)
>   {
>   	return dawr_force_enable;
>   }
> -int set_dawr(struct arch_hw_breakpoint *brk);
> +int set_dawr(struct arch_hw_breakpoint *brk, int nr);

Wondering if it wouldn't make more sense to have nr as first argument.

Christophe

>   #else
>   static inline bool dawr_enabled(void) { return false; }
> -static inline int set_dawr(struct arch_hw_breakpoint *brk) { return -1; }
> +static inline int set_dawr(struct arch_hw_breakpoint *brk, int nr) { return -1; }
>   #endif
>   
>   #endif	/* __KERNEL__ */
> diff --git a/arch/powerpc/kernel/dawr.c b/arch/powerpc/kernel/dawr.c
> index e91b613bf137..311e51ee09f4 100644
> --- a/arch/powerpc/kernel/dawr.c
> +++ b/arch/powerpc/kernel/dawr.c
> @@ -16,7 +16,7 @@
>   bool dawr_force_enable;
>   EXPORT_SYMBOL_GPL(dawr_force_enable);
>   
> -int set_dawr(struct arch_hw_breakpoint *brk)
> +int set_dawr(struct arch_hw_breakpoint *brk, int nr)
>   {
>   	unsigned long dawr, dawrx, mrd;
>   
> @@ -39,15 +39,20 @@ int set_dawr(struct arch_hw_breakpoint *brk)
>   	if (ppc_md.set_dawr)
>   		return ppc_md.set_dawr(dawr, dawrx);
>   
> -	mtspr(SPRN_DAWR0, dawr);
> -	mtspr(SPRN_DAWRX0, dawrx);
> +	if (nr == 0) {
> +		mtspr(SPRN_DAWR0, dawr);
> +		mtspr(SPRN_DAWRX0, dawrx);
> +	} else {
> +		mtspr(SPRN_DAWR1, dawr);
> +		mtspr(SPRN_DAWRX1, dawrx);
> +	}
>   
>   	return 0;
>   }
>   
>   static void set_dawr_cb(void *info)
>   {
> -	set_dawr(info);
> +	set_dawr(info, 0);
>   }
>   
>   static ssize_t dawr_write_file_bool(struct file *file,
> @@ -60,7 +65,7 @@ static ssize_t dawr_write_file_bool(struct file *file,
>   	/* Send error to user if they hypervisor won't allow us to write DAWR */
>   	if (!dawr_force_enable &&
>   	    firmware_has_feature(FW_FEATURE_LPAR) &&
> -	    set_dawr(&null_brk) != H_SUCCESS)
> +	    set_dawr(&null_brk, 0) != H_SUCCESS)
>   		return -ENODEV;
>   
>   	rc = debugfs_write_file_bool(file, user_buf, count, ppos);
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 110db94cdf3c..b548a584e465 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -799,7 +799,7 @@ void __set_breakpoint(struct arch_hw_breakpoint *brk)
>   
>   	if (dawr_enabled())
>   		// Power8 or later
> -		set_dawr(brk);
> +		set_dawr(brk, 0);
>   	else if (IS_ENABLED(CONFIG_PPC_8xx))
>   		set_breakpoint_8xx(brk);
>   	else if (!cpu_has_feature(CPU_FTR_ARCH_207S))
>