Re: [PATCH v4 09/10] powerpc/watchpoint: Return available watchpoints dynamically

Jordan Niethe
2020-07-20T03:46:04Z

On Fri, Jul 17, 2020 at 2:11 PM Ravi Bangoria
<ravi.bangoria@linux.ibm.com> wrote:
>
> So far Book3S Powerpc supported only one watchpoint. Power10 is
> introducing 2nd DAWR. Enable 2nd DAWR support for Power10.
> Availability of 2nd DAWR will depend on CPU_FTR_DAWR1.
>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
> arch/powerpc/include/asm/cputable.h | 4 +++-
> arch/powerpc/include/asm/hw_breakpoint.h | 5 +++--
> 2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
> index 3445c86e1f6f..36a0851a7a9b 100644
> --- a/arch/powerpc/include/asm/cputable.h
> +++ b/arch/powerpc/include/asm/cputable.h
> @@ -633,7 +633,9 @@ enum {
> * Maximum number of hw breakpoint supported on powerpc. Number of
> * breakpoints supported by actual hw might be less than this.
> */
> -#define HBP_NUM_MAX 1
> +#define HBP_NUM_MAX 2
> +#define HBP_NUM_ONE 1
> +#define HBP_NUM_TWO 2
I wonder if these defines are necessary - has it any advantage over
just using the literal?
>
> #endif /* !__ASSEMBLY__ */
>
> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
> index cb424799da0d..d4eab1694bcd 100644
> --- a/arch/powerpc/include/asm/hw_breakpoint.h
> +++ b/arch/powerpc/include/asm/hw_breakpoint.h
> @@ -5,10 +5,11 @@
> * Copyright 2010, IBM Corporation.
> * Author: K.Prasad <prasad@linux.vnet.ibm.com>
> */
> -
Was removing this line deliberate?
> #ifndef _PPC_BOOK3S_64_HW_BREAKPOINT_H
> #define _PPC_BOOK3S_64_HW_BREAKPOINT_H
>
> +#include <asm/cpu_has_feature.h>
> +
> #ifdef __KERNEL__
> struct arch_hw_breakpoint {
> unsigned long address;
> @@ -46,7 +47,7 @@ struct arch_hw_breakpoint {
>
> static inline int nr_wp_slots(void)
> {
> - return HBP_NUM_MAX;
> + return cpu_has_feature(CPU_FTR_DAWR1) ? HBP_NUM_TWO : HBP_NUM_ONE;
So it'd be something like:
+ return cpu_has_feature(CPU_FTR_DAWR1) ? HBP_NUM_MAX : 1;
But thinking that there might be more slots added in the future, it
may be better to make the number of slots a variable that is set
during the init and then have this function return that.
> }
>
> #ifdef CONFIG_HAVE_HW_BREAKPOINT
> --
> 2.26.2
>