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SubjectRe: [PATCH v2 03/16] powerpc/watchpoint: Introduce function to get nr watchpoints dynamically
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Le 01/04/2020 à 08:12, Ravi Bangoria a écrit :
> So far we had only one watchpoint, so we have hardcoded HBP_NUM to 1.
> But future Power architecture is introducing 2nd DAWR and thus kernel
> should be able to dynamically find actual number of watchpoints
> supported by hw it's running on. Introduce function for the same.
> Also convert HBP_NUM macro to HBP_NUM_MAX, which will now represent
> maximum number of watchpoints supported by Powerpc.


Everywhere else in the code, it is called 'breakpoint', not 'watchpoint'.

Wouldn't it be more consistent to call the function nr_bp_slots()
instead of nr_wp_slots() ?

Especially as we are likely going to extend your changes to support
DABR2 in addition to DABR on BOOK3S/32.

Christophe

>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
> ---
> arch/powerpc/include/asm/cputable.h | 6 +++++-
> arch/powerpc/include/asm/hw_breakpoint.h | 5 +++++
> arch/powerpc/include/asm/processor.h | 2 +-
> arch/powerpc/kernel/hw_breakpoint.c | 2 +-
> 4 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
> index 40a4d3c6fd99..c67b94f3334c 100644
> --- a/arch/powerpc/include/asm/cputable.h
> +++ b/arch/powerpc/include/asm/cputable.h
> @@ -614,7 +614,11 @@ enum {
> };
> #endif /* __powerpc64__ */
>
> -#define HBP_NUM 1
> +/*
> + * 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
>
> #endif /* !__ASSEMBLY__ */
>
> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
> index f2f8d8aa8e3b..518b41eef924 100644
> --- a/arch/powerpc/include/asm/hw_breakpoint.h
> +++ b/arch/powerpc/include/asm/hw_breakpoint.h
> @@ -43,6 +43,11 @@ struct arch_hw_breakpoint {
> #define DABR_MAX_LEN 8
> #define DAWR_MAX_LEN 512
>
> +static inline int nr_wp_slots(void)
> +{
> + return HBP_NUM_MAX;
> +}
> +
> #ifdef CONFIG_HAVE_HW_BREAKPOINT
> #include <linux/kdebug.h>
> #include <asm/reg.h>
> diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
> index eedcbfb9a6ff..90f6dbc7ff00 100644
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -180,7 +180,7 @@ struct thread_struct {
> int fpexc_mode; /* floating-point exception mode */
> unsigned int align_ctl; /* alignment handling control */
> #ifdef CONFIG_HAVE_HW_BREAKPOINT
> - struct perf_event *ptrace_bps[HBP_NUM];
> + struct perf_event *ptrace_bps[HBP_NUM_MAX];
> /*
> * Helps identify source of single-step exception and subsequent
> * hw-breakpoint enablement
> diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
> index 72f461bd70fb..4120349e2abe 100644
> --- a/arch/powerpc/kernel/hw_breakpoint.c
> +++ b/arch/powerpc/kernel/hw_breakpoint.c
> @@ -38,7 +38,7 @@ static DEFINE_PER_CPU(struct perf_event *, bp_per_reg);
> int hw_breakpoint_slots(int type)
> {
> if (type == TYPE_DATA)
> - return HBP_NUM;
> + return nr_wp_slots();
> return 0; /* no instruction breakpoints available */
> }
>
>

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