In the subject line, privilege should only have 1 l, and I think it
should probably start with "powerpc/perf:" rather than "powerpc, perf:".

On Mon, 2015-06-08 at 17:08 +0530, Anshuman Khandual wrote:
> From: "[email protected]" <[email protected]>
> 
> 'commit 9de5cb0f6df8 ("powerpc/perf: Add per-event excludes on Power8")'
Does this need a 'Fixes:' tag then?

> broke the PMU based BHRB privilege level filter. BHRB depends on the
> same MMCR0 bits for privilege level filter which was used to freeze all
> the PMCs as a group. Once we moved to individual event based privilege
> filters through MMCR2 register on POWER8, event associated privilege
> filters are no longer applicable to the BHRB captured branches.
> 
> This patch solves the problem by restoring to the previous method of
> privilege level filters for the event in case BHRB based branch stack
> sampling is requested. This patch also changes 'check_excludes' for
> the same reason.
> 
> Signed-off-by: Anshuman Khandual <[email protected]>
> ---
>  arch/powerpc/perf/core-book3s.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
> index c246e65..ae61629 100644
> --- a/arch/powerpc/perf/core-book3s.c
> +++ b/arch/powerpc/perf/core-book3s.c
> @@ -930,7 +930,7 @@ static int power_check_constraints(struct cpu_hw_events 
> *cpuhw,
>   * added events.
>   */
Does this comment need to be updated?
>  static int check_excludes(struct perf_event **ctrs, unsigned int cflags[],
> -                       int n_prev, int n_new)
> +                       int n_prev, int n_new, int bhrb_users)
>  {
>       int eu = 0, ek = 0, eh = 0;
>       int i, n, first;
> @@ -941,7 +941,7 @@ static int check_excludes(struct perf_event **ctrs, 
> unsigned int cflags[],
>        * don't need to do any of this logic. NB. This assumes no PMU has both
>        * per event exclude and limited PMCs.
>        */
Likewise, does this comment need to be updated?
> -     if (ppmu->flags & PPMU_ARCH_207S)
> +     if ((ppmu->flags & PPMU_ARCH_207S) && !bhrb_users)
>               return 0;
>  
>       n = n_prev + n_new;
> @@ -1259,7 +1259,7 @@ static void power_pmu_enable(struct pmu *pmu)
>               goto out;
>       }
>  
> -     if (!(ppmu->flags & PPMU_ARCH_207S)) {
> +     if (!(ppmu->flags & PPMU_ARCH_207S) || cpuhw->bhrb_users)
You're using cpuhw->bhrb_users as a bool here, where it's an int. Could
you make the test more specific so that it's clear exactly what you're
expecting bhrb_users to contain?
>  {
>               /*
>                * Add in MMCR0 freeze bits corresponding to the attr.exclude_*
>                * bits for the first event. We have already checked that all
> @@ -1284,7 +1284,7 @@ static void power_pmu_enable(struct pmu *pmu)
>       mtspr(SPRN_MMCR1, cpuhw->mmcr[1]);
>       mtspr(SPRN_MMCR0, (cpuhw->mmcr[0] & ~(MMCR0_PMC1CE | MMCR0_PMCjCE))
>                               | MMCR0_FC);
> -     if (ppmu->flags & PPMU_ARCH_207S)
> +     if ((ppmu->flags & PPMU_ARCH_207S) && !cpuhw->bhrb_users)
>               mtspr(SPRN_MMCR2, cpuhw->mmcr[3]);
>  
>       /*
> @@ -1436,7 +1436,8 @@ static int power_pmu_add(struct perf_event *event, int 
> ef_flags)
>       if (cpuhw->group_flag & PERF_EVENT_TXN)
>               goto nocheck;
>  
> -     if (check_excludes(cpuhw->event, cpuhw->flags, n0, 1))
> +     if (check_excludes(cpuhw->event, cpuhw->flags,
> +                             n0, 1, cpuhw->bhrb_users))
>               goto out;
>       if (power_check_constraints(cpuhw, cpuhw->events, cpuhw->flags, n0 + 1))
>               goto out;
> @@ -1615,7 +1616,7 @@ static int power_pmu_commit_txn(struct pmu *pmu)
>               return -EAGAIN;
>       cpuhw = this_cpu_ptr(&cpu_hw_events);
>       n = cpuhw->n_events;
> -     if (check_excludes(cpuhw->event, cpuhw->flags, 0, n))
> +     if (check_excludes(cpuhw->event, cpuhw->flags, 0, n, cpuhw->bhrb_users))
>               return -EAGAIN;
>       i = power_check_constraints(cpuhw, cpuhw->events, cpuhw->flags, n);
>       if (i < 0)
> @@ -1828,10 +1829,12 @@ static int power_pmu_event_init(struct perf_event 
> *event)
>       events[n] = ev;
>       ctrs[n] = event;
>       cflags[n] = flags;
> -     if (check_excludes(ctrs, cflags, n, 1))
> +     cpuhw = &get_cpu_var(cpu_hw_events);
Should this be using a this_cpu_ptr rather than a get_cpu_var? (as with
the power_pmu_commit_txn case?)
> +     if (check_excludes(ctrs, cflags, n, 1, cpuhw->bhrb_users)) {
> +             put_cpu_var(cpu_hw_events);
Likewise with this?
>               return -EINVAL;
> +     }
>  
> -     cpuhw = &get_cpu_var(cpu_hw_events);
>       err = power_check_constraints(cpuhw, events, cflags, n + 1);
>  
>       if (has_branch_stack(event)) {

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