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    Subject[PATCH V9 10/10] arm64/perf: Implement branch records save on PMU IRQ
    Date
    This modifies armv8pmu_branch_read() to concatenate live entries along with
    task context stored entries and then process the resultant buffer to create
    perf branch entry array for perf_sample_data. It follows the same principle
    like task sched out.

    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Will Deacon <will@kernel.org>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: linux-arm-kernel@lists.infradead.org
    Cc: linux-kernel@vger.kernel.org
    Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
    ---
    arch/arm64/kernel/brbe.c | 75 +++++++++++++++-------------------------
    1 file changed, 28 insertions(+), 47 deletions(-)

    diff --git a/arch/arm64/kernel/brbe.c b/arch/arm64/kernel/brbe.c
    index 3dcb4407b92a..652af6668d37 100644
    --- a/arch/arm64/kernel/brbe.c
    +++ b/arch/arm64/kernel/brbe.c
    @@ -693,41 +693,45 @@ void armv8pmu_branch_reset(void)
    isb();
    }

    -static bool capture_branch_entry(struct pmu_hw_events *cpuc,
    - struct perf_event *event, int idx)
    +static void brbe_regset_branch_entries(struct pmu_hw_events *cpuc, struct perf_event *event,
    + struct brbe_regset *regset, int idx)
    {
    struct perf_branch_entry *entry = &cpuc->branches->branch_entries[idx];
    - u64 brbinf = get_brbinf_reg(idx);
    -
    - /*
    - * There are no valid entries anymore on the buffer.
    - * Abort the branch record processing to save some
    - * cycles and also reduce the capture/process load
    - * for the user space as well.
    - */
    - if (brbe_invalid(brbinf))
    - return false;
    + u64 brbinf = regset[idx].brbinf;

    perf_clear_branch_entry_bitfields(entry);
    if (brbe_record_is_complete(brbinf)) {
    - entry->from = get_brbsrc_reg(idx);
    - entry->to = get_brbtgt_reg(idx);
    + entry->from = regset[idx].brbsrc;
    + entry->to = regset[idx].brbtgt;
    } else if (brbe_record_is_source_only(brbinf)) {
    - entry->from = get_brbsrc_reg(idx);
    + entry->from = regset[idx].brbsrc;
    entry->to = 0;
    } else if (brbe_record_is_target_only(brbinf)) {
    entry->from = 0;
    - entry->to = get_brbtgt_reg(idx);
    + entry->to = regset[idx].brbtgt;
    }
    capture_brbe_flags(entry, event, brbinf);
    - return true;
    +}
    +
    +static void process_branch_entries(struct pmu_hw_events *cpuc, struct perf_event *event,
    + struct brbe_regset *regset, int nr_regset)
    +{
    + int idx;
    +
    + for (idx = 0; idx < nr_regset; idx++)
    + brbe_regset_branch_entries(cpuc, event, regset, idx);
    +
    + cpuc->branches->branch_stack.nr = nr_regset;
    + cpuc->branches->branch_stack.hw_idx = -1ULL;
    }

    void armv8pmu_branch_read(struct pmu_hw_events *cpuc, struct perf_event *event)
    {
    struct brbe_hw_attr *brbe_attr = (struct brbe_hw_attr *)cpuc->percpu_pmu->private;
    + struct arm64_perf_task_context *task_ctx = event->pmu_ctx->task_ctx_data;
    + struct brbe_regset live[BRBE_MAX_ENTRIES];
    + int nr_live, nr_store;
    u64 brbfcr, brbcr;
    - int idx, loop1_idx1, loop1_idx2, loop2_idx1, loop2_idx2, count;

    brbcr = read_sysreg_s(SYS_BRBCR_EL1);
    brbfcr = read_sysreg_s(SYS_BRBFCR_EL1);
    @@ -739,36 +743,13 @@ void armv8pmu_branch_read(struct pmu_hw_events *cpuc, struct perf_event *event)
    write_sysreg_s(brbfcr | BRBFCR_EL1_PAUSED, SYS_BRBFCR_EL1);
    isb();

    - /* Determine the indices for each loop */
    - loop1_idx1 = BRBE_BANK0_IDX_MIN;
    - if (brbe_attr->brbe_nr <= BRBE_BANK_MAX_ENTRIES) {
    - loop1_idx2 = brbe_attr->brbe_nr - 1;
    - loop2_idx1 = BRBE_BANK1_IDX_MIN;
    - loop2_idx2 = BRBE_BANK0_IDX_MAX;
    - } else {
    - loop1_idx2 = BRBE_BANK0_IDX_MAX;
    - loop2_idx1 = BRBE_BANK1_IDX_MIN;
    - loop2_idx2 = brbe_attr->brbe_nr - 1;
    - }
    -
    - /* Loop through bank 0 */
    - select_brbe_bank(BRBE_BANK_IDX_0);
    - for (idx = 0, count = loop1_idx1; count <= loop1_idx2; idx++, count++) {
    - if (!capture_branch_entry(cpuc, event, idx))
    - goto skip_bank_1;
    - }
    -
    - /* Loop through bank 1 */
    - select_brbe_bank(BRBE_BANK_IDX_1);
    - for (count = loop2_idx1; count <= loop2_idx2; idx++, count++) {
    - if (!capture_branch_entry(cpuc, event, idx))
    - break;
    - }
    -
    -skip_bank_1:
    - cpuc->branches->branch_stack.nr = idx;
    - cpuc->branches->branch_stack.hw_idx = -1ULL;
    + nr_live = capture_brbe_regset(brbe_attr, live);
    + nr_store = task_ctx->nr_brbe_records;
    + nr_store = stitch_stored_live_entries(task_ctx->store, live, nr_store,
    + nr_live, brbe_attr->brbe_nr);
    + process_branch_entries(cpuc, event, task_ctx->store, nr_store);
    process_branch_aborts(cpuc);
    + task_ctx->nr_brbe_records = 0;

    /* Unpause the buffer */
    write_sysreg_s(brbfcr & ~BRBFCR_EL1_PAUSED, SYS_BRBFCR_EL1);
    --
    2.25.1
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