On Fri, Nov 14, 2014 at 03:43:45PM +0200, Alexander Shishkin wrote:
> +static __init int pt_init(void)
> +{
> + int ret, cpu, prior_warn = 0;
> +
> + BUILD_BUG_ON(sizeof(struct topa) > PAGE_SIZE);
> + get_online_cpus();
> + for_each_online_cpu(cpu) {
> + u64 ctl;
> +
> + ret = rdmsrl_safe_on_cpu(cpu, MSR_IA32_RTIT_CTL, &ctl);
> + if (!ret && (ctl & RTIT_CTL_TRACEEN))
> + prior_warn++;
> + }
> + put_online_cpus();
> +
> + ret = pt_pmu_hw_init();
> + if (ret)
> + return ret;
> +
> + if (!pt_cap_get(PT_CAP_topa_output)) {
> + pr_warn("ToPA output is not supported on this CPU\n");
> + return -ENODEV;
> + }
> +
> + if (prior_warn)
> + pr_warn("PT is enabled at boot time, traces may be empty\n");
Should we not also add_exclusive(pt) here?
Also, if its already enabled, should we not return ENODEV as well, no
saying who or what programmed it, we should not be touching it.
> + if (!pt_cap_get(PT_CAP_topa_multiple_entries))
> + pt_pmu.pmu.capabilities =
> + PERF_PMU_CAP_AUX_NO_SG | PERF_PMU_CAP_AUX_SW_DOUBLEBUF;
> +
> + pt_pmu.pmu.capabilities |= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE;
> + pt_pmu.pmu.attr_groups = pt_attr_groups;
> + pt_pmu.pmu.task_ctx_nr = perf_hw_context;
> + pt_pmu.pmu.event_init = pt_event_init;
> + pt_pmu.pmu.add = pt_event_add;
> + pt_pmu.pmu.del = pt_event_del;
> + pt_pmu.pmu.start = pt_event_start;
> + pt_pmu.pmu.stop = pt_event_stop;
> + pt_pmu.pmu.read = pt_event_read;
> + pt_pmu.pmu.setup_aux = pt_buffer_setup_aux;
> + pt_pmu.pmu.free_aux = pt_buffer_free_aux;
> + ret = perf_pmu_register(&pt_pmu.pmu, "intel_pt", -1);
> +
> + return ret;
> +}
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