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Commit e97df763 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf/x86/intel/p6: Add userspace RDPMC quirk for PPro 

PPro machines can die hard when PCE gets enabled due to a CPU erratum.
The safe way it so disable it by default and keep it disabled.

See erratum 26 in:

  http://download.intel.com/design/archives/processors/pro/docs/24268935.pdf



Reported-and-Tested-by: default avatarMark Davies <junk@eslaf.co.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vince@deater.net>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140206170815.GW2936@laptop.programming.kicks-ass.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 2737fce8

arch/x86/kernel/cpu/perf_event.c

+5 −1
Original line number Diff line number Diff line
@@ -1521,6 +1521,8 @@ static int __init init_hw_perf_events(void) 


	pr_cont("%s PMU driver.\n", x86_pmu.name);



	x86_pmu.attr_rdpmc = 1; /* enable userspace RDPMC usage by default */



	for (quirk = x86_pmu.quirks; quirk; quirk = quirk->next)

		quirk->func();
@@ -1534,7 +1536,6 @@ static int __init init_hw_perf_events(void) 
		__EVENT_CONSTRAINT(0, (1ULL << x86_pmu.num_counters) - 1,

				   0, x86_pmu.num_counters, 0, 0);



	x86_pmu.attr_rdpmc = 1; /* enable userspace RDPMC usage by default */

	x86_pmu_format_group.attrs = x86_pmu.format_attrs;



	if (x86_pmu.event_attrs)
@@ -1820,6 +1821,9 @@ static ssize_t set_attr_rdpmc(struct device *cdev, 
	if (ret)

		return ret;



	if (x86_pmu.attr_rdpmc_broken)

		return -ENOTSUPP;



	if (!!val != !!x86_pmu.attr_rdpmc) {

		x86_pmu.attr_rdpmc = !!val;

		smp_call_function(change_rdpmc, (void *)val, 1);

arch/x86/kernel/cpu/perf_event.h

+1 −0
Original line number Diff line number Diff line
@@ -409,6 +409,7 @@ struct x86_pmu { 
	/*

	 * sysfs attrs

	 */

	int		attr_rdpmc_broken;

	int		attr_rdpmc;

	struct attribute **format_attrs;

	struct attribute **event_attrs;

arch/x86/kernel/cpu/perf_event_p6.c

+33 −15
Original line number Diff line number Diff line
@@ -231,31 +231,49 @@ static __initconst const struct x86_pmu p6_pmu = { 


};



static __init void p6_pmu_rdpmc_quirk(void)

{

	if (boot_cpu_data.x86_mask < 9) {

		/*

		 * PPro erratum 26; fixed in stepping 9 and above.

		 */

		pr_warn("Userspace RDPMC support disabled due to a CPU erratum\n");

		x86_pmu.attr_rdpmc_broken = 1;

		x86_pmu.attr_rdpmc = 0;

	}

}



__init int p6_pmu_init(void)

{

	x86_pmu = p6_pmu;



	switch (boot_cpu_data.x86_model) {

	case 1:

	case 3:  /* Pentium Pro */

	case 5:

	case 6:  /* Pentium II */

	case 7:

	case 8:

	case 11: /* Pentium III */

	case 9:

	case 13:

		/* Pentium M */

	case  1: /* Pentium Pro */

		x86_add_quirk(p6_pmu_rdpmc_quirk);

		break;



	case  3: /* Pentium II - Klamath */

	case  5: /* Pentium II - Deschutes */

	case  6: /* Pentium II - Mendocino */

		break;



	case  7: /* Pentium III - Katmai */

	case  8: /* Pentium III - Coppermine */

	case 10: /* Pentium III Xeon */

	case 11: /* Pentium III - Tualatin */

		break;



	case  9: /* Pentium M - Banias */

	case 13: /* Pentium M - Dothan */

		break;



	default:

		pr_cont("unsupported p6 CPU model %d ",

			boot_cpu_data.x86_model);

		pr_cont("unsupported p6 CPU model %d ", boot_cpu_data.x86_model);

		return -ENODEV;

	}



	x86_pmu = p6_pmu;



	memcpy(hw_cache_event_ids, p6_hw_cache_event_ids,

		sizeof(hw_cache_event_ids));





	return 0;

}