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: Mark 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: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140206170815.GW2936@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index b886451..1246b85 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -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);

diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index c1a8618..4972c24 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -409,6 +409,7 @@ struct x86_pmu {
        /*
         * sysfs attrs
         */
+       int             attr_rdpmc_broken;
        int             attr_rdpmc;
        struct attribute **format_attrs;
        struct attribute **event_attrs;

diff --git a/arch/x86/kernel/cpu/perf_event_p6.c b/arch/x86/kernel/cpu/perf_event_p6.c
index b1e2fe1..7c1a0c0 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event_p6.c
+++ b/arch/x86/kernel/cpu/perf_event_p6.c
@@ -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;
 }