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Subject[PATCH 02/21] mce: Add persistent events
Date
From: Borislav Petkov <borislav.petkov@amd.com>

Add the required glue to enable the mce_record tracepoint on boot thus
simulating a persistent event with allocated buffers. Userspace daemon
will hook into it later when booting is done.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
---
arch/x86/kernel/cpu/mcheck/mce.c | 89 ++++++++++++++++++++++++++++++++++++++
1 files changed, 89 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 18cc425..42d2808 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -95,6 +95,7 @@ static char *mce_helper_argv[2] = { mce_helper, NULL };

static DECLARE_WAIT_QUEUE_HEAD(mce_wait);
static DEFINE_PER_CPU(struct mce, mces_seen);
+static DEFINE_PER_CPU(struct perf_event *, mce_event);
static int cpu_missing;

/*
@@ -2063,6 +2064,91 @@ static void __cpuinit mce_reenable_cpu(void *h)
}
}

+struct perf_event_attr pattr = {
+ .type = PERF_TYPE_TRACEPOINT,
+ .size = sizeof(pattr),
+ .sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_CPU | PERF_SAMPLE_TIME,
+};
+
+static int mcheck_enable_perf_event_on_cpu(int cpu)
+{
+ struct perf_event *event;
+ struct perf_buffer *buffer;
+
+ if (!event_mce_record.event.type) {
+ printk(KERN_ERR "mce: Tracepoint not enumerated yet!\n");
+ return -EINVAL;
+ }
+ pattr.config = event_mce_record.event.type;
+ pattr.sample_period = ULLONG_MAX;
+
+ event = perf_event_create_kernel_counter(&pattr, cpu, -1, NULL);
+ if (IS_ERR(event))
+ return -EINVAL;
+
+ buffer = perf_buffer_alloc(128, 0, cpu, 0);
+ if (IS_ERR(buffer))
+ goto err;
+
+ rcu_assign_pointer(event->buffer, buffer);
+ per_cpu(mce_event, cpu) = event;
+
+ perf_event_enable(event);
+
+ return 0;
+
+err:
+ perf_event_release_kernel(event);
+ return -EINVAL;
+}
+
+static void mcheck_disable_perf_event_on_cpu(int cpu)
+{
+ struct perf_event *event = per_cpu(mce_event, cpu);
+
+ if (!event)
+ return;
+
+ perf_event_disable(event);
+
+ if (event->buffer) {
+ perf_buffer_put(event->buffer);
+ rcu_assign_pointer(event->buffer, NULL);
+ }
+
+ per_cpu(mce_event, cpu) = NULL;
+
+ perf_event_release_kernel(event);
+}
+
+static int mcheck_init_perf_event(void)
+{
+ int cpu, i, err = 0;
+
+ get_online_cpus();
+
+ for_each_online_cpu(cpu) {
+ err = mcheck_enable_perf_event_on_cpu(cpu);
+ if (err) {
+ printk(KERN_ERR "mce: error initializing mce tracepoint"
+ " on cpu %d\n", cpu);
+
+ for (i = cpu - 1; i >= 0; i--)
+ mcheck_disable_perf_event_on_cpu(i);
+ }
+ }
+
+ put_online_cpus();
+
+ return err;
+}
+
+/*
+ * This has to run after after event_trace_init() which is an fs_initcall()
+ * currently
+ */
+device_initcall(mcheck_init_perf_event);
+
/* Get notified when a cpu comes on/off. Be hotplug friendly. */
static int __cpuinit
mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
@@ -2076,6 +2162,7 @@ mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
mce_create_device(cpu);
if (threshold_cpu_callback)
threshold_cpu_callback(action, cpu);
+ mcheck_enable_perf_event_on_cpu(cpu);
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
@@ -2087,6 +2174,7 @@ mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
case CPU_DOWN_PREPARE_FROZEN:
del_timer_sync(t);
smp_call_function_single(cpu, mce_disable_cpu, &action, 1);
+ mcheck_disable_perf_event_on_cpu(cpu);
break;
case CPU_DOWN_FAILED:
case CPU_DOWN_FAILED_FROZEN:
@@ -2096,6 +2184,7 @@ mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
add_timer_on(t, cpu);
}
smp_call_function_single(cpu, mce_reenable_cpu, &action, 1);
+ mcheck_enable_perf_event_on_cpu(cpu);
break;
case CPU_POST_DEAD:
/* intentionally ignoring frozen here */
--
1.7.1


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