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From: Borislav Petkov on 6 Aug 2010 10:30
From: Borislav Petkov <borislav.petkov(a)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. Export mce buffer
read-only through debugfs.

Signed-off-by: Borislav Petkov <borislav.petkov(a)amd.com>
---
arch/x86/kernel/cpu/mcheck/mce.c | 135 ++++++++++++++++++++++++++++++++++++++
1 files changed, 135 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 1970ef9..cdff254 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;

/*
@@ -2064,6 +2065,137 @@ 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 mce_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 mce_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 mce_perf_open(struct inode *inode, struct file *file)
+{
+ file->private_data = inode->i_private;
+
+ return 0;
+}
+
+static const struct file_operations perf_mce_fops = {
+ .llseek = no_llseek,
+ .open = mce_perf_open,
+ .poll = perf_poll,
+ .unlocked_ioctl = perf_ioctl,
+ .compat_ioctl = perf_ioctl,
+ .mmap = perf_mmap,
+ .fasync = perf_fasync,
+ .release = perf_release,
+};
+
+static int mce_add_perf_debugfs_entry(struct dentry *dmce, int cpu)
+{
+ struct dentry *fmce_record;
+ char buf[14];
+
+ sprintf(buf, "mce_record%d", cpu);
+
+ fmce_record = debugfs_create_file(buf, S_IRUGO, dmce,
+ per_cpu(mce_event, cpu),
+ &perf_mce_fops);
+
+ if (!fmce_record)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static int mcheck_init_perf_event(void)
+{
+ int cpu, err = 0;
+
+ get_online_cpus();
+
+ for_each_online_cpu(cpu) {
+ err = mce_enable_perf_event_on_cpu(cpu);
+ if (err) {
+ printk(KERN_ERR "mce: error initializing mce tracepoint"
+ " on cpu %d\n", cpu);
+ goto unwind;
+ }
+
+ err = mce_add_perf_debugfs_entry(mce_get_debugfs_dir(), cpu);
+ if (err) {
+ printk(KERN_ERR "mce: error adding debugfs entry"
+ "on cpu %d\n", cpu);
+ goto unwind;
+ }
+ }
+ goto unlock;
+
+unwind:
+ for (--cpu; cpu >= 0; cpu--)
+ mce_disable_perf_event_on_cpu(cpu);
+
+unlock:
+ 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)
@@ -2077,6 +2209,7 @@ 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);
+ mce_enable_perf_event_on_cpu(cpu);
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
@@ -2088,6 +2221,7 @@ 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);
+ mce_disable_perf_event_on_cpu(cpu);
break;
case CPU_DOWN_FAILED:
case CPU_DOWN_FAILED_FROZEN:
@@ -2097,6 +2231,7 @@ 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);
+ mce_enable_perf_event_on_cpu(cpu);
break;
case CPU_POST_DEAD:
/* intentionally ignoring frozen here */
--
1.7.1

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Prev: [RFC PATCH 9/9] tools, ras: Add a RAS daemon
Next: [RFC PATCH 8/9] perf: Carve out mmap helpers for general use