1 files changed, 38 insertions, 31 deletions

diff --git a/arch/x86/kernel/cpu/mce/dev-mcelog.c b/arch/x86/kernel/cpu/mce/dev-mcelog.c
index 9690ec5c8051..8d023239ce18 100644
--- a/arch/x86/kernel/cpu/mce/dev-mcelog.c
+++ b/arch/x86/kernel/cpu/mce/dev-mcelog.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * /dev/mcelog driver
  *
@@ -28,11 +29,7 @@ static char *mce_helper_argv[2] = { mce_helper, NULL };
  * separate MCEs from kernel messages to avoid bogus bug reports.
  */
 
-static struct mce_log_buffer mcelog = {
-	.signature	= MCE_LOG_SIGNATURE,
-	.len		= MCE_LOG_LEN,
-	.recordlen	= sizeof(struct mce),
-};
+static struct mce_log_buffer *mcelog;
 
 static DECLARE_WAIT_QUEUE_HEAD(mce_chrdev_wait);
 
@@ -42,23 +39,27 @@ static int dev_mce_log(struct notifier_block *nb, unsigned long val,
 	struct mce *mce = (struct mce *)data;
 	unsigned int entry;
 
+	if (mce->kflags & MCE_HANDLED_CEC)
+		return NOTIFY_DONE;
+
 	mutex_lock(&mce_chrdev_read_mutex);
 
-	entry = mcelog.next;
+	entry = mcelog->next;
 
 	/*
 	 * When the buffer fills up discard new entries. Assume that the
 	 * earlier errors are the more interesting ones:
 	 */
-	if (entry >= MCE_LOG_LEN) {
-		set_bit(MCE_OVERFLOW, (unsigned long *)&mcelog.flags);
+	if (entry >= mcelog->len) {
+		set_bit(MCE_OVERFLOW, (unsigned long *)&mcelog->flags);
 		goto unlock;
 	}
 
-	mcelog.next = entry + 1;
+	mcelog->next = entry + 1;
 
-	memcpy(mcelog.entry + entry, mce, sizeof(struct mce));
-	mcelog.entry[entry].finished = 1;
+	memcpy(mcelog->entry + entry, mce, sizeof(struct mce));
+	mcelog->entry[entry].finished = 1;
+	mcelog->entry[entry].kflags = 0;
 
 	/* wake processes polling /dev/mcelog */
 	wake_up_interruptible(&mce_chrdev_wait);
@@ -66,6 +67,9 @@ static int dev_mce_log(struct notifier_block *nb, unsigned long val,
 unlock:
 	mutex_unlock(&mce_chrdev_read_mutex);
 
+	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
+		mce->kflags |= MCE_HANDLED_MCELOG;
+
 	return NOTIFY_OK;
 }
 
@@ -101,8 +105,7 @@ static ssize_t set_trigger(struct device *s, struct device_attribute *attr,
 {
 	char *p;
 
-	strncpy(mce_helper, buf, sizeof(mce_helper));
-	mce_helper[sizeof(mce_helper)-1] = 0;
+	strscpy(mce_helper, buf, sizeof(mce_helper));
 	p = strchr(mce_helper, '\n');
 
 	if (p)
@@ -213,21 +216,21 @@ static ssize_t mce_chrdev_read(struct file *filp, char __user *ubuf,
 
 	/* Only supports full reads right now */
 	err = -EINVAL;
-	if (*off != 0 || usize < MCE_LOG_LEN*sizeof(struct mce))
+	if (*off != 0 || usize < mcelog->len * sizeof(struct mce))
 		goto out;
 
-	next = mcelog.next;
+	next = mcelog->next;
 	err = 0;
 
 	for (i = 0; i < next; i++) {
-		struct mce *m = &mcelog.entry[i];
+		struct mce *m = &mcelog->entry[i];
 
 		err |= copy_to_user(buf, m, sizeof(*m));
 		buf += sizeof(*m);
 	}
 
-	memset(mcelog.entry, 0, next * sizeof(struct mce));
-	mcelog.next = 0;
+	memset(mcelog->entry, 0, next * sizeof(struct mce));
+	mcelog->next = 0;
 
 	if (err)
 		err = -EFAULT;
@@ -241,7 +244,7 @@ out:
 static __poll_t mce_chrdev_poll(struct file *file, poll_table *wait)
 {
 	poll_wait(file, &mce_chrdev_wait, wait);
-	if (READ_ONCE(mcelog.next))
+	if (READ_ONCE(mcelog->next))
 		return EPOLLIN | EPOLLRDNORM;
 	if (!mce_apei_read_done && apei_check_mce())
 		return EPOLLIN | EPOLLRDNORM;
@@ -260,16 +263,9 @@ static long mce_chrdev_ioctl(struct file *f, unsigned int cmd,
 	case MCE_GET_RECORD_LEN:
 		return put_user(sizeof(struct mce), p);
 	case MCE_GET_LOG_LEN:
-		return put_user(MCE_LOG_LEN, p);
-	case MCE_GETCLEAR_FLAGS: {
-		unsigned flags;
-
-		do {
-			flags = mcelog.flags;
-		} while (cmpxchg(&mcelog.flags, flags, 0) != flags);
-
-		return put_user(flags, p);
-	}
+		return put_user(mcelog->len, p);
+	case MCE_GETCLEAR_FLAGS:
+		return put_user(xchg(&mcelog->flags, 0), p);
 	default:
 		return -ENOTTY;
 	}
@@ -311,7 +307,7 @@ static ssize_t mce_chrdev_write(struct file *filp, const char __user *ubuf,
 
 	/*
 	 * Need to give user space some time to set everything up,
-	 * so do it a jiffie or two later everywhere.
+	 * so do it a jiffy or two later everywhere.
 	 */
 	schedule_timeout(2);
 
@@ -327,7 +323,7 @@ static const struct file_operations mce_chrdev_ops = {
 	.write			= mce_chrdev_write,
 	.poll			= mce_chrdev_poll,
 	.unlocked_ioctl		= mce_chrdev_ioctl,
-	.llseek			= no_llseek,
+	.compat_ioctl		= compat_ptr_ioctl,
 };
 
 static struct miscdevice mce_chrdev_device = {
@@ -338,8 +334,18 @@ static struct miscdevice mce_chrdev_device = {
 
 static __init int dev_mcelog_init_device(void)
 {
+	int mce_log_len;
 	int err;
 
+	mce_log_len = max(MCE_LOG_MIN_LEN, num_online_cpus());
+	mcelog = kzalloc(struct_size(mcelog, entry, mce_log_len), GFP_KERNEL);
+	if (!mcelog)
+		return -ENOMEM;
+
+	memcpy(mcelog->signature, MCE_LOG_SIGNATURE, sizeof(mcelog->signature));
+	mcelog->len = mce_log_len;
+	mcelog->recordlen = sizeof(struct mce);
+
 	/* register character device /dev/mcelog */
 	err = misc_register(&mce_chrdev_device);
 	if (err) {
@@ -349,6 +355,7 @@ static __init int dev_mcelog_init_device(void)
 		else
 			pr_err("Unable to init device /dev/mcelog (rc: %d)\n", err);
 
+		kfree(mcelog);
 		return err;
 	}