1 files changed, 156 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/mce/genpool.c b/arch/x86/kernel/cpu/mce/genpool.c
new file mode 100644
index 000000000000..3ca9c007a666
--- /dev/null
+++ b/arch/x86/kernel/cpu/mce/genpool.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MCE event pool management in MCE context
+ *
+ * Copyright (C) 2015 Intel Corp.
+ * Author: Chen, Gong <gong.chen@linux.intel.com>
+ */
+#include <linux/smp.h>
+#include <linux/mm.h>
+#include <linux/genalloc.h>
+#include <linux/llist.h>
+#include "internal.h"
+
+/*
+ * printk() is not safe in MCE context. This is a lock-less memory allocator
+ * used to save error information organized in a lock-less list.
+ *
+ * This memory pool is only to be used to save MCE records in MCE context.
+ * MCE events are rare, so a fixed size memory pool should be enough.
+ * Allocate on a sliding scale based on number of CPUs.
+ */
+#define MCE_MIN_ENTRIES	80
+#define MCE_PER_CPU	2
+
+static struct gen_pool *mce_evt_pool;
+static LLIST_HEAD(mce_event_llist);
+
+/*
+ * Compare the record "t" with each of the records on list "l" to see if
+ * an equivalent one is present in the list.
+ */
+static bool is_duplicate_mce_record(struct mce_evt_llist *t, struct mce_evt_llist *l)
+{
+	struct mce_hw_err *err1, *err2;
+	struct mce_evt_llist *node;
+
+	err1 = &t->err;
+
+	llist_for_each_entry(node, &l->llnode, llnode) {
+		err2 = &node->err;
+
+		if (!mce_cmp(&err1->m, &err2->m))
+			return true;
+	}
+	return false;
+}
+
+/*
+ * The system has panicked - we'd like to peruse the list of MCE records
+ * that have been queued, but not seen by anyone yet.  The list is in
+ * reverse time order, so we need to reverse it. While doing that we can
+ * also drop duplicate records (these were logged because some banks are
+ * shared between cores or by all threads on a socket).
+ */
+struct llist_node *mce_gen_pool_prepare_records(void)
+{
+	struct llist_node *head;
+	LLIST_HEAD(new_head);
+	struct mce_evt_llist *node, *t;
+
+	head = llist_del_all(&mce_event_llist);
+	if (!head)
+		return NULL;
+
+	/* squeeze out duplicates while reversing order */
+	llist_for_each_entry_safe(node, t, head, llnode) {
+		if (!is_duplicate_mce_record(node, t))
+			llist_add(&node->llnode, &new_head);
+	}
+
+	return new_head.first;
+}
+
+void mce_gen_pool_process(struct work_struct *__unused)
+{
+	struct mce_evt_llist *node, *tmp;
+	struct llist_node *head;
+	struct mce *mce;
+
+	head = llist_del_all(&mce_event_llist);
+	if (!head)
+		return;
+
+	head = llist_reverse_order(head);
+	llist_for_each_entry_safe(node, tmp, head, llnode) {
+		mce = &node->err.m;
+		blocking_notifier_call_chain(&x86_mce_decoder_chain, 0, mce);
+		gen_pool_free(mce_evt_pool, (unsigned long)node, sizeof(*node));
+	}
+}
+
+bool mce_gen_pool_empty(void)
+{
+	return llist_empty(&mce_event_llist);
+}
+
+bool mce_gen_pool_add(struct mce_hw_err *err)
+{
+	struct mce_evt_llist *node;
+
+	if (filter_mce(&err->m))
+		return false;
+
+	if (!mce_evt_pool)
+		return false;
+
+	node = (void *)gen_pool_alloc(mce_evt_pool, sizeof(*node));
+	if (!node) {
+		pr_warn_ratelimited("MCE records pool full!\n");
+		return false;
+	}
+
+	memcpy(&node->err, err, sizeof(*err));
+	llist_add(&node->llnode, &mce_event_llist);
+
+	return true;
+}
+
+static bool mce_gen_pool_create(void)
+{
+	int mce_numrecords, mce_poolsz, order;
+	struct gen_pool *gpool;
+	void *mce_pool;
+
+	order = order_base_2(sizeof(struct mce_evt_llist));
+	gpool = gen_pool_create(order, -1);
+	if (!gpool)
+		return false;
+
+	mce_numrecords = max(MCE_MIN_ENTRIES, num_possible_cpus() * MCE_PER_CPU);
+	mce_poolsz = mce_numrecords * (1 << order);
+	mce_pool = kmalloc(mce_poolsz, GFP_KERNEL);
+	if (!mce_pool) {
+		gen_pool_destroy(gpool);
+		return false;
+	}
+
+	if (gen_pool_add(gpool, (unsigned long)mce_pool, mce_poolsz, -1)) {
+		gen_pool_destroy(gpool);
+		kfree(mce_pool);
+		return false;
+	}
+
+	mce_evt_pool = gpool;
+
+	return true;
+}
+
+bool mce_gen_pool_init(void)
+{
+	/* Just init mce_gen_pool once. */
+	if (mce_evt_pool)
+		return true;
+
+	return mce_gen_pool_create();
+}