1/*
2 * MCE event pool management in MCE context
3 *
4 * Copyright (C) 2015 Intel Corp.
5 * Author: Chen, Gong <gong.chen@linux.intel.com>
6 *
7 * This file is licensed under GPLv2.
8 */
9#include <linux/smp.h>
10#include <linux/mm.h>
11#include <linux/genalloc.h>
12#include <linux/llist.h>
13#include "mce-internal.h"
14
15/*
16 * printk() is not safe in MCE context. This is a lock-less memory allocator
17 * used to save error information organized in a lock-less list.
18 *
19 * This memory pool is only to be used to save MCE records in MCE context.
20 * MCE events are rare, so a fixed size memory pool should be enough. Use
21 * 2 pages to save MCE events for now (~80 MCE records at most).
22 */
23#define MCE_POOLSZ	(2 * PAGE_SIZE)
24
25static struct gen_pool *mce_evt_pool;
26static LLIST_HEAD(mce_event_llist);
27static char gen_pool_buf[MCE_POOLSZ];
28
29void mce_gen_pool_process(void)
30{
31	struct llist_node *head;
32	struct mce_evt_llist *node, *tmp;
33	struct mce *mce;
34
35	head = llist_del_all(&mce_event_llist);
36	if (!head)
37		return;
38
39	head = llist_reverse_order(head);
40	llist_for_each_entry_safe(node, tmp, head, llnode) {
41		mce = &node->mce;
42		atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, mce);
43		gen_pool_free(mce_evt_pool, (unsigned long)node, sizeof(*node));
44	}
45}
46
47bool mce_gen_pool_empty(void)
48{
49	return llist_empty(&mce_event_llist);
50}
51
52int mce_gen_pool_add(struct mce *mce)
53{
54	struct mce_evt_llist *node;
55
56	if (!mce_evt_pool)
57		return -EINVAL;
58
59	node = (void *)gen_pool_alloc(mce_evt_pool, sizeof(*node));
60	if (!node) {
61		pr_warn_ratelimited("MCE records pool full!\n");
62		return -ENOMEM;
63	}
64
65	memcpy(&node->mce, mce, sizeof(*mce));
66	llist_add(&node->llnode, &mce_event_llist);
67
68	return 0;
69}
70
71static int mce_gen_pool_create(void)
72{
73	struct gen_pool *tmpp;
74	int ret = -ENOMEM;
75
76	tmpp = gen_pool_create(ilog2(sizeof(struct mce_evt_llist)), -1);
77	if (!tmpp)
78		goto out;
79
80	ret = gen_pool_add(tmpp, (unsigned long)gen_pool_buf, MCE_POOLSZ, -1);
81	if (ret) {
82		gen_pool_destroy(tmpp);
83		goto out;
84	}
85
86	mce_evt_pool = tmpp;
87
88out:
89	return ret;
90}
91
92int mce_gen_pool_init(void)
93{
94	/* Just init mce_gen_pool once. */
95	if (mce_evt_pool)
96		return 0;
97
98	return mce_gen_pool_create();
99}
100