xref: /openbmc/linux/arch/x86/kernel/cpu/mce/genpool.c (revision 82664963)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * MCE event pool management in MCE context
4  *
5  * Copyright (C) 2015 Intel Corp.
6  * Author: Chen, Gong <gong.chen@linux.intel.com>
7  */
8 #include <linux/smp.h>
9 #include <linux/mm.h>
10 #include <linux/genalloc.h>
11 #include <linux/llist.h>
12 #include "internal.h"
13 
14 /*
15  * printk() is not safe in MCE context. This is a lock-less memory allocator
16  * used to save error information organized in a lock-less list.
17  *
18  * This memory pool is only to be used to save MCE records in MCE context.
19  * MCE events are rare, so a fixed size memory pool should be enough. Use
20  * 2 pages to save MCE events for now (~80 MCE records at most).
21  */
22 #define MCE_POOLSZ	(2 * PAGE_SIZE)
23 
24 static struct gen_pool *mce_evt_pool;
25 static LLIST_HEAD(mce_event_llist);
26 static char gen_pool_buf[MCE_POOLSZ];
27 
28 /*
29  * Compare the record "t" with each of the records on list "l" to see if
30  * an equivalent one is present in the list.
31  */
is_duplicate_mce_record(struct mce_evt_llist * t,struct mce_evt_llist * l)32 static bool is_duplicate_mce_record(struct mce_evt_llist *t, struct mce_evt_llist *l)
33 {
34 	struct mce_evt_llist *node;
35 	struct mce *m1, *m2;
36 
37 	m1 = &t->mce;
38 
39 	llist_for_each_entry(node, &l->llnode, llnode) {
40 		m2 = &node->mce;
41 
42 		if (!mce_cmp(m1, m2))
43 			return true;
44 	}
45 	return false;
46 }
47 
48 /*
49  * The system has panicked - we'd like to peruse the list of MCE records
50  * that have been queued, but not seen by anyone yet.  The list is in
51  * reverse time order, so we need to reverse it. While doing that we can
52  * also drop duplicate records (these were logged because some banks are
53  * shared between cores or by all threads on a socket).
54  */
mce_gen_pool_prepare_records(void)55 struct llist_node *mce_gen_pool_prepare_records(void)
56 {
57 	struct llist_node *head;
58 	LLIST_HEAD(new_head);
59 	struct mce_evt_llist *node, *t;
60 
61 	head = llist_del_all(&mce_event_llist);
62 	if (!head)
63 		return NULL;
64 
65 	/* squeeze out duplicates while reversing order */
66 	llist_for_each_entry_safe(node, t, head, llnode) {
67 		if (!is_duplicate_mce_record(node, t))
68 			llist_add(&node->llnode, &new_head);
69 	}
70 
71 	return new_head.first;
72 }
73 
mce_gen_pool_process(struct work_struct * __unused)74 void mce_gen_pool_process(struct work_struct *__unused)
75 {
76 	struct llist_node *head;
77 	struct mce_evt_llist *node, *tmp;
78 	struct mce *mce;
79 
80 	head = llist_del_all(&mce_event_llist);
81 	if (!head)
82 		return;
83 
84 	head = llist_reverse_order(head);
85 	llist_for_each_entry_safe(node, tmp, head, llnode) {
86 		mce = &node->mce;
87 		blocking_notifier_call_chain(&x86_mce_decoder_chain, 0, mce);
88 		gen_pool_free(mce_evt_pool, (unsigned long)node, sizeof(*node));
89 	}
90 }
91 
mce_gen_pool_empty(void)92 bool mce_gen_pool_empty(void)
93 {
94 	return llist_empty(&mce_event_llist);
95 }
96 
mce_gen_pool_add(struct mce * mce)97 int mce_gen_pool_add(struct mce *mce)
98 {
99 	struct mce_evt_llist *node;
100 
101 	if (filter_mce(mce))
102 		return -EINVAL;
103 
104 	if (!mce_evt_pool)
105 		return -EINVAL;
106 
107 	node = (void *)gen_pool_alloc(mce_evt_pool, sizeof(*node));
108 	if (!node) {
109 		pr_warn_ratelimited("MCE records pool full!\n");
110 		return -ENOMEM;
111 	}
112 
113 	memcpy(&node->mce, mce, sizeof(*mce));
114 	llist_add(&node->llnode, &mce_event_llist);
115 
116 	return 0;
117 }
118 
mce_gen_pool_create(void)119 static int mce_gen_pool_create(void)
120 {
121 	struct gen_pool *tmpp;
122 	int ret = -ENOMEM;
123 
124 	tmpp = gen_pool_create(ilog2(sizeof(struct mce_evt_llist)), -1);
125 	if (!tmpp)
126 		goto out;
127 
128 	ret = gen_pool_add(tmpp, (unsigned long)gen_pool_buf, MCE_POOLSZ, -1);
129 	if (ret) {
130 		gen_pool_destroy(tmpp);
131 		goto out;
132 	}
133 
134 	mce_evt_pool = tmpp;
135 
136 out:
137 	return ret;
138 }
139 
mce_gen_pool_init(void)140 int mce_gen_pool_init(void)
141 {
142 	/* Just init mce_gen_pool once. */
143 	if (mce_evt_pool)
144 		return 0;
145 
146 	return mce_gen_pool_create();
147 }
148