2 * MCE event pool management in MCE context
4 * Copyright (C) 2015 Intel Corp.
5 * Author: Chen, Gong <gong.chen@linux.intel.com>
7 * This file is licensed under GPLv2.
11 #include <linux/genalloc.h>
12 #include <linux/llist.h>
13 #include "mce-internal.h"
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.
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).
23 #define MCE_POOLSZ (2 * PAGE_SIZE)
25 static struct gen_pool *mce_evt_pool;
26 static LLIST_HEAD(mce_event_llist);
27 static char gen_pool_buf[MCE_POOLSZ];
30 * Compare the record "t" with each of the records on list "l" to see if
31 * an equivalent one is present in the list.
33 static bool is_duplicate_mce_record(struct mce_evt_llist *t, struct mce_evt_llist *l)
35 struct mce_evt_llist *node;
40 llist_for_each_entry(node, &l->llnode, llnode) {
50 * The system has panicked - we'd like to peruse the list of MCE records
51 * that have been queued, but not seen by anyone yet. The list is in
52 * reverse time order, so we need to reverse it. While doing that we can
53 * also drop duplicate records (these were logged because some banks are
54 * shared between cores or by all threads on a socket).
56 struct llist_node *mce_gen_pool_prepare_records(void)
58 struct llist_node *head;
60 struct mce_evt_llist *node, *t;
62 head = llist_del_all(&mce_event_llist);
66 /* squeeze out duplicates while reversing order */
67 llist_for_each_entry_safe(node, t, head, llnode) {
68 if (!is_duplicate_mce_record(node, t))
69 llist_add(&node->llnode, &new_head);
72 return new_head.first;
75 void mce_gen_pool_process(struct work_struct *__unused)
77 struct llist_node *head;
78 struct mce_evt_llist *node, *tmp;
81 head = llist_del_all(&mce_event_llist);
85 head = llist_reverse_order(head);
86 llist_for_each_entry_safe(node, tmp, head, llnode) {
88 blocking_notifier_call_chain(&x86_mce_decoder_chain, 0, mce);
89 gen_pool_free(mce_evt_pool, (unsigned long)node, sizeof(*node));
93 bool mce_gen_pool_empty(void)
95 return llist_empty(&mce_event_llist);
98 int mce_gen_pool_add(struct mce *mce)
100 struct mce_evt_llist *node;
105 node = (void *)gen_pool_alloc(mce_evt_pool, sizeof(*node));
107 pr_warn_ratelimited("MCE records pool full!\n");
111 memcpy(&node->mce, mce, sizeof(*mce));
112 llist_add(&node->llnode, &mce_event_llist);
117 static int mce_gen_pool_create(void)
119 struct gen_pool *tmpp;
122 tmpp = gen_pool_create(ilog2(sizeof(struct mce_evt_llist)), -1);
126 ret = gen_pool_add(tmpp, (unsigned long)gen_pool_buf, MCE_POOLSZ, -1);
128 gen_pool_destroy(tmpp);
138 int mce_gen_pool_init(void)
140 /* Just init mce_gen_pool once. */
144 return mce_gen_pool_create();