arch/x86/kernel/cpu/mcheck/mce-genpool.c

   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
  25 static struct gen_pool *mce_evt_pool;
  26 static LLIST_HEAD(mce_event_llist);
  27 static char gen_pool_buf[MCE_POOLSZ];
  28
  29 void 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
  47 bool mce_gen_pool_empty(void)
  48 {
  49         return llist_empty(&mce_event_llist);
  50 }
  51
  52 int 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
  71 static 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
  88 out:
  89         return ret;
  90 }
  91
  92 int 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 }