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printk() is not safe to use in MCE context. Add a lockless memory allocator pool to save error records in MCE context. Those records will be issued later, in a printk-safe context. The idea is inspired by the APEI/GHES driver. We're very conservative and allocate only two pages for it but since we're going to use those pages throughout the system's lifetime, we allocate them statically to avoid early boot time allocation woes. Signed-off-by: Chen, Gong <gong.chen@linux.intel.com> [ Rewrite. ] Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Link: http://lkml.kernel.org/r/1439396985-12812-3-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
100 lines
2.1 KiB
C
100 lines
2.1 KiB
C
/*
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* MCE event pool management in MCE context
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*
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* Copyright (C) 2015 Intel Corp.
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* Author: Chen, Gong <gong.chen@linux.intel.com>
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*
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* This file is licensed under GPLv2.
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*/
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#include <linux/smp.h>
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#include <linux/mm.h>
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#include <linux/genalloc.h>
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#include <linux/llist.h>
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#include "mce-internal.h"
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/*
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* printk() is not safe in MCE context. This is a lock-less memory allocator
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* used to save error information organized in a lock-less list.
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*
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* This memory pool is only to be used to save MCE records in MCE context.
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* MCE events are rare, so a fixed size memory pool should be enough. Use
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* 2 pages to save MCE events for now (~80 MCE records at most).
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*/
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#define MCE_POOLSZ (2 * PAGE_SIZE)
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static struct gen_pool *mce_evt_pool;
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static LLIST_HEAD(mce_event_llist);
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static char gen_pool_buf[MCE_POOLSZ];
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void mce_gen_pool_process(void)
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{
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struct llist_node *head;
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struct mce_evt_llist *node;
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struct mce *mce;
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head = llist_del_all(&mce_event_llist);
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if (!head)
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return;
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head = llist_reverse_order(head);
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llist_for_each_entry(node, head, llnode) {
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mce = &node->mce;
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atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, mce);
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gen_pool_free(mce_evt_pool, (unsigned long)node, sizeof(*node));
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}
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}
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bool mce_gen_pool_empty(void)
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{
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return llist_empty(&mce_event_llist);
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}
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int mce_gen_pool_add(struct mce *mce)
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{
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struct mce_evt_llist *node;
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if (!mce_evt_pool)
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return -EINVAL;
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node = (void *)gen_pool_alloc(mce_evt_pool, sizeof(*node));
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if (!node) {
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pr_warn_ratelimited("MCE records pool full!\n");
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return -ENOMEM;
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}
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memcpy(&node->mce, mce, sizeof(*mce));
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llist_add(&node->llnode, &mce_event_llist);
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return 0;
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}
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static int mce_gen_pool_create(void)
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{
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struct gen_pool *tmpp;
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int ret = -ENOMEM;
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tmpp = gen_pool_create(ilog2(sizeof(struct mce_evt_llist)), -1);
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if (!tmpp)
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goto out;
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ret = gen_pool_add(tmpp, (unsigned long)gen_pool_buf, MCE_POOLSZ, -1);
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if (ret) {
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gen_pool_destroy(tmpp);
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goto out;
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}
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mce_evt_pool = tmpp;
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out:
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return ret;
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}
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int mce_gen_pool_init(void)
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{
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/* Just init mce_gen_pool once. */
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if (mce_evt_pool)
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return 0;
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return mce_gen_pool_create();
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}
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