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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
* Copyright (C) 2011 Don Zickus Red Hat, Inc.
*
* Pentium III FXSR, SSE support
* Gareth Hughes <gareth@valinux.com>, May 2000
*/
/*
* Handle hardware traps and faults.
*/
#include <linux/spinlock.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/sched/debug.h>
#include <linux/nmi.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <linux/ratelimit.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/atomic.h>
#include <linux/sched/clock.h>
#if defined(CONFIG_EDAC)
#include <linux/edac.h>
#endif
#include <asm/cpu_entry_area.h>
#include <asm/traps.h>
#include <asm/mach_traps.h>
#include <asm/nmi.h>
#include <asm/x86_init.h>
#include <asm/reboot.h>
#include <asm/cache.h>
#include <asm/nospec-branch.h>
#define CREATE_TRACE_POINTS
#include <trace/events/nmi.h>
struct nmi_desc {
raw_spinlock_t lock;
struct list_head head;
};
static struct nmi_desc nmi_desc[NMI_MAX] =
{
{
.lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[0].lock),
.head = LIST_HEAD_INIT(nmi_desc[0].head),
},
{
.lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[1].lock),
.head = LIST_HEAD_INIT(nmi_desc[1].head),
},
{
.lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[2].lock),
.head = LIST_HEAD_INIT(nmi_desc[2].head),
},
{
.lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[3].lock),
.head = LIST_HEAD_INIT(nmi_desc[3].head),
},
};
struct nmi_stats {
unsigned int normal;
unsigned int unknown;
unsigned int external;
unsigned int swallow;
};
static DEFINE_PER_CPU(struct nmi_stats, nmi_stats);
static int ignore_nmis __read_mostly;
int unknown_nmi_panic;
/*
* Prevent NMI reason port (0x61) being accessed simultaneously, can
* only be used in NMI handler.
*/
static DEFINE_RAW_SPINLOCK(nmi_reason_lock);
static int __init setup_unknown_nmi_panic(char *str)
{
unknown_nmi_panic = 1;
return 1;
}
__setup("unknown_nmi_panic", setup_unknown_nmi_panic);
#define nmi_to_desc(type) (&nmi_desc[type])
static u64 nmi_longest_ns = 1 * NSEC_PER_MSEC;
static int __init nmi_warning_debugfs(void)
{
debugfs_create_u64("nmi_longest_ns", 0644,
arch_debugfs_dir, &nmi_longest_ns);
return 0;
}
fs_initcall(nmi_warning_debugfs);
static void nmi_check_duration(struct nmiaction *action, u64 duration)
{
u64 whole_msecs = READ_ONCE(action->max_duration);
int remainder_ns, decimal_msecs;
if (duration < nmi_longest_ns || duration < action->max_duration)
return;
action->max_duration = duration;
remainder_ns = do_div(whole_msecs, (1000 * 1000));
decimal_msecs = remainder_ns / 1000;
printk_ratelimited(KERN_INFO
"INFO: NMI handler (%ps) took too long to run: %lld.%03d msecs\n",
action->handler, whole_msecs, decimal_msecs);
}
static int nmi_handle(unsigned int type, struct pt_regs *regs)
{
struct nmi_desc *desc = nmi_to_desc(type);
struct nmiaction *a;
int handled=0;
rcu_read_lock();
/*
* NMIs are edge-triggered, which means if you have enough
* of them concurrently, you can lose some because only one
* can be latched at any given time. Walk the whole list
* to handle those situations.
*/
list_for_each_entry_rcu(a, &desc->head, list) {
int thishandled;
u64 delta;
delta = sched_clock();
thishandled = a->handler(type, regs);
handled += thishandled;
delta = sched_clock() - delta;
trace_nmi_handler(a->handler, (int)delta, thishandled);
nmi_check_duration(a, delta);
}
rcu_read_unlock();
/* return total number of NMI events handled */
return handled;
}
NOKPROBE_SYMBOL(nmi_handle);
int __register_nmi_handler(unsigned int type, struct nmiaction *action)
{
struct nmi_desc *desc = nmi_to_desc(type);
unsigned long flags;
if (!action->handler)
return -EINVAL;
raw_spin_lock_irqsave(&desc->lock, flags);
/*
* Indicate if there are multiple registrations on the
* internal NMI handler call chains (SERR and IO_CHECK).
*/
WARN_ON_ONCE(type == NMI_SERR && !list_empty(&desc->head));
WARN_ON_ONCE(type == NMI_IO_CHECK && !list_empty(&desc->head));
/*
* some handlers need to be executed first otherwise a fake
* event confuses some handlers (kdump uses this flag)
*/
if (action->flags & NMI_FLAG_FIRST)
list_add_rcu(&action->list, &desc->head);
else
list_add_tail_rcu(&action->list, &desc->head);
raw_spin_unlock_irqrestore(&desc->lock, flags);
return 0;
}
EXPORT_SYMBOL(__register_nmi_handler);
void unregister_nmi_handler(unsigned int type, const char *name)
{
struct nmi_desc *desc = nmi_to_desc(type);
struct nmiaction *n;
unsigned long flags;
raw_spin_lock_irqsave(&desc->lock, flags);
list_for_each_entry_rcu(n, &desc->head, list) {
/*
* the name passed in to describe the nmi handler
* is used as the lookup key
*/
if (!strcmp(n->name, name)) {
WARN(in_nmi(),
"Trying to free NMI (%s) from NMI context!\n", n->name);
list_del_rcu(&n->list);
break;
}
}
raw_spin_unlock_irqrestore(&desc->lock, flags);
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(unregister_nmi_handler);
static void
pci_serr_error(unsigned char reason, struct pt_regs *regs)
{
/* check to see if anyone registered against these types of errors */
if (nmi_handle(NMI_SERR, regs))
return;
pr_emerg("NMI: PCI system error (SERR) for reason %02x on CPU %d.\n",
reason, smp_processor_id());
if (panic_on_unrecovered_nmi)
nmi_panic(regs, "NMI: Not continuing");
pr_emerg("Dazed and confused, but trying to continue\n");
/* Clear and disable the PCI SERR error line. */
reason = (reason & NMI_REASON_CLEAR_MASK) | NMI_REASON_CLEAR_SERR;
outb(reason, NMI_REASON_PORT);
}
NOKPROBE_SYMBOL(pci_serr_error);
static void
io_check_error(unsigned char reason, struct pt_regs *regs)
{
unsigned long i;
/* check to see if anyone registered against these types of errors */
if (nmi_handle(NMI_IO_CHECK, regs))
return;
pr_emerg(
"NMI: IOCK error (debug interrupt?) for reason %02x on CPU %d.\n",
reason, smp_processor_id());
show_regs(regs);
if (panic_on_io_nmi) {
nmi_panic(regs, "NMI IOCK error: Not continuing");
/*
* If we end up here, it means we have received an NMI while
* processing panic(). Simply return without delaying and
* re-enabling NMIs.
*/
return;
}
/* Re-enable the IOCK line, wait for a few seconds */
reason = (reason & NMI_REASON_CLEAR_MASK) | NMI_REASON_CLEAR_IOCHK;
outb(reason, NMI_REASON_PORT);
i = 20000;
while (--i) {
touch_nmi_watchdog();
udelay(100);
}
reason &= ~NMI_REASON_CLEAR_IOCHK;
outb(reason, NMI_REASON_PORT);
}
NOKPROBE_SYMBOL(io_check_error);
static void
unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
{
int handled;
|