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/*
* SGI NMI support routines
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Copyright (c) 2009-2013 Silicon Graphics, Inc. All Rights Reserved.
* Copyright (c) Mike Travis
*/
#include <linux/cpu.h>
#include <linux/nmi.h>
#include <asm/apic.h>
#include <asm/nmi.h>
#include <asm/uv/uv.h>
#include <asm/uv/uv_hub.h>
#include <asm/uv/uv_mmrs.h>
/* BMC sets a bit this MMR non-zero before sending an NMI */
#define UVH_NMI_MMR UVH_SCRATCH5
#define UVH_NMI_MMR_CLEAR (UVH_NMI_MMR + 8)
#define UV_NMI_PENDING_MASK (1UL << 63)
DEFINE_PER_CPU(unsigned long, cpu_last_nmi_count);
static DEFINE_SPINLOCK(uv_nmi_lock);
/*
* When NMI is received, print a stack trace.
*/
int uv_handle_nmi(unsigned int reason, struct pt_regs *regs)
{
unsigned long real_uv_nmi;
int bid;
/*
* Each blade has an MMR that indicates when an NMI has been sent
* to cpus on the blade. If an NMI is detected, atomically
* clear the MMR and update a per-blade NMI count used to
* cause each cpu on the blade to notice a new NMI.
*/
bid = uv_numa_blade_id();
real_uv_nmi = (uv_read_local_mmr(UVH_NMI_MMR) & UV_NMI_PENDING_MASK);
if (unlikely(real_uv_nmi)) {
spin_lock(&uv_blade_info[bid].nmi_lock);
real_uv_nmi = (uv_read_local_mmr(UVH_NMI_MMR) &
UV_NMI_PENDING_MASK);
if (real_uv_nmi) {
uv_blade_info[bid].nmi_count++;
uv_write_local_mmr(UVH_NMI_MMR_CLEAR,
UV_NMI_PENDING_MASK);
}
spin_unlock(&uv_blade_info[bid].nmi_lock);
}
if (likely(__get_cpu_var(cpu_last_nmi_count) ==
uv_blade_info[bid].nmi_count))
return NMI_DONE;
__get_cpu_var(cpu_last_nmi_count) = uv_blade_info[bid].nmi_count;
/*
* Use a lock so only one cpu prints at a time.
* This prevents intermixed output.
*/
spin_lock(&uv_nmi_lock);
pr_info("UV NMI stack dump cpu %u:\n", smp_processor_id());
dump_stack();
spin_unlock(&uv_nmi_lock);
return NMI_HANDLED;
}
void uv_register_nmi_notifier(void)
{
if (register_nmi_handler(NMI_UNKNOWN, uv_handle_nmi, 0, "uv"))
pr_warn("UV NMI handler failed to register\n");
}
void uv_nmi_init(void)
{
unsigned int value;
/*
* Unmask NMI on all cpus
*/
value = apic_read(APIC_LVT1) | APIC_DM_NMI;
value &= ~APIC_LVT_MASKED;
apic_write(APIC_LVT1, value);
}
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