Commit 41ddf73f authored by Sumit Garg's avatar Sumit Garg Committed by Liao Chen
Browse files

arm64: Add framework to turn IPI as NMI 

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8PLUM?from=project-issue
CVE: NA
Reference: https://lore.kernel.org/all/1604317487-14543-2-git-send-email-sumit.garg@linaro.org/



-------------------------------------------------

Introduce framework to turn an IPI as NMI using pseudo NMIs. The main
motivation for this feature is to have an IPI that can be leveraged to
invoke NMI functions on other CPUs.

And current prospective users are NMI backtrace and KGDB CPUs round-up
whose support is added via future patches.

Signed-off-by: default avatarSumit Garg <sumit.garg@linaro.org>
Signed-off-by: default avatarWei Li <liwei391@huawei.com>
Reviewed-by: default avatarXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
Signed-off-by: default avatarRuan Jinjie <ruanjinjie@huawei.com>
Signed-off-by: default avatarLiao Chen <liaochen4@huawei.com>
parent 4eb5a1ca

arch/arm64/include/asm/nmi.h

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/* SPDX-License-Identifier: GPL-2.0 */

#ifndef __ASM_NMI_H

#define __ASM_NMI_H



#ifndef __ASSEMBLER__



#include <linux/cpumask.h>



extern bool arm64_supports_nmi(void);

extern void arm64_send_nmi(cpumask_t *mask);



void set_smp_dynamic_ipi(int ipi);

void dynamic_ipi_setup(int cpu);

void dynamic_ipi_teardown(int cpu);



#endif /* !__ASSEMBLER__ */

#endif

arch/arm64/kernel/ipi_nmi.c

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// SPDX-License-Identifier: GPL-2.0-only

/*

 * NMI support for IPIs

 *

 * Copyright (C) 2020 Linaro Limited

 * Author: Sumit Garg <sumit.garg@linaro.org>

 */



#include <linux/interrupt.h>

#include <linux/irq.h>

#include <linux/smp.h>



#include <asm/nmi.h>



static struct irq_desc *ipi_nmi_desc __read_mostly;

static int ipi_nmi_id __read_mostly;



bool arm64_supports_nmi(void)

{

	if (ipi_nmi_desc)

		return true;



	return false;

}



void arm64_send_nmi(cpumask_t *mask)

{

	if (WARN_ON_ONCE(!ipi_nmi_desc))

		return;



	__ipi_send_mask(ipi_nmi_desc, mask);

}



static irqreturn_t ipi_nmi_handler(int irq, void *data)

{

	/* nop, NMI handlers for special features can be added here. */



	return IRQ_NONE;

}



void dynamic_ipi_setup(int cpu)

{

	if (!ipi_nmi_desc)

		return;



	if (!prepare_percpu_nmi(ipi_nmi_id))

		enable_percpu_nmi(ipi_nmi_id, IRQ_TYPE_NONE);

}



void dynamic_ipi_teardown(int cpu)

{

	if (!ipi_nmi_desc)

		return;



	disable_percpu_nmi(ipi_nmi_id);

	teardown_percpu_nmi(ipi_nmi_id);

}



void __init set_smp_dynamic_ipi(int ipi)

{

	if (!request_percpu_nmi(ipi, ipi_nmi_handler, "IPI", &cpu_number)) {

		ipi_nmi_desc = irq_to_desc(ipi);

		ipi_nmi_id = ipi;

	}

}