From: Sumit Garg sumit.garg@linaro.org
maillist inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7R4EN CVE: NA Reference: https://www.spinics.net/lists/arm-kernel/msg851005.html
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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: Sumit Garg sumit.garg@linaro.org Signed-off-by: Wei Li liwei391@huawei.com Reviewed-by: Xie XiuQi xiexiuqi@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Signed-off-by: Ruan Jinjie ruanjinjie@huawei.com Signed-off-by: Liao Chen liaochen4@huawei.com --- arch/arm64/include/asm/nmi.h | 17 ++++++++++ arch/arm64/kernel/ipi_nmi.c | 65 ++++++++++++++++++++++++++++++++++++ 2 files changed, 82 insertions(+) create mode 100644 arch/arm64/include/asm/nmi.h create mode 100644 arch/arm64/kernel/ipi_nmi.c
diff --git a/arch/arm64/include/asm/nmi.h b/arch/arm64/include/asm/nmi.h new file mode 100644 index 000000000000..4cd14b6af88b --- /dev/null +++ b/arch/arm64/include/asm/nmi.h @@ -0,0 +1,17 @@ +/* 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 diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c new file mode 100644 index 000000000000..a945dcf8015f --- /dev/null +++ b/arch/arm64/kernel/ipi_nmi.c @@ -0,0 +1,65 @@ +// 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; + } +}