[PATCH openEuler-23.09 0/8] arm64: Add framework to turn an IPI as NMI

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Ruan Jinjie

25 Jul 2023 25 Jul '23

11:22 p.m.

arm64: Add framework to turn an IPI as NMI

Sumit Garg (7): arm64: Add framework to turn IPI as NMI irqchip/gic-v3: Enable support for SGIs to act as NMIs arm64: smp: Assign and setup an IPI as NMI nmi: backtrace: Allow runtime arch specific override arm64: ipi_nmi: Add support for NMI backtrace kgdb: Expose default CPUs roundup fallback mechanism arm64: kgdb: Roundup cpus using IPI as NMI

Xiongfeng Wang (1): arm64: ipi_nmi: fix compile error when CONFIG_KGDB is disabled

-- 2.34.1

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25 Jul 25 Jul

4:47 p.m.

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Ruan Jinjie

11:22 p.m.

New subject: [PATCH openEuler-23.09 1/8] arm64: Add framework to turn IPI as NMI

From: Sumit Garg sumit.garg@linaro.org

maillist inclusion category: feature bugzilla: 49593 CVE: NA Reference: https://www.spinics.net/lists/arm-kernel/msg851005.html

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

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.

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; + } +}

-- 2.34.1

Ruan Jinjie

11:22 p.m.

New subject: [PATCH openEuler-23.09 2/8] irqchip/gic-v3: Enable support for SGIs to act as NMIs

From: Sumit Garg sumit.garg@linaro.org

maillist inclusion category: feature bugzilla: 49593 CVE: NA Reference: https://www.spinics.net/lists/arm-kernel/msg851005.html

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

Add support to handle SGIs as pseudo NMIs. As SGIs or IPIs default to a special flow handler: handle_percpu_devid_fasteoi_ipi(), so skip NMI handler update in case of SGIs.

Also, enable NMI support prior to gic_smp_init() as allocation of SGIs as IRQs/NMIs happen as part of this routine.

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c index a605aa79435a..43beff9c5a41 100644 --- a/drivers/irqchip/irq-gic-v3.c +++ b/drivers/irqchip/irq-gic-v3.c @@ -524,6 +524,7 @@ static u32 gic_get_ppi_index(struct irq_data *d) static int gic_irq_nmi_setup(struct irq_data *d) { struct irq_desc *desc = irq_to_desc(d->irq); + u32 idx;

if (!gic_supports_nmi()) return -EINVAL; @@ -541,16 +542,22 @@ static int gic_irq_nmi_setup(struct irq_data *d) return -EINVAL;

/* desc lock should already be held */ - if (gic_irq_in_rdist(d)) { - u32 idx = gic_get_ppi_index(d); + switch (get_intid_range(d)) { + case SGI_RANGE: + break; + case PPI_RANGE: + case EPPI_RANGE: + idx = gic_get_ppi_index(d);

/* Setting up PPI as NMI, only switch handler for first NMI */ if (!refcount_inc_not_zero(&ppi_nmi_refs[idx])) { refcount_set(&ppi_nmi_refs[idx], 1); desc->handle_irq = handle_percpu_devid_fasteoi_nmi; } - } else { + break; + default: desc->handle_irq = handle_fasteoi_nmi; + break; }

gic_irq_set_prio(d, GICD_INT_NMI_PRI); @@ -561,6 +568,7 @@ static int gic_irq_nmi_setup(struct irq_data *d) static void gic_irq_nmi_teardown(struct irq_data *d) { struct irq_desc *desc = irq_to_desc(d->irq); + u32 idx;

if (WARN_ON(!gic_supports_nmi())) return; @@ -578,14 +586,20 @@ static void gic_irq_nmi_teardown(struct irq_data *d) return;

/* Tearing down NMI, only switch handler for last NMI */ if (refcount_dec_and_test(&ppi_nmi_refs[idx])) desc->handle_irq = handle_percpu_devid_irq; - } else { + break; + default: desc->handle_irq = handle_fasteoi_irq; + break; }

gic_irq_set_prio(d, GICD_INT_DEF_PRI); @@ -1976,6 +1990,7 @@ static int __init gic_init_bases(phys_addr_t dist_phys_base,

gic_dist_init(); gic_cpu_init(); + gic_enable_nmi_support(); gic_smp_init(); gic_cpu_pm_init();

@@ -1988,8 +2003,6 @@ static int __init gic_init_bases(phys_addr_t dist_phys_base, gicv2m_init(handle, gic_data.domain); }

- gic_enable_nmi_support(); - return 0;

out_free:

-- 2.34.1

Ruan Jinjie

11:22 p.m.

New subject: [PATCH openEuler-23.09 3/8] arm64: smp: Assign and setup an IPI as NMI

From: Sumit Garg sumit.garg@linaro.org

maillist inclusion category: feature bugzilla: 49593 CVE: NA Reference: https://www.spinics.net/lists/arm-kernel/msg851005.html

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

Assign an unused IPI which can be turned as NMI using ipi_nmi framework. Also, invoke corresponding dynamic IPI setup/teardown APIs.

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index d00d4cbb31b1..0449a8a1627d 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -43,6 +43,7 @@ #include <asm/daifflags.h> #include <asm/kvm_mmu.h> #include <asm/mmu_context.h> +#include <asm/nmi.h> #include <asm/numa.h> #include <asm/processor.h> #include <asm/smp_plat.h> @@ -939,6 +940,8 @@ static void ipi_setup(int cpu)

for (i = 0; i < nr_ipi; i++) enable_percpu_irq(ipi_irq_base + i, 0); + + dynamic_ipi_setup(cpu); }

#ifdef CONFIG_HOTPLUG_CPU @@ -951,6 +954,8 @@ static void ipi_teardown(int cpu)

for (i = 0; i < nr_ipi; i++) disable_percpu_irq(ipi_irq_base + i); + + dynamic_ipi_teardown(cpu); } #endif

@@ -972,6 +977,9 @@ void __init set_smp_ipi_range(int ipi_base, int n) irq_set_status_flags(ipi_base + i, IRQ_HIDDEN); }

+ if (n > nr_ipi) + set_smp_dynamic_ipi(ipi_base + nr_ipi); + ipi_irq_base = ipi_base;

/* Setup the boot CPU immediately */

-- 2.34.1

Ruan Jinjie

11:22 p.m.

New subject: [PATCH openEuler-23.09 4/8] nmi: backtrace: Allow runtime arch specific override

From: Sumit Garg sumit.garg@linaro.org

maillist inclusion category: feature bugzilla: 49593 CVE: NA Reference: https://www.spinics.net/lists/arm-kernel/msg851005.html

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

Add a boolean return to arch_trigger_cpumask_backtrace() to support a use-case where a particular architecture detects at runtime if it supports NMI backtrace or it would like to fallback to default implementation using SMP cross-calls.

Currently such an architecture example is arm64 supporting pseudo NMIs feature which is only available on platforms which have support for GICv3 or later version.

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 --- arch/arm/include/asm/irq.h | 2 +- arch/arm/kernel/smp.c | 3 ++- arch/arm64/kernel/Makefile | 2 +- arch/mips/include/asm/irq.h | 2 +- arch/mips/kernel/process.c | 3 ++- arch/powerpc/include/asm/nmi.h | 2 +- arch/powerpc/kernel/stacktrace.c | 3 ++- arch/sparc/include/asm/irq_64.h | 2 +- arch/sparc/kernel/process_64.c | 4 +++- arch/x86/include/asm/irq.h | 2 +- arch/x86/kernel/apic/hw_nmi.c | 3 ++- include/linux/nmi.h | 12 ++++-------- 12 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h index a7c2337b0c7d..e6b62c7d6f0e 100644 --- a/arch/arm/include/asm/irq.h +++ b/arch/arm/include/asm/irq.h @@ -32,7 +32,7 @@ void init_IRQ(void); #ifdef CONFIG_SMP #include <linux/cpumask.h>

-extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask, +extern bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self); #define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace #endif diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 87f8d0e5e314..fd9f9f419a6a 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -850,7 +850,8 @@ static void raise_nmi(cpumask_t *mask) __ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask); }

-void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) +bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) { nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi); + return true; } diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 7c2bb4e72476..3dd4f65d93ca 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -34,7 +34,7 @@ obj-y := debug-monitors.o entry.o irq.o fpsimd.o \ cpufeature.o alternative.o cacheinfo.o \ smp.o smp_spin_table.o topology.o smccc-call.o \ syscall.o proton-pack.o idreg-override.o idle.o \ - patching.o + patching.o ipi_nmi.o

obj-$(CONFIG_COMPAT) += sys32.o signal32.o \ sys_compat.o diff --git a/arch/mips/include/asm/irq.h b/arch/mips/include/asm/irq.h index 44f9824c1d8c..daf16173486a 100644 --- a/arch/mips/include/asm/irq.h +++ b/arch/mips/include/asm/irq.h @@ -77,7 +77,7 @@ extern int cp0_fdc_irq;

extern int get_c0_fdc_int(void);

-void arch_trigger_cpumask_backtrace(const struct cpumask *mask, +bool arch_trigger_cpumask_backtrace(const struct cpumask *mask, bool exclude_self); #define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index a3225912c862..197a0e2ae12f 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -750,9 +750,10 @@ static void raise_backtrace(cpumask_t *mask) } }

int mips_get_process_fp_mode(struct task_struct *task) diff --git a/arch/powerpc/include/asm/nmi.h b/arch/powerpc/include/asm/nmi.h index c3c7adef74de..135f65adcf63 100644 --- a/arch/powerpc/include/asm/nmi.h +++ b/arch/powerpc/include/asm/nmi.h @@ -12,7 +12,7 @@ static inline void watchdog_nmi_set_timeout_pct(u64 pct) {} #endif

#ifdef CONFIG_NMI_IPI -extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask, +extern bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self); #define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace #endif diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c index 5de8597eaab8..0fee4bded7ba 100644 --- a/arch/powerpc/kernel/stacktrace.c +++ b/arch/powerpc/kernel/stacktrace.c @@ -221,8 +221,9 @@ static void raise_backtrace_ipi(cpumask_t *mask) } }

-void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) +bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) { nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace_ipi); + return true; } #endif /* defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI) */ diff --git a/arch/sparc/include/asm/irq_64.h b/arch/sparc/include/asm/irq_64.h index 154df2cf19f4..00a0051a9da0 100644 --- a/arch/sparc/include/asm/irq_64.h +++ b/arch/sparc/include/asm/irq_64.h @@ -87,7 +87,7 @@ static inline unsigned long get_softint(void) return retval; }

diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c index b51d8fb0ecdc..93972780d6e7 100644 --- a/arch/sparc/kernel/process_64.c +++ b/arch/sparc/kernel/process_64.c @@ -236,7 +236,7 @@ static void __global_reg_poll(struct global_reg_snapshot *gp) } }

-void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) +bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) { struct thread_info *tp = current_thread_info(); struct pt_regs *regs = get_irq_regs(); @@ -291,6 +291,8 @@ void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));

spin_unlock_irqrestore(&global_cpu_snapshot_lock, flags); + + return true; }

#ifdef CONFIG_MAGIC_SYSRQ diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h index 768aa234cbb4..f731638cc38e 100644 --- a/arch/x86/include/asm/irq.h +++ b/arch/x86/include/asm/irq.h @@ -43,7 +43,7 @@ extern void init_ISA_irqs(void); extern void __init init_IRQ(void);

#ifdef CONFIG_X86_LOCAL_APIC -void arch_trigger_cpumask_backtrace(const struct cpumask *mask, +bool arch_trigger_cpumask_backtrace(const struct cpumask *mask, bool exclude_self);

#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c index 34a992e275ef..e7dcd28bc824 100644 --- a/arch/x86/kernel/apic/hw_nmi.c +++ b/arch/x86/kernel/apic/hw_nmi.c @@ -34,10 +34,11 @@ static void nmi_raise_cpu_backtrace(cpumask_t *mask) apic->send_IPI_mask(mask, NMI_VECTOR); }

static int nmi_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs) diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 048c0b9aa623..7d8a77cd1e03 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -145,26 +145,22 @@ static inline void touch_nmi_watchdog(void) #ifdef arch_trigger_cpumask_backtrace static inline bool trigger_all_cpu_backtrace(void) { - arch_trigger_cpumask_backtrace(cpu_online_mask, false); - return true; + return arch_trigger_cpumask_backtrace(cpu_online_mask, false); }

static inline bool trigger_allbutself_cpu_backtrace(void) { - arch_trigger_cpumask_backtrace(cpu_online_mask, true); - return true; + return arch_trigger_cpumask_backtrace(cpu_online_mask, true); }

static inline bool trigger_cpumask_backtrace(struct cpumask *mask) { - arch_trigger_cpumask_backtrace(mask, false); - return true; + return arch_trigger_cpumask_backtrace(mask, false); }

static inline bool trigger_single_cpu_backtrace(int cpu) { - arch_trigger_cpumask_backtrace(cpumask_of(cpu), false); - return true; + return arch_trigger_cpumask_backtrace(cpumask_of(cpu), false); }

/* generic implementation */

-- 2.34.1

Ruan Jinjie

11:23 p.m.

New subject: [PATCH openEuler-23.09 5/8] arm64: ipi_nmi: Add support for NMI backtrace

From: Sumit Garg sumit.garg@linaro.org

maillist inclusion category: feature bugzilla: 49593 CVE: NA Reference: https://www.spinics.net/lists/arm-kernel/msg851005.html

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

Enable NMI backtrace support on arm64 using IPI turned as an NMI leveraging pseudo NMIs support. It is now possible for users to get a backtrace of a CPU stuck in hard-lockup using magic SYSRQ.

diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h index fac08e18bcd5..9e926b4f7d47 100644 --- a/arch/arm64/include/asm/irq.h +++ b/arch/arm64/include/asm/irq.h @@ -6,6 +6,12 @@

#include <asm-generic/irq.h>

+#ifdef CONFIG_SMP +extern bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, + bool exclude_self); +#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace +#endif + struct pt_regs;

int set_handle_irq(void (*handle_irq)(struct pt_regs *)); diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c index a945dcf8015f..597dcf7fb59c 100644 --- a/arch/arm64/kernel/ipi_nmi.c +++ b/arch/arm64/kernel/ipi_nmi.c @@ -8,6 +8,7 @@

#include <linux/interrupt.h> #include <linux/irq.h> +#include <linux/nmi.h> #include <linux/smp.h>

#include <asm/nmi.h> @@ -31,11 +32,24 @@ void arm64_send_nmi(cpumask_t *mask) __ipi_send_mask(ipi_nmi_desc, mask); }

+bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) +{ + if (!ipi_nmi_desc) + return false; + + nmi_trigger_cpumask_backtrace(mask, exclude_self, arm64_send_nmi); + + return true; +} + static irqreturn_t ipi_nmi_handler(int irq, void *data) { - /* nop, NMI handlers for special features can be added here. */ + irqreturn_t ret = IRQ_NONE; + + if (nmi_cpu_backtrace(get_irq_regs())) + ret = IRQ_HANDLED;

- return IRQ_NONE; + return ret; }

void dynamic_ipi_setup(int cpu)

-- 2.34.1

Ruan Jinjie

11:23 p.m.

New subject: [PATCH openEuler-23.09 6/8] kgdb: Expose default CPUs roundup fallback mechanism

From: Sumit Garg sumit.garg@linaro.org

maillist inclusion category: feature bugzilla: 49593 CVE: NA Reference: https://www.spinics.net/lists/arm-kernel/msg851005.html

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

Add a new API kgdb_smp_call_nmi_hook() to expose default CPUs roundup mechanism to a particular archichecture as a runtime fallback if it detects to not support NMI roundup.

Currently such an architecture example is arm64 supporting pseudo NMIs feature which is only available on platforms which have support for GICv3 or later version.

diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index 258cdde8d356..87713bd390f3 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -199,6 +199,18 @@ kgdb_arch_handle_qxfer_pkt(char *remcom_in_buffer,

extern void kgdb_call_nmi_hook(void *ignored);

+/** + * kgdb_smp_call_nmi_hook - Provide default fallback mechanism to + * round-up CPUs + * + * If you're using the default implementation of kgdb_roundup_cpus() + * this function will be called. And if an arch detects at runtime to + * not support NMI based roundup then it can fallback to default + * mechanism using this API. + */ + +extern void kgdb_smp_call_nmi_hook(void); + /** * kgdb_roundup_cpus - Get other CPUs into a holding pattern * diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index d5e9ccde3ab8..14d40a7d6a4b 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -238,7 +238,7 @@ NOKPROBE_SYMBOL(kgdb_call_nmi_hook); static DEFINE_PER_CPU(call_single_data_t, kgdb_roundup_csd) = CSD_INIT(kgdb_call_nmi_hook, NULL);

-void __weak kgdb_roundup_cpus(void) +void kgdb_smp_call_nmi_hook(void) { call_single_data_t *csd; int this_cpu = raw_smp_processor_id(); @@ -269,6 +269,12 @@ void __weak kgdb_roundup_cpus(void) kgdb_info[cpu].rounding_up = false; } } +NOKPROBE_SYMBOL(kgdb_smp_call_nmi_hook); + +void __weak kgdb_roundup_cpus(void) +{ + kgdb_smp_call_nmi_hook(); +} NOKPROBE_SYMBOL(kgdb_roundup_cpus);

#endif

-- 2.34.1

Ruan Jinjie

11:23 p.m.

New subject: [PATCH openEuler-23.09 7/8] arm64: kgdb: Roundup cpus using IPI as NMI

From: Sumit Garg sumit.garg@linaro.org

maillist inclusion category: feature bugzilla: 49593 CVE: NA Reference: https://www.spinics.net/lists/arm-kernel/msg851005.html

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

arm64 platforms with GICv3 or later supports pseudo NMIs which can be leveraged to roundup CPUs which are stuck in hard lockup state with interrupts disabled that wouldn't be possible with a normal IPI.

So instead switch to roundup CPUs using IPI turned as NMI. And in case a particular arm64 platform doesn't supports pseudo NMIs, it will switch back to default kgdb CPUs roundup mechanism.

diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c index 597dcf7fb59c..898d69c37429 100644 --- a/arch/arm64/kernel/ipi_nmi.c +++ b/arch/arm64/kernel/ipi_nmi.c @@ -8,6 +8,7 @@

#include <linux/interrupt.h> #include <linux/irq.h> +#include <linux/kgdb.h> #include <linux/nmi.h> #include <linux/smp.h>

@@ -45,10 +46,14 @@ bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) static irqreturn_t ipi_nmi_handler(int irq, void *data) { irqreturn_t ret = IRQ_NONE; + unsigned int cpu = smp_processor_id();

if (nmi_cpu_backtrace(get_irq_regs())) ret = IRQ_HANDLED;

+ if (!kgdb_nmicallback(cpu, get_irq_regs())) + ret = IRQ_HANDLED; + return ret; }

diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index 4e1f983df3d1..98d8c1027f06 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -17,6 +17,7 @@

#include <asm/debug-monitors.h> #include <asm/insn.h> +#include <asm/nmi.h> #include <asm/patching.h> #include <asm/traps.h>

@@ -356,3 +357,20 @@ int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) return aarch64_insn_write((void *)bpt->bpt_addr, *(u32 *)bpt->saved_instr); } + +void kgdb_roundup_cpus(void) +{ + struct cpumask mask; + + if (!arm64_supports_nmi()) { + kgdb_smp_call_nmi_hook(); + return; + } + + cpumask_copy(&mask, cpu_online_mask); + cpumask_clear_cpu(raw_smp_processor_id(), &mask); + if (cpumask_empty(&mask)) + return; + + arm64_send_nmi(&mask); +}

-- 2.34.1

Ruan Jinjie

11:23 p.m.

New subject: [PATCH openEuler-23.09 8/8] arm64: ipi_nmi: fix compile error when CONFIG_KGDB is disabled

From: Xiongfeng Wang wangxiongfeng2@huawei.com

hulk inclusion category: bugfix bugzilla: 50485 CVE: NA

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

Fix the following compile error.

arch/arm64/kernel/ipi_nmi.c: In function ‘ipi_nmi_handler’: arch/arm64/kernel/ipi_nmi.c:54:7: error: implicit declaration of function ‘kgdb_nmicallback’ [-Werror=implicit-function-declaration] if (!kgdb_nmicallback(cpu, get_irq_regs())) ^~~~~~~~~~~~~~~~

Signed-off-by: Xiongfeng Wang wangxiongfeng2@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 --- arch/arm64/kernel/ipi_nmi.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c index 898d69c37429..3b105852fc17 100644 --- a/arch/arm64/kernel/ipi_nmi.c +++ b/arch/arm64/kernel/ipi_nmi.c @@ -46,13 +46,14 @@ bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) static irqreturn_t ipi_nmi_handler(int irq, void *data) { irqreturn_t ret = IRQ_NONE; - unsigned int cpu = smp_processor_id();

if (nmi_cpu_backtrace(get_irq_regs())) ret = IRQ_HANDLED;

- if (!kgdb_nmicallback(cpu, get_irq_regs())) +#ifdef CONFIG_KGDB + if (!kgdb_nmicallback(smp_processor_id(), get_irq_regs())) ret = IRQ_HANDLED; +#endif

return ret; }

-- 2.34.1

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