[PATCH OLK-6.6 v4 0/7] arm64: Add support to turn an IPI as NMI
With pseudo NMIs support available its possible to configure SGIs to be triggered as pseudo NMIs running in NMI context. And kernel features such as: - NMI backtrace can leverage IPI turned as NMI to get a backtrace of CPU stuck in hard lockup using magic SYSRQ. - kgdb relies on NMI support to round up CPUs which are stuck in hard lockup state with interrupts disabled. This patch-set adds framework to turn an IPI as NMI which can be triggered as a pseudo NMI which in turn invokes registered NMI handlers. After this patch-set we should be able to get a backtrace for a CPU stuck in HARDLOCKUP. 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 arch/arm/include/asm/irq.h | 2 +- arch/arm/kernel/smp.c | 3 +- arch/arm64/include/asm/irq.h | 6 +++ arch/arm64/include/asm/nmi.h | 17 +++++++ arch/arm64/kernel/Makefile | 2 +- arch/arm64/kernel/ipi_nmi.c | 84 ++++++++++++++++++++++++++++++++ arch/arm64/kernel/kgdb.c | 18 +++++++ arch/arm64/kernel/smp.c | 8 +++ arch/mips/include/asm/irq.h | 2 +- arch/mips/kernel/process.c | 3 +- arch/powerpc/include/asm/irq.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 +- drivers/irqchip/irq-gic-v3.c | 29 ++++++++--- include/linux/kgdb.h | 12 +++++ include/linux/nmi.h | 12 ++--- kernel/debug/debug_core.c | 8 ++- 20 files changed, 194 insertions(+), 28 deletions(-) create mode 100644 arch/arm64/include/asm/nmi.h create mode 100644 arch/arm64/kernel/ipi_nmi.c -- 2.34.1
From: Chen Jiahao <chenjiahao16@huawei.com> hulk inclusion category: bugfix bugzilla: 187431, https://gitee.com/openeuler/kernel/issues/I5ZUTK -------------------------------- f86d165bfe5f ("arm64: Add non nmi ipi backtrace support") introduced the IPI backtrace support on arm64 with NMI unsupported. However a warning message comes when triggering the non-NMI IPI backtrace: WARNING: CPU: 6 PID: 1121 at kernel/smp.c:680 smp_call_function_many_cond+0x78/0x3dc Modules linked in: soft_lockup_test(OE) [last unloaded: soft_lockup_test] CPU: 6 PID: 1121 Comm: loop_thread Tainted: G OEL 5.10.0+ #9 Hardware name: linux,dummy-virt (DT) pstate: 40000085 (nZcv daIf -PAN -UAO -TCO BTYPE=--) pc : smp_call_function_many_cond+0x78/0x3dc lr : smp_call_function_many+0x40/0x50 sp : ffffffc010033c10 x29: ffffffc010033c10 x28: 0000000000000000 x27: ffffffd5dfe2a9a8 x26: ffffffa9bfdb4430 x25: 0000000000000000 x24: 0000000000000000 x23: ffffffd5dfe29000 x22: 0000000000000000 x21: 0000000000000006 x20: ffffffd5df216418 x19: ffffffd5dfe2a9a8 x18: 0000000000000000 x17: 0000000000000000 x16: ffffffd5df293d78 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 0025001680000006 x8 : 4e4d492066726f6d x7 : 53656e64696e6720 x6 : 0000000000000001 x5 : ffffffa9bfdb0750 x4 : 0000000000000000 x3 : 0000000000000000 x2 : ffffffd3e01ab000 x1 : ffffffd5dfc03000 x0 : 0000000000010000 Call trace: smp_call_function_many_cond+0x78/0x3dc smp_call_function_many+0x40/0x50 arm64_send_ipi+0x30/0x3c nmi_trigger_cpumask_backtrace+0xfc/0x154 arch_trigger_cpumask_backtrace+0x3c/0x58 watchdog_timer_fn+0x1d4/0x220 __hrtimer_run_queues+0x1bc/0x2c8 hrtimer_run_queues+0xe4/0x110 run_local_timers+0x24/0x50 update_process_times+0x5c/0x88 tick_periodic+0xd0/0xec tick_handle_periodic+0x38/0x8c arch_timer_handler_virt+0x38/0x50 handle_percpu_devid_irq+0xe0/0x1e0 generic_handle_irq+0x34/0x4c __handle_domain_irq+0xb0/0xb8 gic_handle_irq+0x98/0xb8 el1_irq+0xa8/0x140 loop_func+0x14/0x28 [soft_lockup_test] kthread+0x120/0x130 ret_from_fork+0x10/0x18 The cause is calling smp_call_function_many to send IPI to other CPUs in a softirq handling context, which is unsafe and may lead to deadlock. Use smp_call_function_single_async() instead to avoid the warning above. Fixes: f86d165bfe5f ("arm64: Add non nmi ipi backtrace support") Signed-off-by: Chen Jiahao <chenjiahao16@huawei.com> Reviewed-by: Zhang Jianhua <chris.zjh@huawei.com> Reviewed-by: Liao Chang <liaochang1@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- arch/arm64/kernel/ipi_nmi.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c index 2cf28e511b23..9a8f7c256117 100644 --- a/arch/arm64/kernel/ipi_nmi.c +++ b/arch/arm64/kernel/ipi_nmi.c @@ -40,9 +40,25 @@ static void ipi_cpu_backtrace(void *info) printk_safe_exit(); } +static DEFINE_PER_CPU(call_single_data_t, cpu_backtrace_csd) = + CSD_INIT(ipi_cpu_backtrace, NULL); + static void arm64_send_ipi(cpumask_t *mask) { - smp_call_function_many(mask, ipi_cpu_backtrace, NULL, false); + call_single_data_t *csd; + int this_cpu = raw_smp_processor_id(); + int cpu; + int ret; + + for_each_online_cpu(cpu) { + if (cpu == this_cpu) + continue; + + csd = &per_cpu(cpu_backtrace_csd, cpu); + ret = smp_call_function_single_async(cpu, csd); + if (ret) + pr_info("Sending IPI failed to CPU %d\n", cpu); + } } bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) -- 2.34.1
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Liao Chen