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 | 4 +- 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/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 ++- 18 files changed, 192 insertions(+), 27 deletions(-) create mode 100644 arch/arm64/include/asm/nmi.h create mode 100644 arch/arm64/kernel/ipi_nmi.c