Hi Akashi, (CC: Marc who knows how this irqchip wizardry works Cover letter: https://www.spinics.net/lists/arm-kernel/msg529520.html ) On 07/09/16 05:29, AKASHI Takahiro wrote: > Primary kernel calls machine_crash_shutdown() to shut down non-boot cpus > and save registers' status in per-cpu ELF notes before starting crash > dump kernel. See kernel_kexec(). > Even if not all secondary cpus have shut down, we do kdump anyway. > > As we don't have to make non-boot(crashed) cpus offline (to preserve > correct status of cpus at crash dump) before shutting down, this patch > also adds a variant of smp_send_stop(). > > Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org> > --- > arch/arm64/include/asm/hardirq.h | 2 +- > arch/arm64/include/asm/kexec.h | 41 ++++++++++++++++++++++++- > arch/arm64/include/asm/smp.h | 2 ++ > arch/arm64/kernel/machine_kexec.c | 56 ++++++++++++++++++++++++++++++++-- > arch/arm64/kernel/smp.c | 63 +++++++++++++++++++++++++++++++++++++++ > 5 files changed, 159 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/include/asm/hardirq.h b/arch/arm64/include/asm/hardirq.h > index 8740297..1473fc2 100644 > --- a/arch/arm64/include/asm/hardirq.h > +++ b/arch/arm64/include/asm/hardirq.h > @@ -20,7 +20,7 @@ > #include <linux/threads.h> > #include <asm/irq.h> > > -#define NR_IPI 6 > +#define NR_IPI 7 > > typedef struct { > unsigned int __softirq_pending; > diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h > index 04744dc..a908958 100644 > --- a/arch/arm64/include/asm/kexec.h > +++ b/arch/arm64/include/asm/kexec.h > @@ -40,7 +40,46 @@ > static inline void crash_setup_regs(struct pt_regs *newregs, > struct pt_regs *oldregs) > { > - /* Empty routine needed to avoid build errors. */ > + if (oldregs) { > + memcpy(newregs, oldregs, sizeof(*newregs)); > + } else { > + u64 tmp1, tmp2; > + > + __asm__ __volatile__ ( > + "stp x0, x1, [%2, #16 * 0]\n" > + "stp x2, x3, [%2, #16 * 1]\n" > + "stp x4, x5, [%2, #16 * 2]\n" > + "stp x6, x7, [%2, #16 * 3]\n" > + "stp x8, x9, [%2, #16 * 4]\n" > + "stp x10, x11, [%2, #16 * 5]\n" > + "stp x12, x13, [%2, #16 * 6]\n" > + "stp x14, x15, [%2, #16 * 7]\n" > + "stp x16, x17, [%2, #16 * 8]\n" > + "stp x18, x19, [%2, #16 * 9]\n" > + "stp x20, x21, [%2, #16 * 10]\n" > + "stp x22, x23, [%2, #16 * 11]\n" > + "stp x24, x25, [%2, #16 * 12]\n" > + "stp x26, x27, [%2, #16 * 13]\n" > + "stp x28, x29, [%2, #16 * 14]\n" > + "mov %0, sp\n" > + "stp x30, %0, [%2, #16 * 15]\n" > + > + "/* faked current PSTATE */\n" > + "mrs %0, CurrentEL\n" > + "mrs %1, DAIF\n" > + "orr %0, %0, %1\n" > + "mrs %1, NZCV\n" > + "orr %0, %0, %1\n" > + What about SPSEL? While we don't use it, it is correctly preserved for everything except a CPU that calls panic()... > + /* pc */ > + "adr %1, 1f\n" > + "1:\n" > + "stp %1, %0, [%2, #16 * 16]\n" > + : "=r" (tmp1), "=r" (tmp2), "+r" (newregs) > + : > + : "memory" > + ); > + } > } > > #endif /* __ASSEMBLY__ */ > diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h > index 0226447..6b0f2c7 100644 > --- a/arch/arm64/include/asm/smp.h > +++ b/arch/arm64/include/asm/smp.h > @@ -136,6 +136,8 @@ static inline void cpu_panic_kernel(void) > */ > bool cpus_are_stuck_in_kernel(void); > > +extern void smp_send_crash_stop(void); > + > #endif /* ifndef __ASSEMBLY__ */ > > #endif /* ifndef __ASM_SMP_H */ > diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c > index bc96c8a..8ac9dba8 100644 > --- a/arch/arm64/kernel/machine_kexec.c > +++ b/arch/arm64/kernel/machine_kexec.c > @@ -9,6 +9,9 @@ > * published by the Free Software Foundation. > */ > > +#include <linux/interrupt.h> > +#include <linux/irq.h> > +#include <linux/kernel.h> > #include <linux/kexec.h> > #include <linux/smp.h> > > @@ -22,6 +25,7 @@ > extern const unsigned char arm64_relocate_new_kernel[]; > extern const unsigned long arm64_relocate_new_kernel_size; > > +bool in_crash_kexec; static? > static unsigned long kimage_start; > > /** > @@ -148,7 +152,8 @@ void machine_kexec(struct kimage *kimage) > /* > * New cpus may have become stuck_in_kernel after we loaded the image. > */ > - BUG_ON(cpus_are_stuck_in_kernel() || (num_online_cpus() > 1)); > + BUG_ON((cpus_are_stuck_in_kernel() || (num_online_cpus() > 1)) && > + !WARN_ON(in_crash_kexec)); In the kdump case, num_online_cpus() is unchanged as ipi_cpu_crash_stop() doesn't update the online cpu masks, so this WARN_ON always fires. This is confusing as the 'failed to stop secondary CPUs' message doesn't appear, because those CPUs did stop, and waiting_for_crash_ipi has the expected value... > > reboot_code_buffer_phys = page_to_phys(kimage->control_code_page); > reboot_code_buffer = phys_to_virt(reboot_code_buffer_phys); > @@ -200,13 +205,58 @@ void machine_kexec(struct kimage *kimage) > * relocation is complete. > */ > > - cpu_soft_restart(1, reboot_code_buffer_phys, kimage->head, > + cpu_soft_restart(!in_crash_kexec, reboot_code_buffer_phys, kimage->head, > kimage_start, 0); > > BUG(); /* Should never get here. */ > } > +static void machine_kexec_mask_interrupts(void) > +{ > + unsigned int i; > + struct irq_desc *desc; > + > + for_each_irq_desc(i, desc) { > + struct irq_chip *chip; > + int ret; > + > + chip = irq_desc_get_chip(desc); > + if (!chip) > + continue; > + > + /* > + * First try to remove the active state. If this > + * fails, try to EOI the interrupt. > + */ > + ret = irq_set_irqchip_state(i, IRQCHIP_STATE_ACTIVE, false); > + > + if (ret && irqd_irq_inprogress(&desc->irq_data) && > + chip->irq_eoi) > + chip->irq_eoi(&desc->irq_data); > + > + if (chip->irq_mask) > + chip->irq_mask(&desc->irq_data); > + > + if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data)) > + chip->irq_disable(&desc->irq_data); > + } > +} This function is over my head ... I have no idea how this works, I can only comment that its different to the version under arch/arm /me adds Marc Z to CC. > +/** > + * machine_crash_shutdown - shutdown non-crashing cpus and save registers > + */ > void machine_crash_shutdown(struct pt_regs *regs) > { > - /* Empty routine needed to avoid build errors. */ > + local_irq_disable(); > + > + in_crash_kexec = true; > + > + /* shutdown non-crashing cpus */ > + smp_send_crash_stop(); > + > + /* for crashing cpu */ > + crash_save_cpu(regs, smp_processor_id()); > + machine_kexec_mask_interrupts(); > + > + pr_info("Starting crashdump kernel...\n"); > } > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index d93d433..b401b25 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -37,6 +37,7 @@ > #include <linux/completion.h> > #include <linux/of.h> > #include <linux/irq_work.h> > +#include <linux/kexec.h> > > #include <asm/alternative.h> > #include <asm/atomic.h> > @@ -71,6 +72,7 @@ enum ipi_msg_type { > IPI_RESCHEDULE, > IPI_CALL_FUNC, > IPI_CPU_STOP, > + IPI_CPU_CRASH_STOP, > IPI_TIMER, > IPI_IRQ_WORK, > IPI_WAKEUP > @@ -734,6 +736,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = { > S(IPI_RESCHEDULE, "Rescheduling interrupts"), > S(IPI_CALL_FUNC, "Function call interrupts"), > S(IPI_CPU_STOP, "CPU stop interrupts"), > + S(IPI_CPU_CRASH_STOP, "CPU stop (for crash dump) interrupts"), > S(IPI_TIMER, "Timer broadcast interrupts"), > S(IPI_IRQ_WORK, "IRQ work interrupts"), > S(IPI_WAKEUP, "CPU wake-up interrupts"), > @@ -808,6 +811,29 @@ static void ipi_cpu_stop(unsigned int cpu) > cpu_relax(); > } > > +#ifdef CONFIG_KEXEC_CORE > +static atomic_t waiting_for_crash_ipi; > +#endif > + > +static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs) > +{ > +#ifdef CONFIG_KEXEC_CORE > + crash_save_cpu(regs, cpu); > + > + atomic_dec(&waiting_for_crash_ipi); > + > + local_irq_disable(); > + > +#ifdef CONFIG_HOTPLUG_CPU > + if (cpu_ops[cpu]->cpu_die) > + cpu_ops[cpu]->cpu_die(cpu); > +#endif > + > + /* just in case */ > + cpu_park_loop(); > +#endif > +} > + > /* > * Main handler for inter-processor interrupts > */ > @@ -838,6 +864,15 @@ void handle_IPI(int ipinr, struct pt_regs *regs) > irq_exit(); > break; > > + case IPI_CPU_CRASH_STOP: > + if (IS_ENABLED(CONFIG_KEXEC_CORE)) { > + irq_enter(); > + ipi_cpu_crash_stop(cpu, regs); > + > + unreachable(); > + } > + break; > + > #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST > case IPI_TIMER: > irq_enter(); > @@ -910,6 +945,34 @@ void smp_send_stop(void) > cpumask_pr_args(cpu_online_mask)); > } > > +#ifdef CONFIG_KEXEC_CORE > +void smp_send_crash_stop(void) > +{ > + cpumask_t mask; > + unsigned long timeout; > + > + if (num_online_cpus() == 1) > + return; > + > + cpumask_copy(&mask, cpu_online_mask); > + cpumask_clear_cpu(smp_processor_id(), &mask); > + > + atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1); > + > + pr_crit("SMP: stopping secondary CPUs\n"); > + smp_cross_call(&mask, IPI_CPU_CRASH_STOP); > + > + /* Wait up to one second for other CPUs to stop */ > + timeout = USEC_PER_SEC; > + while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--) > + udelay(1); > + > + if (atomic_read(&waiting_for_crash_ipi) > 0) > + pr_warning("SMP: failed to stop secondary CPUs %*pbl\n", > + cpumask_pr_args(cpu_online_mask)); > +} > +#endif This is very similar to smp_send_stop() which also has the timeout. Is it possible to merge them? You could use in_crash_kexec to choose the IPI type. > + > /* > * not supported here > */ > Reviewed-by: James Morse <james.morse at arm.com> Thanks, James
