[PATCH v34 08/14] arm64: kdump: implement machine_crash_shutdown()
AKASHI Takahiro
takahiro.akashi at linaro.org
Mon Mar 27 23:51:26 PDT 2017
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>
Reviewed-by: James Morse <james.morse at arm.com>
Acked-by: Catalin Marinas <catalin.marinas at arm.com>
---
arch/arm64/include/asm/hardirq.h | 2 +-
arch/arm64/include/asm/kexec.h | 42 +++++++++++++++++++++++-
arch/arm64/include/asm/smp.h | 3 ++
arch/arm64/kernel/machine_kexec.c | 58 ++++++++++++++++++++++++++++++---
arch/arm64/kernel/smp.c | 68 +++++++++++++++++++++++++++++++++++++++
5 files changed, 167 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/include/asm/hardirq.h b/arch/arm64/include/asm/hardirq.h
index 8740297dac77..1473fc2f7ab7 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 90aabbe893b7..e17f0529a882 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -40,7 +40,47 @@
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, SPSEL\n"
+ "orr %0, %0, %1\n"
+ "mrs %1, DAIF\n"
+ "orr %0, %0, %1\n"
+ "mrs %1, NZCV\n"
+ "orr %0, %0, %1\n"
+ /* pc */
+ "adr %1, 1f\n"
+ "1:\n"
+ "stp %1, %0, [%2, #16 * 16]\n"
+ : "=&r" (tmp1), "=&r" (tmp2)
+ : "r" (newregs)
+ : "memory"
+ );
+ }
}
#if defined(CONFIG_KEXEC_CORE) && defined(CONFIG_HIBERNATION)
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index d050d720a1b4..55f08c5acfad 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -148,6 +148,9 @@ static inline void cpu_panic_kernel(void)
*/
bool cpus_are_stuck_in_kernel(void);
+extern void smp_send_crash_stop(void);
+extern bool smp_crash_stop_failed(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 a6d66b98d795..779a80046066 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/page-flags.h>
#include <linux/smp.h>
@@ -143,11 +146,15 @@ void machine_kexec(struct kimage *kimage)
{
phys_addr_t reboot_code_buffer_phys;
void *reboot_code_buffer;
+ bool in_kexec_crash = (kimage == kexec_crash_image);
+ bool stuck_cpus = cpus_are_stuck_in_kernel();
/*
* 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(!in_kexec_crash && (stuck_cpus || (num_online_cpus() > 1)));
+ WARN(in_kexec_crash && (stuck_cpus || smp_crash_stop_failed()),
+ "Some CPUs may be stale, kdump will be unreliable.\n");
reboot_code_buffer_phys = page_to_phys(kimage->control_code_page);
reboot_code_buffer = phys_to_virt(reboot_code_buffer_phys);
@@ -199,15 +206,58 @@ void machine_kexec(struct kimage *kimage)
* relocation is complete.
*/
- cpu_soft_restart(1, reboot_code_buffer_phys, kimage->head,
- kimage->start, 0);
+ cpu_soft_restart(kimage != kexec_crash_image,
+ 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);
+ }
+}
+
+/**
+ * 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();
+
+ /* 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");
}
void arch_kexec_protect_crashkres(void)
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index ef1caae02110..8016914591d2 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -39,6 +39,7 @@
#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>
@@ -76,6 +77,7 @@ enum ipi_msg_type {
IPI_RESCHEDULE,
IPI_CALL_FUNC,
IPI_CPU_STOP,
+ IPI_CPU_CRASH_STOP,
IPI_TIMER,
IPI_IRQ_WORK,
IPI_WAKEUP
@@ -755,6 +757,7 @@ 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"),
@@ -829,6 +832,29 @@ static void ipi_cpu_stop(unsigned int cpu)
cpu_relax();
}
+#ifdef CONFIG_KEXEC_CORE
+static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
+#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
*/
@@ -859,6 +885,15 @@ 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();
@@ -931,6 +966,39 @@ 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(&mask));
+}
+
+bool smp_crash_stop_failed(void)
+{
+ return (atomic_read(&waiting_for_crash_ipi) > 0);
+}
+#endif
+
/*
* not supported here
*/
--
2.11.1
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