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Commit 78fd584c authored by AKASHI Takahiro's avatar AKASHI Takahiro Committed by Catalin Marinas
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arm64: kdump: implement machine_crash_shutdown() 



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: default avatarAKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: default avatarJames Morse <james.morse@arm.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 254a41c0

arch/arm64/include/asm/hardirq.h

+1 −1
Original line number Diff line number Diff line
@@ -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;

arch/arm64/include/asm/kexec.h

+41 −1
Original line number Diff line number Diff line
@@ -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)

arch/arm64/include/asm/smp.h

+3 −0
Original line number Diff line number Diff line
@@ -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 */

arch/arm64/kernel/machine_kexec.c

+54 −4
Original line number Diff line number Diff line
@@ -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)

arch/arm64/kernel/smp.c

+68 −0
Original line number Diff line number Diff line
@@ -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
@@ -756,6 +758,7 @@ 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"),
@@ -830,6 +833,29 @@ 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

 */
@@ -860,6 +886,15 @@ 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();
@@ -932,6 +967,39 @@ 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

 */