arch/powerpc/kernel/crash.c - linux - Git at Google

 /*
  * Architecture specific (PPC64) functions for kexec based crash dumps.
  *
  * Copyright (C) 2005, IBM Corp.
  *
  * Created by: Haren Myneni
  *
  * This source code is licensed under the GNU General Public License,
  * Version 2.  See the file COPYING for more details.
  *
  */

 #undef DEBUG

 #include <linux/kernel.h>
 #include <linux/smp.h>
 #include <linux/reboot.h>
 #include <linux/kexec.h>
 #include <linux/bootmem.h>
 #include <linux/export.h>
 #include <linux/crash_dump.h>
 #include <linux/delay.h>
 #include <linux/elf.h>
 #include <linux/elfcore.h>
 #include <linux/init.h>
 #include <linux/irq.h>
 #include <linux/types.h>
 #include <linux/memblock.h>

 #include <asm/processor.h>
 #include <asm/machdep.h>
 #include <asm/kexec.h>
 #include <asm/kdump.h>
 #include <asm/prom.h>
 #include <asm/firmware.h>
 #include <asm/smp.h>
 #include <asm/system.h>
 #include <asm/setjmp.h>

 #ifdef DEBUG
 #include <asm/udbg.h>
 #define DBG(fmt...) udbg_printf(fmt)
 #else
 #define DBG(fmt...)
 #endif

 /* This keeps a track of which one is crashing cpu. */
 int crashing_cpu = -1;
 static cpumask_t cpus_in_crash = CPU_MASK_NONE;
 cpumask_t cpus_in_sr = CPU_MASK_NONE;

 #define CRASH_HANDLER_MAX 3
 /* NULL terminated list of shutdown handles */
 static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
 static DEFINE_SPINLOCK(crash_handlers_lock);

 #ifdef CONFIG_SMP
 static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);

 void crash_ipi_callback(struct pt_regs *regs)
 {
 	int cpu = smp_processor_id();

 	if (!cpu_online(cpu))
 		return;

 	hard_irq_disable();
 	if (!cpumask_test_cpu(cpu, &cpus_in_crash))
 		crash_save_cpu(regs, cpu);
 	cpumask_set_cpu(cpu, &cpus_in_crash);

 	/*
 	 * Entered via soft-reset - could be the kdump
 	 * process is invoked using soft-reset or user activated
 	 * it if some CPU did not respond to an IPI.
 	 * For soft-reset, the secondary CPU can enter this func
 	 * twice. 1 - using IPI, and 2. soft-reset.
 	 * Tell the kexec CPU that entered via soft-reset and ready
 	 * to go down.
 	 */
 	if (cpumask_test_cpu(cpu, &cpus_in_sr)) {
 		cpumask_clear_cpu(cpu, &cpus_in_sr);
 		atomic_inc(&enter_on_soft_reset);
 	}

 	/*
 	 * Starting the kdump boot.
 	 * This barrier is needed to make sure that all CPUs are stopped.
 	 * If not, soft-reset will be invoked to bring other CPUs.
 	 */
 	while (!cpumask_test_cpu(crashing_cpu, &cpus_in_crash))
 		cpu_relax();

 	if (ppc_md.kexec_cpu_down)
 		ppc_md.kexec_cpu_down(1, 1);

 #ifdef CONFIG_PPC64
 	kexec_smp_wait();
 #else
 	for (;;);	/* FIXME */
 #endif

 	/* NOTREACHED */
 }

 /*
  * Wait until all CPUs are entered via soft-reset.
  */
 static void crash_soft_reset_check(int cpu)
 {
 	unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */

 	cpumask_clear_cpu(cpu, &cpus_in_sr);
 	while (atomic_read(&enter_on_soft_reset) != ncpus)
 		cpu_relax();
 }


 static void crash_kexec_prepare_cpus(int cpu)
 {
 	unsigned int msecs;

 	unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */

 	crash_send_ipi(crash_ipi_callback);
 	smp_wmb();

 	/*
 	 * FIXME: Until we will have the way to stop other CPUs reliably,
 	 * the crash CPU will send an IPI and wait for other CPUs to
 	 * respond.
 	 * Delay of at least 10 seconds.
 	 */
 	printk(KERN_EMERG "Sending IPI to other cpus...\n");
 	msecs = 10000;
 	while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {
 		cpu_relax();
 		mdelay(1);
 	}

 	/* Would it be better to replace the trap vector here? */

 	/*
 	 * FIXME: In case if we do not get all CPUs, one possibility: ask the
 	 * user to do soft reset such that we get all.
 	 * Soft-reset will be used until better mechanism is implemented.
 	 */
 	if (cpumask_weight(&cpus_in_crash) < ncpus) {
 		printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
 			ncpus - cpumask_weight(&cpus_in_crash));
 		printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
 		cpumask_clear(&cpus_in_sr);
 		atomic_set(&enter_on_soft_reset, 0);
 		while (cpumask_weight(&cpus_in_crash) < ncpus)
 			cpu_relax();
 	}
 	/*
 	 * Make sure all CPUs are entered via soft-reset if the kdump is
 	 * invoked using soft-reset.
 	 */
 	if (cpumask_test_cpu(cpu, &cpus_in_sr))
 		crash_soft_reset_check(cpu);
 	/* Leave the IPI callback set */
 }

 /*
  * This function will be called by secondary cpus or by kexec cpu
  * if soft-reset is activated to stop some CPUs.
  */
 void crash_kexec_secondary(struct pt_regs *regs)
 {
 	int cpu = smp_processor_id();
 	unsigned long flags;
 	int msecs = 5;

 	local_irq_save(flags);
 	/* Wait 5ms if the kexec CPU is not entered yet. */
 	while (crashing_cpu < 0) {
 		if (--msecs < 0) {
 			/*
 			 * Either kdump image is not loaded or
 			 * kdump process is not started - Probably xmon
 			 * exited using 'x'(exit and recover) or
 			 * kexec_should_crash() failed for all running tasks.
 			 */
 			cpumask_clear_cpu(cpu, &cpus_in_sr);
 			local_irq_restore(flags);
 			return;
 		}
 		mdelay(1);
 		cpu_relax();
 	}
 	if (cpu == crashing_cpu) {
 		/*
 		 * Panic CPU will enter this func only via soft-reset.
 		 * Wait until all secondary CPUs entered and
 		 * then start kexec boot.
 		 */
 		crash_soft_reset_check(cpu);
 		cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
 		if (ppc_md.kexec_cpu_down)
 			ppc_md.kexec_cpu_down(1, 0);
 		machine_kexec(kexec_crash_image);
 		/* NOTREACHED */
 	}
 	crash_ipi_callback(regs);
 }

 #else	/* ! CONFIG_SMP */

 static void crash_kexec_prepare_cpus(int cpu)
 {
 	/*
 	 * move the secondarys to us so that we can copy
 	 * the new kernel 0-0x100 safely
 	 *
 	 * do this if kexec in setup.c ?
 	 */
 #ifdef CONFIG_PPC64
 	smp_release_cpus();
 #else
 	/* FIXME */
 #endif
 }

 void crash_kexec_secondary(struct pt_regs *regs)
 {
 	cpumask_clear(&cpus_in_sr);
 }
 #endif	/* CONFIG_SMP */

 /* wait for all the CPUs to hit real mode but timeout if they don't come in */
 #if defined(CONFIG_SMP) && defined(CONFIG_PPC_STD_MMU_64)
 static void crash_kexec_wait_realmode(int cpu)
 {
 	unsigned int msecs;
 	int i;

 	msecs = 10000;
 	for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
 		if (i == cpu)
 			continue;

 		while (paca[i].kexec_state < KEXEC_STATE_REAL_MODE) {
 			barrier();
 			if (!cpu_possible(i) || !cpu_online(i) || (msecs <= 0))
 				break;
 			msecs--;
 			mdelay(1);
 		}
 	}
 	mb();
 }
 #else
 static inline void crash_kexec_wait_realmode(int cpu) {}
 #endif	/* CONFIG_SMP && CONFIG_PPC_STD_MMU_64 */

 /*
  * Register a function to be called on shutdown.  Only use this if you
  * can't reset your device in the second kernel.
  */
 int crash_shutdown_register(crash_shutdown_t handler)
 {
 	unsigned int i, rc;

 	spin_lock(&crash_handlers_lock);
 	for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
 		if (!crash_shutdown_handles[i]) {
 			/* Insert handle at first empty entry */
 			crash_shutdown_handles[i] = handler;
 			rc = 0;
 			break;
 		}

 	if (i == CRASH_HANDLER_MAX) {
 		printk(KERN_ERR "Crash shutdown handles full, "
 		       "not registered.\n");
 		rc = 1;
 	}

 	spin_unlock(&crash_handlers_lock);
 	return rc;
 }
 EXPORT_SYMBOL(crash_shutdown_register);

 int crash_shutdown_unregister(crash_shutdown_t handler)
 {
 	unsigned int i, rc;

 	spin_lock(&crash_handlers_lock);
 	for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
 		if (crash_shutdown_handles[i] == handler)
 			break;

 	if (i == CRASH_HANDLER_MAX) {
 		printk(KERN_ERR "Crash shutdown handle not found\n");
 		rc = 1;
 	} else {
 		/* Shift handles down */
 		for (; crash_shutdown_handles[i]; i++)
 			crash_shutdown_handles[i] =
 				crash_shutdown_handles[i+1];
 		rc = 0;
 	}

 	spin_unlock(&crash_handlers_lock);
 	return rc;
 }
 EXPORT_SYMBOL(crash_shutdown_unregister);

 static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
 static int crash_shutdown_cpu = -1;

 static int handle_fault(struct pt_regs *regs)
 {
 	if (crash_shutdown_cpu == smp_processor_id())
 		longjmp(crash_shutdown_buf, 1);
 	return 0;
 }

 void default_machine_crash_shutdown(struct pt_regs *regs)
 {
 	unsigned int i;
 	int (*old_handler)(struct pt_regs *regs);


 	/*
 	 * This function is only called after the system
 	 * has panicked or is otherwise in a critical state.
 	 * The minimum amount of code to allow a kexec'd kernel
 	 * to run successfully needs to happen here.
 	 *
 	 * In practice this means stopping other cpus in
 	 * an SMP system.
 	 * The kernel is broken so disable interrupts.
 	 */
 	hard_irq_disable();

 	/*
 	 * Make a note of crashing cpu. Will be used in machine_kexec
 	 * such that another IPI will not be sent.
 	 */
 	crashing_cpu = smp_processor_id();
 	crash_save_cpu(regs, crashing_cpu);
 	crash_kexec_prepare_cpus(crashing_cpu);
 	cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
 	crash_kexec_wait_realmode(crashing_cpu);

 	machine_kexec_mask_interrupts();

 	/*
 	 * Call registered shutdown routines savely.  Swap out
 	 * __debugger_fault_handler, and replace on exit.
 	 */
 	old_handler = __debugger_fault_handler;
 	__debugger_fault_handler = handle_fault;
 	crash_shutdown_cpu = smp_processor_id();
 	for (i = 0; crash_shutdown_handles[i]; i++) {
 		if (setjmp(crash_shutdown_buf) == 0) {
 			/*
 			 * Insert syncs and delay to ensure
 			 * instructions in the dangerous region don't
 			 * leak away from this protected region.
 			 */
 			asm volatile("sync; isync");
 			/* dangerous region */
 			crash_shutdown_handles[i]();
 			asm volatile("sync; isync");
 		}
 	}
 	crash_shutdown_cpu = -1;
 	__debugger_fault_handler = old_handler;

 	if (ppc_md.kexec_cpu_down)
 		ppc_md.kexec_cpu_down(1, 0);
 }
	/*
	* Architecture specific (PPC64) functions for kexec based crash dumps.
	*
	* Copyright (C) 2005, IBM Corp.
	*
	* Created by: Haren Myneni
	*
	* This source code is licensed under the GNU General Public License,
	* Version 2. See the file COPYING for more details.
	*
	*/

	#undef DEBUG

	#include <linux/kernel.h>
	#include <linux/smp.h>
	#include <linux/reboot.h>
	#include <linux/kexec.h>
	#include <linux/bootmem.h>
	#include <linux/export.h>
	#include <linux/crash_dump.h>
	#include <linux/delay.h>
	#include <linux/elf.h>
	#include <linux/elfcore.h>
	#include <linux/init.h>
	#include <linux/irq.h>
	#include <linux/types.h>
	#include <linux/memblock.h>

	#include <asm/processor.h>
	#include <asm/machdep.h>
	#include <asm/kexec.h>
	#include <asm/kdump.h>
	#include <asm/prom.h>
	#include <asm/firmware.h>
	#include <asm/smp.h>
	#include <asm/system.h>
	#include <asm/setjmp.h>

	#ifdef DEBUG
	#include <asm/udbg.h>
	#define DBG(fmt...) udbg_printf(fmt)
	#else
	#define DBG(fmt...)
	#endif

	/* This keeps a track of which one is crashing cpu. */
	int crashing_cpu = -1;
	static cpumask_t cpus_in_crash = CPU_MASK_NONE;
	cpumask_t cpus_in_sr = CPU_MASK_NONE;

	#define CRASH_HANDLER_MAX 3
	/* NULL terminated list of shutdown handles */
	static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
	static DEFINE_SPINLOCK(crash_handlers_lock);

	#ifdef CONFIG_SMP
	static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);

	void crash_ipi_callback(struct pt_regs *regs)
	{
	int cpu = smp_processor_id();

	if (!cpu_online(cpu))
	return;

	hard_irq_disable();
	if (!cpumask_test_cpu(cpu, &cpus_in_crash))
	crash_save_cpu(regs, cpu);
	cpumask_set_cpu(cpu, &cpus_in_crash);

	/*
	* Entered via soft-reset - could be the kdump
	* process is invoked using soft-reset or user activated
	* it if some CPU did not respond to an IPI.
	* For soft-reset, the secondary CPU can enter this func
	* twice. 1 - using IPI, and 2. soft-reset.
	* Tell the kexec CPU that entered via soft-reset and ready
	* to go down.
	*/
	if (cpumask_test_cpu(cpu, &cpus_in_sr)) {
	cpumask_clear_cpu(cpu, &cpus_in_sr);
	atomic_inc(&enter_on_soft_reset);
	}

	/*
	* Starting the kdump boot.
	* This barrier is needed to make sure that all CPUs are stopped.
	* If not, soft-reset will be invoked to bring other CPUs.
	*/
	while (!cpumask_test_cpu(crashing_cpu, &cpus_in_crash))
	cpu_relax();

	if (ppc_md.kexec_cpu_down)
	ppc_md.kexec_cpu_down(1, 1);

	#ifdef CONFIG_PPC64
	kexec_smp_wait();
	#else
	for (;;); /* FIXME */
	#endif

	/* NOTREACHED */
	}

	/*
	* Wait until all CPUs are entered via soft-reset.
	*/
	static void crash_soft_reset_check(int cpu)
	{
	unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */

	cpumask_clear_cpu(cpu, &cpus_in_sr);
	while (atomic_read(&enter_on_soft_reset) != ncpus)
	cpu_relax();
	}


	static void crash_kexec_prepare_cpus(int cpu)
	{
	unsigned int msecs;

	unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */

	crash_send_ipi(crash_ipi_callback);
	smp_wmb();

	/*
	* FIXME: Until we will have the way to stop other CPUs reliably,
	* the crash CPU will send an IPI and wait for other CPUs to
	* respond.
	* Delay of at least 10 seconds.
	*/
	printk(KERN_EMERG "Sending IPI to other cpus...\n");
	msecs = 10000;
	while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {
	cpu_relax();
	mdelay(1);
	}

	/* Would it be better to replace the trap vector here? */

	/*
	* FIXME: In case if we do not get all CPUs, one possibility: ask the
	* user to do soft reset such that we get all.
	* Soft-reset will be used until better mechanism is implemented.
	*/
	if (cpumask_weight(&cpus_in_crash) < ncpus) {
	printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
	ncpus - cpumask_weight(&cpus_in_crash));
	printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
	cpumask_clear(&cpus_in_sr);
	atomic_set(&enter_on_soft_reset, 0);
	while (cpumask_weight(&cpus_in_crash) < ncpus)
	cpu_relax();
	}
	/*
	* Make sure all CPUs are entered via soft-reset if the kdump is
	* invoked using soft-reset.
	*/
	if (cpumask_test_cpu(cpu, &cpus_in_sr))
	crash_soft_reset_check(cpu);
	/* Leave the IPI callback set */
	}

	/*
	* This function will be called by secondary cpus or by kexec cpu
	* if soft-reset is activated to stop some CPUs.
	*/
	void crash_kexec_secondary(struct pt_regs *regs)
	{
	int cpu = smp_processor_id();
	unsigned long flags;
	int msecs = 5;

	local_irq_save(flags);
	/* Wait 5ms if the kexec CPU is not entered yet. */
	while (crashing_cpu < 0) {
	if (--msecs < 0) {
	/*
	* Either kdump image is not loaded or
	* kdump process is not started - Probably xmon
	* exited using 'x'(exit and recover) or
	* kexec_should_crash() failed for all running tasks.
	*/
	cpumask_clear_cpu(cpu, &cpus_in_sr);
	local_irq_restore(flags);
	return;
	}
	mdelay(1);
	cpu_relax();
	}
	if (cpu == crashing_cpu) {
	/*
	* Panic CPU will enter this func only via soft-reset.
	* Wait until all secondary CPUs entered and
	* then start kexec boot.
	*/
	crash_soft_reset_check(cpu);
	cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
	if (ppc_md.kexec_cpu_down)
	ppc_md.kexec_cpu_down(1, 0);
	machine_kexec(kexec_crash_image);
	/* NOTREACHED */
	}
	crash_ipi_callback(regs);
	}

	#else /* ! CONFIG_SMP */

	static void crash_kexec_prepare_cpus(int cpu)
	{
	/*
	* move the secondarys to us so that we can copy
	* the new kernel 0-0x100 safely
	*
	* do this if kexec in setup.c ?
	*/
	#ifdef CONFIG_PPC64
	smp_release_cpus();
	#else
	/* FIXME */
	#endif
	}

	void crash_kexec_secondary(struct pt_regs *regs)
	{
	cpumask_clear(&cpus_in_sr);
	}
	#endif /* CONFIG_SMP */

	/* wait for all the CPUs to hit real mode but timeout if they don't come in */
	#if defined(CONFIG_SMP) && defined(CONFIG_PPC_STD_MMU_64)
	static void crash_kexec_wait_realmode(int cpu)
	{
	unsigned int msecs;
	int i;

	msecs = 10000;
	for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
	if (i == cpu)
	continue;

	while (paca[i].kexec_state < KEXEC_STATE_REAL_MODE) {
	barrier();
	if (!cpu_possible(i) \|\| !cpu_online(i) \|\| (msecs <= 0))
	break;
	msecs--;
	mdelay(1);
	}
	}
	mb();
	}
	#else
	static inline void crash_kexec_wait_realmode(int cpu) {}
	#endif /* CONFIG_SMP && CONFIG_PPC_STD_MMU_64 */

	/*
	* Register a function to be called on shutdown. Only use this if you
	* can't reset your device in the second kernel.
	*/
	int crash_shutdown_register(crash_shutdown_t handler)
	{
	unsigned int i, rc;

	spin_lock(&crash_handlers_lock);
	for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
	if (!crash_shutdown_handles[i]) {
	/* Insert handle at first empty entry */
	crash_shutdown_handles[i] = handler;
	rc = 0;
	break;
	}

	if (i == CRASH_HANDLER_MAX) {
	printk(KERN_ERR "Crash shutdown handles full, "
	"not registered.\n");
	rc = 1;
	}

	spin_unlock(&crash_handlers_lock);
	return rc;
	}
	EXPORT_SYMBOL(crash_shutdown_register);

	int crash_shutdown_unregister(crash_shutdown_t handler)
	{
	unsigned int i, rc;

	spin_lock(&crash_handlers_lock);
	for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
	if (crash_shutdown_handles[i] == handler)
	break;

	if (i == CRASH_HANDLER_MAX) {
	printk(KERN_ERR "Crash shutdown handle not found\n");
	rc = 1;
	} else {
	/* Shift handles down */
	for (; crash_shutdown_handles[i]; i++)
	crash_shutdown_handles[i] =
	crash_shutdown_handles[i+1];
	rc = 0;
	}

	spin_unlock(&crash_handlers_lock);
	return rc;
	}
	EXPORT_SYMBOL(crash_shutdown_unregister);

	static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
	static int crash_shutdown_cpu = -1;

	static int handle_fault(struct pt_regs *regs)
	{
	if (crash_shutdown_cpu == smp_processor_id())
	longjmp(crash_shutdown_buf, 1);
	return 0;
	}

	void default_machine_crash_shutdown(struct pt_regs *regs)
	{
	unsigned int i;
	int (old_handler)(struct pt_regs regs);


	/*
	* This function is only called after the system
	* has panicked or is otherwise in a critical state.
	* The minimum amount of code to allow a kexec'd kernel
	* to run successfully needs to happen here.
	*
	* In practice this means stopping other cpus in
	* an SMP system.
	* The kernel is broken so disable interrupts.
	*/
	hard_irq_disable();

	/*
	* Make a note of crashing cpu. Will be used in machine_kexec
	* such that another IPI will not be sent.
	*/
	crashing_cpu = smp_processor_id();
	crash_save_cpu(regs, crashing_cpu);
	crash_kexec_prepare_cpus(crashing_cpu);
	cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
	crash_kexec_wait_realmode(crashing_cpu);

	machine_kexec_mask_interrupts();

	/*
	* Call registered shutdown routines savely. Swap out
	* __debugger_fault_handler, and replace on exit.
	*/
	old_handler = __debugger_fault_handler;
	__debugger_fault_handler = handle_fault;
	crash_shutdown_cpu = smp_processor_id();
	for (i = 0; crash_shutdown_handles[i]; i++) {
	if (setjmp(crash_shutdown_buf) == 0) {
	/*
	* Insert syncs and delay to ensure
	* instructions in the dangerous region don't
	* leak away from this protected region.
	*/
	asm volatile("sync; isync");
	/* dangerous region */
	crash_shutdown_handles[i]();
	asm volatile("sync; isync");
	}
	}
	crash_shutdown_cpu = -1;
	__debugger_fault_handler = old_handler;

	if (ppc_md.kexec_cpu_down)
	ppc_md.kexec_cpu_down(1, 0);
	}