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/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/irq.h>

 #include <asm/processor.h>
 #include <asm/machdep.h>
 #include <asm/kexec.h>
 #include <asm/kdump.h>
 #include <asm/lmb.h>
 #include <asm/firmware.h>
 #include <asm/smp.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;

 static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
 							       size_t data_len)
 {
 	struct elf_note note;

 	note.n_namesz = strlen(name) + 1;
 	note.n_descsz = data_len;
 	note.n_type   = type;
 	memcpy(buf, &note, sizeof(note));
 	buf += (sizeof(note) +3)/4;
 	memcpy(buf, name, note.n_namesz);
 	buf += (note.n_namesz + 3)/4;
 	memcpy(buf, data, note.n_descsz);
 	buf += (note.n_descsz + 3)/4;

 	return buf;
 }

 static void final_note(u32 *buf)
 {
 	struct elf_note note;

 	note.n_namesz = 0;
 	note.n_descsz = 0;
 	note.n_type   = 0;
 	memcpy(buf, &note, sizeof(note));
 }

 static void crash_save_this_cpu(struct pt_regs *regs, int cpu)
 {
 	struct elf_prstatus prstatus;
 	u32 *buf;

 	if ((cpu < 0) || (cpu >= NR_CPUS))
 		return;

 	/* Using ELF notes here is opportunistic.
 	 * I need a well defined structure format
 	 * for the data I pass, and I need tags
 	 * on the data to indicate what information I have
 	 * squirrelled away.  ELF notes happen to provide
 	 * all of that that no need to invent something new.
 	 */
 	buf = (u32*)per_cpu_ptr(crash_notes, cpu);
 	if (!buf)
 		return;

 	memset(&prstatus, 0, sizeof(prstatus));
 	prstatus.pr_pid = current->pid;
 	elf_core_copy_regs(&prstatus.pr_reg, regs);
 	buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
 			sizeof(prstatus));
 	final_note(buf);
 }

 #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;

 	local_irq_disable();
 	if (!cpu_isset(cpu, cpus_in_crash))
 		crash_save_this_cpu(regs, cpu);
 	cpu_set(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 (cpu_isset(cpu, cpus_in_sr)) {
 		cpu_clear(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 (!cpu_isset(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 */

 	cpu_clear(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 CPUSs reliabally,
 	 * 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 ((cpus_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 (cpus_weight(cpus_in_crash) < ncpus) {
 		printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
 			ncpus - cpus_weight(cpus_in_crash));
 		printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
 		cpus_in_sr = CPU_MASK_NONE;
 		atomic_set(&enter_on_soft_reset, 0);
 		while (cpus_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 (cpu_isset(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.
 			 */
 			cpu_clear(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);
 		cpu_set(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
 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)
 {
 	cpus_in_sr = CPU_MASK_NONE;
 }
 #endif

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

 	/*
 	 * 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.
 	 */
 	local_irq_disable();

 	for_each_irq(irq) {
 		struct irq_desc *desc = irq_desc + irq;

 		if (desc->status & IRQ_INPROGRESS)
 			desc->chip->end(irq);

 		if (!(desc->status & IRQ_DISABLED))
 			desc->chip->disable(irq);
 	}

 	/*
 	 * 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_this_cpu(regs, crashing_cpu);
 	crash_kexec_prepare_cpus(crashing_cpu);
 	cpu_set(crashing_cpu, cpus_in_crash);
 	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/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/irq.h>

	#include <asm/processor.h>
	#include <asm/machdep.h>
	#include <asm/kexec.h>
	#include <asm/kdump.h>
	#include <asm/lmb.h>
	#include <asm/firmware.h>
	#include <asm/smp.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;

	static u32 append_elf_note(u32 buf, char name, unsigned type, void data,
	size_t data_len)
	{
	struct elf_note note;

	note.n_namesz = strlen(name) + 1;
	note.n_descsz = data_len;
	note.n_type = type;
	memcpy(buf, &note, sizeof(note));
	buf += (sizeof(note) +3)/4;
	memcpy(buf, name, note.n_namesz);
	buf += (note.n_namesz + 3)/4;
	memcpy(buf, data, note.n_descsz);
	buf += (note.n_descsz + 3)/4;

	return buf;
	}

	static void final_note(u32 *buf)
	{
	struct elf_note note;

	note.n_namesz = 0;
	note.n_descsz = 0;
	note.n_type = 0;
	memcpy(buf, &note, sizeof(note));
	}

	static void crash_save_this_cpu(struct pt_regs *regs, int cpu)
	{
	struct elf_prstatus prstatus;
	u32 *buf;

	if ((cpu < 0) \|\| (cpu >= NR_CPUS))
	return;

	/* Using ELF notes here is opportunistic.
	* I need a well defined structure format
	* for the data I pass, and I need tags
	* on the data to indicate what information I have
	* squirrelled away. ELF notes happen to provide
	* all of that that no need to invent something new.
	*/
	buf = (u32*)per_cpu_ptr(crash_notes, cpu);
	if (!buf)
	return;

	memset(&prstatus, 0, sizeof(prstatus));
	prstatus.pr_pid = current->pid;
	elf_core_copy_regs(&prstatus.pr_reg, regs);
	buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
	sizeof(prstatus));
	final_note(buf);
	}

	#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;

	local_irq_disable();
	if (!cpu_isset(cpu, cpus_in_crash))
	crash_save_this_cpu(regs, cpu);
	cpu_set(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 (cpu_isset(cpu, cpus_in_sr)) {
	cpu_clear(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 (!cpu_isset(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 */

	cpu_clear(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 CPUSs reliabally,
	* 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 ((cpus_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 (cpus_weight(cpus_in_crash) < ncpus) {
	printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
	ncpus - cpus_weight(cpus_in_crash));
	printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
	cpus_in_sr = CPU_MASK_NONE;
	atomic_set(&enter_on_soft_reset, 0);
	while (cpus_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 (cpu_isset(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.
	*/
	cpu_clear(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);
	cpu_set(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
	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)
	{
	cpus_in_sr = CPU_MASK_NONE;
	}
	#endif

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

	/*
	* 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.
	*/
	local_irq_disable();

	for_each_irq(irq) {
	struct irq_desc *desc = irq_desc + irq;

	if (desc->status & IRQ_INPROGRESS)
	desc->chip->end(irq);

	if (!(desc->status & IRQ_DISABLED))
	desc->chip->disable(irq);
	}

	/*
	* 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_this_cpu(regs, crashing_cpu);
	crash_kexec_prepare_cpus(crashing_cpu);
	cpu_set(crashing_cpu, cpus_in_crash);
	if (ppc_md.kexec_cpu_down)
	ppc_md.kexec_cpu_down(1, 0);
	}