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-rw-r--r--arch/powerpc/kexec/crash.c394
1 files changed, 394 insertions, 0 deletions
diff --git a/arch/powerpc/kexec/crash.c b/arch/powerpc/kexec/crash.c
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+++ b/arch/powerpc/kexec/crash.c
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+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Architecture specific (PPC64) functions for kexec based crash dumps.
+ *
+ * Copyright (C) 2005, IBM Corp.
+ *
+ * Created by: Haren Myneni
+ */
+
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <linux/reboot.h>
+#include <linux/kexec.h>
+#include <linux/export.h>
+#include <linux/crash_dump.h>
+#include <linux/delay.h>
+#include <linux/irq.h>
+#include <linux/types.h>
+
+#include <asm/processor.h>
+#include <asm/machdep.h>
+#include <asm/kexec.h>
+#include <asm/smp.h>
+#include <asm/setjmp.h>
+#include <asm/debug.h>
+#include <asm/interrupt.h>
+
+/*
+ * The primary CPU waits a while for all secondary CPUs to enter. This is to
+ * avoid sending an IPI if the secondary CPUs are entering
+ * crash_kexec_secondary on their own (eg via a system reset).
+ *
+ * The secondary timeout has to be longer than the primary. Both timeouts are
+ * in milliseconds.
+ */
+#define PRIMARY_TIMEOUT 500
+#define SECONDARY_TIMEOUT 1000
+
+#define IPI_TIMEOUT 10000
+#define REAL_MODE_TIMEOUT 10000
+
+static int time_to_dump;
+
+/*
+ * In case of system reset, secondary CPUs enter crash_kexec_secondary with out
+ * having to send an IPI explicitly. So, indicate if the crash is via
+ * system reset to avoid sending another IPI.
+ */
+static int is_via_system_reset;
+
+/*
+ * crash_wake_offline should be set to 1 by platforms that intend to wake
+ * up offline cpus prior to jumping to a kdump kernel. Currently powernv
+ * sets it to 1, since we want to avoid things from happening when an
+ * offline CPU wakes up due to something like an HMI (malfunction error),
+ * which propagates to all threads.
+ */
+int crash_wake_offline;
+
+#define CRASH_HANDLER_MAX 3
+/* List of shutdown handles */
+static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX];
+static DEFINE_SPINLOCK(crash_handlers_lock);
+
+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;
+}
+
+#ifdef CONFIG_SMP
+
+static atomic_t cpus_in_crash;
+void crash_ipi_callback(struct pt_regs *regs)
+{
+ static cpumask_t cpus_state_saved = CPU_MASK_NONE;
+
+ int cpu = smp_processor_id();
+
+ hard_irq_disable();
+ if (!cpumask_test_cpu(cpu, &cpus_state_saved)) {
+ crash_save_cpu(regs, cpu);
+ cpumask_set_cpu(cpu, &cpus_state_saved);
+ }
+
+ atomic_inc(&cpus_in_crash);
+ smp_mb__after_atomic();
+
+ /*
+ * Starting the kdump boot.
+ * This barrier is needed to make sure that all CPUs are stopped.
+ */
+ while (!time_to_dump)
+ 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 */
+}
+
+static void crash_kexec_prepare_cpus(void)
+{
+ unsigned int msecs;
+ volatile unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
+ volatile int tries = 0;
+ int (*old_handler)(struct pt_regs *regs);
+
+ printk(KERN_EMERG "Sending IPI to other CPUs\n");
+
+ if (crash_wake_offline)
+ ncpus = num_present_cpus() - 1;
+
+ /*
+ * If we came in via system reset, secondaries enter via crash_kexec_secondary().
+ * So, wait a while for the secondary CPUs to enter for that case.
+ * Else, send IPI to all other CPUs.
+ */
+ if (is_via_system_reset)
+ mdelay(PRIMARY_TIMEOUT);
+ else
+ crash_send_ipi(crash_ipi_callback);
+ smp_wmb();
+
+again:
+ /*
+ * 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.
+ */
+ msecs = IPI_TIMEOUT;
+ while ((atomic_read(&cpus_in_crash) < ncpus) && (--msecs > 0))
+ mdelay(1);
+
+ /* Would it be better to replace the trap vector here? */
+
+ if (atomic_read(&cpus_in_crash) >= ncpus) {
+ printk(KERN_EMERG "IPI complete\n");
+ return;
+ }
+
+ printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n",
+ ncpus - atomic_read(&cpus_in_crash));
+
+ /*
+ * If we have a panic timeout set then we can't wait indefinitely
+ * for someone to activate system reset. We also give up on the
+ * second time through if system reset fail to work.
+ */
+ if ((panic_timeout > 0) || (tries > 0))
+ return;
+
+ /*
+ * A system reset will cause all CPUs to take an 0x100 exception.
+ * The primary CPU returns here via setjmp, and the secondary
+ * CPUs reexecute the crash_kexec_secondary path.
+ */
+ old_handler = __debugger;
+ __debugger = handle_fault;
+ crash_shutdown_cpu = smp_processor_id();
+
+ if (setjmp(crash_shutdown_buf) == 0) {
+ printk(KERN_EMERG "Activate system reset (dumprestart) "
+ "to stop other cpu(s)\n");
+
+ /*
+ * A system reset will force all CPUs to execute the
+ * crash code again. We need to reset cpus_in_crash so we
+ * wait for everyone to do this.
+ */
+ atomic_set(&cpus_in_crash, 0);
+ smp_mb();
+
+ while (atomic_read(&cpus_in_crash) < ncpus)
+ cpu_relax();
+ }
+
+ crash_shutdown_cpu = -1;
+ __debugger = old_handler;
+
+ tries++;
+ goto again;
+}
+
+/*
+ * This function will be called by secondary cpus.
+ */
+void crash_kexec_secondary(struct pt_regs *regs)
+{
+ unsigned long flags;
+ int msecs = SECONDARY_TIMEOUT;
+
+ local_irq_save(flags);
+
+ /* Wait for the primary crash CPU to signal its progress */
+ while (crashing_cpu < 0) {
+ if (--msecs < 0) {
+ /* No response, kdump image may not have been loaded */
+ local_irq_restore(flags);
+ return;
+ }
+
+ mdelay(1);
+ }
+
+ crash_ipi_callback(regs);
+}
+
+#else /* ! CONFIG_SMP */
+
+static void crash_kexec_prepare_cpus(void)
+{
+ /*
+ * move the secondaries 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)
+{
+}
+#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_PPC64)
+noinstr static void __maybe_unused crash_kexec_wait_realmode(int cpu)
+{
+ unsigned int msecs;
+ int i;
+
+ msecs = REAL_MODE_TIMEOUT;
+ for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
+ if (i == cpu)
+ continue;
+
+ while (paca_ptrs[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_PPC64 */
+
+void crash_kexec_prepare(void)
+{
+ /* Avoid hardlocking with irresponsive CPU holding logbuf_lock */
+ printk_deferred_enter();
+
+ /*
+ * 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_kexec_prepare_cpus();
+}
+
+/*
+ * 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 (; i < (CRASH_HANDLER_MAX - 1); i++)
+ crash_shutdown_handles[i] =
+ crash_shutdown_handles[i+1];
+ /*
+ * Reset last entry to NULL now that it has been shifted down,
+ * this will allow new handles to be added here.
+ */
+ crash_shutdown_handles[i] = NULL;
+ rc = 0;
+ }
+
+ spin_unlock(&crash_handlers_lock);
+ return rc;
+}
+EXPORT_SYMBOL(crash_shutdown_unregister);
+
+void default_machine_crash_shutdown(struct pt_regs *regs)
+{
+ volatile unsigned int i;
+ int (*old_handler)(struct pt_regs *regs);
+
+ if (TRAP(regs) == INTERRUPT_SYSTEM_RESET)
+ is_via_system_reset = 1;
+
+ crash_smp_send_stop();
+
+ crash_save_cpu(regs, crashing_cpu);
+
+ time_to_dump = 1;
+
+ crash_kexec_wait_realmode(crashing_cpu);
+
+ machine_kexec_mask_interrupts();
+
+ /*
+ * Call registered shutdown routines safely. 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; i < CRASH_HANDLER_MAX && 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);
+}