1 files changed, 374 insertions, 0 deletions
diff --git a/arch/powerpc/kexec/crash.c b/arch/powerpc/kexec/crash.c
new file mode 100644
index 000000000000..d488311efab1
--- /dev/null
+++ b/arch/powerpc/kexec/crash.c
@@ -0,0 +1,374 @@
+// 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/prom.h>
+#include <asm/smp.h>
+#include <asm/setjmp.h>
+#include <asm/debug.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;
+/*
+ * 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(int cpu)
+{
+	unsigned int msecs;
+	unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
+	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;
+
+	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(int cpu)
+{
+	/*
+	 * 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)
+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 */
+
+/*
+ * 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)
+{
+	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();
+
+	/*
+	 * If we came in via system reset, wait a while for the secondary
+	 * CPUs to enter.
+	 */
+	if (TRAP(regs) == 0x100)
+		mdelay(PRIMARY_TIMEOUT);
+
+	crash_kexec_prepare_cpus(crashing_cpu);
+
+	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);
+}