| // 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> |
| #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; |
| /* |
| * 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); |
| |
| /* 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(); |
| |
| /* |
| * If we came in via system reset, wait a while for the secondary |
| * CPUs to enter. |
| */ |
| if (TRAP(regs) == INTERRUPT_SYSTEM_RESET) |
| 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); |
| } |