// 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); }