diff options
Diffstat (limited to 'arch/powerpc/kexec/crash.c')
| -rw-r--r-- | arch/powerpc/kexec/crash.c | 592 |
1 files changed, 592 insertions, 0 deletions
diff --git a/arch/powerpc/kexec/crash.c b/arch/powerpc/kexec/crash.c new file mode 100644 index 000000000000..a325c1c02f96 --- /dev/null +++ b/arch/powerpc/kexec/crash.c @@ -0,0 +1,592 @@ +// 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 <linux/libfdt.h> +#include <linux/memory.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> +#include <asm/kexec_ranges.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; + + if (IS_ENABLED(CONFIG_SMP)) + crash_smp_send_stop(); + else + crash_kexec_prepare(); + + 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); +} + +#ifdef CONFIG_CRASH_HOTPLUG +#undef pr_fmt +#define pr_fmt(fmt) "crash hp: " fmt + +/* + * Advertise preferred elfcorehdr size to userspace via + * /sys/kernel/crash_elfcorehdr_size sysfs interface. + */ +unsigned int arch_crash_get_elfcorehdr_size(void) +{ + unsigned long phdr_cnt; + + /* A program header for possible CPUs + vmcoreinfo */ + phdr_cnt = num_possible_cpus() + 1; + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) + phdr_cnt += CONFIG_CRASH_MAX_MEMORY_RANGES; + + return sizeof(struct elfhdr) + (phdr_cnt * sizeof(Elf64_Phdr)); +} + +/** + * update_crash_elfcorehdr() - Recreate the elfcorehdr and replace it with old + * elfcorehdr in the kexec segment array. + * @image: the active struct kimage + * @mn: struct memory_notify data handler + */ +static void update_crash_elfcorehdr(struct kimage *image, struct memory_notify *mn) +{ + int ret; + struct crash_mem *cmem = NULL; + struct kexec_segment *ksegment; + void *ptr, *mem, *elfbuf = NULL; + unsigned long elfsz, memsz, base_addr, size; + + ksegment = &image->segment[image->elfcorehdr_index]; + mem = (void *) ksegment->mem; + memsz = ksegment->memsz; + + ret = get_crash_memory_ranges(&cmem); + if (ret) { + pr_err("Failed to get crash mem range\n"); + return; + } + + /* + * The hot unplugged memory is part of crash memory ranges, + * remove it here. + */ + if (image->hp_action == KEXEC_CRASH_HP_REMOVE_MEMORY) { + base_addr = PFN_PHYS(mn->start_pfn); + size = mn->nr_pages * PAGE_SIZE; + ret = remove_mem_range(&cmem, base_addr, size); + if (ret) { + pr_err("Failed to remove hot-unplugged memory from crash memory ranges\n"); + goto out; + } + } + + ret = crash_prepare_elf64_headers(cmem, false, &elfbuf, &elfsz); + if (ret) { + pr_err("Failed to prepare elf header\n"); + goto out; + } + + /* + * It is unlikely that kernel hit this because elfcorehdr kexec + * segment (memsz) is built with addition space to accommodate growing + * number of crash memory ranges while loading the kdump kernel. It is + * Just to avoid any unforeseen case. + */ + if (elfsz > memsz) { + pr_err("Updated crash elfcorehdr elfsz %lu > memsz %lu", elfsz, memsz); + goto out; + } + + ptr = __va(mem); + if (ptr) { + /* Temporarily invalidate the crash image while it is replaced */ + xchg(&kexec_crash_image, NULL); + + /* Replace the old elfcorehdr with newly prepared elfcorehdr */ + memcpy((void *)ptr, elfbuf, elfsz); + + /* The crash image is now valid once again */ + xchg(&kexec_crash_image, image); + } +out: + kvfree(cmem); + kvfree(elfbuf); +} + +/** + * get_fdt_index - Loop through the kexec segment array and find + * the index of the FDT segment. + * @image: a pointer to kexec_crash_image + * + * Returns the index of FDT segment in the kexec segment array + * if found; otherwise -1. + */ +static int get_fdt_index(struct kimage *image) +{ + void *ptr; + unsigned long mem; + int i, fdt_index = -1; + + /* Find the FDT segment index in kexec segment array. */ + for (i = 0; i < image->nr_segments; i++) { + mem = image->segment[i].mem; + ptr = __va(mem); + + if (ptr && fdt_magic(ptr) == FDT_MAGIC) { + fdt_index = i; + break; + } + } + + return fdt_index; +} + +/** + * update_crash_fdt - updates the cpus node of the crash FDT. + * + * @image: a pointer to kexec_crash_image + */ +static void update_crash_fdt(struct kimage *image) +{ + void *fdt; + int fdt_index; + + fdt_index = get_fdt_index(image); + if (fdt_index < 0) { + pr_err("Unable to locate FDT segment.\n"); + return; + } + + fdt = __va((void *)image->segment[fdt_index].mem); + + /* Temporarily invalidate the crash image while it is replaced */ + xchg(&kexec_crash_image, NULL); + + /* update FDT to reflect changes in CPU resources */ + if (update_cpus_node(fdt)) + pr_err("Failed to update crash FDT"); + + /* The crash image is now valid once again */ + xchg(&kexec_crash_image, image); +} + +int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags) +{ +#ifdef CONFIG_KEXEC_FILE + if (image->file_mode) + return 1; +#endif + return kexec_flags & KEXEC_CRASH_HOTPLUG_SUPPORT; +} + +/** + * arch_crash_handle_hotplug_event - Handle crash CPU/Memory hotplug events to update the + * necessary kexec segments based on the hotplug event. + * @image: a pointer to kexec_crash_image + * @arg: struct memory_notify handler for memory hotplug case and NULL for CPU hotplug case. + * + * Update the kdump image based on the type of hotplug event, represented by image->hp_action. + * CPU add: Update the FDT segment to include the newly added CPU. + * CPU remove: No action is needed, with the assumption that it's okay to have offline CPUs + * part of the FDT. + * Memory add/remove: No action is taken as this is not yet supported. + */ +void arch_crash_handle_hotplug_event(struct kimage *image, void *arg) +{ + struct memory_notify *mn; + + switch (image->hp_action) { + case KEXEC_CRASH_HP_REMOVE_CPU: + return; + + case KEXEC_CRASH_HP_ADD_CPU: + update_crash_fdt(image); + break; + + case KEXEC_CRASH_HP_REMOVE_MEMORY: + case KEXEC_CRASH_HP_ADD_MEMORY: + mn = (struct memory_notify *)arg; + update_crash_elfcorehdr(image, mn); + return; + default: + pr_warn_once("Unknown hotplug action\n"); + } +} +#endif /* CONFIG_CRASH_HOTPLUG */ |