// SPDX-License-Identifier: GPL-2.0-only /* * PPC64 code to handle Linux booting another kernel. * * Copyright (C) 2004-2005, IBM Corp. * * Created by: Milton D Miller II */ #include <linux/kexec.h> #include <linux/smp.h> #include <linux/thread_info.h> #include <linux/init_task.h> #include <linux/errno.h> #include <linux/kernel.h> #include <linux/cpu.h> #include <linux/hardirq.h> #include <linux/of.h> #include <asm/page.h> #include <asm/current.h> #include <asm/machdep.h> #include <asm/cacheflush.h> #include <asm/firmware.h> #include <asm/paca.h> #include <asm/mmu.h> #include <asm/sections.h> /* _end */ #include <asm/smp.h> #include <asm/hw_breakpoint.h> #include <asm/svm.h> #include <asm/ultravisor.h> int machine_kexec_prepare(struct kimage *image) { int i; unsigned long begin, end; /* limits of segment */ unsigned long low, high; /* limits of blocked memory range */ struct device_node *node; const unsigned long *basep; const unsigned int *sizep; /* * Since we use the kernel fault handlers and paging code to * handle the virtual mode, we must make sure no destination * overlaps kernel static data or bss. */ for (i = 0; i < image->nr_segments; i++) if (image->segment[i].mem < __pa(_end)) return -ETXTBSY; /* We also should not overwrite the tce tables */ for_each_node_by_type(node, "pci") { basep = of_get_property(node, "linux,tce-base", NULL); sizep = of_get_property(node, "linux,tce-size", NULL); if (basep == NULL || sizep == NULL) continue; low = *basep; high = low + (*sizep); for (i = 0; i < image->nr_segments; i++) { begin = image->segment[i].mem; end = begin + image->segment[i].memsz; if ((begin < high) && (end > low)) { of_node_put(node); return -ETXTBSY; } } } return 0; } /* Called during kexec sequence with MMU off */ static notrace void copy_segments(unsigned long ind) { unsigned long entry; unsigned long *ptr; void *dest; void *addr; /* * We rely on kexec_load to create a lists that properly * initializes these pointers before they are used. * We will still crash if the list is wrong, but at least * the compiler will be quiet. */ ptr = NULL; dest = NULL; for (entry = ind; !(entry & IND_DONE); entry = *ptr++) { addr = __va(entry & PAGE_MASK); switch (entry & IND_FLAGS) { case IND_DESTINATION: dest = addr; break; case IND_INDIRECTION: ptr = addr; break; case IND_SOURCE: copy_page(dest, addr); dest += PAGE_SIZE; } } } /* Called during kexec sequence with MMU off */ notrace void kexec_copy_flush(struct kimage *image) { long i, nr_segments = image->nr_segments; struct kexec_segment ranges[KEXEC_SEGMENT_MAX]; /* save the ranges on the stack to efficiently flush the icache */ memcpy(ranges, image->segment, sizeof(ranges)); /* * After this call we may not use anything allocated in dynamic * memory, including *image. * * Only globals and the stack are allowed. */ copy_segments(image->head); /* * we need to clear the icache for all dest pages sometime, * including ones that were in place on the original copy */ for (i = 0; i < nr_segments; i++) flush_icache_range((unsigned long)__va(ranges[i].mem), (unsigned long)__va(ranges[i].mem + ranges[i].memsz)); } #ifdef CONFIG_SMP static int kexec_all_irq_disabled = 0; static void kexec_smp_down(void *arg) { local_irq_disable(); hard_irq_disable(); mb(); /* make sure our irqs are disabled before we say they are */ get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF; while(kexec_all_irq_disabled == 0) cpu_relax(); mb(); /* make sure all irqs are disabled before this */ hw_breakpoint_disable(); /* * Now every CPU has IRQs off, we can clear out any pending * IPIs and be sure that no more will come in after this. */ if (ppc_md.kexec_cpu_down) ppc_md.kexec_cpu_down(0, 1); reset_sprs(); kexec_smp_wait(); /* NOTREACHED */ } static void kexec_prepare_cpus_wait(int wait_state) { int my_cpu, i, notified=-1; hw_breakpoint_disable(); my_cpu = get_cpu(); /* Make sure each CPU has at least made it to the state we need. * * FIXME: There is a (slim) chance of a problem if not all of the CPUs * are correctly onlined. If somehow we start a CPU on boot with RTAS * start-cpu, but somehow that CPU doesn't write callin_cpu_map[] in * time, the boot CPU will timeout. If it does eventually execute * stuff, the secondary will start up (paca_ptrs[]->cpu_start was * written) and get into a peculiar state. * If the platform supports smp_ops->take_timebase(), the secondary CPU * will probably be spinning in there. If not (i.e. pseries), the * secondary will continue on and try to online itself/idle/etc. If it * survives that, we need to find these * possible-but-not-online-but-should-be CPUs and chaperone them into * kexec_smp_wait(). */ for_each_online_cpu(i) { if (i == my_cpu) continue; while (paca_ptrs[i]->kexec_state < wait_state) { barrier(); if (i != notified) { printk(KERN_INFO "kexec: waiting for cpu %d " "(physical %d) to enter %i state\n", i, paca_ptrs[i]->hw_cpu_id, wait_state); notified = i; } } } mb(); } /* * We need to make sure each present CPU is online. The next kernel will scan * the device tree and assume primary threads are online and query secondary * threads via RTAS to online them if required. If we don't online primary * threads, they will be stuck. However, we also online secondary threads as we * may be using 'cede offline'. In this case RTAS doesn't see the secondary * threads as offline -- and again, these CPUs will be stuck. * * So, we online all CPUs that should be running, including secondary threads. */ static void wake_offline_cpus(void) { int cpu = 0; for_each_present_cpu(cpu) { if (!cpu_online(cpu)) { printk(KERN_INFO "kexec: Waking offline cpu %d.\n", cpu); WARN_ON(add_cpu(cpu)); } } } static void kexec_prepare_cpus(void) { wake_offline_cpus(); smp_call_function(kexec_smp_down, NULL, /* wait */0); local_irq_disable(); hard_irq_disable(); mb(); /* make sure IRQs are disabled before we say they are */ get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF; kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF); /* we are sure every CPU has IRQs off at this point */ kexec_all_irq_disabled = 1; /* * Before removing MMU mappings make sure all CPUs have entered real * mode: */ kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE); /* after we tell the others to go down */ if (ppc_md.kexec_cpu_down) ppc_md.kexec_cpu_down(0, 0); put_cpu(); } #else /* ! SMP */ static void kexec_prepare_cpus(void) { /* * move the secondarys to us so that we can copy * the new kernel 0-0x100 safely * * do this if kexec in setup.c ? * * We need to release the cpus if we are ever going from an * UP to an SMP kernel. */ smp_release_cpus(); if (ppc_md.kexec_cpu_down) ppc_md.kexec_cpu_down(0, 0); local_irq_disable(); hard_irq_disable(); } #endif /* SMP */ /* * kexec thread structure and stack. * * We need to make sure that this is 16384-byte aligned due to the * way process stacks are handled. It also must be statically allocated * or allocated as part of the kimage, because everything else may be * overwritten when we copy the kexec image. We piggyback on the * "init_task" linker section here to statically allocate a stack. * * We could use a smaller stack if we don't care about anything using * current, but that audit has not been performed. */ static union thread_union kexec_stack __init_task_data = { }; /* * For similar reasons to the stack above, the kexecing CPU needs to be on a * static PACA; we switch to kexec_paca. */ static struct paca_struct kexec_paca; /* Our assembly helper, in misc_64.S */ extern void kexec_sequence(void *newstack, unsigned long start, void *image, void *control, void (*clear_all)(void), bool copy_with_mmu_off) __noreturn; /* too late to fail here */ void default_machine_kexec(struct kimage *image) { bool copy_with_mmu_off; /* prepare control code if any */ /* * If the kexec boot is the normal one, need to shutdown other cpus * into our wait loop and quiesce interrupts. * Otherwise, in the case of crashed mode (crashing_cpu >= 0), * stopping other CPUs and collecting their pt_regs is done before * using debugger IPI. */ if (!kdump_in_progress()) kexec_prepare_cpus(); printk("kexec: Starting switchover sequence.\n"); /* switch to a staticly allocated stack. Based on irq stack code. * We setup preempt_count to avoid using VMX in memcpy. * XXX: the task struct will likely be invalid once we do the copy! */ current_thread_info()->flags = 0; current_thread_info()->preempt_count = HARDIRQ_OFFSET; /* We need a static PACA, too; copy this CPU's PACA over and switch to * it. Also poison per_cpu_offset and NULL lppaca to catch anyone using * non-static data. */ memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct)); kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL; #ifdef CONFIG_PPC_PSERIES kexec_paca.lppaca_ptr = NULL; #endif if (is_secure_guest() && !(image->preserve_context || image->type == KEXEC_TYPE_CRASH)) { uv_unshare_all_pages(); printk("kexec: Unshared all shared pages.\n"); } paca_ptrs[kexec_paca.paca_index] = &kexec_paca; setup_paca(&kexec_paca); /* * The lppaca should be unregistered at this point so the HV won't * touch it. In the case of a crash, none of the lppacas are * unregistered so there is not much we can do about it here. */ /* * On Book3S, the copy must happen with the MMU off if we are either * using Radix page tables or we are not in an LPAR since we can * overwrite the page tables while copying. * * In an LPAR, we keep the MMU on otherwise we can't access beyond * the RMA. On BookE there is no real MMU off mode, so we have to * keep it enabled as well (but then we have bolted TLB entries). */ #ifdef CONFIG_PPC_BOOK3E_64 copy_with_mmu_off = false; #else copy_with_mmu_off = radix_enabled() || !(firmware_has_feature(FW_FEATURE_LPAR) || firmware_has_feature(FW_FEATURE_PS3_LV1)); #endif /* Some things are best done in assembly. Finding globals with * a toc is easier in C, so pass in what we can. */ kexec_sequence(&kexec_stack, image->start, image, page_address(image->control_code_page), mmu_cleanup_all, copy_with_mmu_off); /* NOTREACHED */ } #ifdef CONFIG_PPC_64S_HASH_MMU /* Values we need to export to the second kernel via the device tree. */ static unsigned long htab_base; static unsigned long htab_size; static struct property htab_base_prop = { .name = "linux,htab-base", .length = sizeof(unsigned long), .value = &htab_base, }; static struct property htab_size_prop = { .name = "linux,htab-size", .length = sizeof(unsigned long), .value = &htab_size, }; static int __init export_htab_values(void) { struct device_node *node; /* On machines with no htab htab_address is NULL */ if (!htab_address) return -ENODEV; node = of_find_node_by_path("/chosen"); if (!node) return -ENODEV; /* remove any stale properties so ours can be found */ of_remove_property(node, of_find_property(node, htab_base_prop.name, NULL)); of_remove_property(node, of_find_property(node, htab_size_prop.name, NULL)); htab_base = cpu_to_be64(__pa(htab_address)); of_add_property(node, &htab_base_prop); htab_size = cpu_to_be64(htab_size_bytes); of_add_property(node, &htab_size_prop); of_node_put(node); return 0; } late_initcall(export_htab_values); #endif /* CONFIG_PPC_64S_HASH_MMU */