// SPDX-License-Identifier: GPL-2.0-only /* * crash.c - kernel crash support code. * Copyright (C) 2002-2004 Eric Biederman */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include "kallsyms_internal.h" #include "kexec_internal.h" /* Per cpu memory for storing cpu states in case of system crash. */ note_buf_t __percpu *crash_notes; /* vmcoreinfo stuff */ unsigned char *vmcoreinfo_data; size_t vmcoreinfo_size; u32 *vmcoreinfo_note; /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */ static unsigned char *vmcoreinfo_data_safecopy; int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map, void **addr, unsigned long *sz) { Elf64_Ehdr *ehdr; Elf64_Phdr *phdr; unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz; unsigned char *buf; unsigned int cpu, i; unsigned long long notes_addr; unsigned long mstart, mend; /* extra phdr for vmcoreinfo ELF note */ nr_phdr = nr_cpus + 1; nr_phdr += mem->nr_ranges; /* * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping * area (for example, ffffffff80000000 - ffffffffa0000000 on x86_64). * I think this is required by tools like gdb. So same physical * memory will be mapped in two ELF headers. One will contain kernel * text virtual addresses and other will have __va(physical) addresses. */ nr_phdr++; elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr); elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN); buf = vzalloc(elf_sz); if (!buf) return -ENOMEM; ehdr = (Elf64_Ehdr *)buf; phdr = (Elf64_Phdr *)(ehdr + 1); memcpy(ehdr->e_ident, ELFMAG, SELFMAG); ehdr->e_ident[EI_CLASS] = ELFCLASS64; ehdr->e_ident[EI_DATA] = ELFDATA2LSB; ehdr->e_ident[EI_VERSION] = EV_CURRENT; ehdr->e_ident[EI_OSABI] = ELF_OSABI; memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD); ehdr->e_type = ET_CORE; ehdr->e_machine = ELF_ARCH; ehdr->e_version = EV_CURRENT; ehdr->e_phoff = sizeof(Elf64_Ehdr); ehdr->e_ehsize = sizeof(Elf64_Ehdr); ehdr->e_phentsize = sizeof(Elf64_Phdr); /* Prepare one phdr of type PT_NOTE for each possible CPU */ for_each_possible_cpu(cpu) { phdr->p_type = PT_NOTE; notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu)); phdr->p_offset = phdr->p_paddr = notes_addr; phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t); (ehdr->e_phnum)++; phdr++; } /* Prepare one PT_NOTE header for vmcoreinfo */ phdr->p_type = PT_NOTE; phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note(); phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE; (ehdr->e_phnum)++; phdr++; /* Prepare PT_LOAD type program header for kernel text region */ if (need_kernel_map) { phdr->p_type = PT_LOAD; phdr->p_flags = PF_R|PF_W|PF_X; phdr->p_vaddr = (unsigned long) _text; phdr->p_filesz = phdr->p_memsz = _end - _text; phdr->p_offset = phdr->p_paddr = __pa_symbol(_text); ehdr->e_phnum++; phdr++; } /* Go through all the ranges in mem->ranges[] and prepare phdr */ for (i = 0; i < mem->nr_ranges; i++) { mstart = mem->ranges[i].start; mend = mem->ranges[i].end; phdr->p_type = PT_LOAD; phdr->p_flags = PF_R|PF_W|PF_X; phdr->p_offset = mstart; phdr->p_paddr = mstart; phdr->p_vaddr = (unsigned long) __va(mstart); phdr->p_filesz = phdr->p_memsz = mend - mstart + 1; phdr->p_align = 0; ehdr->e_phnum++; #ifdef CONFIG_KEXEC_FILE kexec_dprintk("Crash PT_LOAD ELF header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n", phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz, ehdr->e_phnum, phdr->p_offset); #endif phdr++; } *addr = buf; *sz = elf_sz; return 0; } int crash_exclude_mem_range(struct crash_mem *mem, unsigned long long mstart, unsigned long long mend) { int i; unsigned long long start, end, p_start, p_end; for (i = 0; i < mem->nr_ranges; i++) { start = mem->ranges[i].start; end = mem->ranges[i].end; p_start = mstart; p_end = mend; if (p_start > end) continue; /* * Because the memory ranges in mem->ranges are stored in * ascending order, when we detect `p_end < start`, we can * immediately exit the for loop, as the subsequent memory * ranges will definitely be outside the range we are looking * for. */ if (p_end < start) break; /* Truncate any area outside of range */ if (p_start < start) p_start = start; if (p_end > end) p_end = end; /* Found completely overlapping range */ if (p_start == start && p_end == end) { memmove(&mem->ranges[i], &mem->ranges[i + 1], (mem->nr_ranges - (i + 1)) * sizeof(mem->ranges[i])); i--; mem->nr_ranges--; } else if (p_start > start && p_end < end) { /* Split original range */ if (mem->nr_ranges >= mem->max_nr_ranges) return -ENOMEM; memmove(&mem->ranges[i + 2], &mem->ranges[i + 1], (mem->nr_ranges - (i + 1)) * sizeof(mem->ranges[i])); mem->ranges[i].end = p_start - 1; mem->ranges[i + 1].start = p_end + 1; mem->ranges[i + 1].end = end; i++; mem->nr_ranges++; } else if (p_start != start) mem->ranges[i].end = p_start - 1; else mem->ranges[i].start = p_end + 1; } return 0; } Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type, void *data, size_t data_len) { struct elf_note *note = (struct elf_note *)buf; note->n_namesz = strlen(name) + 1; note->n_descsz = data_len; note->n_type = type; buf += DIV_ROUND_UP(sizeof(*note), sizeof(Elf_Word)); memcpy(buf, name, note->n_namesz); buf += DIV_ROUND_UP(note->n_namesz, sizeof(Elf_Word)); memcpy(buf, data, data_len); buf += DIV_ROUND_UP(data_len, sizeof(Elf_Word)); return buf; } void final_note(Elf_Word *buf) { memset(buf, 0, sizeof(struct elf_note)); } static void update_vmcoreinfo_note(void) { u32 *buf = vmcoreinfo_note; if (!vmcoreinfo_size) return; buf = append_elf_note(buf, VMCOREINFO_NOTE_NAME, 0, vmcoreinfo_data, vmcoreinfo_size); final_note(buf); } void crash_update_vmcoreinfo_safecopy(void *ptr) { if (ptr) memcpy(ptr, vmcoreinfo_data, vmcoreinfo_size); vmcoreinfo_data_safecopy = ptr; } void crash_save_vmcoreinfo(void) { if (!vmcoreinfo_note) return; /* Use the safe copy to generate vmcoreinfo note if have */ if (vmcoreinfo_data_safecopy) vmcoreinfo_data = vmcoreinfo_data_safecopy; vmcoreinfo_append_str("CRASHTIME=%lld\n", ktime_get_real_seconds()); update_vmcoreinfo_note(); } void vmcoreinfo_append_str(const char *fmt, ...) { va_list args; char buf[0x50]; size_t r; va_start(args, fmt); r = vscnprintf(buf, sizeof(buf), fmt, args); va_end(args); r = min(r, (size_t)VMCOREINFO_BYTES - vmcoreinfo_size); memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r); vmcoreinfo_size += r; WARN_ONCE(vmcoreinfo_size == VMCOREINFO_BYTES, "vmcoreinfo data exceeds allocated size, truncating"); } /* * provide an empty default implementation here -- architecture * code may override this */ void __weak arch_crash_save_vmcoreinfo(void) {} phys_addr_t __weak paddr_vmcoreinfo_note(void) { return __pa(vmcoreinfo_note); } EXPORT_SYMBOL(paddr_vmcoreinfo_note); static int __init crash_save_vmcoreinfo_init(void) { vmcoreinfo_data = (unsigned char *)get_zeroed_page(GFP_KERNEL); if (!vmcoreinfo_data) { pr_warn("Memory allocation for vmcoreinfo_data failed\n"); return -ENOMEM; } vmcoreinfo_note = alloc_pages_exact(VMCOREINFO_NOTE_SIZE, GFP_KERNEL | __GFP_ZERO); if (!vmcoreinfo_note) { free_page((unsigned long)vmcoreinfo_data); vmcoreinfo_data = NULL; pr_warn("Memory allocation for vmcoreinfo_note failed\n"); return -ENOMEM; } VMCOREINFO_OSRELEASE(init_uts_ns.name.release); VMCOREINFO_BUILD_ID(); VMCOREINFO_PAGESIZE(PAGE_SIZE); VMCOREINFO_SYMBOL(init_uts_ns); VMCOREINFO_OFFSET(uts_namespace, name); VMCOREINFO_SYMBOL(node_online_map); #ifdef CONFIG_MMU VMCOREINFO_SYMBOL_ARRAY(swapper_pg_dir); #endif VMCOREINFO_SYMBOL(_stext); vmcoreinfo_append_str("NUMBER(VMALLOC_START)=0x%lx\n", (unsigned long) VMALLOC_START); #ifndef CONFIG_NUMA VMCOREINFO_SYMBOL(mem_map); VMCOREINFO_SYMBOL(contig_page_data); #endif #ifdef CONFIG_SPARSEMEM VMCOREINFO_SYMBOL_ARRAY(mem_section); VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS); VMCOREINFO_STRUCT_SIZE(mem_section); VMCOREINFO_OFFSET(mem_section, section_mem_map); VMCOREINFO_NUMBER(SECTION_SIZE_BITS); VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS); #endif VMCOREINFO_STRUCT_SIZE(page); VMCOREINFO_STRUCT_SIZE(pglist_data); VMCOREINFO_STRUCT_SIZE(zone); VMCOREINFO_STRUCT_SIZE(free_area); VMCOREINFO_STRUCT_SIZE(list_head); VMCOREINFO_SIZE(nodemask_t); VMCOREINFO_OFFSET(page, flags); VMCOREINFO_OFFSET(page, _refcount); VMCOREINFO_OFFSET(page, mapping); VMCOREINFO_OFFSET(page, lru); VMCOREINFO_OFFSET(page, _mapcount); VMCOREINFO_OFFSET(page, private); VMCOREINFO_OFFSET(page, compound_head); VMCOREINFO_OFFSET(pglist_data, node_zones); VMCOREINFO_OFFSET(pglist_data, nr_zones); #ifdef CONFIG_FLATMEM VMCOREINFO_OFFSET(pglist_data, node_mem_map); #endif VMCOREINFO_OFFSET(pglist_data, node_start_pfn); VMCOREINFO_OFFSET(pglist_data, node_spanned_pages); VMCOREINFO_OFFSET(pglist_data, node_id); VMCOREINFO_OFFSET(zone, free_area); VMCOREINFO_OFFSET(zone, vm_stat); VMCOREINFO_OFFSET(zone, spanned_pages); VMCOREINFO_OFFSET(free_area, free_list); VMCOREINFO_OFFSET(list_head, next); VMCOREINFO_OFFSET(list_head, prev); VMCOREINFO_LENGTH(zone.free_area, NR_PAGE_ORDERS); log_buf_vmcoreinfo_setup(); VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES); VMCOREINFO_NUMBER(NR_FREE_PAGES); VMCOREINFO_NUMBER(PG_lru); VMCOREINFO_NUMBER(PG_private); VMCOREINFO_NUMBER(PG_swapcache); VMCOREINFO_NUMBER(PG_swapbacked); VMCOREINFO_NUMBER(PG_slab); #ifdef CONFIG_MEMORY_FAILURE VMCOREINFO_NUMBER(PG_hwpoison); #endif VMCOREINFO_NUMBER(PG_head_mask); #define PAGE_BUDDY_MAPCOUNT_VALUE (~PG_buddy) VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE); #ifdef CONFIG_HUGETLB_PAGE VMCOREINFO_NUMBER(PG_hugetlb); #define PAGE_OFFLINE_MAPCOUNT_VALUE (~PG_offline) VMCOREINFO_NUMBER(PAGE_OFFLINE_MAPCOUNT_VALUE); #endif #ifdef CONFIG_KALLSYMS VMCOREINFO_SYMBOL(kallsyms_names); VMCOREINFO_SYMBOL(kallsyms_num_syms); VMCOREINFO_SYMBOL(kallsyms_token_table); VMCOREINFO_SYMBOL(kallsyms_token_index); #ifdef CONFIG_KALLSYMS_BASE_RELATIVE VMCOREINFO_SYMBOL(kallsyms_offsets); VMCOREINFO_SYMBOL(kallsyms_relative_base); #else VMCOREINFO_SYMBOL(kallsyms_addresses); #endif /* CONFIG_KALLSYMS_BASE_RELATIVE */ #endif /* CONFIG_KALLSYMS */ arch_crash_save_vmcoreinfo(); update_vmcoreinfo_note(); return 0; } subsys_initcall(crash_save_vmcoreinfo_init); static int __init crash_notes_memory_init(void) { /* Allocate memory for saving cpu registers. */ size_t size, align; /* * crash_notes could be allocated across 2 vmalloc pages when percpu * is vmalloc based . vmalloc doesn't guarantee 2 continuous vmalloc * pages are also on 2 continuous physical pages. In this case the * 2nd part of crash_notes in 2nd page could be lost since only the * starting address and size of crash_notes are exported through sysfs. * Here round up the size of crash_notes to the nearest power of two * and pass it to __alloc_percpu as align value. This can make sure * crash_notes is allocated inside one physical page. */ size = sizeof(note_buf_t); align = min(roundup_pow_of_two(sizeof(note_buf_t)), PAGE_SIZE); /* * Break compile if size is bigger than PAGE_SIZE since crash_notes * definitely will be in 2 pages with that. */ BUILD_BUG_ON(size > PAGE_SIZE); crash_notes = __alloc_percpu(size, align); if (!crash_notes) { pr_warn("Memory allocation for saving cpu register states failed\n"); return -ENOMEM; } return 0; } subsys_initcall(crash_notes_memory_init); #ifdef CONFIG_CRASH_HOTPLUG #undef pr_fmt #define pr_fmt(fmt) "crash hp: " fmt /* * Different than kexec/kdump loading/unloading/jumping/shrinking which * usually rarely happen, there will be many crash hotplug events notified * during one short period, e.g one memory board is hot added and memory * regions are online. So mutex lock __crash_hotplug_lock is used to * serialize the crash hotplug handling specifically. */ static DEFINE_MUTEX(__crash_hotplug_lock); #define crash_hotplug_lock() mutex_lock(&__crash_hotplug_lock) #define crash_hotplug_unlock() mutex_unlock(&__crash_hotplug_lock) /* * This routine utilized when the crash_hotplug sysfs node is read. * It reflects the kernel's ability/permission to update the crash * elfcorehdr directly. */ int crash_check_update_elfcorehdr(void) { int rc = 0; crash_hotplug_lock(); /* Obtain lock while reading crash information */ if (!kexec_trylock()) { pr_info("kexec_trylock() failed, elfcorehdr may be inaccurate\n"); crash_hotplug_unlock(); return 0; } if (kexec_crash_image) { if (kexec_crash_image->file_mode) rc = 1; else rc = kexec_crash_image->update_elfcorehdr; } /* Release lock now that update complete */ kexec_unlock(); crash_hotplug_unlock(); return rc; } /* * To accurately reflect hot un/plug changes of cpu and memory resources * (including onling and offlining of those resources), the elfcorehdr * (which is passed to the crash kernel via the elfcorehdr= parameter) * must be updated with the new list of CPUs and memories. * * In order to make changes to elfcorehdr, two conditions are needed: * First, the segment containing the elfcorehdr must be large enough * to permit a growing number of resources; the elfcorehdr memory size * is based on NR_CPUS_DEFAULT and CRASH_MAX_MEMORY_RANGES. * Second, purgatory must explicitly exclude the elfcorehdr from the * list of segments it checks (since the elfcorehdr changes and thus * would require an update to purgatory itself to update the digest). */ static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu) { struct kimage *image; crash_hotplug_lock(); /* Obtain lock while changing crash information */ if (!kexec_trylock()) { pr_info("kexec_trylock() failed, elfcorehdr may be inaccurate\n"); crash_hotplug_unlock(); return; } /* Check kdump is not loaded */ if (!kexec_crash_image) goto out; image = kexec_crash_image; /* Check that updating elfcorehdr is permitted */ if (!(image->file_mode || image->update_elfcorehdr)) goto out; if (hp_action == KEXEC_CRASH_HP_ADD_CPU || hp_action == KEXEC_CRASH_HP_REMOVE_CPU) pr_debug("hp_action %u, cpu %u\n", hp_action, cpu); else pr_debug("hp_action %u\n", hp_action); /* * The elfcorehdr_index is set to -1 when the struct kimage * is allocated. Find the segment containing the elfcorehdr, * if not already found. */ if (image->elfcorehdr_index < 0) { unsigned long mem; unsigned char *ptr; unsigned int n; for (n = 0; n < image->nr_segments; n++) { mem = image->segment[n].mem; ptr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT)); if (ptr) { /* The segment containing elfcorehdr */ if (memcmp(ptr, ELFMAG, SELFMAG) == 0) image->elfcorehdr_index = (int)n; kunmap_local(ptr); } } } if (image->elfcorehdr_index < 0) { pr_err("unable to locate elfcorehdr segment"); goto out; } /* Needed in order for the segments to be updated */ arch_kexec_unprotect_crashkres(); /* Differentiate between normal load and hotplug update */ image->hp_action = hp_action; /* Now invoke arch-specific update handler */ arch_crash_handle_hotplug_event(image); /* No longer handling a hotplug event */ image->hp_action = KEXEC_CRASH_HP_NONE; image->elfcorehdr_updated = true; /* Change back to read-only */ arch_kexec_protect_crashkres(); /* Errors in the callback is not a reason to rollback state */ out: /* Release lock now that update complete */ kexec_unlock(); crash_hotplug_unlock(); } static int crash_memhp_notifier(struct notifier_block *nb, unsigned long val, void *v) { switch (val) { case MEM_ONLINE: crash_handle_hotplug_event(KEXEC_CRASH_HP_ADD_MEMORY, KEXEC_CRASH_HP_INVALID_CPU); break; case MEM_OFFLINE: crash_handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_MEMORY, KEXEC_CRASH_HP_INVALID_CPU); break; } return NOTIFY_OK; } static struct notifier_block crash_memhp_nb = { .notifier_call = crash_memhp_notifier, .priority = 0 }; static int crash_cpuhp_online(unsigned int cpu) { crash_handle_hotplug_event(KEXEC_CRASH_HP_ADD_CPU, cpu); return 0; } static int crash_cpuhp_offline(unsigned int cpu) { crash_handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_CPU, cpu); return 0; } static int __init crash_hotplug_init(void) { int result = 0; if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) register_memory_notifier(&crash_memhp_nb); if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) { result = cpuhp_setup_state_nocalls(CPUHP_BP_PREPARE_DYN, "crash/cpuhp", crash_cpuhp_online, crash_cpuhp_offline); } return result; } subsys_initcall(crash_hotplug_init); #endif