Something went wrong. Try again.
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Something went wrong. Try again.
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701// SPDX-License-Identifier: GPL-2.0-only/* * crash.c - kernel crash support code. * Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com> */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/buildid.h>#include <linux/init.h>#include <linux/utsname.h>#include <linux/vmalloc.h>#include <linux/sizes.h>#include <linux/kexec.h>#include <linux/memory.h>#include <linux/mm.h>#include <linux/cpuhotplug.h>#include <linux/memblock.h>#include <linux/kmemleak.h>#include <linux/crash_core.h>#include <linux/reboot.h>#include <linux/btf.h>#include <linux/objtool.h>#include <linux/delay.h>#include <linux/panic.h>
#include <asm/page.h>#include <asm/sections.h>
#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;
/* time to wait for possible DMA to finish before starting the kdump kernel * when a CMA reservation is used */#define CMA_DMA_TIMEOUT_SEC 10
#ifdef CONFIG_CRASH_DUMP
int kimage_crash_copy_vmcoreinfo(struct kimage *image){ struct page *vmcoreinfo_base; struct page *vmcoreinfo_pages[DIV_ROUND_UP(VMCOREINFO_BYTES, PAGE_SIZE)]; unsigned int order, nr_pages; int i; void *safecopy;
nr_pages = DIV_ROUND_UP(VMCOREINFO_BYTES, PAGE_SIZE); order = get_order(VMCOREINFO_BYTES);
if (!IS_ENABLED(CONFIG_CRASH_DUMP)) return 0; if (image->type != KEXEC_TYPE_CRASH) return 0;
/* * For kdump, allocate one vmcoreinfo safe copy from the * crash memory. as we have arch_kexec_protect_crashkres() * after kexec syscall, we naturally protect it from write * (even read) access under kernel direct mapping. But on * the other hand, we still need to operate it when crash * happens to generate vmcoreinfo note, hereby we rely on * vmap for this purpose. */ vmcoreinfo_base = kimage_alloc_control_pages(image, order); if (!vmcoreinfo_base) { pr_warn("Could not allocate vmcoreinfo buffer\n"); return -ENOMEM; } for (i = 0; i < nr_pages; i++) vmcoreinfo_pages[i] = vmcoreinfo_base + i;
safecopy = vmap(vmcoreinfo_pages, nr_pages, VM_MAP, PAGE_KERNEL); if (!safecopy) { pr_warn("Could not vmap vmcoreinfo buffer\n"); return -ENOMEM; }
image->vmcoreinfo_data_copy = safecopy; crash_update_vmcoreinfo_safecopy(safecopy);
return 0;}
int kexec_should_crash(struct task_struct *p){ /* * If crash_kexec_post_notifiers is enabled, don't run * crash_kexec() here yet, which must be run after panic * notifiers in panic(). */ if (crash_kexec_post_notifiers) return 0; /* * There are 4 panic() calls in make_task_dead() path, each of which * corresponds to each of these 4 conditions. */ if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops) return 1; return 0;}
int kexec_crash_loaded(void){ return !!kexec_crash_image;}EXPORT_SYMBOL_GPL(kexec_crash_loaded);
static void crash_cma_clear_pending_dma(void){ if (!crashk_cma_cnt) return;
mdelay(CMA_DMA_TIMEOUT_SEC * 1000);}
/* * No panic_cpu check version of crash_kexec(). This function is called * only when panic_cpu holds the current CPU number; this is the only CPU * which processes crash_kexec routines. */void __noclone __crash_kexec(struct pt_regs *regs){ /* Take the kexec_lock here to prevent sys_kexec_load * running on one cpu from replacing the crash kernel * we are using after a panic on a different cpu. * * If the crash kernel was not located in a fixed area * of memory the xchg(&kexec_crash_image) would be * sufficient. But since I reuse the memory... */ if (kexec_trylock()) { if (kexec_crash_image) { struct pt_regs fixed_regs;
crash_setup_regs(&fixed_regs, regs); crash_save_vmcoreinfo(); machine_crash_shutdown(&fixed_regs); crash_cma_clear_pending_dma(); machine_kexec(kexec_crash_image); } kexec_unlock(); }}STACK_FRAME_NON_STANDARD(__crash_kexec);
__bpf_kfunc void crash_kexec(struct pt_regs *regs){ if (panic_try_start()) { /* This is the 1st CPU which comes here, so go ahead. */ __crash_kexec(regs);
/* * Reset panic_cpu to allow another panic()/crash_kexec() * call. */ panic_reset(); }}
static inline resource_size_t crash_resource_size(const struct resource *res){ return !res->end ? 0 : resource_size(res);}
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;}
/** * crash_exclude_mem_range - exclude a mem range for existing ranges * @mem: mem->range contains an array of ranges sorted in ascending order * @mstart: the start of to-be-excluded range * @mend: the start of to-be-excluded range * * If you are unsure if a range split will happen, to avoid function call * failure because of -ENOMEM, always make sure * mem->max_nr_ranges == mem->nr_ranges + 1 * before calling the function each time. * * returns 0 if a memory range is excluded successfully * return -ENOMEM if mem->ranges doesn't have space to hold split ranges */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;}EXPORT_SYMBOL_GPL(crash_exclude_mem_range);
ssize_t crash_get_memory_size(void){ ssize_t size = 0;
if (!kexec_trylock()) return -EBUSY;
size += crash_resource_size(&crashk_res); size += crash_resource_size(&crashk_low_res);
kexec_unlock(); return size;}
static int __crash_shrink_memory(struct resource *old_res, unsigned long new_size){ struct resource *ram_res;
ram_res = kzalloc_obj(*ram_res); if (!ram_res) return -ENOMEM;
ram_res->start = old_res->start + new_size; ram_res->end = old_res->end; ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM; ram_res->name = "System RAM";
if (!new_size) { release_resource(old_res); old_res->start = 0; old_res->end = 0; } else { old_res->end = ram_res->start - 1; }
crash_free_reserved_phys_range(ram_res->start, ram_res->end); insert_resource(&iomem_resource, ram_res);
return 0;}
int crash_shrink_memory(unsigned long new_size){ int ret = 0; unsigned long old_size, low_size;
if (!kexec_trylock()) return -EBUSY;
if (kexec_crash_image) { ret = -ENOENT; goto unlock; }
low_size = crash_resource_size(&crashk_low_res); old_size = crash_resource_size(&crashk_res) + low_size; new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN); if (new_size >= old_size) { ret = (new_size == old_size) ? 0 : -EINVAL; goto unlock; }
/* * (low_size > new_size) implies that low_size is greater than zero. * This also means that if low_size is zero, the else branch is taken. * * If low_size is greater than 0, (low_size > new_size) indicates that * crashk_low_res also needs to be shrunken. Otherwise, only crashk_res * needs to be shrunken. */ if (low_size > new_size) { ret = __crash_shrink_memory(&crashk_res, 0); if (ret) goto unlock;
ret = __crash_shrink_memory(&crashk_low_res, new_size); } else { ret = __crash_shrink_memory(&crashk_res, new_size - low_size); }
/* Swap crashk_res and crashk_low_res if needed */ if (!crashk_res.end && crashk_low_res.end) { crashk_res.start = crashk_low_res.start; crashk_res.end = crashk_low_res.end; release_resource(&crashk_low_res); crashk_low_res.start = 0; crashk_low_res.end = 0; insert_resource(&iomem_resource, &crashk_res); }
unlock: kexec_unlock(); return ret;}
void crash_save_cpu(struct pt_regs *regs, int cpu){ struct elf_prstatus prstatus; u32 *buf;
if ((cpu < 0) || (cpu >= nr_cpu_ids)) return;
/* Using ELF notes here is opportunistic. * I need a well defined structure format * for the data I pass, and I need tags * on the data to indicate what information I have * squirrelled away. ELF notes happen to provide * all of that, so there is no need to invent something new. */ buf = (u32 *)per_cpu_ptr(crash_notes, cpu); if (!buf) return; memset(&prstatus, 0, sizeof(prstatus)); prstatus.common.pr_pid = current->pid; elf_core_copy_regs(&prstatus.pr_reg, regs); buf = append_elf_note(buf, NN_PRSTATUS, NT_PRSTATUS, &prstatus, sizeof(prstatus)); final_note(buf);}
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);
#endif /*CONFIG_CRASH_DUMP*/
#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 kdump * image directly. */int crash_check_hotplug_support(void){ int rc = 0;
crash_hotplug_lock(); /* Obtain lock while reading crash information */ if (!kexec_trylock()) { if (!kexec_in_progress) pr_info("kexec_trylock() failed, kdump image may be inaccurate\n"); crash_hotplug_unlock(); return 0; } if (kexec_crash_image) { rc = kexec_crash_image->hotplug_support; } /* 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 relevant * kexec segments must be updated with latest CPU and Memory resources. * * Architectures must ensure two things for all segments that need * updating during hotplug events: * * 1. Segments must be large enough to accommodate a growing number of * resources. * 2. Exclude the segments from SHA verification. * * For example, on most architectures, the elfcorehdr (which is passed * to the crash kernel via the elfcorehdr= parameter) must include the * new list of CPUs and memory. To make changes to the elfcorehdr, it * should be large enough to permit a growing number of CPU and Memory * resources. One can estimate the elfcorehdr memory size based on * NR_CPUS_DEFAULT and CRASH_MAX_MEMORY_RANGES. The elfcorehdr is * excluded from SHA verification by default if the architecture * supports crash hotplug. */static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu, void *arg){ struct kimage *image;
crash_hotplug_lock(); /* Obtain lock while changing crash information */ if (!kexec_trylock()) { if (!kexec_in_progress) pr_info("kexec_trylock() failed, kdump image 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 kexec segments update is permitted */ if (!image->hotplug_support) 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, arg);
/* 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 *arg){ switch (val) { case MEM_ONLINE: crash_handle_hotplug_event(KEXEC_CRASH_HP_ADD_MEMORY, KEXEC_CRASH_HP_INVALID_CPU, arg); break;
case MEM_OFFLINE: crash_handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_MEMORY, KEXEC_CRASH_HP_INVALID_CPU, arg); 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, NULL); return 0;}
static int crash_cpuhp_offline(unsigned int cpu){ crash_handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_CPU, cpu, NULL); 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