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![Baoquan He](/assets/img/avatar_default.png)
Currently, KEXEC_CORE select CRASH_CORE automatically because crash codes need be built in to avoid compiling error when building kexec code even though the crash dumping functionality is not enabled. E.g -------------------- CONFIG_CRASH_CORE=y CONFIG_KEXEC_CORE=y CONFIG_KEXEC=y CONFIG_KEXEC_FILE=y --------------------- After splitting out crashkernel reservation code and vmcoreinfo exporting code, there's only crash related code left in kernel/crash_core.c. Now move crash related codes from kexec_core.c to crash_core.c and only build it in when CONFIG_CRASH_DUMP=y. And also wrap up crash codes inside CONFIG_CRASH_DUMP ifdeffery scope, or replace inappropriate CONFIG_KEXEC_CORE ifdef with CONFIG_CRASH_DUMP ifdef in generic kernel files. With these changes, crash_core codes are abstracted from kexec codes and can be disabled at all if only kexec reboot feature is wanted. Link: https://lkml.kernel.org/r/20240124051254.67105-5-bhe@redhat.com Signed-off-by: Baoquan He <bhe@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Hari Bathini <hbathini@linux.ibm.com> Cc: Pingfan Liu <piliu@redhat.com> Cc: Klara Modin <klarasmodin@gmail.com> Cc: Michael Kelley <mhklinux@outlook.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Yang Li <yang.lee@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
665 lines
18 KiB
C
665 lines
18 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* crash.c - kernel crash support code.
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* Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
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*/
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#include <linux/buildid.h>
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#include <linux/init.h>
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#include <linux/utsname.h>
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#include <linux/vmalloc.h>
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#include <linux/sizes.h>
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#include <linux/kexec.h>
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#include <linux/memory.h>
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#include <linux/mm.h>
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#include <linux/cpuhotplug.h>
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#include <linux/memblock.h>
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#include <linux/kmemleak.h>
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#include <linux/crash_core.h>
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#include <linux/reboot.h>
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#include <linux/btf.h>
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#include <linux/objtool.h>
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#include <asm/page.h>
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#include <asm/sections.h>
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#include <crypto/sha1.h>
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#include "kallsyms_internal.h"
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#include "kexec_internal.h"
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/* Per cpu memory for storing cpu states in case of system crash. */
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note_buf_t __percpu *crash_notes;
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#ifdef CONFIG_CRASH_DUMP
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int kimage_crash_copy_vmcoreinfo(struct kimage *image)
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{
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struct page *vmcoreinfo_page;
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void *safecopy;
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if (!IS_ENABLED(CONFIG_CRASH_DUMP))
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return 0;
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if (image->type != KEXEC_TYPE_CRASH)
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return 0;
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/*
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* For kdump, allocate one vmcoreinfo safe copy from the
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* crash memory. as we have arch_kexec_protect_crashkres()
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* after kexec syscall, we naturally protect it from write
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* (even read) access under kernel direct mapping. But on
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* the other hand, we still need to operate it when crash
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* happens to generate vmcoreinfo note, hereby we rely on
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* vmap for this purpose.
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*/
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vmcoreinfo_page = kimage_alloc_control_pages(image, 0);
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if (!vmcoreinfo_page) {
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pr_warn("Could not allocate vmcoreinfo buffer\n");
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return -ENOMEM;
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}
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safecopy = vmap(&vmcoreinfo_page, 1, VM_MAP, PAGE_KERNEL);
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if (!safecopy) {
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pr_warn("Could not vmap vmcoreinfo buffer\n");
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return -ENOMEM;
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}
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image->vmcoreinfo_data_copy = safecopy;
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crash_update_vmcoreinfo_safecopy(safecopy);
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return 0;
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}
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int kexec_should_crash(struct task_struct *p)
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{
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/*
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* If crash_kexec_post_notifiers is enabled, don't run
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* crash_kexec() here yet, which must be run after panic
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* notifiers in panic().
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*/
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if (crash_kexec_post_notifiers)
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return 0;
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/*
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* There are 4 panic() calls in make_task_dead() path, each of which
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* corresponds to each of these 4 conditions.
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*/
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if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
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return 1;
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return 0;
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}
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int kexec_crash_loaded(void)
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{
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return !!kexec_crash_image;
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}
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EXPORT_SYMBOL_GPL(kexec_crash_loaded);
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/*
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* No panic_cpu check version of crash_kexec(). This function is called
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* only when panic_cpu holds the current CPU number; this is the only CPU
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* which processes crash_kexec routines.
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*/
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void __noclone __crash_kexec(struct pt_regs *regs)
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{
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/* Take the kexec_lock here to prevent sys_kexec_load
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* running on one cpu from replacing the crash kernel
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* we are using after a panic on a different cpu.
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*
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* If the crash kernel was not located in a fixed area
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* of memory the xchg(&kexec_crash_image) would be
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* sufficient. But since I reuse the memory...
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*/
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if (kexec_trylock()) {
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if (kexec_crash_image) {
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struct pt_regs fixed_regs;
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crash_setup_regs(&fixed_regs, regs);
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crash_save_vmcoreinfo();
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machine_crash_shutdown(&fixed_regs);
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machine_kexec(kexec_crash_image);
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}
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kexec_unlock();
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}
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}
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STACK_FRAME_NON_STANDARD(__crash_kexec);
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__bpf_kfunc void crash_kexec(struct pt_regs *regs)
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{
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int old_cpu, this_cpu;
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/*
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* Only one CPU is allowed to execute the crash_kexec() code as with
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* panic(). Otherwise parallel calls of panic() and crash_kexec()
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* may stop each other. To exclude them, we use panic_cpu here too.
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*/
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old_cpu = PANIC_CPU_INVALID;
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this_cpu = raw_smp_processor_id();
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if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
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/* This is the 1st CPU which comes here, so go ahead. */
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__crash_kexec(regs);
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/*
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* Reset panic_cpu to allow another panic()/crash_kexec()
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* call.
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*/
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atomic_set(&panic_cpu, PANIC_CPU_INVALID);
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}
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}
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static inline resource_size_t crash_resource_size(const struct resource *res)
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{
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return !res->end ? 0 : resource_size(res);
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}
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int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
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void **addr, unsigned long *sz)
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{
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Elf64_Ehdr *ehdr;
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Elf64_Phdr *phdr;
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unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
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unsigned char *buf;
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unsigned int cpu, i;
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unsigned long long notes_addr;
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unsigned long mstart, mend;
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/* extra phdr for vmcoreinfo ELF note */
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nr_phdr = nr_cpus + 1;
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nr_phdr += mem->nr_ranges;
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/*
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* kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
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* area (for example, ffffffff80000000 - ffffffffa0000000 on x86_64).
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* I think this is required by tools like gdb. So same physical
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* memory will be mapped in two ELF headers. One will contain kernel
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* text virtual addresses and other will have __va(physical) addresses.
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*/
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nr_phdr++;
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elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
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elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);
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buf = vzalloc(elf_sz);
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if (!buf)
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return -ENOMEM;
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ehdr = (Elf64_Ehdr *)buf;
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phdr = (Elf64_Phdr *)(ehdr + 1);
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memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
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ehdr->e_ident[EI_CLASS] = ELFCLASS64;
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ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
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ehdr->e_ident[EI_VERSION] = EV_CURRENT;
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ehdr->e_ident[EI_OSABI] = ELF_OSABI;
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memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
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ehdr->e_type = ET_CORE;
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ehdr->e_machine = ELF_ARCH;
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ehdr->e_version = EV_CURRENT;
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ehdr->e_phoff = sizeof(Elf64_Ehdr);
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ehdr->e_ehsize = sizeof(Elf64_Ehdr);
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ehdr->e_phentsize = sizeof(Elf64_Phdr);
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/* Prepare one phdr of type PT_NOTE for each possible CPU */
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for_each_possible_cpu(cpu) {
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phdr->p_type = PT_NOTE;
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notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
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phdr->p_offset = phdr->p_paddr = notes_addr;
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phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
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(ehdr->e_phnum)++;
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phdr++;
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}
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/* Prepare one PT_NOTE header for vmcoreinfo */
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phdr->p_type = PT_NOTE;
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phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
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phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
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(ehdr->e_phnum)++;
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phdr++;
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/* Prepare PT_LOAD type program header for kernel text region */
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if (need_kernel_map) {
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phdr->p_type = PT_LOAD;
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phdr->p_flags = PF_R|PF_W|PF_X;
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phdr->p_vaddr = (unsigned long) _text;
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phdr->p_filesz = phdr->p_memsz = _end - _text;
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phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
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ehdr->e_phnum++;
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phdr++;
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}
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/* Go through all the ranges in mem->ranges[] and prepare phdr */
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for (i = 0; i < mem->nr_ranges; i++) {
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mstart = mem->ranges[i].start;
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mend = mem->ranges[i].end;
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phdr->p_type = PT_LOAD;
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phdr->p_flags = PF_R|PF_W|PF_X;
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phdr->p_offset = mstart;
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phdr->p_paddr = mstart;
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phdr->p_vaddr = (unsigned long) __va(mstart);
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phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
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phdr->p_align = 0;
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ehdr->e_phnum++;
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#ifdef CONFIG_KEXEC_FILE
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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",
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phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
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ehdr->e_phnum, phdr->p_offset);
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#endif
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phdr++;
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}
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*addr = buf;
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*sz = elf_sz;
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return 0;
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}
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int crash_exclude_mem_range(struct crash_mem *mem,
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unsigned long long mstart, unsigned long long mend)
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{
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int i;
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unsigned long long start, end, p_start, p_end;
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for (i = 0; i < mem->nr_ranges; i++) {
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start = mem->ranges[i].start;
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end = mem->ranges[i].end;
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p_start = mstart;
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p_end = mend;
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if (p_start > end)
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continue;
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/*
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* Because the memory ranges in mem->ranges are stored in
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* ascending order, when we detect `p_end < start`, we can
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* immediately exit the for loop, as the subsequent memory
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* ranges will definitely be outside the range we are looking
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* for.
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*/
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if (p_end < start)
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break;
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/* Truncate any area outside of range */
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if (p_start < start)
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p_start = start;
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if (p_end > end)
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p_end = end;
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/* Found completely overlapping range */
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if (p_start == start && p_end == end) {
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memmove(&mem->ranges[i], &mem->ranges[i + 1],
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(mem->nr_ranges - (i + 1)) * sizeof(mem->ranges[i]));
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i--;
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mem->nr_ranges--;
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} else if (p_start > start && p_end < end) {
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/* Split original range */
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if (mem->nr_ranges >= mem->max_nr_ranges)
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return -ENOMEM;
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memmove(&mem->ranges[i + 2], &mem->ranges[i + 1],
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(mem->nr_ranges - (i + 1)) * sizeof(mem->ranges[i]));
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mem->ranges[i].end = p_start - 1;
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mem->ranges[i + 1].start = p_end + 1;
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mem->ranges[i + 1].end = end;
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i++;
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mem->nr_ranges++;
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} else if (p_start != start)
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mem->ranges[i].end = p_start - 1;
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else
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mem->ranges[i].start = p_end + 1;
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}
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return 0;
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}
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ssize_t crash_get_memory_size(void)
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{
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ssize_t size = 0;
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if (!kexec_trylock())
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return -EBUSY;
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size += crash_resource_size(&crashk_res);
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size += crash_resource_size(&crashk_low_res);
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kexec_unlock();
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return size;
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}
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static int __crash_shrink_memory(struct resource *old_res,
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unsigned long new_size)
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{
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struct resource *ram_res;
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ram_res = kzalloc(sizeof(*ram_res), GFP_KERNEL);
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if (!ram_res)
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return -ENOMEM;
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ram_res->start = old_res->start + new_size;
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ram_res->end = old_res->end;
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ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM;
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ram_res->name = "System RAM";
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if (!new_size) {
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release_resource(old_res);
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old_res->start = 0;
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old_res->end = 0;
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} else {
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crashk_res.end = ram_res->start - 1;
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}
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crash_free_reserved_phys_range(ram_res->start, ram_res->end);
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insert_resource(&iomem_resource, ram_res);
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return 0;
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}
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int crash_shrink_memory(unsigned long new_size)
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{
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int ret = 0;
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unsigned long old_size, low_size;
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if (!kexec_trylock())
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return -EBUSY;
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if (kexec_crash_image) {
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ret = -ENOENT;
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goto unlock;
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}
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low_size = crash_resource_size(&crashk_low_res);
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old_size = crash_resource_size(&crashk_res) + low_size;
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new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN);
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if (new_size >= old_size) {
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ret = (new_size == old_size) ? 0 : -EINVAL;
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goto unlock;
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}
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/*
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* (low_size > new_size) implies that low_size is greater than zero.
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* This also means that if low_size is zero, the else branch is taken.
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*
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* If low_size is greater than 0, (low_size > new_size) indicates that
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* crashk_low_res also needs to be shrunken. Otherwise, only crashk_res
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* needs to be shrunken.
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*/
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if (low_size > new_size) {
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ret = __crash_shrink_memory(&crashk_res, 0);
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if (ret)
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goto unlock;
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ret = __crash_shrink_memory(&crashk_low_res, new_size);
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} else {
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ret = __crash_shrink_memory(&crashk_res, new_size - low_size);
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}
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/* Swap crashk_res and crashk_low_res if needed */
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if (!crashk_res.end && crashk_low_res.end) {
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crashk_res.start = crashk_low_res.start;
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crashk_res.end = crashk_low_res.end;
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release_resource(&crashk_low_res);
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crashk_low_res.start = 0;
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crashk_low_res.end = 0;
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insert_resource(&iomem_resource, &crashk_res);
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}
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unlock:
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kexec_unlock();
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return ret;
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}
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void crash_save_cpu(struct pt_regs *regs, int cpu)
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{
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struct elf_prstatus prstatus;
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u32 *buf;
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if ((cpu < 0) || (cpu >= nr_cpu_ids))
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return;
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/* Using ELF notes here is opportunistic.
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* I need a well defined structure format
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* for the data I pass, and I need tags
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* on the data to indicate what information I have
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* squirrelled away. ELF notes happen to provide
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* all of that, so there is no need to invent something new.
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*/
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buf = (u32 *)per_cpu_ptr(crash_notes, cpu);
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if (!buf)
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return;
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memset(&prstatus, 0, sizeof(prstatus));
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prstatus.common.pr_pid = current->pid;
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elf_core_copy_regs(&prstatus.pr_reg, regs);
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buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
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&prstatus, sizeof(prstatus));
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final_note(buf);
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}
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static int __init crash_notes_memory_init(void)
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{
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/* Allocate memory for saving cpu registers. */
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size_t size, align;
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/*
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* crash_notes could be allocated across 2 vmalloc pages when percpu
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* is vmalloc based . vmalloc doesn't guarantee 2 continuous vmalloc
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* pages are also on 2 continuous physical pages. In this case the
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* 2nd part of crash_notes in 2nd page could be lost since only the
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* starting address and size of crash_notes are exported through sysfs.
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* Here round up the size of crash_notes to the nearest power of two
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* and pass it to __alloc_percpu as align value. This can make sure
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* crash_notes is allocated inside one physical page.
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*/
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size = sizeof(note_buf_t);
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align = min(roundup_pow_of_two(sizeof(note_buf_t)), PAGE_SIZE);
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/*
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* 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 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
|