// SPDX-License-Identifier: GPL-2.0-only
/*
 *      fs/proc/vmcore.c Interface for accessing the crash
 *                               dump from the system's previous life.
 *      Heavily borrowed from fs/proc/kcore.c
 *      Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
 *      Copyright (C) IBM Corporation, 2004. All rights reserved
 *
 */

#define pr_fmt(fmt) "vmcore: " fmt

#include <linux/mm.h>
#include <linux/kcore.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/printk.h>
#include <linux/memblock.h>
#include <linux/init.h>
#include <linux/crash_dump.h>
#include <linux/list.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/uio.h>
#include <linux/cc_platform.h>
#include <asm/io.h>
#include "internal.h"

/* List representing chunks of contiguous memory areas and their offsets in
 * vmcore file.
 */
static LIST_HEAD(vmcore_list);

/* Stores the pointer to the buffer containing kernel elf core headers. */
static char *elfcorebuf;
static size_t elfcorebuf_sz;
static size_t elfcorebuf_sz_orig;

static char *elfnotes_buf;
static size_t elfnotes_sz;
/* Size of all notes minus the device dump notes */
static size_t elfnotes_orig_sz;

/* Total size of vmcore file. */
static u64 vmcore_size;

static struct proc_dir_entry *proc_vmcore;

#ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
struct vmcoredd_node {
        struct list_head list;  /* List of dumps */
        void *buf;              /* Buffer containing device's dump */
        unsigned int size;      /* Size of the buffer */
};

/* Device Dump list and mutex to synchronize access to list */
static LIST_HEAD(vmcoredd_list);

static bool vmcoredd_disabled;
core_param(novmcoredd, vmcoredd_disabled, bool, 0);
#endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */

/* Device Dump Size */
static size_t vmcoredd_orig_sz;

static DEFINE_MUTEX(vmcore_mutex);

DEFINE_STATIC_SRCU(vmcore_cb_srcu);
/* List of registered vmcore callbacks. */
static LIST_HEAD(vmcore_cb_list);
/* Whether the vmcore has been opened once. */
static bool vmcore_opened;
/* Whether the vmcore is currently open. */
static unsigned int vmcore_open;

static void vmcore_process_device_ram(struct vmcore_cb *cb);

void register_vmcore_cb(struct vmcore_cb *cb)
{
        INIT_LIST_HEAD(&cb->next);
        mutex_lock(&vmcore_mutex);
        list_add_tail(&cb->next, &vmcore_cb_list);
        /*
         * Registering a vmcore callback after the vmcore was opened is
         * very unusual (e.g., manual driver loading).
         */
        if (vmcore_opened)
                pr_warn_once("Unexpected vmcore callback registration\n");
        if (!vmcore_open && cb->get_device_ram)
                vmcore_process_device_ram(cb);
        mutex_unlock(&vmcore_mutex);
}
EXPORT_SYMBOL_GPL(register_vmcore_cb);

void unregister_vmcore_cb(struct vmcore_cb *cb)
{
        mutex_lock(&vmcore_mutex);
        list_del_rcu(&cb->next);
        /*
         * Unregistering a vmcore callback after the vmcore was opened is
         * very unusual (e.g., forced driver removal), but we cannot stop
         * unregistering.
         */
        if (vmcore_opened)
                pr_warn_once("Unexpected vmcore callback unregistration\n");
        mutex_unlock(&vmcore_mutex);

        synchronize_srcu(&vmcore_cb_srcu);
}
EXPORT_SYMBOL_GPL(unregister_vmcore_cb);

static bool pfn_is_ram(unsigned long pfn)
{
        struct vmcore_cb *cb;
        bool ret = true;

        list_for_each_entry_srcu(cb, &vmcore_cb_list, next,
                                 srcu_read_lock_held(&vmcore_cb_srcu)) {
                if (unlikely(!cb->pfn_is_ram))
                        continue;
                ret = cb->pfn_is_ram(cb, pfn);
                if (!ret)
                        break;
        }

        return ret;
}

static int open_vmcore(struct inode *inode, struct file *file)
{
        mutex_lock(&vmcore_mutex);
        vmcore_opened = true;
        if (vmcore_open + 1 == 0) {
                mutex_unlock(&vmcore_mutex);
                return -EBUSY;
        }
        vmcore_open++;
        mutex_unlock(&vmcore_mutex);

        return 0;
}

static int release_vmcore(struct inode *inode, struct file *file)
{
        mutex_lock(&vmcore_mutex);
        vmcore_open--;
        mutex_unlock(&vmcore_mutex);

        return 0;
}

/* Reads a page from the oldmem device from given offset. */
ssize_t read_from_oldmem(struct iov_iter *iter, size_t count,
                         u64 *ppos, bool encrypted)
{
        unsigned long pfn, offset;
        ssize_t nr_bytes;
        ssize_t read = 0, tmp;
        int idx;

        if (!count)
                return 0;

        offset = (unsigned long)(*ppos % PAGE_SIZE);
        pfn = (unsigned long)(*ppos / PAGE_SIZE);

        idx = srcu_read_lock(&vmcore_cb_srcu);
        do {
                if (count > (PAGE_SIZE - offset))
                        nr_bytes = PAGE_SIZE - offset;
                else
                        nr_bytes = count;

                /* If pfn is not ram, return zeros for sparse dump files */
                if (!pfn_is_ram(pfn)) {
                        tmp = iov_iter_zero(nr_bytes, iter);
                } else {
                        if (encrypted)
                                tmp = copy_oldmem_page_encrypted(iter, pfn,
                                                                 nr_bytes,
                                                                 offset);
                        else
                                tmp = copy_oldmem_page(iter, pfn, nr_bytes,
                                                       offset);
                }
                if (tmp < nr_bytes) {
                        srcu_read_unlock(&vmcore_cb_srcu, idx);
                        return -EFAULT;
                }

                *ppos += nr_bytes;
                count -= nr_bytes;
                read += nr_bytes;
                ++pfn;
                offset = 0;
        } while (count);
        srcu_read_unlock(&vmcore_cb_srcu, idx);

        return read;
}

/*
 * Architectures may override this function to allocate ELF header in 2nd kernel
 */
int __weak elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size)
{
        return 0;
}

/*
 * Architectures may override this function to free header
 */
void __weak elfcorehdr_free(unsigned long long addr)
{}

/*
 * Architectures may override this function to read from ELF header
 */
ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
{
        struct kvec kvec = { .iov_base = buf, .iov_len = count };
        struct iov_iter iter;

        iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);

        return read_from_oldmem(&iter, count, ppos, false);
}

/*
 * Architectures may override this function to read from notes sections
 */
ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
{
        struct kvec kvec = { .iov_base = buf, .iov_len = count };
        struct iov_iter iter;

        iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);

        return read_from_oldmem(&iter, count, ppos,
                        cc_platform_has(CC_ATTR_MEM_ENCRYPT));
}

/*
 * Architectures may override this function to map oldmem
 */
int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma,
                                  unsigned long from, unsigned long pfn,
                                  unsigned long size, pgprot_t prot)
{
        prot = pgprot_encrypted(prot);
        return remap_pfn_range(vma, from, pfn, size, prot);
}

/*
 * Architectures which support memory encryption override this.
 */
ssize_t __weak copy_oldmem_page_encrypted(struct iov_iter *iter,
                unsigned long pfn, size_t csize, unsigned long offset)
{
        return copy_oldmem_page(iter, pfn, csize, offset);
}

#ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
static int vmcoredd_copy_dumps(struct iov_iter *iter, u64 start, size_t size)
{
        struct vmcoredd_node *dump;
        u64 offset = 0;
        size_t tsz;
        char *buf;

        list_for_each_entry(dump, &vmcoredd_list, list) {
                if (start < offset + dump->size) {
                        tsz = min(offset + (u64)dump->size - start, (u64)size);
                        buf = dump->buf + start - offset;
                        if (copy_to_iter(buf, tsz, iter) < tsz)
                                return -EFAULT;

                        size -= tsz;
                        start += tsz;

                        /* Leave now if buffer filled already */
                        if (!size)
                                return 0;
                }
                offset += dump->size;
        }

        return 0;
}

#ifdef CONFIG_MMU
static int vmcoredd_mmap_dumps(struct vm_area_struct *vma, unsigned long dst,
                               u64 start, size_t size)
{
        struct vmcoredd_node *dump;
        u64 offset = 0;
        size_t tsz;
        char *buf;

        list_for_each_entry(dump, &vmcoredd_list, list) {
                if (start < offset + dump->size) {
                        tsz = min(offset + (u64)dump->size - start, (u64)size);
                        buf = dump->buf + start - offset;
                        if (remap_vmalloc_range_partial(vma, dst, buf, 0,
                                                        tsz))
                                return -EFAULT;

                        size -= tsz;
                        start += tsz;
                        dst += tsz;

                        /* Leave now if buffer filled already */
                        if (!size)
                                return 0;
                }
                offset += dump->size;
        }

        return 0;
}
#endif /* CONFIG_MMU */
#endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */

/* Read from the ELF header and then the crash dump. On error, negative value is
 * returned otherwise number of bytes read are returned.
 */
static ssize_t __read_vmcore(struct iov_iter *iter, loff_t *fpos)
{
        struct vmcore_range *m = NULL;
        ssize_t acc = 0, tmp;
        size_t tsz;
        u64 start;

        if (!iov_iter_count(iter) || *fpos >= vmcore_size)
                return 0;

        iov_iter_truncate(iter, vmcore_size - *fpos);

        /* Read ELF core header */
        if (*fpos < elfcorebuf_sz) {
                tsz = min(elfcorebuf_sz - (size_t)*fpos, iov_iter_count(iter));
                if (copy_to_iter(elfcorebuf + *fpos, tsz, iter) < tsz)
                        return -EFAULT;
                *fpos += tsz;
                acc += tsz;

                /* leave now if filled buffer already */
                if (!iov_iter_count(iter))
                        return acc;
        }

        /* Read ELF note segment */
        if (*fpos < elfcorebuf_sz + elfnotes_sz) {
                void *kaddr;

                /* We add device dumps before other elf notes because the
                 * other elf notes may not fill the elf notes buffer
                 * completely and we will end up with zero-filled data
                 * between the elf notes and the device dumps. Tools will
                 * then try to decode this zero-filled data as valid notes
                 * and we don't want that. Hence, adding device dumps before
                 * the other elf notes ensure that zero-filled data can be
                 * avoided.
                 */
#ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
                /* Read device dumps */
                if (*fpos < elfcorebuf_sz + vmcoredd_orig_sz) {
                        tsz = min(elfcorebuf_sz + vmcoredd_orig_sz -
                                  (size_t)*fpos, iov_iter_count(iter));
                        start = *fpos - elfcorebuf_sz;
                        if (vmcoredd_copy_dumps(iter, start, tsz))
                                return -EFAULT;

                        *fpos += tsz;
                        acc += tsz;

                        /* leave now if filled buffer already */
                        if (!iov_iter_count(iter))
                                return acc;
                }
#endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */

                /* Read remaining elf notes */
                tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)*fpos,
                          iov_iter_count(iter));
                kaddr = elfnotes_buf + *fpos - elfcorebuf_sz - vmcoredd_orig_sz;
                if (copy_to_iter(kaddr, tsz, iter) < tsz)
                        return -EFAULT;

                *fpos += tsz;
                acc += tsz;

                /* leave now if filled buffer already */
                if (!iov_iter_count(iter))
                        return acc;

                cond_resched();
        }

        list_for_each_entry(m, &vmcore_list, list) {
                if (*fpos < m->offset + m->size) {
                        tsz = (size_t)min_t(unsigned long long,
                                            m->offset + m->size - *fpos,
                                            iov_iter_count(iter));
                        start = m->paddr + *fpos - m->offset;
                        tmp = read_from_oldmem(iter, tsz, &start,
                                        cc_platform_has(CC_ATTR_MEM_ENCRYPT));
                        if (tmp < 0)
                                return tmp;
                        *fpos += tsz;
                        acc += tsz;

                        /* leave now if filled buffer already */
                        if (!iov_iter_count(iter))
                                return acc;
                }

                cond_resched();
        }

        return acc;
}

static ssize_t read_vmcore(struct kiocb *iocb, struct iov_iter *iter)
{
        return __read_vmcore(iter, &iocb->ki_pos);
}

/**
 * vmcore_alloc_buf - allocate buffer in vmalloc memory
 * @size: size of buffer
 *
 * If CONFIG_MMU is defined, use vmalloc_user() to allow users to mmap
 * the buffer to user-space by means of remap_vmalloc_range().
 *
 * If CONFIG_MMU is not defined, use vzalloc() since mmap_vmcore() is
 * disabled and there's no need to allow users to mmap the buffer.
 */
static inline char *vmcore_alloc_buf(size_t size)
{
#ifdef CONFIG_MMU
        return vmalloc_user(size);
#else
        return vzalloc(size);
#endif
}

/*
 * Disable mmap_vmcore() if CONFIG_MMU is not defined. MMU is
 * essential for mmap_vmcore() in order to map physically
 * non-contiguous objects (ELF header, ELF note segment and memory
 * regions in the 1st kernel pointed to by PT_LOAD entries) into
 * virtually contiguous user-space in ELF layout.
 */
#ifdef CONFIG_MMU

/*
 * The vmcore fault handler uses the page cache and fills data using the
 * standard __read_vmcore() function.
 *
 * On s390 the fault handler is used for memory regions that can't be mapped
 * directly with remap_pfn_range().
 */
static vm_fault_t mmap_vmcore_fault(struct vm_fault *vmf)
{
#ifdef CONFIG_S390
        struct address_space *mapping = vmf->vma->vm_file->f_mapping;
        pgoff_t index = vmf->pgoff;
        struct iov_iter iter;
        struct kvec kvec;
        struct page *page;
        loff_t offset;
        int rc;

        page = find_or_create_page(mapping, index, GFP_KERNEL);
        if (!page)
                return VM_FAULT_OOM;
        if (!PageUptodate(page)) {
                offset = (loff_t) index << PAGE_SHIFT;
                kvec.iov_base = page_address(page);
                kvec.iov_len = PAGE_SIZE;
                iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, PAGE_SIZE);

                rc = __read_vmcore(&iter, &offset);
                if (rc < 0) {
                        unlock_page(page);
                        put_page(page);
                        return vmf_error(rc);
                }
                SetPageUptodate(page);
        }
        unlock_page(page);
        vmf->page = page;
        return 0;
#else
        return VM_FAULT_SIGBUS;
#endif
}

static const struct vm_operations_struct vmcore_mmap_ops = {
        .fault = mmap_vmcore_fault,
};

/*
 * remap_oldmem_pfn_checked - do remap_oldmem_pfn_range replacing all pages
 * reported as not being ram with the zero page.
 *
 * @vma: vm_area_struct describing requested mapping
 * @from: start remapping from
 * @pfn: page frame number to start remapping to
 * @size: remapping size
 * @prot: protection bits
 *
 * Returns zero on success, -EAGAIN on failure.
 */
static int remap_oldmem_pfn_checked(struct vm_area_struct *vma,
                                    unsigned long from, unsigned long pfn,
                                    unsigned long size, pgprot_t prot)
{
        unsigned long map_size;
        unsigned long pos_start, pos_end, pos;
        unsigned long zeropage_pfn = my_zero_pfn(0);
        size_t len = 0;

        pos_start = pfn;
        pos_end = pfn + (size >> PAGE_SHIFT);

        for (pos = pos_start; pos < pos_end; ++pos) {
                if (!pfn_is_ram(pos)) {
                        /*
                         * We hit a page which is not ram. Remap the continuous
                         * region between pos_start and pos-1 and replace
                         * the non-ram page at pos with the zero page.
                         */
                        if (pos > pos_start) {
                                /* Remap continuous region */
                                map_size = (pos - pos_start) << PAGE_SHIFT;
                                if (remap_oldmem_pfn_range(vma, from + len,
                                                           pos_start, map_size,
                                                           prot))
                                        goto fail;
                                len += map_size;
                        }
                        /* Remap the zero page */
                        if (remap_oldmem_pfn_range(vma, from + len,
                                                   zeropage_pfn,
                                                   PAGE_SIZE, prot))
                                goto fail;
                        len += PAGE_SIZE;
                        pos_start = pos + 1;
                }
        }
        if (pos > pos_start) {
                /* Remap the rest */
                map_size = (pos - pos_start) << PAGE_SHIFT;
                if (remap_oldmem_pfn_range(vma, from + len, pos_start,
                                           map_size, prot))
                        goto fail;
        }
        return 0;
fail:
        do_munmap(vma->vm_mm, from, len, NULL);
        return -EAGAIN;
}

static int vmcore_remap_oldmem_pfn(struct vm_area_struct *vma,
                            unsigned long from, unsigned long pfn,
                            unsigned long size, pgprot_t prot)
{
        int ret, idx;

        /*
         * Check if a callback was registered to avoid looping over all
         * pages without a reason.
         */
        idx = srcu_read_lock(&vmcore_cb_srcu);
        if (!list_empty(&vmcore_cb_list))
                ret = remap_oldmem_pfn_checked(vma, from, pfn, size, prot);
        else
                ret = remap_oldmem_pfn_range(vma, from, pfn, size, prot);
        srcu_read_unlock(&vmcore_cb_srcu, idx);
        return ret;
}

static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
{
        size_t size = vma->vm_end - vma->vm_start;
        u64 start, end, len, tsz;
        struct vmcore_range *m;

        start = (u64)vma->vm_pgoff << PAGE_SHIFT;
        end = start + size;

        if (size > vmcore_size || end > vmcore_size)
                return -EINVAL;

        if (vma->vm_flags & (VM_WRITE | VM_EXEC))
                return -EPERM;

        vm_flags_mod(vma, VM_MIXEDMAP, VM_MAYWRITE | VM_MAYEXEC);
        vma->vm_ops = &vmcore_mmap_ops;

        len = 0;

        if (start < elfcorebuf_sz) {
                u64 pfn;

                tsz = min(elfcorebuf_sz - (size_t)start, size);
                pfn = __pa(elfcorebuf + start) >> PAGE_SHIFT;
                if (remap_pfn_range(vma, vma->vm_start, pfn, tsz,
                                    vma->vm_page_prot))
                        return -EAGAIN;
                size -= tsz;
                start += tsz;
                len += tsz;

                if (size == 0)
                        return 0;
        }

        if (start < elfcorebuf_sz + elfnotes_sz) {
                void *kaddr;

                /* We add device dumps before other elf notes because the
                 * other elf notes may not fill the elf notes buffer
                 * completely and we will end up with zero-filled data
                 * between the elf notes and the device dumps. Tools will
                 * then try to decode this zero-filled data as valid notes
                 * and we don't want that. Hence, adding device dumps before
                 * the other elf notes ensure that zero-filled data can be
                 * avoided. This also ensures that the device dumps and
                 * other elf notes can be properly mmaped at page aligned
                 * address.
                 */
#ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
                /* Read device dumps */
                if (start < elfcorebuf_sz + vmcoredd_orig_sz) {
                        u64 start_off;

                        tsz = min(elfcorebuf_sz + vmcoredd_orig_sz -
                                  (size_t)start, size);
                        start_off = start - elfcorebuf_sz;
                        if (vmcoredd_mmap_dumps(vma, vma->vm_start + len,
                                                start_off, tsz))
                                goto fail;

                        size -= tsz;
                        start += tsz;
                        len += tsz;

                        /* leave now if filled buffer already */
                        if (!size)
                                return 0;
                }
#endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */

                /* Read remaining elf notes */
                tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)start, size);
                kaddr = elfnotes_buf + start - elfcorebuf_sz - vmcoredd_orig_sz;
                if (remap_vmalloc_range_partial(vma, vma->vm_start + len,
                                                kaddr, 0, tsz))
                        goto fail;

                size -= tsz;
                start += tsz;
                len += tsz;

                if (size == 0)
                        return 0;
        }

        list_for_each_entry(m, &vmcore_list, list) {
                if (start < m->offset + m->size) {
                        u64 paddr = 0;

                        tsz = (size_t)min_t(unsigned long long,
                                            m->offset + m->size - start, size);
                        paddr = m->paddr + start - m->offset;
                        if (vmcore_remap_oldmem_pfn(vma, vma->vm_start + len,
                                                    paddr >> PAGE_SHIFT, tsz,
                                                    vma->vm_page_prot))
                                goto fail;
                        size -= tsz;
                        start += tsz;
                        len += tsz;

                        if (size == 0)
                                return 0;
                }
        }

        return 0;
fail:
        do_munmap(vma->vm_mm, vma->vm_start, len, NULL);
        return -EAGAIN;
}
#else
static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
{
        return -ENOSYS;
}
#endif

static const struct proc_ops vmcore_proc_ops = {
        .proc_open      = open_vmcore,
        .proc_release   = release_vmcore,
        .proc_read_iter = read_vmcore,
        .proc_lseek     = default_llseek,
        .proc_mmap      = mmap_vmcore,
};

static u64 get_vmcore_size(size_t elfsz, size_t elfnotesegsz,
                           struct list_head *vc_list)
{
        struct vmcore_range *m;
        u64 size;

        size = elfsz + elfnotesegsz;
        list_for_each_entry(m, vc_list, list) {
                size += m->size;
        }
        return size;
}

/**
 * update_note_header_size_elf64 - update p_memsz member of each PT_NOTE entry
 *
 * @ehdr_ptr: ELF header
 *
 * This function updates p_memsz member of each PT_NOTE entry in the
 * program header table pointed to by @ehdr_ptr to real size of ELF
 * note segment.
 */
static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr)
{
        int i, rc=0;
        Elf64_Phdr *phdr_ptr;
        Elf64_Nhdr *nhdr_ptr;

        phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                void *notes_section;
                u64 offset, max_sz, sz, real_sz = 0;
                if (phdr_ptr->p_type != PT_NOTE)
                        continue;
                max_sz = phdr_ptr->p_memsz;
                offset = phdr_ptr->p_offset;
                notes_section = kmalloc(max_sz, GFP_KERNEL);
                if (!notes_section)
                        return -ENOMEM;
                rc = elfcorehdr_read_notes(notes_section, max_sz, &offset);
                if (rc < 0) {
                        kfree(notes_section);
                        return rc;
                }
                nhdr_ptr = notes_section;
                while (nhdr_ptr->n_namesz != 0) {
                        sz = sizeof(Elf64_Nhdr) +
                                (((u64)nhdr_ptr->n_namesz + 3) & ~3) +
                                (((u64)nhdr_ptr->n_descsz + 3) & ~3);
                        if ((real_sz + sz) > max_sz) {
                                pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n",
                                        nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
                                break;
                        }
                        real_sz += sz;
                        nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
                }
                kfree(notes_section);
                phdr_ptr->p_memsz = real_sz;
                if (real_sz == 0) {
                        pr_warn("Warning: Zero PT_NOTE entries found\n");
                }
        }

        return 0;
}

/**
 * get_note_number_and_size_elf64 - get the number of PT_NOTE program
 * headers and sum of real size of their ELF note segment headers and
 * data.
 *
 * @ehdr_ptr: ELF header
 * @nr_ptnote: buffer for the number of PT_NOTE program headers
 * @sz_ptnote: buffer for size of unique PT_NOTE program header
 *
 * This function is used to merge multiple PT_NOTE program headers
 * into a unique single one. The resulting unique entry will have
 * @sz_ptnote in its phdr->p_mem.
 *
 * It is assumed that program headers with PT_NOTE type pointed to by
 * @ehdr_ptr has already been updated by update_note_header_size_elf64
 * and each of PT_NOTE program headers has actual ELF note segment
 * size in its p_memsz member.
 */
static int __init get_note_number_and_size_elf64(const Elf64_Ehdr *ehdr_ptr,
                                                 int *nr_ptnote, u64 *sz_ptnote)
{
        int i;
        Elf64_Phdr *phdr_ptr;

        *nr_ptnote = *sz_ptnote = 0;

        phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                if (phdr_ptr->p_type != PT_NOTE)
                        continue;
                *nr_ptnote += 1;
                *sz_ptnote += phdr_ptr->p_memsz;
        }

        return 0;
}

/**
 * copy_notes_elf64 - copy ELF note segments in a given buffer
 *
 * @ehdr_ptr: ELF header
 * @notes_buf: buffer into which ELF note segments are copied
 *
 * This function is used to copy ELF note segment in the 1st kernel
 * into the buffer @notes_buf in the 2nd kernel. It is assumed that
 * size of the buffer @notes_buf is equal to or larger than sum of the
 * real ELF note segment headers and data.
 *
 * It is assumed that program headers with PT_NOTE type pointed to by
 * @ehdr_ptr has already been updated by update_note_header_size_elf64
 * and each of PT_NOTE program headers has actual ELF note segment
 * size in its p_memsz member.
 */
static int __init copy_notes_elf64(const Elf64_Ehdr *ehdr_ptr, char *notes_buf)
{
        int i, rc=0;
        Elf64_Phdr *phdr_ptr;

        phdr_ptr = (Elf64_Phdr*)(ehdr_ptr + 1);

        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                u64 offset;
                if (phdr_ptr->p_type != PT_NOTE)
                        continue;
                offset = phdr_ptr->p_offset;
                rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz,
                                           &offset);
                if (rc < 0)
                        return rc;
                notes_buf += phdr_ptr->p_memsz;
        }

        return 0;
}

/* Merges all the PT_NOTE headers into one. */
static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
                                           char **notes_buf, size_t *notes_sz)
{
        int i, nr_ptnote=0, rc=0;
        char *tmp;
        Elf64_Ehdr *ehdr_ptr;
        Elf64_Phdr phdr;
        u64 phdr_sz = 0, note_off;

        ehdr_ptr = (Elf64_Ehdr *)elfptr;

        rc = update_note_header_size_elf64(ehdr_ptr);
        if (rc < 0)
                return rc;

        rc = get_note_number_and_size_elf64(ehdr_ptr, &nr_ptnote, &phdr_sz);
        if (rc < 0)
                return rc;

        *notes_sz = roundup(phdr_sz, PAGE_SIZE);
        *notes_buf = vmcore_alloc_buf(*notes_sz);
        if (!*notes_buf)
                return -ENOMEM;

        rc = copy_notes_elf64(ehdr_ptr, *notes_buf);
        if (rc < 0)
                return rc;

        /* Prepare merged PT_NOTE program header. */
        phdr.p_type    = PT_NOTE;
        phdr.p_flags   = 0;
        note_off = sizeof(Elf64_Ehdr) +
                        (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr);
        phdr.p_offset  = roundup(note_off, PAGE_SIZE);
        phdr.p_vaddr   = phdr.p_paddr = 0;
        phdr.p_filesz  = phdr.p_memsz = phdr_sz;
        phdr.p_align   = 4;

        /* Add merged PT_NOTE program header*/
        tmp = elfptr + sizeof(Elf64_Ehdr);
        memcpy(tmp, &phdr, sizeof(phdr));
        tmp += sizeof(phdr);

        /* Remove unwanted PT_NOTE program headers. */
        i = (nr_ptnote - 1) * sizeof(Elf64_Phdr);
        *elfsz = *elfsz - i;
        memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr)));
        memset(elfptr + *elfsz, 0, i);
        *elfsz = roundup(*elfsz, PAGE_SIZE);

        /* Modify e_phnum to reflect merged headers. */
        ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;

        /* Store the size of all notes.  We need this to update the note
         * header when the device dumps will be added.
         */
        elfnotes_orig_sz = phdr.p_memsz;

        return 0;
}

/**
 * update_note_header_size_elf32 - update p_memsz member of each PT_NOTE entry
 *
 * @ehdr_ptr: ELF header
 *
 * This function updates p_memsz member of each PT_NOTE entry in the
 * program header table pointed to by @ehdr_ptr to real size of ELF
 * note segment.
 */
static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr)
{
        int i, rc=0;
        Elf32_Phdr *phdr_ptr;
        Elf32_Nhdr *nhdr_ptr;

        phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                void *notes_section;
                u64 offset, max_sz, sz, real_sz = 0;
                if (phdr_ptr->p_type != PT_NOTE)
                        continue;
                max_sz = phdr_ptr->p_memsz;
                offset = phdr_ptr->p_offset;
                notes_section = kmalloc(max_sz, GFP_KERNEL);
                if (!notes_section)
                        return -ENOMEM;
                rc = elfcorehdr_read_notes(notes_section, max_sz, &offset);
                if (rc < 0) {
                        kfree(notes_section);
                        return rc;
                }
                nhdr_ptr = notes_section;
                while (nhdr_ptr->n_namesz != 0) {
                        sz = sizeof(Elf32_Nhdr) +
                                (((u64)nhdr_ptr->n_namesz + 3) & ~3) +
                                (((u64)nhdr_ptr->n_descsz + 3) & ~3);
                        if ((real_sz + sz) > max_sz) {
                                pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n",
                                        nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
                                break;
                        }
                        real_sz += sz;
                        nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
                }
                kfree(notes_section);
                phdr_ptr->p_memsz = real_sz;
                if (real_sz == 0) {
                        pr_warn("Warning: Zero PT_NOTE entries found\n");
                }
        }

        return 0;
}

/**
 * get_note_number_and_size_elf32 - get the number of PT_NOTE program
 * headers and sum of real size of their ELF note segment headers and
 * data.
 *
 * @ehdr_ptr: ELF header
 * @nr_ptnote: buffer for the number of PT_NOTE program headers
 * @sz_ptnote: buffer for size of unique PT_NOTE program header
 *
 * This function is used to merge multiple PT_NOTE program headers
 * into a unique single one. The resulting unique entry will have
 * @sz_ptnote in its phdr->p_mem.
 *
 * It is assumed that program headers with PT_NOTE type pointed to by
 * @ehdr_ptr has already been updated by update_note_header_size_elf32
 * and each of PT_NOTE program headers has actual ELF note segment
 * size in its p_memsz member.
 */
static int __init get_note_number_and_size_elf32(const Elf32_Ehdr *ehdr_ptr,
                                                 int *nr_ptnote, u64 *sz_ptnote)
{
        int i;
        Elf32_Phdr *phdr_ptr;

        *nr_ptnote = *sz_ptnote = 0;

        phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                if (phdr_ptr->p_type != PT_NOTE)
                        continue;
                *nr_ptnote += 1;
                *sz_ptnote += phdr_ptr->p_memsz;
        }

        return 0;
}

/**
 * copy_notes_elf32 - copy ELF note segments in a given buffer
 *
 * @ehdr_ptr: ELF header
 * @notes_buf: buffer into which ELF note segments are copied
 *
 * This function is used to copy ELF note segment in the 1st kernel
 * into the buffer @notes_buf in the 2nd kernel. It is assumed that
 * size of the buffer @notes_buf is equal to or larger than sum of the
 * real ELF note segment headers and data.
 *
 * It is assumed that program headers with PT_NOTE type pointed to by
 * @ehdr_ptr has already been updated by update_note_header_size_elf32
 * and each of PT_NOTE program headers has actual ELF note segment
 * size in its p_memsz member.
 */
static int __init copy_notes_elf32(const Elf32_Ehdr *ehdr_ptr, char *notes_buf)
{
        int i, rc=0;
        Elf32_Phdr *phdr_ptr;

        phdr_ptr = (Elf32_Phdr*)(ehdr_ptr + 1);

        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                u64 offset;
                if (phdr_ptr->p_type != PT_NOTE)
                        continue;
                offset = phdr_ptr->p_offset;
                rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz,
                                           &offset);
                if (rc < 0)
                        return rc;
                notes_buf += phdr_ptr->p_memsz;
        }

        return 0;
}

/* Merges all the PT_NOTE headers into one. */
static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
                                           char **notes_buf, size_t *notes_sz)
{
        int i, nr_ptnote=0, rc=0;
        char *tmp;
        Elf32_Ehdr *ehdr_ptr;
        Elf32_Phdr phdr;
        u64 phdr_sz = 0, note_off;

        ehdr_ptr = (Elf32_Ehdr *)elfptr;

        rc = update_note_header_size_elf32(ehdr_ptr);
        if (rc < 0)
                return rc;

        rc = get_note_number_and_size_elf32(ehdr_ptr, &nr_ptnote, &phdr_sz);
        if (rc < 0)
                return rc;

        *notes_sz = roundup(phdr_sz, PAGE_SIZE);
        *notes_buf = vmcore_alloc_buf(*notes_sz);
        if (!*notes_buf)
                return -ENOMEM;

        rc = copy_notes_elf32(ehdr_ptr, *notes_buf);
        if (rc < 0)
                return rc;

        /* Prepare merged PT_NOTE program header. */
        phdr.p_type    = PT_NOTE;
        phdr.p_flags   = 0;
        note_off = sizeof(Elf32_Ehdr) +
                        (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr);
        phdr.p_offset  = roundup(note_off, PAGE_SIZE);
        phdr.p_vaddr   = phdr.p_paddr = 0;
        phdr.p_filesz  = phdr.p_memsz = phdr_sz;
        phdr.p_align   = 4;

        /* Add merged PT_NOTE program header*/
        tmp = elfptr + sizeof(Elf32_Ehdr);
        memcpy(tmp, &phdr, sizeof(phdr));
        tmp += sizeof(phdr);

        /* Remove unwanted PT_NOTE program headers. */
        i = (nr_ptnote - 1) * sizeof(Elf32_Phdr);
        *elfsz = *elfsz - i;
        memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr)));
        memset(elfptr + *elfsz, 0, i);
        *elfsz = roundup(*elfsz, PAGE_SIZE);

        /* Modify e_phnum to reflect merged headers. */
        ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;

        /* Store the size of all notes.  We need this to update the note
         * header when the device dumps will be added.
         */
        elfnotes_orig_sz = phdr.p_memsz;

        return 0;
}

/* Add memory chunks represented by program headers to vmcore list. Also update
 * the new offset fields of exported program headers. */
static int __init process_ptload_program_headers_elf64(char *elfptr,
                                                size_t elfsz,
                                                size_t elfnotes_sz,
                                                struct list_head *vc_list)
{
        int i;
        Elf64_Ehdr *ehdr_ptr;
        Elf64_Phdr *phdr_ptr;
        loff_t vmcore_off;

        ehdr_ptr = (Elf64_Ehdr *)elfptr;
        phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */

        /* Skip ELF header, program headers and ELF note segment. */
        vmcore_off = elfsz + elfnotes_sz;

        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                u64 paddr, start, end, size;

                if (phdr_ptr->p_type != PT_LOAD)
                        continue;

                paddr = phdr_ptr->p_offset;
                start = rounddown(paddr, PAGE_SIZE);
                end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
                size = end - start;

                if (vmcore_alloc_add_range(vc_list, start, size))
                        return -ENOMEM;

                /* Update the program header offset. */
                phdr_ptr->p_offset = vmcore_off + (paddr - start);
                vmcore_off = vmcore_off + size;
        }
        return 0;
}

static int __init process_ptload_program_headers_elf32(char *elfptr,
                                                size_t elfsz,
                                                size_t elfnotes_sz,
                                                struct list_head *vc_list)
{
        int i;
        Elf32_Ehdr *ehdr_ptr;
        Elf32_Phdr *phdr_ptr;
        loff_t vmcore_off;

        ehdr_ptr = (Elf32_Ehdr *)elfptr;
        phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */

        /* Skip ELF header, program headers and ELF note segment. */
        vmcore_off = elfsz + elfnotes_sz;

        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                u64 paddr, start, end, size;

                if (phdr_ptr->p_type != PT_LOAD)
                        continue;

                paddr = phdr_ptr->p_offset;
                start = rounddown(paddr, PAGE_SIZE);
                end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
                size = end - start;

                if (vmcore_alloc_add_range(vc_list, start, size))
                        return -ENOMEM;

                /* Update the program header offset */
                phdr_ptr->p_offset = vmcore_off + (paddr - start);
                vmcore_off = vmcore_off + size;
        }
        return 0;
}

/* Sets offset fields of vmcore elements. */
static void set_vmcore_list_offsets(size_t elfsz, size_t elfnotes_sz,
                                    struct list_head *vc_list)
{
        struct vmcore_range *m;
        loff_t vmcore_off;

        /* Skip ELF header, program headers and ELF note segment. */
        vmcore_off = elfsz + elfnotes_sz;

        list_for_each_entry(m, vc_list, list) {
                m->offset = vmcore_off;
                vmcore_off += m->size;
        }
}

static void free_elfcorebuf(void)
{
        free_pages((unsigned long)elfcorebuf, get_order(elfcorebuf_sz_orig));
        elfcorebuf = NULL;
        vfree(elfnotes_buf);
        elfnotes_buf = NULL;
}

static int __init parse_crash_elf64_headers(void)
{
        int rc=0;
        Elf64_Ehdr ehdr;
        u64 addr;

        addr = elfcorehdr_addr;

        /* Read ELF header */
        rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf64_Ehdr), &addr);
        if (rc < 0)
                return rc;

        /* Do some basic Verification. */
        if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
                (ehdr.e_type != ET_CORE) ||
                !vmcore_elf64_check_arch(&ehdr) ||
                ehdr.e_ident[EI_CLASS] != ELFCLASS64 ||
                ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
                ehdr.e_version != EV_CURRENT ||
                ehdr.e_ehsize != sizeof(Elf64_Ehdr) ||
                ehdr.e_phentsize != sizeof(Elf64_Phdr) ||
                ehdr.e_phnum == 0) {
                pr_warn("Warning: Core image elf header is not sane\n");
                return -EINVAL;
        }

        /* Read in all elf headers. */
        elfcorebuf_sz_orig = sizeof(Elf64_Ehdr) +
                                ehdr.e_phnum * sizeof(Elf64_Phdr);
        elfcorebuf_sz = elfcorebuf_sz_orig;
        elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
                                              get_order(elfcorebuf_sz_orig));
        if (!elfcorebuf)
                return -ENOMEM;
        addr = elfcorehdr_addr;
        rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr);
        if (rc < 0)
                goto fail;

        /* Merge all PT_NOTE headers into one. */
        rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz,
                                      &elfnotes_buf, &elfnotes_sz);
        if (rc)
                goto fail;
        rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
                                                  elfnotes_sz, &vmcore_list);
        if (rc)
                goto fail;
        set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
        return 0;
fail:
        free_elfcorebuf();
        return rc;
}

static int __init parse_crash_elf32_headers(void)
{
        int rc=0;
        Elf32_Ehdr ehdr;
        u64 addr;

        addr = elfcorehdr_addr;

        /* Read ELF header */
        rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf32_Ehdr), &addr);
        if (rc < 0)
                return rc;

        /* Do some basic Verification. */
        if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
                (ehdr.e_type != ET_CORE) ||
                !vmcore_elf32_check_arch(&ehdr) ||
                ehdr.e_ident[EI_CLASS] != ELFCLASS32||
                ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
                ehdr.e_version != EV_CURRENT ||
                ehdr.e_ehsize != sizeof(Elf32_Ehdr) ||
                ehdr.e_phentsize != sizeof(Elf32_Phdr) ||
                ehdr.e_phnum == 0) {
                pr_warn("Warning: Core image elf header is not sane\n");
                return -EINVAL;
        }

        /* Read in all elf headers. */
        elfcorebuf_sz_orig = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
        elfcorebuf_sz = elfcorebuf_sz_orig;
        elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
                                              get_order(elfcorebuf_sz_orig));
        if (!elfcorebuf)
                return -ENOMEM;
        addr = elfcorehdr_addr;
        rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr);
        if (rc < 0)
                goto fail;

        /* Merge all PT_NOTE headers into one. */
        rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz,
                                      &elfnotes_buf, &elfnotes_sz);
        if (rc)
                goto fail;
        rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
                                                  elfnotes_sz, &vmcore_list);
        if (rc)
                goto fail;
        set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
        return 0;
fail:
        free_elfcorebuf();
        return rc;
}

static int __init parse_crash_elf_headers(void)
{
        unsigned char e_ident[EI_NIDENT];
        u64 addr;
        int rc=0;

        addr = elfcorehdr_addr;
        rc = elfcorehdr_read(e_ident, EI_NIDENT, &addr);
        if (rc < 0)
                return rc;
        if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
                pr_warn("Warning: Core image elf header not found\n");
                return -EINVAL;
        }

        if (e_ident[EI_CLASS] == ELFCLASS64) {
                rc = parse_crash_elf64_headers();
                if (rc)
                        return rc;
        } else if (e_ident[EI_CLASS] == ELFCLASS32) {
                rc = parse_crash_elf32_headers();
                if (rc)
                        return rc;
        } else {
                pr_warn("Warning: Core image elf header is not sane\n");
                return -EINVAL;
        }

        /* Determine vmcore size. */
        vmcore_size = get_vmcore_size(elfcorebuf_sz, elfnotes_sz,
                                      &vmcore_list);

        return 0;
}

#ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
/**
 * vmcoredd_write_header - Write vmcore device dump header at the
 * beginning of the dump's buffer.
 * @buf: Output buffer where the note is written
 * @data: Dump info
 * @size: Size of the dump
 *
 * Fills beginning of the dump's buffer with vmcore device dump header.
 */
static void vmcoredd_write_header(void *buf, struct vmcoredd_data *data,
                                  u32 size)
{
        struct vmcoredd_header *vdd_hdr = (struct vmcoredd_header *)buf;

        vdd_hdr->n_namesz = sizeof(vdd_hdr->name);
        vdd_hdr->n_descsz = size + sizeof(vdd_hdr->dump_name);
        vdd_hdr->n_type = NT_VMCOREDD;

        strscpy_pad(vdd_hdr->name, VMCOREDD_NOTE_NAME);
        strscpy_pad(vdd_hdr->dump_name, data->dump_name);
}

/**
 * vmcoredd_update_program_headers - Update all ELF program headers
 * @elfptr: Pointer to elf header
 * @elfnotesz: Size of elf notes aligned to page size
 * @vmcoreddsz: Size of device dumps to be added to elf note header
 *
 * Determine type of ELF header (Elf64 or Elf32) and update the elf note size.
 * Also update the offsets of all the program headers after the elf note header.
 */
static void vmcoredd_update_program_headers(char *elfptr, size_t elfnotesz,
                                            size_t vmcoreddsz)
{
        unsigned char *e_ident = (unsigned char *)elfptr;
        u64 start, end, size;
        loff_t vmcore_off;
        u32 i;

        vmcore_off = elfcorebuf_sz + elfnotesz;

        if (e_ident[EI_CLASS] == ELFCLASS64) {
                Elf64_Ehdr *ehdr = (Elf64_Ehdr *)elfptr;
                Elf64_Phdr *phdr = (Elf64_Phdr *)(elfptr + sizeof(Elf64_Ehdr));

                /* Update all program headers */
                for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
                        if (phdr->p_type == PT_NOTE) {
                                /* Update note size */
                                phdr->p_memsz = elfnotes_orig_sz + vmcoreddsz;
                                phdr->p_filesz = phdr->p_memsz;
                                continue;
                        }

                        start = rounddown(phdr->p_offset, PAGE_SIZE);
                        end = roundup(phdr->p_offset + phdr->p_memsz,
                                      PAGE_SIZE);
                        size = end - start;
                        phdr->p_offset = vmcore_off + (phdr->p_offset - start);
                        vmcore_off += size;
                }
        } else {
                Elf32_Ehdr *ehdr = (Elf32_Ehdr *)elfptr;
                Elf32_Phdr *phdr = (Elf32_Phdr *)(elfptr + sizeof(Elf32_Ehdr));

                /* Update all program headers */
                for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
                        if (phdr->p_type == PT_NOTE) {
                                /* Update note size */
                                phdr->p_memsz = elfnotes_orig_sz + vmcoreddsz;
                                phdr->p_filesz = phdr->p_memsz;
                                continue;
                        }

                        start = rounddown(phdr->p_offset, PAGE_SIZE);
                        end = roundup(phdr->p_offset + phdr->p_memsz,
                                      PAGE_SIZE);
                        size = end - start;
                        phdr->p_offset = vmcore_off + (phdr->p_offset - start);
                        vmcore_off += size;
                }
        }
}

/**
 * vmcoredd_update_size - Update the total size of the device dumps and update
 * ELF header
 * @dump_size: Size of the current device dump to be added to total size
 *
 * Update the total size of all the device dumps and update the ELF program
 * headers. Calculate the new offsets for the vmcore list and update the
 * total vmcore size.
 */
static void vmcoredd_update_size(size_t dump_size)
{
        vmcoredd_orig_sz += dump_size;
        elfnotes_sz = roundup(elfnotes_orig_sz, PAGE_SIZE) + vmcoredd_orig_sz;
        vmcoredd_update_program_headers(elfcorebuf, elfnotes_sz,
                                        vmcoredd_orig_sz);

        /* Update vmcore list offsets */
        set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);

        vmcore_size = get_vmcore_size(elfcorebuf_sz, elfnotes_sz,
                                      &vmcore_list);
        proc_vmcore->size = vmcore_size;
}

/**
 * vmcore_add_device_dump - Add a buffer containing device dump to vmcore
 * @data: dump info.
 *
 * Allocate a buffer and invoke the calling driver's dump collect routine.
 * Write ELF note at the beginning of the buffer to indicate vmcore device
 * dump and add the dump to global list.
 */
int vmcore_add_device_dump(struct vmcoredd_data *data)
{
        struct vmcoredd_node *dump;
        void *buf = NULL;
        size_t data_size;
        int ret;

        if (vmcoredd_disabled) {
                pr_err_once("Device dump is disabled\n");
                return -EINVAL;
        }

        if (!data || !strlen(data->dump_name) ||
            !data->vmcoredd_callback || !data->size)
                return -EINVAL;

        dump = vzalloc(sizeof(*dump));
        if (!dump)
                return -ENOMEM;

        /* Keep size of the buffer page aligned so that it can be mmaped */
        data_size = roundup(sizeof(struct vmcoredd_header) + data->size,
                            PAGE_SIZE);

        /* Allocate buffer for driver's to write their dumps */
        buf = vmcore_alloc_buf(data_size);
        if (!buf) {
                ret = -ENOMEM;
                goto out_err;
        }

        vmcoredd_write_header(buf, data, data_size -
                              sizeof(struct vmcoredd_header));

        /* Invoke the driver's dump collection routing */
        ret = data->vmcoredd_callback(data, buf +
                                      sizeof(struct vmcoredd_header));
        if (ret)
                goto out_err;

        dump->buf = buf;
        dump->size = data_size;

        /* Add the dump to driver sysfs list and update the elfcore hdr */
        scoped_guard(mutex, &vmcore_mutex) {
                if (vmcore_opened)
                        pr_warn_once("Unexpected adding of device dump\n");
                if (vmcore_open) {
                        ret = -EBUSY;
                        goto out_err;
                }

                list_add_tail(&dump->list, &vmcoredd_list);
                vmcoredd_update_size(data_size);
        }
        return 0;

out_err:
        vfree(buf);
        vfree(dump);

        return ret;
}
EXPORT_SYMBOL(vmcore_add_device_dump);
#endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */

#ifdef CONFIG_PROC_VMCORE_DEVICE_RAM
static int vmcore_realloc_elfcore_buffer_elf64(size_t new_size)
{
        char *elfcorebuf_new;

        if (WARN_ON_ONCE(new_size < elfcorebuf_sz))
                return -EINVAL;
        if (get_order(elfcorebuf_sz_orig) == get_order(new_size)) {
                elfcorebuf_sz_orig = new_size;
                return 0;
        }

        elfcorebuf_new = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
                                                  get_order(new_size));
        if (!elfcorebuf_new)
                return -ENOMEM;
        memcpy(elfcorebuf_new, elfcorebuf, elfcorebuf_sz);
        free_pages((unsigned long)elfcorebuf, get_order(elfcorebuf_sz_orig));
        elfcorebuf = elfcorebuf_new;
        elfcorebuf_sz_orig = new_size;
        return 0;
}

static void vmcore_reset_offsets_elf64(void)
{
        Elf64_Phdr *phdr_start = (Elf64_Phdr *)(elfcorebuf + sizeof(Elf64_Ehdr));
        loff_t vmcore_off = elfcorebuf_sz + elfnotes_sz;
        Elf64_Ehdr *ehdr = (Elf64_Ehdr *)elfcorebuf;
        Elf64_Phdr *phdr;
        int i;

        for (i = 0, phdr = phdr_start; i < ehdr->e_phnum; i++, phdr++) {
                u64 start, end;

                /*
                 * After merge_note_headers_elf64() we should only have a single
                 * PT_NOTE entry that starts immediately after elfcorebuf_sz.
                 */
                if (phdr->p_type == PT_NOTE) {
                        phdr->p_offset = elfcorebuf_sz;
                        continue;
                }

                start = rounddown(phdr->p_offset, PAGE_SIZE);
                end = roundup(phdr->p_offset + phdr->p_memsz, PAGE_SIZE);
                phdr->p_offset = vmcore_off + (phdr->p_offset - start);
                vmcore_off = vmcore_off + end - start;
        }
        set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
}

static int vmcore_add_device_ram_elf64(struct list_head *list, size_t count)
{
        Elf64_Phdr *phdr_start = (Elf64_Phdr *)(elfcorebuf + sizeof(Elf64_Ehdr));
        Elf64_Ehdr *ehdr = (Elf64_Ehdr *)elfcorebuf;
        struct vmcore_range *cur;
        Elf64_Phdr *phdr;
        size_t new_size;
        int rc;

        if ((Elf32_Half)(ehdr->e_phnum + count) != ehdr->e_phnum + count) {
                pr_err("too many device ram ranges\n");
                return -ENOSPC;
        }

        /* elfcorebuf_sz must always cover full pages. */
        new_size = sizeof(Elf64_Ehdr) +
                   (ehdr->e_phnum + count) * sizeof(Elf64_Phdr);
        new_size = roundup(new_size, PAGE_SIZE);

        /*
         * Make sure we have sufficient space to include the new PT_LOAD
         * entries.
         */
        rc = vmcore_realloc_elfcore_buffer_elf64(new_size);
        if (rc) {
                pr_err("resizing elfcore failed\n");
                return rc;
        }

        /* Modify our used elfcore buffer size to cover the new entries. */
        elfcorebuf_sz = new_size;

        /* Fill the added PT_LOAD entries. */
        phdr = phdr_start + ehdr->e_phnum;
        list_for_each_entry(cur, list, list) {
                WARN_ON_ONCE(!IS_ALIGNED(cur->paddr | cur->size, PAGE_SIZE));
                elfcorehdr_fill_device_ram_ptload_elf64(phdr, cur->paddr, cur->size);

                /* p_offset will be adjusted later. */
                phdr++;
                ehdr->e_phnum++;
        }
        list_splice_tail(list, &vmcore_list);

        /* We changed elfcorebuf_sz and added new entries; reset all offsets. */
        vmcore_reset_offsets_elf64();

        /* Finally, recalculate the total vmcore size. */
        vmcore_size = get_vmcore_size(elfcorebuf_sz, elfnotes_sz,
                                      &vmcore_list);
        proc_vmcore->size = vmcore_size;
        return 0;
}

static void vmcore_process_device_ram(struct vmcore_cb *cb)
{
        unsigned char *e_ident = (unsigned char *)elfcorebuf;
        struct vmcore_range *first, *m;
        LIST_HEAD(list);
        int count;

        /* We only support Elf64 dumps for now. */
        if (WARN_ON_ONCE(e_ident[EI_CLASS] != ELFCLASS64)) {
                pr_err("device ram ranges only support Elf64\n");
                return;
        }

        if (cb->get_device_ram(cb, &list)) {
                pr_err("obtaining device ram ranges failed\n");
                return;
        }
        count = list_count_nodes(&list);
        if (!count)
                return;

        /*
         * For some reason these ranges are already know? Might happen
         * with unusual register->unregister->register sequences; we'll simply
         * sanity check using the first range.
         */
        first = list_first_entry(&list, struct vmcore_range, list);
        list_for_each_entry(m, &vmcore_list, list) {
                unsigned long long m_end = m->paddr + m->size;
                unsigned long long first_end = first->paddr + first->size;

                if (first->paddr < m_end && m->paddr < first_end)
                        goto out_free;
        }

        /* If adding the mem nodes succeeds, they must not be freed. */
        if (!vmcore_add_device_ram_elf64(&list, count))
                return;
out_free:
        vmcore_free_ranges(&list);
}
#else /* !CONFIG_PROC_VMCORE_DEVICE_RAM */
static void vmcore_process_device_ram(struct vmcore_cb *cb)
{
}
#endif /* CONFIG_PROC_VMCORE_DEVICE_RAM */

/* Free all dumps in vmcore device dump list */
static void vmcore_free_device_dumps(void)
{
#ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
        mutex_lock(&vmcore_mutex);
        while (!list_empty(&vmcoredd_list)) {
                struct vmcoredd_node *dump;

                dump = list_first_entry(&vmcoredd_list, struct vmcoredd_node,
                                        list);
                list_del(&dump->list);
                vfree(dump->buf);
                vfree(dump);
        }
        mutex_unlock(&vmcore_mutex);
#endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
}

/* Init function for vmcore module. */
static int __init vmcore_init(void)
{
        int rc = 0;

        /* Allow architectures to allocate ELF header in 2nd kernel */
        rc = elfcorehdr_alloc(&elfcorehdr_addr, &elfcorehdr_size);
        if (rc)
                return rc;
        /*
         * If elfcorehdr= has been passed in cmdline or created in 2nd kernel,
         * then capture the dump.
         */
        if (!(is_vmcore_usable()))
                return rc;
        rc = parse_crash_elf_headers();
        if (rc) {
                elfcorehdr_free(elfcorehdr_addr);
                pr_warn("not initialized\n");
                return rc;
        }
        elfcorehdr_free(elfcorehdr_addr);
        elfcorehdr_addr = ELFCORE_ADDR_ERR;

        proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &vmcore_proc_ops);
        if (proc_vmcore)
                proc_vmcore->size = vmcore_size;
        return 0;
}
fs_initcall(vmcore_init);

/* Cleanup function for vmcore module. */
void vmcore_cleanup(void)
{
        if (proc_vmcore) {
                proc_remove(proc_vmcore);
                proc_vmcore = NULL;
        }

        vmcore_free_ranges(&vmcore_list);
        free_elfcorebuf();

        /* clear vmcore device dump list */
        vmcore_free_device_dumps();
}