/*
 *      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
 *
 */

#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/highmem.h>
#include <linux/bootmem.h>
#include <linux/init.h>
#include <linux/crash_dump.h>
#include <linux/list.h>
#include <asm/uaccess.h>
#include <asm/io.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;

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

static struct proc_dir_entry *proc_vmcore = NULL;

/* Reads a page from the oldmem device from given offset. */
static ssize_t read_from_oldmem(char *buf, size_t count,
                                u64 *ppos, int userbuf)
{
        unsigned long pfn, offset;
        size_t nr_bytes;
        ssize_t read = 0, tmp;

        if (!count)
                return 0;

        offset = (unsigned long)(*ppos % PAGE_SIZE);
        pfn = (unsigned long)(*ppos / PAGE_SIZE);
        if (pfn > saved_max_pfn)
                return -EINVAL;

        do {
                if (count > (PAGE_SIZE - offset))
                        nr_bytes = PAGE_SIZE - offset;
                else
                        nr_bytes = count;

                tmp = copy_oldmem_page(pfn, buf, nr_bytes, offset, userbuf);
                if (tmp < 0)
                        return tmp;
                *ppos += nr_bytes;
                count -= nr_bytes;
                buf += nr_bytes;
                read += nr_bytes;
                ++pfn;
                offset = 0;
        } while (count);

        return read;
}

/* Maps vmcore file offset to respective physical address in memroy. */
static u64 map_offset_to_paddr(loff_t offset, struct list_head *vc_list,
                                        struct vmcore **m_ptr)
{
        struct vmcore *m;
        u64 paddr;

        list_for_each_entry(m, vc_list, list) {
                u64 start, end;
                start = m->offset;
                end = m->offset + m->size - 1;
                if (offset >= start && offset <= end) {
                        paddr = m->paddr + offset - start;
                        *m_ptr = m;
                        return paddr;
                }
        }
        *m_ptr = NULL;
        return 0;
}

/* 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 file *file, char __user *buffer,
                                size_t buflen, loff_t *fpos)
{
        ssize_t acc = 0, tmp;
        size_t tsz;
        u64 start, nr_bytes;
        struct vmcore *curr_m = NULL;

        if (buflen == 0 || *fpos >= vmcore_size)
                return 0;

        /* trim buflen to not go beyond EOF */
        if (buflen > vmcore_size - *fpos)
                buflen = vmcore_size - *fpos;

        /* Read ELF core header */
        if (*fpos < elfcorebuf_sz) {
                tsz = elfcorebuf_sz - *fpos;
                if (buflen < tsz)
                        tsz = buflen;
                if (copy_to_user(buffer, elfcorebuf + *fpos, tsz))
                        return -EFAULT;
                buflen -= tsz;
                *fpos += tsz;
                buffer += tsz;
                acc += tsz;

                /* leave now if filled buffer already */
                if (buflen == 0)
                        return acc;
        }

        start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m);
        if (!curr_m)
                return -EINVAL;
        if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
                tsz = buflen;

        /* Calculate left bytes in current memory segment. */
        nr_bytes = (curr_m->size - (start - curr_m->paddr));
        if (tsz > nr_bytes)
                tsz = nr_bytes;

        while (buflen) {
                tmp = read_from_oldmem(buffer, tsz, &start, 1);
                if (tmp < 0)
                        return tmp;
                buflen -= tsz;
                *fpos += tsz;
                buffer += tsz;
                acc += tsz;
                if (start >= (curr_m->paddr + curr_m->size)) {
                        if (curr_m->list.next == &vmcore_list)
                                return acc;     /*EOF*/
                        curr_m = list_entry(curr_m->list.next,
                                                struct vmcore, list);
                        start = curr_m->paddr;
                }
                if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
                        tsz = buflen;
                /* Calculate left bytes in current memory segment. */
                nr_bytes = (curr_m->size - (start - curr_m->paddr));
                if (tsz > nr_bytes)
                        tsz = nr_bytes;
        }
        return acc;
}

static const struct file_operations proc_vmcore_operations = {
        .read           = read_vmcore,
};

static struct vmcore* __init get_new_element(void)
{
        struct vmcore *p;

        p = kmalloc(sizeof(*p), GFP_KERNEL);
        if (p)
                memset(p, 0, sizeof(*p));
        return p;
}

static u64 __init get_vmcore_size_elf64(char *elfptr)
{
        int i;
        u64 size;
        Elf64_Ehdr *ehdr_ptr;
        Elf64_Phdr *phdr_ptr;

        ehdr_ptr = (Elf64_Ehdr *)elfptr;
        phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
        size = sizeof(Elf64_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr));
        for (i = 0; i < ehdr_ptr->e_phnum; i++) {
                size += phdr_ptr->p_memsz;
                phdr_ptr++;
        }
        return size;
}

static u64 __init get_vmcore_size_elf32(char *elfptr)
{
        int i;
        u64 size;
        Elf32_Ehdr *ehdr_ptr;
        Elf32_Phdr *phdr_ptr;

        ehdr_ptr = (Elf32_Ehdr *)elfptr;
        phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
        size = sizeof(Elf32_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr));
        for (i = 0; i < ehdr_ptr->e_phnum; i++) {
                size += phdr_ptr->p_memsz;
                phdr_ptr++;
        }
        return size;
}

/* Merges all the PT_NOTE headers into one. */
static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
                                                struct list_head *vc_list)
{
        int i, nr_ptnote=0, rc=0;
        char *tmp;
        Elf64_Ehdr *ehdr_ptr;
        Elf64_Phdr phdr, *phdr_ptr;
        Elf64_Nhdr *nhdr_ptr;
        u64 phdr_sz = 0, note_off;

        ehdr_ptr = (Elf64_Ehdr *)elfptr;
        phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                int j;
                void *notes_section;
                struct vmcore *new;
                u64 offset, max_sz, sz, real_sz = 0;
                if (phdr_ptr->p_type != PT_NOTE)
                        continue;
                nr_ptnote++;
                max_sz = phdr_ptr->p_memsz;
                offset = phdr_ptr->p_offset;
                notes_section = kmalloc(max_sz, GFP_KERNEL);
                if (!notes_section)
                        return -ENOMEM;
                rc = read_from_oldmem(notes_section, max_sz, &offset, 0);
                if (rc < 0) {
                        kfree(notes_section);
                        return rc;
                }
                nhdr_ptr = notes_section;
                for (j = 0; j < max_sz; j += sz) {
                        if (nhdr_ptr->n_namesz == 0)
                                break;
                        sz = sizeof(Elf64_Nhdr) +
                                ((nhdr_ptr->n_namesz + 3) & ~3) +
                                ((nhdr_ptr->n_descsz + 3) & ~3);
                        real_sz += sz;
                        nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
                }

                /* Add this contiguous chunk of notes section to vmcore list.*/
                new = get_new_element();
                if (!new) {
                        kfree(notes_section);
                        return -ENOMEM;
                }
                new->paddr = phdr_ptr->p_offset;
                new->size = real_sz;
                list_add_tail(&new->list, vc_list);
                phdr_sz += real_sz;
                kfree(notes_section);
        }

        /* 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  = note_off;
        phdr.p_vaddr   = phdr.p_paddr = 0;
        phdr.p_filesz  = phdr.p_memsz = phdr_sz;
        phdr.p_align   = 0;

        /* 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)));

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

        return 0;
}

/* Merges all the PT_NOTE headers into one. */
static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
                                                struct list_head *vc_list)
{
        int i, nr_ptnote=0, rc=0;
        char *tmp;
        Elf32_Ehdr *ehdr_ptr;
        Elf32_Phdr phdr, *phdr_ptr;
        Elf32_Nhdr *nhdr_ptr;
        u64 phdr_sz = 0, note_off;

        ehdr_ptr = (Elf32_Ehdr *)elfptr;
        phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                int j;
                void *notes_section;
                struct vmcore *new;
                u64 offset, max_sz, sz, real_sz = 0;
                if (phdr_ptr->p_type != PT_NOTE)
                        continue;
                nr_ptnote++;
                max_sz = phdr_ptr->p_memsz;
                offset = phdr_ptr->p_offset;
                notes_section = kmalloc(max_sz, GFP_KERNEL);
                if (!notes_section)
                        return -ENOMEM;
                rc = read_from_oldmem(notes_section, max_sz, &offset, 0);
                if (rc < 0) {
                        kfree(notes_section);
                        return rc;
                }
                nhdr_ptr = notes_section;
                for (j = 0; j < max_sz; j += sz) {
                        if (nhdr_ptr->n_namesz == 0)
                                break;
                        sz = sizeof(Elf32_Nhdr) +
                                ((nhdr_ptr->n_namesz + 3) & ~3) +
                                ((nhdr_ptr->n_descsz + 3) & ~3);
                        real_sz += sz;
                        nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
                }

                /* Add this contiguous chunk of notes section to vmcore list.*/
                new = get_new_element();
                if (!new) {
                        kfree(notes_section);
                        return -ENOMEM;
                }
                new->paddr = phdr_ptr->p_offset;
                new->size = real_sz;
                list_add_tail(&new->list, vc_list);
                phdr_sz += real_sz;
                kfree(notes_section);
        }

        /* 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  = note_off;
        phdr.p_vaddr   = phdr.p_paddr = 0;
        phdr.p_filesz  = phdr.p_memsz = phdr_sz;
        phdr.p_align   = 0;

        /* 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)));

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

        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,
                                                struct list_head *vc_list)
{
        int i;
        Elf64_Ehdr *ehdr_ptr;
        Elf64_Phdr *phdr_ptr;
        loff_t vmcore_off;
        struct vmcore *new;

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

        /* First program header is PT_NOTE header. */
        vmcore_off = sizeof(Elf64_Ehdr) +
                        (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr) +
                        phdr_ptr->p_memsz; /* Note sections */

        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                if (phdr_ptr->p_type != PT_LOAD)
                        continue;

                /* Add this contiguous chunk of memory to vmcore list.*/
                new = get_new_element();
                if (!new)
                        return -ENOMEM;
                new->paddr = phdr_ptr->p_offset;
                new->size = phdr_ptr->p_memsz;
                list_add_tail(&new->list, vc_list);

                /* Update the program header offset. */
                phdr_ptr->p_offset = vmcore_off;
                vmcore_off = vmcore_off + phdr_ptr->p_memsz;
        }
        return 0;
}

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

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

        /* First program header is PT_NOTE header. */
        vmcore_off = sizeof(Elf32_Ehdr) +
                        (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr) +
                        phdr_ptr->p_memsz; /* Note sections */

        for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
                if (phdr_ptr->p_type != PT_LOAD)
                        continue;

                /* Add this contiguous chunk of memory to vmcore list.*/
                new = get_new_element();
                if (!new)
                        return -ENOMEM;
                new->paddr = phdr_ptr->p_offset;
                new->size = phdr_ptr->p_memsz;
                list_add_tail(&new->list, vc_list);

                /* Update the program header offset */
                phdr_ptr->p_offset = vmcore_off;
                vmcore_off = vmcore_off + phdr_ptr->p_memsz;
        }
        return 0;
}

/* Sets offset fields of vmcore elements. */
static void __init set_vmcore_list_offsets_elf64(char *elfptr,
                                                struct list_head *vc_list)
{
        loff_t vmcore_off;
        Elf64_Ehdr *ehdr_ptr;
        struct vmcore *m;

        ehdr_ptr = (Elf64_Ehdr *)elfptr;

        /* Skip Elf header and program headers. */
        vmcore_off = sizeof(Elf64_Ehdr) +
                        (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr);

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

/* Sets offset fields of vmcore elements. */
static void __init set_vmcore_list_offsets_elf32(char *elfptr,
                                                struct list_head *vc_list)
{
        loff_t vmcore_off;
        Elf32_Ehdr *ehdr_ptr;
        struct vmcore *m;

        ehdr_ptr = (Elf32_Ehdr *)elfptr;

        /* Skip Elf header and program headers. */
        vmcore_off = sizeof(Elf32_Ehdr) +
                        (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr);

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

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

        addr = elfcorehdr_addr;

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

        /* Do some basic Verification. */
        if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
                (ehdr.e_type != ET_CORE) ||
                !vmcore_elf_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) {
                printk(KERN_WARNING "Warning: Core image elf header is not"
                                        "sane\n");
                return -EINVAL;
        }

        /* Read in all elf headers. */
        elfcorebuf_sz = sizeof(Elf64_Ehdr) + ehdr.e_phnum * sizeof(Elf64_Phdr);
        elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
        if (!elfcorebuf)
                return -ENOMEM;
        addr = elfcorehdr_addr;
        rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
        if (rc < 0) {
                kfree(elfcorebuf);
                return rc;
        }

        /* Merge all PT_NOTE headers into one. */
        rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
        if (rc) {
                kfree(elfcorebuf);
                return rc;
        }
        rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
                                                        &vmcore_list);
        if (rc) {
                kfree(elfcorebuf);
                return rc;
        }
        set_vmcore_list_offsets_elf64(elfcorebuf, &vmcore_list);
        return 0;
}

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

        addr = elfcorehdr_addr;

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

        /* Do some basic Verification. */
        if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
                (ehdr.e_type != ET_CORE) ||
                !elf_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) {
                printk(KERN_WARNING "Warning: Core image elf header is not"
                                        "sane\n");
                return -EINVAL;
        }

        /* Read in all elf headers. */
        elfcorebuf_sz = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
        elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
        if (!elfcorebuf)
                return -ENOMEM;
        addr = elfcorehdr_addr;
        rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
        if (rc < 0) {
                kfree(elfcorebuf);
                return rc;
        }

        /* Merge all PT_NOTE headers into one. */
        rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
        if (rc) {
                kfree(elfcorebuf);
                return rc;
        }
        rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
                                                                &vmcore_list);
        if (rc) {
                kfree(elfcorebuf);
                return rc;
        }
        set_vmcore_list_offsets_elf32(elfcorebuf, &vmcore_list);
        return 0;
}

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

        addr = elfcorehdr_addr;
        rc = read_from_oldmem(e_ident, EI_NIDENT, &addr, 0);
        if (rc < 0)
                return rc;
        if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
                printk(KERN_WARNING "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;

                /* Determine vmcore size. */
                vmcore_size = get_vmcore_size_elf64(elfcorebuf);
        } else if (e_ident[EI_CLASS] == ELFCLASS32) {
                rc = parse_crash_elf32_headers();
                if (rc)
                        return rc;

                /* Determine vmcore size. */
                vmcore_size = get_vmcore_size_elf32(elfcorebuf);
        } else {
                printk(KERN_WARNING "Warning: Core image elf header is not"
                                        " sane\n");
                return -EINVAL;
        }
        return 0;
}

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

        /* If elfcorehdr= has been passed in cmdline, then capture the dump.*/
        if (!(is_vmcore_usable()))
                return rc;
        rc = parse_crash_elf_headers();
        if (rc) {
                printk(KERN_WARNING "Kdump: vmcore not initialized\n");
                return rc;
        }

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