/*
 *      fs/proc/kcore.c kernel ELF core dumper
 *
 *      Modelled on fs/exec.c:aout_core_dump()
 *      Jeremy Fitzhardinge <jeremy@sw.oz.au>
 *      ELF version written by David Howells <David.Howells@nexor.co.uk>
 *      Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
 *      Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
 *      Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
 */

#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/user.h>
#include <linux/capability.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/vmalloc.h>
#include <linux/highmem.h>
#include <linux/printk.h>
#include <linux/bootmem.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/list.h>
#include <linux/ioport.h>
#include <linux/memory.h>
#include <asm/sections.h>

#define CORE_STR "CORE"

#ifndef ELF_CORE_EFLAGS
#define ELF_CORE_EFLAGS 0
#endif

static struct proc_dir_entry *proc_root_kcore;


#ifndef kc_vaddr_to_offset
#define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
#endif
#ifndef kc_offset_to_vaddr
#define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
#endif

/* An ELF note in memory */
struct memelfnote
{
        const char *name;
        int type;
        unsigned int datasz;
        void *data;
};

static LIST_HEAD(kclist_head);
static DEFINE_RWLOCK(kclist_lock);
static int kcore_need_update = 1;

void
kclist_add(struct kcore_list *new, void *addr, size_t size, int type)
{
        new->addr = (unsigned long)addr;
        new->size = size;
        new->type = type;

        write_lock(&kclist_lock);
        list_add_tail(&new->list, &kclist_head);
        write_unlock(&kclist_lock);
}

static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
{
        size_t try, size;
        struct kcore_list *m;

        *nphdr = 1; /* PT_NOTE */
        size = 0;

        list_for_each_entry(m, &kclist_head, list) {
                try = kc_vaddr_to_offset((size_t)m->addr + m->size);
                if (try > size)
                        size = try;
                *nphdr = *nphdr + 1;
        }
        *elf_buflen =   sizeof(struct elfhdr) + 
                        (*nphdr + 2)*sizeof(struct elf_phdr) + 
                        3 * ((sizeof(struct elf_note)) +
                             roundup(sizeof(CORE_STR), 4)) +
                        roundup(sizeof(struct elf_prstatus), 4) +
                        roundup(sizeof(struct elf_prpsinfo), 4) +
                        roundup(sizeof(struct task_struct), 4);
        *elf_buflen = PAGE_ALIGN(*elf_buflen);
        return size + *elf_buflen;
}

static void free_kclist_ents(struct list_head *head)
{
        struct kcore_list *tmp, *pos;

        list_for_each_entry_safe(pos, tmp, head, list) {
                list_del(&pos->list);
                kfree(pos);
        }
}
/*
 * Replace all KCORE_RAM/KCORE_VMEMMAP information with passed list.
 */
static void __kcore_update_ram(struct list_head *list)
{
        int nphdr;
        size_t size;
        struct kcore_list *tmp, *pos;
        LIST_HEAD(garbage);

        write_lock(&kclist_lock);
        if (kcore_need_update) {
                list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
                        if (pos->type == KCORE_RAM
                                || pos->type == KCORE_VMEMMAP)
                                list_move(&pos->list, &garbage);
                }
                list_splice_tail(list, &kclist_head);
        } else
                list_splice(list, &garbage);
        kcore_need_update = 0;
        proc_root_kcore->size = get_kcore_size(&nphdr, &size);
        write_unlock(&kclist_lock);

        free_kclist_ents(&garbage);
}


#ifdef CONFIG_HIGHMEM
/*
 * If no highmem, we can assume [0...max_low_pfn) continuous range of memory
 * because memory hole is not as big as !HIGHMEM case.
 * (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
 */
static int kcore_update_ram(void)
{
        LIST_HEAD(head);
        struct kcore_list *ent;
        int ret = 0;

        ent = kmalloc(sizeof(*ent), GFP_KERNEL);
        if (!ent)
                return -ENOMEM;
        ent->addr = (unsigned long)__va(0);
        ent->size = max_low_pfn << PAGE_SHIFT;
        ent->type = KCORE_RAM;
        list_add(&ent->list, &head);
        __kcore_update_ram(&head);
        return ret;
}

#else /* !CONFIG_HIGHMEM */

#ifdef CONFIG_SPARSEMEM_VMEMMAP
/* calculate vmemmap's address from given system ram pfn and register it */
static int
get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
{
        unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
        unsigned long nr_pages = ent->size >> PAGE_SHIFT;
        unsigned long start, end;
        struct kcore_list *vmm, *tmp;


        start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
        end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
        end = ALIGN(end, PAGE_SIZE);
        /* overlap check (because we have to align page */
        list_for_each_entry(tmp, head, list) {
                if (tmp->type != KCORE_VMEMMAP)
                        continue;
                if (start < tmp->addr + tmp->size)
                        if (end > tmp->addr)
                                end = tmp->addr;
        }
        if (start < end) {
                vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
                if (!vmm)
                        return 0;
                vmm->addr = start;
                vmm->size = end - start;
                vmm->type = KCORE_VMEMMAP;
                list_add_tail(&vmm->list, head);
        }
        return 1;

}
#else
static int
get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
{
        return 1;
}

#endif

static int
kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
{
        struct list_head *head = (struct list_head *)arg;
        struct kcore_list *ent;

        ent = kmalloc(sizeof(*ent), GFP_KERNEL);
        if (!ent)
                return -ENOMEM;
        ent->addr = (unsigned long)__va((pfn << PAGE_SHIFT));
        ent->size = nr_pages << PAGE_SHIFT;

        /* Sanity check: Can happen in 32bit arch...maybe */
        if (ent->addr < (unsigned long) __va(0))
                goto free_out;

        /* cut not-mapped area. ....from ppc-32 code. */
        if (ULONG_MAX - ent->addr < ent->size)
                ent->size = ULONG_MAX - ent->addr;

        /* cut when vmalloc() area is higher than direct-map area */
        if (VMALLOC_START > (unsigned long)__va(0)) {
                if (ent->addr > VMALLOC_START)
                        goto free_out;
                if (VMALLOC_START - ent->addr < ent->size)
                        ent->size = VMALLOC_START - ent->addr;
        }

        ent->type = KCORE_RAM;
        list_add_tail(&ent->list, head);

        if (!get_sparsemem_vmemmap_info(ent, head)) {
                list_del(&ent->list);
                goto free_out;
        }

        return 0;
free_out:
        kfree(ent);
        return 1;
}

static int kcore_update_ram(void)
{
        int nid, ret;
        unsigned long end_pfn;
        LIST_HEAD(head);

        /* Not inialized....update now */
        /* find out "max pfn" */
        end_pfn = 0;
        for_each_node_state(nid, N_MEMORY) {
                unsigned long node_end;
                node_end  = NODE_DATA(nid)->node_start_pfn +
                        NODE_DATA(nid)->node_spanned_pages;
                if (end_pfn < node_end)
                        end_pfn = node_end;
        }
        /* scan 0 to max_pfn */
        ret = walk_system_ram_range(0, end_pfn, &head, kclist_add_private);
        if (ret) {
                free_kclist_ents(&head);
                return -ENOMEM;
        }
        __kcore_update_ram(&head);
        return ret;
}
#endif /* CONFIG_HIGHMEM */

/*****************************************************************************/
/*
 * determine size of ELF note
 */
static int notesize(struct memelfnote *en)
{
        int sz;

        sz = sizeof(struct elf_note);
        sz += roundup((strlen(en->name) + 1), 4);
        sz += roundup(en->datasz, 4);

        return sz;
} /* end notesize() */

/*****************************************************************************/
/*
 * store a note in the header buffer
 */
static char *storenote(struct memelfnote *men, char *bufp)
{
        struct elf_note en;

#define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)

        en.n_namesz = strlen(men->name) + 1;
        en.n_descsz = men->datasz;
        en.n_type = men->type;

        DUMP_WRITE(&en, sizeof(en));
        DUMP_WRITE(men->name, en.n_namesz);

        /* XXX - cast from long long to long to avoid need for libgcc.a */
        bufp = (char*) roundup((unsigned long)bufp,4);
        DUMP_WRITE(men->data, men->datasz);
        bufp = (char*) roundup((unsigned long)bufp,4);

#undef DUMP_WRITE

        return bufp;
} /* end storenote() */

/*
 * store an ELF coredump header in the supplied buffer
 * nphdr is the number of elf_phdr to insert
 */
static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
{
        struct elf_prstatus prstatus;   /* NT_PRSTATUS */
        struct elf_prpsinfo prpsinfo;   /* NT_PRPSINFO */
        struct elf_phdr *nhdr, *phdr;
        struct elfhdr *elf;
        struct memelfnote notes[3];
        off_t offset = 0;
        struct kcore_list *m;

        /* setup ELF header */
        elf = (struct elfhdr *) bufp;
        bufp += sizeof(struct elfhdr);
        offset += sizeof(struct elfhdr);
        memcpy(elf->e_ident, ELFMAG, SELFMAG);
        elf->e_ident[EI_CLASS]  = ELF_CLASS;
        elf->e_ident[EI_DATA]   = ELF_DATA;
        elf->e_ident[EI_VERSION]= EV_CURRENT;
        elf->e_ident[EI_OSABI] = ELF_OSABI;
        memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
        elf->e_type     = ET_CORE;
        elf->e_machine  = ELF_ARCH;
        elf->e_version  = EV_CURRENT;
        elf->e_entry    = 0;
        elf->e_phoff    = sizeof(struct elfhdr);
        elf->e_shoff    = 0;
        elf->e_flags    = ELF_CORE_EFLAGS;
        elf->e_ehsize   = sizeof(struct elfhdr);
        elf->e_phentsize= sizeof(struct elf_phdr);
        elf->e_phnum    = nphdr;
        elf->e_shentsize= 0;
        elf->e_shnum    = 0;
        elf->e_shstrndx = 0;

        /* setup ELF PT_NOTE program header */
        nhdr = (struct elf_phdr *) bufp;
        bufp += sizeof(struct elf_phdr);
        offset += sizeof(struct elf_phdr);
        nhdr->p_type    = PT_NOTE;
        nhdr->p_offset  = 0;
        nhdr->p_vaddr   = 0;
        nhdr->p_paddr   = 0;
        nhdr->p_filesz  = 0;
        nhdr->p_memsz   = 0;
        nhdr->p_flags   = 0;
        nhdr->p_align   = 0;

        /* setup ELF PT_LOAD program header for every area */
        list_for_each_entry(m, &kclist_head, list) {
                phdr = (struct elf_phdr *) bufp;
                bufp += sizeof(struct elf_phdr);
                offset += sizeof(struct elf_phdr);

                phdr->p_type    = PT_LOAD;
                phdr->p_flags   = PF_R|PF_W|PF_X;
                phdr->p_offset  = kc_vaddr_to_offset(m->addr) + dataoff;
                phdr->p_vaddr   = (size_t)m->addr;
                phdr->p_paddr   = 0;
                phdr->p_filesz  = phdr->p_memsz = m->size;
                phdr->p_align   = PAGE_SIZE;
        }

        /*
         * Set up the notes in similar form to SVR4 core dumps made
         * with info from their /proc.
         */
        nhdr->p_offset  = offset;

        /* set up the process status */
        notes[0].name = CORE_STR;
        notes[0].type = NT_PRSTATUS;
        notes[0].datasz = sizeof(struct elf_prstatus);
        notes[0].data = &prstatus;

        memset(&prstatus, 0, sizeof(struct elf_prstatus));

        nhdr->p_filesz  = notesize(&notes[0]);
        bufp = storenote(&notes[0], bufp);

        /* set up the process info */
        notes[1].name   = CORE_STR;
        notes[1].type   = NT_PRPSINFO;
        notes[1].datasz = sizeof(struct elf_prpsinfo);
        notes[1].data   = &prpsinfo;

        memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
        prpsinfo.pr_state       = 0;
        prpsinfo.pr_sname       = 'R';
        prpsinfo.pr_zomb        = 0;

        strcpy(prpsinfo.pr_fname, "vmlinux");
        strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);

        nhdr->p_filesz  += notesize(&notes[1]);
        bufp = storenote(&notes[1], bufp);

        /* set up the task structure */
        notes[2].name   = CORE_STR;
        notes[2].type   = NT_TASKSTRUCT;
        notes[2].datasz = sizeof(struct task_struct);
        notes[2].data   = current;

        nhdr->p_filesz  += notesize(&notes[2]);
        bufp = storenote(&notes[2], bufp);

} /* end elf_kcore_store_hdr() */

/*****************************************************************************/
/*
 * read from the ELF header and then kernel memory
 */
static ssize_t
read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
{
        ssize_t acc = 0;
        size_t size, tsz;
        size_t elf_buflen;
        int nphdr;
        unsigned long start;

        read_lock(&kclist_lock);
        size = get_kcore_size(&nphdr, &elf_buflen);

        if (buflen == 0 || *fpos >= size) {
                read_unlock(&kclist_lock);
                return 0;
        }

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

        /* construct an ELF core header if we'll need some of it */
        if (*fpos < elf_buflen) {
                char * elf_buf;

                tsz = elf_buflen - *fpos;
                if (buflen < tsz)
                        tsz = buflen;
                elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);
                if (!elf_buf) {
                        read_unlock(&kclist_lock);
                        return -ENOMEM;
                }
                elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
                read_unlock(&kclist_lock);
                if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
                        kfree(elf_buf);
                        return -EFAULT;
                }
                kfree(elf_buf);
                buflen -= tsz;
                *fpos += tsz;
                buffer += tsz;
                acc += tsz;

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

        /*
         * Check to see if our file offset matches with any of
         * the addresses in the elf_phdr on our list.
         */
        start = kc_offset_to_vaddr(*fpos - elf_buflen);
        if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
                tsz = buflen;
                
        while (buflen) {
                struct kcore_list *m;

                read_lock(&kclist_lock);
                list_for_each_entry(m, &kclist_head, list) {
                        if (start >= m->addr && start < (m->addr+m->size))
                                break;
                }
                read_unlock(&kclist_lock);

                if (&m->list == &kclist_head) {
                        if (clear_user(buffer, tsz))
                                return -EFAULT;
                } else if (is_vmalloc_or_module_addr((void *)start)) {
                        char * elf_buf;

                        elf_buf = kzalloc(tsz, GFP_KERNEL);
                        if (!elf_buf)
                                return -ENOMEM;
                        vread(elf_buf, (char *)start, tsz);
                        /* we have to zero-fill user buffer even if no read */
                        if (copy_to_user(buffer, elf_buf, tsz)) {
                                kfree(elf_buf);
                                return -EFAULT;
                        }
                        kfree(elf_buf);
                } else {
                        if (kern_addr_valid(start)) {
                                unsigned long n;

                                n = copy_to_user(buffer, (char *)start, tsz);
                                /*
                                 * We cannot distinguish between fault on source
                                 * and fault on destination. When this happens
                                 * we clear too and hope it will trigger the
                                 * EFAULT again.
                                 */
                                if (n) { 
                                        if (clear_user(buffer + tsz - n,
                                                                n))
                                                return -EFAULT;
                                }
                        } else {
                                if (clear_user(buffer, tsz))
                                        return -EFAULT;
                        }
                }
                buflen -= tsz;
                *fpos += tsz;
                buffer += tsz;
                acc += tsz;
                start += tsz;
                tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
        }

        return acc;
}


static int open_kcore(struct inode *inode, struct file *filp)
{
        if (!capable(CAP_SYS_RAWIO))
                return -EPERM;
        if (kcore_need_update)
                kcore_update_ram();
        if (i_size_read(inode) != proc_root_kcore->size) {
                mutex_lock(&inode->i_mutex);
                i_size_write(inode, proc_root_kcore->size);
                mutex_unlock(&inode->i_mutex);
        }
        return 0;
}


static const struct file_operations proc_kcore_operations = {
        .read           = read_kcore,
        .open           = open_kcore,
        .llseek         = default_llseek,
};

#ifdef CONFIG_MEMORY_HOTPLUG
/* just remember that we have to update kcore */
static int __meminit kcore_callback(struct notifier_block *self,
                                    unsigned long action, void *arg)
{
        switch (action) {
        case MEM_ONLINE:
        case MEM_OFFLINE:
                write_lock(&kclist_lock);
                kcore_need_update = 1;
                write_unlock(&kclist_lock);
        }
        return NOTIFY_OK;
}
#endif


static struct kcore_list kcore_vmalloc;

#ifdef CONFIG_ARCH_PROC_KCORE_TEXT
static struct kcore_list kcore_text;
/*
 * If defined, special segment is used for mapping kernel text instead of
 * direct-map area. We need to create special TEXT section.
 */
static void __init proc_kcore_text_init(void)
{
        kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
}
#else
static void __init proc_kcore_text_init(void)
{
}
#endif

#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
/*
 * MODULES_VADDR has no intersection with VMALLOC_ADDR.
 */
struct kcore_list kcore_modules;
static void __init add_modules_range(void)
{
        kclist_add(&kcore_modules, (void *)MODULES_VADDR,
                        MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
}
#else
static void __init add_modules_range(void)
{
}
#endif

static int __init proc_kcore_init(void)
{
        proc_root_kcore = proc_create("kcore", S_IRUSR, NULL,
                                      &proc_kcore_operations);
        if (!proc_root_kcore) {
                pr_err("couldn't create /proc/kcore\n");
                return 0; /* Always returns 0. */
        }
        /* Store text area if it's special */
        proc_kcore_text_init();
        /* Store vmalloc area */
        kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
                VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
        add_modules_range();
        /* Store direct-map area from physical memory map */
        kcore_update_ram();
        hotplug_memory_notifier(kcore_callback, 0);

        return 0;
}
module_init(proc_kcore_init);