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/*

 *      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/a.out.h>

#include <linux/capability.h>

#include <linux/elf.h>

#include <linux/elfcore.h>

#include <linux/vmalloc.h>

#include <linux/highmem.h>

#include <linux/init.h>

#include <asm/uaccess.h>

#include <asm/io.h>

#define CORE_STR "CORE"

static int open_kcore(struct inode * inode, struct file * filp)

{

        return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;

}

static ssize_t read_kcore(struct file *, char __user *, size_t, loff_t *);

const struct file_operations proc_kcore_operations = {

        .read           = read_kcore,

        .open           = open_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 struct kcore_list *kclist;

static DEFINE_RWLOCK(kclist_lock);

void

kclist_add(struct kcore_list *new, void *addr, size_t size)

{

        new->addr = (unsigned long)addr;

        new->size = size;

        write_lock(&kclist_lock);

        new->next = kclist;

        kclist = new;

        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;

        for (m=kclist; m; m=m->next) {

                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;

}

/*****************************************************************************/

/*

 * 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;

#if defined(CONFIG_H8300)

        elf->e_flags    = ELF_FLAGS;

#else

        elf->e_flags    = 0;

#endif

        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 */

        for (m=kclist; m; m=m->next) {

                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);

        proc_root_kcore->size = 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);

                for (m=kclist; m; m=m->next) {

                        if (start >= m->addr && start < (m->addr+m->size))

                                break;

                }

                read_unlock(&kclist_lock);

                if (m == NULL) {

                        if (clear_user(buffer, tsz))

                                return -EFAULT;

                } else if ((start >= VMALLOC_START) && (start < VMALLOC_END)) {

                        char * elf_buf;

                        struct vm_struct *m;

                        unsigned long curstart = start;

                        unsigned long cursize = tsz;

                        elf_buf = kzalloc(tsz, GFP_KERNEL);

                        if (!elf_buf)

                                return -ENOMEM;

                        read_lock(&vmlist_lock);

                        for (m=vmlist; m && cursize; m=m->next) {

                                unsigned long vmstart;

                                unsigned long vmsize;

                                unsigned long msize = m->size - PAGE_SIZE;

                                if (((unsigned long)m->addr + msize) <

                                                                curstart)

                                        continue;

                                if ((unsigned long)m->addr > (curstart +

                                                                cursize))

                                        break;

                                vmstart = (curstart < (unsigned long)m->addr ?

                                        (unsigned long)m->addr : curstart);

                                if (((unsigned long)m->addr + msize) >

                                                        (curstart + cursize))

                                        vmsize = curstart + cursize - vmstart;

                                else

                                        vmsize = (unsigned long)m->addr +

                                                        msize - vmstart;

                                curstart = vmstart + vmsize;

                                cursize -= vmsize;

                                /* don't dump ioremap'd stuff! (TA) */

                                if (m->flags & VM_IOREMAP)

                                        continue;

                                memcpy(elf_buf + (vmstart - start),

                                        (char *)vmstart, vmsize);

                        }

                        read_unlock(&vmlist_lock);

                        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 distingush 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;

}