// SPDX-License-Identifier: GPL-2.0-or-later
/* binfmt_elf_fdpic.c: FDPIC ELF binary format
 *
 * Copyright (C) 2003, 2004, 2006 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 * Derived from binfmt_elf.c
 */

#include <linux/module.h>

#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/sched/coredump.h>
#include <linux/sched/task_stack.h>
#include <linux/sched/cputime.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/binfmts.h>
#include <linux/string.h>
#include <linux/file.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/security.h>
#include <linux/highmem.h>
#include <linux/highuid.h>
#include <linux/personality.h>
#include <linux/ptrace.h>
#include <linux/init.h>
#include <linux/elf.h>
#include <linux/elf-fdpic.h>
#include <linux/elfcore.h>
#include <linux/coredump.h>
#include <linux/dax.h>

#include <linux/uaccess.h>
#include <asm/param.h>
#include <asm/pgalloc.h>

typedef char *elf_caddr_t;

#if 0
#define kdebug(fmt, ...) printk("FDPIC "fmt"\n" ,##__VA_ARGS__ )
#else
#define kdebug(fmt, ...) do {} while(0)
#endif

#if 0
#define kdcore(fmt, ...) printk("FDPIC "fmt"\n" ,##__VA_ARGS__ )
#else
#define kdcore(fmt, ...) do {} while(0)
#endif

MODULE_LICENSE("GPL");

static int load_elf_fdpic_binary(struct linux_binprm *);
static int elf_fdpic_fetch_phdrs(struct elf_fdpic_params *, struct file *);
static int elf_fdpic_map_file(struct elf_fdpic_params *, struct file *,
                              struct mm_struct *, const char *);

static int create_elf_fdpic_tables(struct linux_binprm *, struct mm_struct *,
                                   struct elf_fdpic_params *,
                                   struct elf_fdpic_params *);

#ifndef CONFIG_MMU
static int elf_fdpic_map_file_constdisp_on_uclinux(struct elf_fdpic_params *,
                                                   struct file *,
                                                   struct mm_struct *);
#endif

static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *,
                                             struct file *, struct mm_struct *);

#ifdef CONFIG_ELF_CORE
static int elf_fdpic_core_dump(struct coredump_params *cprm);
#endif

static struct linux_binfmt elf_fdpic_format = {
        .module         = THIS_MODULE,
        .load_binary    = load_elf_fdpic_binary,
#ifdef CONFIG_ELF_CORE
        .core_dump      = elf_fdpic_core_dump,
#endif
        .min_coredump   = ELF_EXEC_PAGESIZE,
};

static int __init init_elf_fdpic_binfmt(void)
{
        register_binfmt(&elf_fdpic_format);
        return 0;
}

static void __exit exit_elf_fdpic_binfmt(void)
{
        unregister_binfmt(&elf_fdpic_format);
}

core_initcall(init_elf_fdpic_binfmt);
module_exit(exit_elf_fdpic_binfmt);

static int is_elf(struct elfhdr *hdr, struct file *file)
{
        if (memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0)
                return 0;
        if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN)
                return 0;
        if (!elf_check_arch(hdr))
                return 0;
        if (!file->f_op->mmap)
                return 0;
        return 1;
}

#ifndef elf_check_fdpic
#define elf_check_fdpic(x) 0
#endif

#ifndef elf_check_const_displacement
#define elf_check_const_displacement(x) 0
#endif

static int is_constdisp(struct elfhdr *hdr)
{
        if (!elf_check_fdpic(hdr))
                return 1;
        if (elf_check_const_displacement(hdr))
                return 1;
        return 0;
}

/*****************************************************************************/
/*
 * read the program headers table into memory
 */
static int elf_fdpic_fetch_phdrs(struct elf_fdpic_params *params,
                                 struct file *file)
{
        struct elf32_phdr *phdr;
        unsigned long size;
        int retval, loop;
        loff_t pos = params->hdr.e_phoff;

        if (params->hdr.e_phentsize != sizeof(struct elf_phdr))
                return -ENOMEM;
        if (params->hdr.e_phnum > 65536U / sizeof(struct elf_phdr))
                return -ENOMEM;

        size = params->hdr.e_phnum * sizeof(struct elf_phdr);
        params->phdrs = kmalloc(size, GFP_KERNEL);
        if (!params->phdrs)
                return -ENOMEM;

        retval = kernel_read(file, params->phdrs, size, &pos);
        if (unlikely(retval != size))
                return retval < 0 ? retval : -ENOEXEC;

        /* determine stack size for this binary */
        phdr = params->phdrs;
        for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
                if (phdr->p_type != PT_GNU_STACK)
                        continue;

                if (phdr->p_flags & PF_X)
                        params->flags |= ELF_FDPIC_FLAG_EXEC_STACK;
                else
                        params->flags |= ELF_FDPIC_FLAG_NOEXEC_STACK;

                params->stack_size = phdr->p_memsz;
                break;
        }

        return 0;
}

/*****************************************************************************/
/*
 * load an fdpic binary into various bits of memory
 */
static int load_elf_fdpic_binary(struct linux_binprm *bprm)
{
        struct elf_fdpic_params exec_params, interp_params;
        struct pt_regs *regs = current_pt_regs();
        struct elf_phdr *phdr;
        unsigned long stack_size, entryaddr;
#ifdef ELF_FDPIC_PLAT_INIT
        unsigned long dynaddr;
#endif
#ifndef CONFIG_MMU
        unsigned long stack_prot;
#endif
        struct file *interpreter = NULL; /* to shut gcc up */
        char *interpreter_name = NULL;
        int executable_stack;
        int retval, i;
        loff_t pos;

        kdebug("____ LOAD %d ____", current->pid);

        memset(&exec_params, 0, sizeof(exec_params));
        memset(&interp_params, 0, sizeof(interp_params));

        exec_params.hdr = *(struct elfhdr *) bprm->buf;
        exec_params.flags = ELF_FDPIC_FLAG_PRESENT | ELF_FDPIC_FLAG_EXECUTABLE;

        /* check that this is a binary we know how to deal with */
        retval = -ENOEXEC;
        if (!is_elf(&exec_params.hdr, bprm->file))
                goto error;
        if (!elf_check_fdpic(&exec_params.hdr)) {
#ifdef CONFIG_MMU
                /* binfmt_elf handles non-fdpic elf except on nommu */
                goto error;
#else
                /* nommu can only load ET_DYN (PIE) ELF */
                if (exec_params.hdr.e_type != ET_DYN)
                        goto error;
#endif
        }

        /* read the program header table */
        retval = elf_fdpic_fetch_phdrs(&exec_params, bprm->file);
        if (retval < 0)
                goto error;

        /* scan for a program header that specifies an interpreter */
        phdr = exec_params.phdrs;

        for (i = 0; i < exec_params.hdr.e_phnum; i++, phdr++) {
                switch (phdr->p_type) {
                case PT_INTERP:
                        retval = -ENOMEM;
                        if (phdr->p_filesz > PATH_MAX)
                                goto error;
                        retval = -ENOENT;
                        if (phdr->p_filesz < 2)
                                goto error;

                        /* read the name of the interpreter into memory */
                        interpreter_name = kmalloc(phdr->p_filesz, GFP_KERNEL);
                        if (!interpreter_name)
                                goto error;

                        pos = phdr->p_offset;
                        retval = kernel_read(bprm->file, interpreter_name,
                                             phdr->p_filesz, &pos);
                        if (unlikely(retval != phdr->p_filesz)) {
                                if (retval >= 0)
                                        retval = -ENOEXEC;
                                goto error;
                        }

                        retval = -ENOENT;
                        if (interpreter_name[phdr->p_filesz - 1] != '\0')
                                goto error;

                        kdebug("Using ELF interpreter %s", interpreter_name);

                        /* replace the program with the interpreter */
                        interpreter = open_exec(interpreter_name);
                        retval = PTR_ERR(interpreter);
                        if (IS_ERR(interpreter)) {
                                interpreter = NULL;
                                goto error;
                        }

                        /*
                         * If the binary is not readable then enforce
                         * mm->dumpable = 0 regardless of the interpreter's
                         * permissions.
                         */
                        would_dump(bprm, interpreter);

                        pos = 0;
                        retval = kernel_read(interpreter, bprm->buf,
                                        BINPRM_BUF_SIZE, &pos);
                        if (unlikely(retval != BINPRM_BUF_SIZE)) {
                                if (retval >= 0)
                                        retval = -ENOEXEC;
                                goto error;
                        }

                        interp_params.hdr = *((struct elfhdr *) bprm->buf);
                        break;

                case PT_LOAD:
#ifdef CONFIG_MMU
                        if (exec_params.load_addr == 0)
                                exec_params.load_addr = phdr->p_vaddr;
#endif
                        break;
                }

        }

        if (is_constdisp(&exec_params.hdr))
                exec_params.flags |= ELF_FDPIC_FLAG_CONSTDISP;

        /* perform insanity checks on the interpreter */
        if (interpreter_name) {
                retval = -ELIBBAD;
                if (!is_elf(&interp_params.hdr, interpreter))
                        goto error;

                interp_params.flags = ELF_FDPIC_FLAG_PRESENT;

                /* read the interpreter's program header table */
                retval = elf_fdpic_fetch_phdrs(&interp_params, interpreter);
                if (retval < 0)
                        goto error;
        }

        stack_size = exec_params.stack_size;
        if (exec_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
                executable_stack = EXSTACK_ENABLE_X;
        else if (exec_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK)
                executable_stack = EXSTACK_DISABLE_X;
        else
                executable_stack = EXSTACK_DEFAULT;

        if (stack_size == 0) {
                stack_size = interp_params.stack_size;
                if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
                        executable_stack = EXSTACK_ENABLE_X;
                else if (interp_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK)
                        executable_stack = EXSTACK_DISABLE_X;
                else
                        executable_stack = EXSTACK_DEFAULT;
        }

        retval = -ENOEXEC;
        if (stack_size == 0)
                stack_size = 131072UL; /* same as exec.c's default commit */

        if (is_constdisp(&interp_params.hdr))
                interp_params.flags |= ELF_FDPIC_FLAG_CONSTDISP;

        /* flush all traces of the currently running executable */
        retval = flush_old_exec(bprm);
        if (retval)
                goto error;

        /* there's now no turning back... the old userspace image is dead,
         * defunct, deceased, etc.
         */
        if (elf_check_fdpic(&exec_params.hdr))
                set_personality(PER_LINUX_FDPIC);
        else
                set_personality(PER_LINUX);
        if (elf_read_implies_exec(&exec_params.hdr, executable_stack))
                current->personality |= READ_IMPLIES_EXEC;

        setup_new_exec(bprm);

        set_binfmt(&elf_fdpic_format);

        current->mm->start_code = 0;
        current->mm->end_code = 0;
        current->mm->start_stack = 0;
        current->mm->start_data = 0;
        current->mm->end_data = 0;
        current->mm->context.exec_fdpic_loadmap = 0;
        current->mm->context.interp_fdpic_loadmap = 0;

#ifdef CONFIG_MMU
        elf_fdpic_arch_lay_out_mm(&exec_params,
                                  &interp_params,
                                  &current->mm->start_stack,
                                  &current->mm->start_brk);

        retval = setup_arg_pages(bprm, current->mm->start_stack,
                                 executable_stack);
        if (retval < 0)
                goto error;
#ifdef ARCH_HAS_SETUP_ADDITIONAL_PAGES
        retval = arch_setup_additional_pages(bprm, !!interpreter_name);
        if (retval < 0)
                goto error;
#endif
#endif

        /* load the executable and interpreter into memory */
        retval = elf_fdpic_map_file(&exec_params, bprm->file, current->mm,
                                    "executable");
        if (retval < 0)
                goto error;

        if (interpreter_name) {
                retval = elf_fdpic_map_file(&interp_params, interpreter,
                                            current->mm, "interpreter");
                if (retval < 0) {
                        printk(KERN_ERR "Unable to load interpreter\n");
                        goto error;
                }

                allow_write_access(interpreter);
                fput(interpreter);
                interpreter = NULL;
        }

#ifdef CONFIG_MMU
        if (!current->mm->start_brk)
                current->mm->start_brk = current->mm->end_data;

        current->mm->brk = current->mm->start_brk =
                PAGE_ALIGN(current->mm->start_brk);

#else
        /* create a stack area and zero-size brk area */
        stack_size = (stack_size + PAGE_SIZE - 1) & PAGE_MASK;
        if (stack_size < PAGE_SIZE * 2)
                stack_size = PAGE_SIZE * 2;

        stack_prot = PROT_READ | PROT_WRITE;
        if (executable_stack == EXSTACK_ENABLE_X ||
            (executable_stack == EXSTACK_DEFAULT && VM_STACK_FLAGS & VM_EXEC))
                stack_prot |= PROT_EXEC;

        current->mm->start_brk = vm_mmap(NULL, 0, stack_size, stack_prot,
                                         MAP_PRIVATE | MAP_ANONYMOUS |
                                         MAP_UNINITIALIZED | MAP_GROWSDOWN,
                                         0);

        if (IS_ERR_VALUE(current->mm->start_brk)) {
                retval = current->mm->start_brk;
                current->mm->start_brk = 0;
                goto error;
        }

        current->mm->brk = current->mm->start_brk;
        current->mm->context.end_brk = current->mm->start_brk;
        current->mm->start_stack = current->mm->start_brk + stack_size;
#endif

        install_exec_creds(bprm);
        if (create_elf_fdpic_tables(bprm, current->mm,
                                    &exec_params, &interp_params) < 0)
                goto error;

        kdebug("- start_code  %lx", current->mm->start_code);
        kdebug("- end_code    %lx", current->mm->end_code);
        kdebug("- start_data  %lx", current->mm->start_data);
        kdebug("- end_data    %lx", current->mm->end_data);
        kdebug("- start_brk   %lx", current->mm->start_brk);
        kdebug("- brk         %lx", current->mm->brk);
        kdebug("- start_stack %lx", current->mm->start_stack);

#ifdef ELF_FDPIC_PLAT_INIT
        /*
         * The ABI may specify that certain registers be set up in special
         * ways (on i386 %edx is the address of a DT_FINI function, for
         * example.  This macro performs whatever initialization to
         * the regs structure is required.
         */
        dynaddr = interp_params.dynamic_addr ?: exec_params.dynamic_addr;
        ELF_FDPIC_PLAT_INIT(regs, exec_params.map_addr, interp_params.map_addr,
                            dynaddr);
#endif

        finalize_exec(bprm);
        /* everything is now ready... get the userspace context ready to roll */
        entryaddr = interp_params.entry_addr ?: exec_params.entry_addr;
        start_thread(regs, entryaddr, current->mm->start_stack);

        retval = 0;

error:
        if (interpreter) {
                allow_write_access(interpreter);
                fput(interpreter);
        }
        kfree(interpreter_name);
        kfree(exec_params.phdrs);
        kfree(exec_params.loadmap);
        kfree(interp_params.phdrs);
        kfree(interp_params.loadmap);
        return retval;
}

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

#ifndef ELF_BASE_PLATFORM
/*
 * AT_BASE_PLATFORM indicates the "real" hardware/microarchitecture.
 * If the arch defines ELF_BASE_PLATFORM (in asm/elf.h), the value
 * will be copied to the user stack in the same manner as AT_PLATFORM.
 */
#define ELF_BASE_PLATFORM NULL
#endif

/*
 * present useful information to the program by shovelling it onto the new
 * process's stack
 */
static int create_elf_fdpic_tables(struct linux_binprm *bprm,
                                   struct mm_struct *mm,
                                   struct elf_fdpic_params *exec_params,
                                   struct elf_fdpic_params *interp_params)
{
        const struct cred *cred = current_cred();
        unsigned long sp, csp, nitems;
        elf_caddr_t __user *argv, *envp;
        size_t platform_len = 0, len;
        char *k_platform, *k_base_platform;
        char __user *u_platform, *u_base_platform, *p;
        int loop;
        int nr; /* reset for each csp adjustment */

#ifdef CONFIG_MMU
        /* In some cases (e.g. Hyper-Threading), we want to avoid L1 evictions
         * by the processes running on the same package. One thing we can do is
         * to shuffle the initial stack for them, so we give the architecture
         * an opportunity to do so here.
         */
        sp = arch_align_stack(bprm->p);
#else
        sp = mm->start_stack;

        /* stack the program arguments and environment */
        if (transfer_args_to_stack(bprm, &sp) < 0)
                return -EFAULT;
        sp &= ~15;
#endif

        /*
         * If this architecture has a platform capability string, copy it
         * to userspace.  In some cases (Sparc), this info is impossible
         * for userspace to get any other way, in others (i386) it is
         * merely difficult.
         */
        k_platform = ELF_PLATFORM;
        u_platform = NULL;

        if (k_platform) {
                platform_len = strlen(k_platform) + 1;
                sp -= platform_len;
                u_platform = (char __user *) sp;
                if (__copy_to_user(u_platform, k_platform, platform_len) != 0)
                        return -EFAULT;
        }

        /*
         * If this architecture has a "base" platform capability
         * string, copy it to userspace.
         */
        k_base_platform = ELF_BASE_PLATFORM;
        u_base_platform = NULL;

        if (k_base_platform) {
                platform_len = strlen(k_base_platform) + 1;
                sp -= platform_len;
                u_base_platform = (char __user *) sp;
                if (__copy_to_user(u_base_platform, k_base_platform, platform_len) != 0)
                        return -EFAULT;
        }

        sp &= ~7UL;

        /* stack the load map(s) */
        len = sizeof(struct elf32_fdpic_loadmap);
        len += sizeof(struct elf32_fdpic_loadseg) * exec_params->loadmap->nsegs;
        sp = (sp - len) & ~7UL;
        exec_params->map_addr = sp;

        if (copy_to_user((void __user *) sp, exec_params->loadmap, len) != 0)
                return -EFAULT;

        current->mm->context.exec_fdpic_loadmap = (unsigned long) sp;

        if (interp_params->loadmap) {
                len = sizeof(struct elf32_fdpic_loadmap);
                len += sizeof(struct elf32_fdpic_loadseg) *
                        interp_params->loadmap->nsegs;
                sp = (sp - len) & ~7UL;
                interp_params->map_addr = sp;

                if (copy_to_user((void __user *) sp, interp_params->loadmap,
                                 len) != 0)
                        return -EFAULT;

                current->mm->context.interp_fdpic_loadmap = (unsigned long) sp;
        }

        /* force 16 byte _final_ alignment here for generality */
#define DLINFO_ITEMS 15

        nitems = 1 + DLINFO_ITEMS + (k_platform ? 1 : 0) +
                (k_base_platform ? 1 : 0) + AT_VECTOR_SIZE_ARCH;

        if (bprm->interp_flags & BINPRM_FLAGS_EXECFD)
                nitems++;

        csp = sp;
        sp -= nitems * 2 * sizeof(unsigned long);
        sp -= (bprm->envc + 1) * sizeof(char *);        /* envv[] */
        sp -= (bprm->argc + 1) * sizeof(char *);        /* argv[] */
        sp -= 1 * sizeof(unsigned long);                /* argc */

        csp -= sp & 15UL;
        sp -= sp & 15UL;

        /* put the ELF interpreter info on the stack */
#define NEW_AUX_ENT(id, val)                                            \
        do {                                                            \
                struct { unsigned long _id, _val; } __user *ent;        \
                                                                        \
                ent = (void __user *) csp;                              \
                __put_user((id), &ent[nr]._id);                         \
                __put_user((val), &ent[nr]._val);                       \
                nr++;                                                   \
        } while (0)

        nr = 0;
        csp -= 2 * sizeof(unsigned long);
        NEW_AUX_ENT(AT_NULL, 0);
        if (k_platform) {
                nr = 0;
                csp -= 2 * sizeof(unsigned long);
                NEW_AUX_ENT(AT_PLATFORM,
                            (elf_addr_t) (unsigned long) u_platform);
        }

        if (k_base_platform) {
                nr = 0;
                csp -= 2 * sizeof(unsigned long);
                NEW_AUX_ENT(AT_BASE_PLATFORM,
                            (elf_addr_t) (unsigned long) u_base_platform);
        }

        if (bprm->interp_flags & BINPRM_FLAGS_EXECFD) {
                nr = 0;
                csp -= 2 * sizeof(unsigned long);
                NEW_AUX_ENT(AT_EXECFD, bprm->interp_data);
        }

        nr = 0;
        csp -= DLINFO_ITEMS * 2 * sizeof(unsigned long);
        NEW_AUX_ENT(AT_HWCAP,   ELF_HWCAP);
#ifdef ELF_HWCAP2
        NEW_AUX_ENT(AT_HWCAP2,  ELF_HWCAP2);
#endif
        NEW_AUX_ENT(AT_PAGESZ,  PAGE_SIZE);
        NEW_AUX_ENT(AT_CLKTCK,  CLOCKS_PER_SEC);
        NEW_AUX_ENT(AT_PHDR,    exec_params->ph_addr);
        NEW_AUX_ENT(AT_PHENT,   sizeof(struct elf_phdr));
        NEW_AUX_ENT(AT_PHNUM,   exec_params->hdr.e_phnum);
        NEW_AUX_ENT(AT_BASE,    interp_params->elfhdr_addr);
        NEW_AUX_ENT(AT_FLAGS,   0);
        NEW_AUX_ENT(AT_ENTRY,   exec_params->entry_addr);
        NEW_AUX_ENT(AT_UID,     (elf_addr_t) from_kuid_munged(cred->user_ns, cred->uid));
        NEW_AUX_ENT(AT_EUID,    (elf_addr_t) from_kuid_munged(cred->user_ns, cred->euid));
        NEW_AUX_ENT(AT_GID,     (elf_addr_t) from_kgid_munged(cred->user_ns, cred->gid));
        NEW_AUX_ENT(AT_EGID,    (elf_addr_t) from_kgid_munged(cred->user_ns, cred->egid));
        NEW_AUX_ENT(AT_SECURE,  bprm->secureexec);
        NEW_AUX_ENT(AT_EXECFN,  bprm->exec);

#ifdef ARCH_DLINFO
        nr = 0;
        csp -= AT_VECTOR_SIZE_ARCH * 2 * sizeof(unsigned long);

        /* ARCH_DLINFO must come last so platform specific code can enforce
         * special alignment requirements on the AUXV if necessary (eg. PPC).
         */
        ARCH_DLINFO;
#endif
#undef NEW_AUX_ENT

        /* allocate room for argv[] and envv[] */
        csp -= (bprm->envc + 1) * sizeof(elf_caddr_t);
        envp = (elf_caddr_t __user *) csp;
        csp -= (bprm->argc + 1) * sizeof(elf_caddr_t);
        argv = (elf_caddr_t __user *) csp;

        /* stack argc */
        csp -= sizeof(unsigned long);
        __put_user(bprm->argc, (unsigned long __user *) csp);

        BUG_ON(csp != sp);

        /* fill in the argv[] array */
#ifdef CONFIG_MMU
        current->mm->arg_start = bprm->p;
#else
        current->mm->arg_start = current->mm->start_stack -
                (MAX_ARG_PAGES * PAGE_SIZE - bprm->p);
#endif

        p = (char __user *) current->mm->arg_start;
        for (loop = bprm->argc; loop > 0; loop--) {
                __put_user((elf_caddr_t) p, argv++);
                len = strnlen_user(p, MAX_ARG_STRLEN);
                if (!len || len > MAX_ARG_STRLEN)
                        return -EINVAL;
                p += len;
        }
        __put_user(NULL, argv);
        current->mm->arg_end = (unsigned long) p;

        /* fill in the envv[] array */
        current->mm->env_start = (unsigned long) p;
        for (loop = bprm->envc; loop > 0; loop--) {
                __put_user((elf_caddr_t)(unsigned long) p, envp++);
                len = strnlen_user(p, MAX_ARG_STRLEN);
                if (!len || len > MAX_ARG_STRLEN)
                        return -EINVAL;
                p += len;
        }
        __put_user(NULL, envp);
        current->mm->env_end = (unsigned long) p;

        mm->start_stack = (unsigned long) sp;
        return 0;
}

/*****************************************************************************/
/*
 * load the appropriate binary image (executable or interpreter) into memory
 * - we assume no MMU is available
 * - if no other PIC bits are set in params->hdr->e_flags
 *   - we assume that the LOADable segments in the binary are independently relocatable
 *   - we assume R/O executable segments are shareable
 * - else
 *   - we assume the loadable parts of the image to require fixed displacement
 *   - the image is not shareable
 */
static int elf_fdpic_map_file(struct elf_fdpic_params *params,
                              struct file *file,
                              struct mm_struct *mm,
                              const char *what)
{
        struct elf32_fdpic_loadmap *loadmap;
#ifdef CONFIG_MMU
        struct elf32_fdpic_loadseg *mseg;
#endif
        struct elf32_fdpic_loadseg *seg;
        struct elf32_phdr *phdr;
        unsigned long load_addr, stop;
        unsigned nloads, tmp;
        size_t size;
        int loop, ret;

        /* allocate a load map table */
        nloads = 0;
        for (loop = 0; loop < params->hdr.e_phnum; loop++)
                if (params->phdrs[loop].p_type == PT_LOAD)
                        nloads++;

        if (nloads == 0)
                return -ELIBBAD;

        size = sizeof(*loadmap) + nloads * sizeof(*seg);
        loadmap = kzalloc(size, GFP_KERNEL);
        if (!loadmap)
                return -ENOMEM;

        params->loadmap = loadmap;

        loadmap->version = ELF32_FDPIC_LOADMAP_VERSION;
        loadmap->nsegs = nloads;

        load_addr = params->load_addr;
        seg = loadmap->segs;

        /* map the requested LOADs into the memory space */
        switch (params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) {
        case ELF_FDPIC_FLAG_CONSTDISP:
        case ELF_FDPIC_FLAG_CONTIGUOUS:
#ifndef CONFIG_MMU
                ret = elf_fdpic_map_file_constdisp_on_uclinux(params, file, mm);
                if (ret < 0)
                        return ret;
                break;
#endif
        default:
                ret = elf_fdpic_map_file_by_direct_mmap(params, file, mm);
                if (ret < 0)
                        return ret;
                break;
        }

        /* map the entry point */
        if (params->hdr.e_entry) {
                seg = loadmap->segs;
                for (loop = loadmap->nsegs; loop > 0; loop--, seg++) {
                        if (params->hdr.e_entry >= seg->p_vaddr &&
                            params->hdr.e_entry < seg->p_vaddr + seg->p_memsz) {
                                params->entry_addr =
                                        (params->hdr.e_entry - seg->p_vaddr) +
                                        seg->addr;
                                break;
                        }
                }
        }

        /* determine where the program header table has wound up if mapped */
        stop = params->hdr.e_phoff;
        stop += params->hdr.e_phnum * sizeof (struct elf_phdr);
        phdr = params->phdrs;

        for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
                if (phdr->p_type != PT_LOAD)
                        continue;

                if (phdr->p_offset > params->hdr.e_phoff ||
                    phdr->p_offset + phdr->p_filesz < stop)
                        continue;

                seg = loadmap->segs;
                for (loop = loadmap->nsegs; loop > 0; loop--, seg++) {
                        if (phdr->p_vaddr >= seg->p_vaddr &&
                            phdr->p_vaddr + phdr->p_filesz <=
                            seg->p_vaddr + seg->p_memsz) {
                                params->ph_addr =
                                        (phdr->p_vaddr - seg->p_vaddr) +
                                        seg->addr +
                                        params->hdr.e_phoff - phdr->p_offset;
                                break;
                        }
                }
                break;
        }

        /* determine where the dynamic section has wound up if there is one */
        phdr = params->phdrs;
        for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
                if (phdr->p_type != PT_DYNAMIC)
                        continue;

                seg = loadmap->segs;
                for (loop = loadmap->nsegs; loop > 0; loop--, seg++) {
                        if (phdr->p_vaddr >= seg->p_vaddr &&
                            phdr->p_vaddr + phdr->p_memsz <=
                            seg->p_vaddr + seg->p_memsz) {
                                Elf32_Dyn __user *dyn;
                                Elf32_Sword d_tag;

                                params->dynamic_addr =
                                        (phdr->p_vaddr - seg->p_vaddr) +
                                        seg->addr;

                                /* check the dynamic section contains at least
                                 * one item, and that the last item is a NULL
                                 * entry */
                                if (phdr->p_memsz == 0 ||
                                    phdr->p_memsz % sizeof(Elf32_Dyn) != 0)
                                        goto dynamic_error;

                                tmp = phdr->p_memsz / sizeof(Elf32_Dyn);
                                dyn = (Elf32_Dyn __user *)params->dynamic_addr;
                                __get_user(d_tag, &dyn[tmp - 1].d_tag);
                                if (d_tag != 0)
                                        goto dynamic_error;
                                break;
                        }
                }
                break;
        }

        /* now elide adjacent segments in the load map on MMU linux
         * - on uClinux the holes between may actually be filled with system
         *   stuff or stuff from other processes
         */
#ifdef CONFIG_MMU
        nloads = loadmap->nsegs;
        mseg = loadmap->segs;
        seg = mseg + 1;
        for (loop = 1; loop < nloads; loop++) {
                /* see if we have a candidate for merging */
                if (seg->p_vaddr - mseg->p_vaddr == seg->addr - mseg->addr) {
                        load_addr = PAGE_ALIGN(mseg->addr + mseg->p_memsz);
                        if (load_addr == (seg->addr & PAGE_MASK)) {
                                mseg->p_memsz +=
                                        load_addr -
                                        (mseg->addr + mseg->p_memsz);
                                mseg->p_memsz += seg->addr & ~PAGE_MASK;
                                mseg->p_memsz += seg->p_memsz;
                                loadmap->nsegs--;
                                continue;
                        }
                }

                mseg++;
                if (mseg != seg)
                        *mseg = *seg;
        }
#endif

        kdebug("Mapped Object [%s]:", what);
        kdebug("- elfhdr   : %lx", params->elfhdr_addr);
        kdebug("- entry    : %lx", params->entry_addr);
        kdebug("- PHDR[]   : %lx", params->ph_addr);
        kdebug("- DYNAMIC[]: %lx", params->dynamic_addr);
        seg = loadmap->segs;
        for (loop = 0; loop < loadmap->nsegs; loop++, seg++)
                kdebug("- LOAD[%d] : %08x-%08x [va=%x ms=%x]",
                       loop,
                       seg->addr, seg->addr + seg->p_memsz - 1,
                       seg->p_vaddr, seg->p_memsz);

        return 0;

dynamic_error:
        printk("ELF FDPIC %s with invalid DYNAMIC section (inode=%lu)\n",
               what, file_inode(file)->i_ino);
        return -ELIBBAD;
}

/*****************************************************************************/
/*
 * map a file with constant displacement under uClinux
 */
#ifndef CONFIG_MMU
static int elf_fdpic_map_file_constdisp_on_uclinux(
        struct elf_fdpic_params *params,
        struct file *file,
        struct mm_struct *mm)
{
        struct elf32_fdpic_loadseg *seg;
        struct elf32_phdr *phdr;
        unsigned long load_addr, base = ULONG_MAX, top = 0, maddr = 0, mflags;
        int loop, ret;

        load_addr = params->load_addr;
        seg = params->loadmap->segs;

        /* determine the bounds of the contiguous overall allocation we must
         * make */
        phdr = params->phdrs;
        for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
                if (params->phdrs[loop].p_type != PT_LOAD)
                        continue;

                if (base > phdr->p_vaddr)
                        base = phdr->p_vaddr;
                if (top < phdr->p_vaddr + phdr->p_memsz)
                        top = phdr->p_vaddr + phdr->p_memsz;
        }

        /* allocate one big anon block for everything */
        mflags = MAP_PRIVATE;
        if (params->flags & ELF_FDPIC_FLAG_EXECUTABLE)
                mflags |= MAP_EXECUTABLE;

        maddr = vm_mmap(NULL, load_addr, top - base,
                        PROT_READ | PROT_WRITE | PROT_EXEC, mflags, 0);
        if (IS_ERR_VALUE(maddr))
                return (int) maddr;

        if (load_addr != 0)
                load_addr += PAGE_ALIGN(top - base);

        /* and then load the file segments into it */
        phdr = params->phdrs;
        for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
                if (params->phdrs[loop].p_type != PT_LOAD)
                        continue;

                seg->addr = maddr + (phdr->p_vaddr - base);
                seg->p_vaddr = phdr->p_vaddr;
                seg->p_memsz = phdr->p_memsz;

                ret = read_code(file, seg->addr, phdr->p_offset,
                                       phdr->p_filesz);
                if (ret < 0)
                        return ret;

                /* map the ELF header address if in this segment */
                if (phdr->p_offset == 0)
                        params->elfhdr_addr = seg->addr;

                /* clear any space allocated but not loaded */
                if (phdr->p_filesz < phdr->p_memsz) {
                        if (clear_user((void *) (seg->addr + phdr->p_filesz),
                                       phdr->p_memsz - phdr->p_filesz))
                                return -EFAULT;
                }

                if (mm) {
                        if (phdr->p_flags & PF_X) {
                                if (!mm->start_code) {
                                        mm->start_code = seg->addr;
                                        mm->end_code = seg->addr +
                                                phdr->p_memsz;
                                }
                        } else if (!mm->start_data) {
                                mm->start_data = seg->addr;
                                mm->end_data = seg->addr + phdr->p_memsz;
                        }
                }

                seg++;
        }

        return 0;
}
#endif

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

/*
 * map a binary by direct mmap() of the individual PT_LOAD segments
 */
static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
                                             struct file *file,
                                             struct mm_struct *mm)
{
        struct elf32_fdpic_loadseg *seg;
        struct elf32_phdr *phdr;
        unsigned long load_addr, delta_vaddr;
        int loop, dvset;

        load_addr = params->load_addr;
        delta_vaddr = 0;
        dvset = 0;

        seg = params->loadmap->segs;

        /* deal with each load segment separately */
        phdr = params->phdrs;
        for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
                unsigned long maddr, disp, excess, excess1;
                int prot = 0, flags;

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

                kdebug("[LOAD] va=%lx of=%lx fs=%lx ms=%lx",
                       (unsigned long) phdr->p_vaddr,
                       (unsigned long) phdr->p_offset,
                       (unsigned long) phdr->p_filesz,
                       (unsigned long) phdr->p_memsz);

                /* determine the mapping parameters */
                if (phdr->p_flags & PF_R) prot |= PROT_READ;
                if (phdr->p_flags & PF_W) prot |= PROT_WRITE;
                if (phdr->p_flags & PF_X) prot |= PROT_EXEC;

                flags = MAP_PRIVATE | MAP_DENYWRITE;
                if (params->flags & ELF_FDPIC_FLAG_EXECUTABLE)
                        flags |= MAP_EXECUTABLE;

                maddr = 0;

                switch (params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) {
                case ELF_FDPIC_FLAG_INDEPENDENT:
                        /* PT_LOADs are independently locatable */
                        break;

                case ELF_FDPIC_FLAG_HONOURVADDR:
                        /* the specified virtual address must be honoured */
                        maddr = phdr->p_vaddr;
                        flags |= MAP_FIXED;
                        break;

                case ELF_FDPIC_FLAG_CONSTDISP:
                        /* constant displacement
                         * - can be mapped anywhere, but must be mapped as a
                         *   unit
                         */
                        if (!dvset) {
                                maddr = load_addr;
                                delta_vaddr = phdr->p_vaddr;
                                dvset = 1;
                        } else {
                                maddr = load_addr + phdr->p_vaddr - delta_vaddr;
                                flags |= MAP_FIXED;
                        }
                        break;

                case ELF_FDPIC_FLAG_CONTIGUOUS:
                        /* contiguity handled later */
                        break;

                default:
                        BUG();
                }

                maddr &= PAGE_MASK;

                /* create the mapping */
                disp = phdr->p_vaddr & ~PAGE_MASK;
                maddr = vm_mmap(file, maddr, phdr->p_memsz + disp, prot, flags,
                                phdr->p_offset - disp);

                kdebug("mmap[%d] <file> sz=%lx pr=%x fl=%x of=%lx --> %08lx",
                       loop, phdr->p_memsz + disp, prot, flags,
                       phdr->p_offset - disp, maddr);

                if (IS_ERR_VALUE(maddr))
                        return (int) maddr;

                if ((params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) ==
                    ELF_FDPIC_FLAG_CONTIGUOUS)
                        load_addr += PAGE_ALIGN(phdr->p_memsz + disp);

                seg->addr = maddr + disp;
                seg->p_vaddr = phdr->p_vaddr;
                seg->p_memsz = phdr->p_memsz;

                /* map the ELF header address if in this segment */
                if (phdr->p_offset == 0)
                        params->elfhdr_addr = seg->addr;

                /* clear the bit between beginning of mapping and beginning of
                 * PT_LOAD */
                if (prot & PROT_WRITE && disp > 0) {
                        kdebug("clear[%d] ad=%lx sz=%lx", loop, maddr, disp);
                        if (clear_user((void __user *) maddr, disp))
                                return -EFAULT;
                        maddr += disp;
                }

                /* clear any space allocated but not loaded
                 * - on uClinux we can just clear the lot
                 * - on MMU linux we'll get a SIGBUS beyond the last page
                 *   extant in the file
                 */
                excess = phdr->p_memsz - phdr->p_filesz;
                excess1 = PAGE_SIZE - ((maddr + phdr->p_filesz) & ~PAGE_MASK);

#ifdef CONFIG_MMU
                if (excess > excess1) {
                        unsigned long xaddr = maddr + phdr->p_filesz + excess1;
                        unsigned long xmaddr;

                        flags |= MAP_FIXED | MAP_ANONYMOUS;
                        xmaddr = vm_mmap(NULL, xaddr, excess - excess1,
                                         prot, flags, 0);

                        kdebug("mmap[%d] <anon>"
                               " ad=%lx sz=%lx pr=%x fl=%x of=0 --> %08lx",
                               loop, xaddr, excess - excess1, prot, flags,
                               xmaddr);

                        if (xmaddr != xaddr)
                                return -ENOMEM;
                }

                if (prot & PROT_WRITE && excess1 > 0) {
                        kdebug("clear[%d] ad=%lx sz=%lx",
                               loop, maddr + phdr->p_filesz, excess1);
                        if (clear_user((void __user *) maddr + phdr->p_filesz,
                                       excess1))
                                return -EFAULT;
                }

#else
                if (excess > 0) {
                        kdebug("clear[%d] ad=%lx sz=%lx",
                               loop, maddr + phdr->p_filesz, excess);
                        if (clear_user((void *) maddr + phdr->p_filesz, excess))
                                return -EFAULT;
                }
#endif

                if (mm) {
                        if (phdr->p_flags & PF_X) {
                                if (!mm->start_code) {
                                        mm->start_code = maddr;
                                        mm->end_code = maddr + phdr->p_memsz;
                                }
                        } else if (!mm->start_data) {
                                mm->start_data = maddr;
                                mm->end_data = maddr + phdr->p_memsz;
                        }
                }

                seg++;
        }

        return 0;
}

/*****************************************************************************/
/*
 * ELF-FDPIC core dumper
 *
 * Modelled on fs/exec.c:aout_core_dump()
 * Jeremy Fitzhardinge <jeremy@sw.oz.au>
 *
 * Modelled on fs/binfmt_elf.c core dumper
 */
#ifdef CONFIG_ELF_CORE

/*
 * Decide whether a segment is worth dumping; default is yes to be
 * sure (missing info is worse than too much; etc).
 * Personally I'd include everything, and use the coredump limit...
 *
 * I think we should skip something. But I am not sure how. H.J.
 */
static int maydump(struct vm_area_struct *vma, unsigned long mm_flags)
{
        int dump_ok;

        /* Do not dump I/O mapped devices or special mappings */
        if (vma->vm_flags & VM_IO) {
                kdcore("%08lx: %08lx: no (IO)", vma->vm_start, vma->vm_flags);
                return 0;
        }

        /* If we may not read the contents, don't allow us to dump
         * them either. "dump_write()" can't handle it anyway.
         */
        if (!(vma->vm_flags & VM_READ)) {
                kdcore("%08lx: %08lx: no (!read)", vma->vm_start, vma->vm_flags);
                return 0;
        }

        /* support for DAX */
        if (vma_is_dax(vma)) {
                if (vma->vm_flags & VM_SHARED) {
                        dump_ok = test_bit(MMF_DUMP_DAX_SHARED, &mm_flags);
                        kdcore("%08lx: %08lx: %s (DAX shared)", vma->vm_start,
                               vma->vm_flags, dump_ok ? "yes" : "no");
                } else {
                        dump_ok = test_bit(MMF_DUMP_DAX_PRIVATE, &mm_flags);
                        kdcore("%08lx: %08lx: %s (DAX private)", vma->vm_start,
                               vma->vm_flags, dump_ok ? "yes" : "no");
                }
                return dump_ok;
        }

        /* By default, dump shared memory if mapped from an anonymous file. */
        if (vma->vm_flags & VM_SHARED) {
                if (file_inode(vma->vm_file)->i_nlink == 0) {
                        dump_ok = test_bit(MMF_DUMP_ANON_SHARED, &mm_flags);
                        kdcore("%08lx: %08lx: %s (share)", vma->vm_start,
                               vma->vm_flags, dump_ok ? "yes" : "no");
                        return dump_ok;
                }

                dump_ok = test_bit(MMF_DUMP_MAPPED_SHARED, &mm_flags);
                kdcore("%08lx: %08lx: %s (share)", vma->vm_start,
                       vma->vm_flags, dump_ok ? "yes" : "no");
                return dump_ok;
        }

#ifdef CONFIG_MMU
        /* By default, if it hasn't been written to, don't write it out */
        if (!vma->anon_vma) {
                dump_ok = test_bit(MMF_DUMP_MAPPED_PRIVATE, &mm_flags);
                kdcore("%08lx: %08lx: %s (!anon)", vma->vm_start,
                       vma->vm_flags, dump_ok ? "yes" : "no");
                return dump_ok;
        }
#endif

        dump_ok = test_bit(MMF_DUMP_ANON_PRIVATE, &mm_flags);
        kdcore("%08lx: %08lx: %s", vma->vm_start, vma->vm_flags,
               dump_ok ? "yes" : "no");
        return dump_ok;
}

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

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;
}

/* #define DEBUG */

static int writenote(struct memelfnote *men, struct coredump_params *cprm)
{
        struct elf_note en;
        en.n_namesz = strlen(men->name) + 1;
        en.n_descsz = men->datasz;
        en.n_type = men->type;

        return dump_emit(cprm, &en, sizeof(en)) &&
                dump_emit(cprm, men->name, en.n_namesz) && dump_align(cprm, 4) &&
                dump_emit(cprm, men->data, men->datasz) && dump_align(cprm, 4);
}

static inline void fill_elf_fdpic_header(struct elfhdr *elf, int segs)
{
        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_FDPIC_CORE_EFLAGS;
        elf->e_ehsize = sizeof(struct elfhdr);
        elf->e_phentsize = sizeof(struct elf_phdr);
        elf->e_phnum = segs;
        elf->e_shentsize = 0;
        elf->e_shnum = 0;
        elf->e_shstrndx = 0;
        return;
}

static inline void fill_elf_note_phdr(struct elf_phdr *phdr, int sz, loff_t offset)
{
        phdr->p_type = PT_NOTE;
        phdr->p_offset = offset;
        phdr->p_vaddr = 0;
        phdr->p_paddr = 0;
        phdr->p_filesz = sz;
        phdr->p_memsz = 0;
        phdr->p_flags = 0;
        phdr->p_align = 0;
        return;
}

static inline void fill_note(struct memelfnote *note, const char *name, int type,
                unsigned int sz, void *data)
{
        note->name = name;
        note->type = type;
        note->datasz = sz;
        note->data = data;
        return;
}

/*
 * fill up all the fields in prstatus from the given task struct, except
 * registers which need to be filled up separately.
 */
static void fill_prstatus(struct elf_prstatus *prstatus,
                          struct task_struct *p, long signr)
{
        prstatus->pr_info.si_signo = prstatus->pr_cursig = signr;
        prstatus->pr_sigpend = p->pending.signal.sig[0];
        prstatus->pr_sighold = p->blocked.sig[0];
        rcu_read_lock();
        prstatus->pr_ppid = task_pid_vnr(rcu_dereference(p->real_parent));
        rcu_read_unlock();
        prstatus->pr_pid = task_pid_vnr(p);
        prstatus->pr_pgrp = task_pgrp_vnr(p);
        prstatus->pr_sid = task_session_vnr(p);
        if (thread_group_leader(p)) {
                struct task_cputime cputime;

                /*
                 * This is the record for the group leader.  It shows the
                 * group-wide total, not its individual thread total.
                 */
                thread_group_cputime(p, &cputime);
                prstatus->pr_utime = ns_to_timeval(cputime.utime);
                prstatus->pr_stime = ns_to_timeval(cputime.stime);
        } else {
                u64 utime, stime;

                task_cputime(p, &utime, &stime);
                prstatus->pr_utime = ns_to_timeval(utime);
                prstatus->pr_stime = ns_to_timeval(stime);
        }
        prstatus->pr_cutime = ns_to_timeval(p->signal->cutime);
        prstatus->pr_cstime = ns_to_timeval(p->signal->cstime);

        prstatus->pr_exec_fdpic_loadmap = p->mm->context.exec_fdpic_loadmap;
        prstatus->pr_interp_fdpic_loadmap = p->mm->context.interp_fdpic_loadmap;
}

static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p,
                       struct mm_struct *mm)
{
        const struct cred *cred;
        unsigned int i, len;

        /* first copy the parameters from user space */
        memset(psinfo, 0, sizeof(struct elf_prpsinfo));

        len = mm->arg_end - mm->arg_start;
        if (len >= ELF_PRARGSZ)
                len = ELF_PRARGSZ - 1;
        if (copy_from_user(&psinfo->pr_psargs,
                           (const char __user *) mm->arg_start, len))
                return -EFAULT;
        for (i = 0; i < len; i++)
                if (psinfo->pr_psargs[i] == 0)
                        psinfo->pr_psargs[i] = ' ';
        psinfo->pr_psargs[len] = 0;

        rcu_read_lock();
        psinfo->pr_ppid = task_pid_vnr(rcu_dereference(p->real_parent));
        rcu_read_unlock();
        psinfo->pr_pid = task_pid_vnr(p);
        psinfo->pr_pgrp = task_pgrp_vnr(p);
        psinfo->pr_sid = task_session_vnr(p);

        i = p->state ? ffz(~p->state) + 1 : 0;
        psinfo->pr_state = i;
        psinfo->pr_sname = (i > 5) ? '.' : "RSDTZW"[i];
        psinfo->pr_zomb = psinfo->pr_sname == 'Z';
        psinfo->pr_nice = task_nice(p);
        psinfo->pr_flag = p->flags;
        rcu_read_lock();
        cred = __task_cred(p);
        SET_UID(psinfo->pr_uid, from_kuid_munged(cred->user_ns, cred->uid));
        SET_GID(psinfo->pr_gid, from_kgid_munged(cred->user_ns, cred->gid));
        rcu_read_unlock();
        strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname));

        return 0;
}

/* Here is the structure in which status of each thread is captured. */
struct elf_thread_status
{
        struct list_head list;
        struct elf_prstatus prstatus;   /* NT_PRSTATUS */
        elf_fpregset_t fpu;             /* NT_PRFPREG */
        struct task_struct *thread;
#ifdef ELF_CORE_COPY_XFPREGS
        elf_fpxregset_t xfpu;           /* ELF_CORE_XFPREG_TYPE */
#endif
        struct memelfnote notes[3];
        int num_notes;
};

/*
 * In order to add the specific thread information for the elf file format,
 * we need to keep a linked list of every thread's pr_status and then create
 * a single section for them in the final core file.
 */
static int elf_dump_thread_status(long signr, struct elf_thread_status *t)
{
        struct task_struct *p = t->thread;
        int sz = 0;

        t->num_notes = 0;

        fill_prstatus(&t->prstatus, p, signr);
        elf_core_copy_task_regs(p, &t->prstatus.pr_reg);

        fill_note(&t->notes[0], "CORE", NT_PRSTATUS, sizeof(t->prstatus),
                  &t->prstatus);
        t->num_notes++;
        sz += notesize(&t->notes[0]);

        t->prstatus.pr_fpvalid = elf_core_copy_task_fpregs(p, NULL, &t->fpu);
        if (t->prstatus.pr_fpvalid) {
                fill_note(&t->notes[1], "CORE", NT_PRFPREG, sizeof(t->fpu),
                          &t->fpu);
                t->num_notes++;
                sz += notesize(&t->notes[1]);
        }

#ifdef ELF_CORE_COPY_XFPREGS
        if (elf_core_copy_task_xfpregs(p, &t->xfpu)) {
                fill_note(&t->notes[2], "LINUX", ELF_CORE_XFPREG_TYPE,
                          sizeof(t->xfpu), &t->xfpu);
                t->num_notes++;
                sz += notesize(&t->notes[2]);
        }
#endif
        return sz;
}

static void fill_extnum_info(struct elfhdr *elf, struct elf_shdr *shdr4extnum,
                             elf_addr_t e_shoff, int segs)
{
        elf->e_shoff = e_shoff;
        elf->e_shentsize = sizeof(*shdr4extnum);
        elf->e_shnum = 1;
        elf->e_shstrndx = SHN_UNDEF;

        memset(shdr4extnum, 0, sizeof(*shdr4extnum));

        shdr4extnum->sh_type = SHT_NULL;
        shdr4extnum->sh_size = elf->e_shnum;
        shdr4extnum->sh_link = elf->e_shstrndx;
        shdr4extnum->sh_info = segs;
}

/*
 * dump the segments for an MMU process
 */
static bool elf_fdpic_dump_segments(struct coredump_params *cprm)
{
        struct vm_area_struct *vma;

        for (vma = current->mm->mmap; vma; vma = vma->vm_next) {
#ifdef CONFIG_MMU
                unsigned long addr;
#endif

                if (!maydump(vma, cprm->mm_flags))
                        continue;

#ifdef CONFIG_MMU
                for (addr = vma->vm_start; addr < vma->vm_end;
                                                        addr += PAGE_SIZE) {
                        bool res;
                        struct page *page = get_dump_page(addr);
                        if (page) {
                                void *kaddr = kmap(page);
                                res = dump_emit(cprm, kaddr, PAGE_SIZE);
                                kunmap(page);
                                put_page(page);
                        } else {
                                res = dump_skip(cprm, PAGE_SIZE);
                        }
                        if (!res)
                                return false;
                }
#else
                if (!dump_emit(cprm, (void *) vma->vm_start,
                                vma->vm_end - vma->vm_start))
                        return false;
#endif
        }
        return true;
}

static size_t elf_core_vma_data_size(unsigned long mm_flags)
{
        struct vm_area_struct *vma;
        size_t size = 0;

        for (vma = current->mm->mmap; vma; vma = vma->vm_next)
                if (maydump(vma, mm_flags))
                        size += vma->vm_end - vma->vm_start;
        return size;
}

/*
 * Actual dumper
 *
 * This is a two-pass process; first we find the offsets of the bits,
 * and then they are actually written out.  If we run out of core limit
 * we just truncate.
 */
static int elf_fdpic_core_dump(struct coredump_params *cprm)
{
#define NUM_NOTES       6
        int has_dumped = 0;
        mm_segment_t fs;
        int segs;
        int i;
        struct vm_area_struct *vma;
        struct elfhdr *elf = NULL;
        loff_t offset = 0, dataoff;
        int numnote;
        struct memelfnote *notes = NULL;
        struct elf_prstatus *prstatus = NULL;   /* NT_PRSTATUS */
        struct elf_prpsinfo *psinfo = NULL;     /* NT_PRPSINFO */
        LIST_HEAD(thread_list);
        struct list_head *t;
        elf_fpregset_t *fpu = NULL;
#ifdef ELF_CORE_COPY_XFPREGS
        elf_fpxregset_t *xfpu = NULL;
#endif
        int thread_status_size = 0;
        elf_addr_t *auxv;
        struct elf_phdr *phdr4note = NULL;
        struct elf_shdr *shdr4extnum = NULL;
        Elf_Half e_phnum;
        elf_addr_t e_shoff;
        struct core_thread *ct;
        struct elf_thread_status *tmp;

        /*
         * We no longer stop all VM operations.
         *
         * This is because those proceses that could possibly change map_count
         * or the mmap / vma pages are now blocked in do_exit on current
         * finishing this core dump.
         *
         * Only ptrace can touch these memory addresses, but it doesn't change
         * the map_count or the pages allocated. So no possibility of crashing
         * exists while dumping the mm->vm_next areas to the core file.
         */

        /* alloc memory for large data structures: too large to be on stack */
        elf = kmalloc(sizeof(*elf), GFP_KERNEL);
        if (!elf)
                goto cleanup;
        prstatus = kzalloc(sizeof(*prstatus), GFP_KERNEL);
        if (!prstatus)
                goto cleanup;
        psinfo = kmalloc(sizeof(*psinfo), GFP_KERNEL);
        if (!psinfo)
                goto cleanup;
        notes = kmalloc_array(NUM_NOTES, sizeof(struct memelfnote),
                              GFP_KERNEL);
        if (!notes)
                goto cleanup;
        fpu = kmalloc(sizeof(*fpu), GFP_KERNEL);
        if (!fpu)
                goto cleanup;
#ifdef ELF_CORE_COPY_XFPREGS
        xfpu = kmalloc(sizeof(*xfpu), GFP_KERNEL);
        if (!xfpu)
                goto cleanup;
#endif

        for (ct = current->mm->core_state->dumper.next;
                                        ct; ct = ct->next) {
                tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);
                if (!tmp)
                        goto cleanup;

                tmp->thread = ct->task;
                list_add(&tmp->list, &thread_list);
        }

        list_for_each(t, &thread_list) {
                struct elf_thread_status *tmp;
                int sz;

                tmp = list_entry(t, struct elf_thread_status, list);
                sz = elf_dump_thread_status(cprm->siginfo->si_signo, tmp);
                thread_status_size += sz;
        }

        /* now collect the dump for the current */
        fill_prstatus(prstatus, current, cprm->siginfo->si_signo);
        elf_core_copy_regs(&prstatus->pr_reg, cprm->regs);

        segs = current->mm->map_count;
        segs += elf_core_extra_phdrs();

        /* for notes section */
        segs++;

        /* If segs > PN_XNUM(0xffff), then e_phnum overflows. To avoid
         * this, kernel supports extended numbering. Have a look at
         * include/linux/elf.h for further information. */
        e_phnum = segs > PN_XNUM ? PN_XNUM : segs;

        /* Set up header */
        fill_elf_fdpic_header(elf, e_phnum);

        has_dumped = 1;
        /*
         * Set up the notes in similar form to SVR4 core dumps made
         * with info from their /proc.
         */

        fill_note(notes + 0, "CORE", NT_PRSTATUS, sizeof(*prstatus), prstatus);
        fill_psinfo(psinfo, current->group_leader, current->mm);
        fill_note(notes + 1, "CORE", NT_PRPSINFO, sizeof(*psinfo), psinfo);

        numnote = 2;

        auxv = (elf_addr_t *) current->mm->saved_auxv;

        i = 0;
        do
                i += 2;
        while (auxv[i - 2] != AT_NULL);
        fill_note(&notes[numnote++], "CORE", NT_AUXV,
                  i * sizeof(elf_addr_t), auxv);

        /* Try to dump the FPU. */
        if ((prstatus->pr_fpvalid =
             elf_core_copy_task_fpregs(current, cprm->regs, fpu)))
                fill_note(notes + numnote++,
                          "CORE", NT_PRFPREG, sizeof(*fpu), fpu);
#ifdef ELF_CORE_COPY_XFPREGS
        if (elf_core_copy_task_xfpregs(current, xfpu))
                fill_note(notes + numnote++,
                          "LINUX", ELF_CORE_XFPREG_TYPE, sizeof(*xfpu), xfpu);
#endif

        fs = get_fs();
        set_fs(KERNEL_DS);

        offset += sizeof(*elf);                         /* Elf header */
        offset += segs * sizeof(struct elf_phdr);       /* Program headers */

        /* Write notes phdr entry */
        {
                int sz = 0;

                for (i = 0; i < numnote; i++)
                        sz += notesize(notes + i);

                sz += thread_status_size;

                phdr4note = kmalloc(sizeof(*phdr4note), GFP_KERNEL);
                if (!phdr4note)
                        goto end_coredump;

                fill_elf_note_phdr(phdr4note, sz, offset);
                offset += sz;
        }

        /* Page-align dumped data */
        dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE);

        offset += elf_core_vma_data_size(cprm->mm_flags);
        offset += elf_core_extra_data_size();
        e_shoff = offset;

        if (e_phnum == PN_XNUM) {
                shdr4extnum = kmalloc(sizeof(*shdr4extnum), GFP_KERNEL);
                if (!shdr4extnum)
                        goto end_coredump;
                fill_extnum_info(elf, shdr4extnum, e_shoff, segs);
        }

        offset = dataoff;

        if (!dump_emit(cprm, elf, sizeof(*elf)))
                goto end_coredump;

        if (!dump_emit(cprm, phdr4note, sizeof(*phdr4note)))
                goto end_coredump;

        /* write program headers for segments dump */
        for (vma = current->mm->mmap; vma; vma = vma->vm_next) {
                struct elf_phdr phdr;
                size_t sz;

                sz = vma->vm_end - vma->vm_start;

                phdr.p_type = PT_LOAD;
                phdr.p_offset = offset;
                phdr.p_vaddr = vma->vm_start;
                phdr.p_paddr = 0;
                phdr.p_filesz = maydump(vma, cprm->mm_flags) ? sz : 0;
                phdr.p_memsz = sz;
                offset += phdr.p_filesz;
                phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0;
                if (vma->vm_flags & VM_WRITE)
                        phdr.p_flags |= PF_W;
                if (vma->vm_flags & VM_EXEC)
                        phdr.p_flags |= PF_X;
                phdr.p_align = ELF_EXEC_PAGESIZE;

                if (!dump_emit(cprm, &phdr, sizeof(phdr)))
                        goto end_coredump;
        }

        if (!elf_core_write_extra_phdrs(cprm, offset))
                goto end_coredump;

        /* write out the notes section */
        for (i = 0; i < numnote; i++)
                if (!writenote(notes + i, cprm))
                        goto end_coredump;

        /* write out the thread status notes section */
        list_for_each(t, &thread_list) {
                struct elf_thread_status *tmp =
                                list_entry(t, struct elf_thread_status, list);

                for (i = 0; i < tmp->num_notes; i++)
                        if (!writenote(&tmp->notes[i], cprm))
                                goto end_coredump;
        }

        if (!dump_skip(cprm, dataoff - cprm->pos))
                goto end_coredump;

        if (!elf_fdpic_dump_segments(cprm))
                goto end_coredump;

        if (!elf_core_write_extra_data(cprm))
                goto end_coredump;

        if (e_phnum == PN_XNUM) {
                if (!dump_emit(cprm, shdr4extnum, sizeof(*shdr4extnum)))
                        goto end_coredump;
        }

        if (cprm->file->f_pos != offset) {
                /* Sanity check */
                printk(KERN_WARNING
                       "elf_core_dump: file->f_pos (%lld) != offset (%lld)\n",
                       cprm->file->f_pos, offset);
        }

end_coredump:
        set_fs(fs);

cleanup:
        while (!list_empty(&thread_list)) {
                struct list_head *tmp = thread_list.next;
                list_del(tmp);
                kfree(list_entry(tmp, struct elf_thread_status, list));
        }
        kfree(phdr4note);
        kfree(elf);
        kfree(prstatus);
        kfree(psinfo);
        kfree(notes);
        kfree(fpu);
        kfree(shdr4extnum);
#ifdef ELF_CORE_COPY_XFPREGS
        kfree(xfpu);
#endif
        return has_dumped;
#undef NUM_NOTES
}

#endif          /* CONFIG_ELF_CORE */