xref: /kernel/linux/linux-6.6/fs/binfmt_elf_fdpic.c

// 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/regset.h>

#include <linux/uaccess.h>
#include <asm/param.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,
	.min_coredump	= ELF_EXEC_PAGESIZE,
#endif
};

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 elf_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 = begin_new_exec(bprm);
	if (retval)
		goto error;

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

	retval = create_elf_fdpic_tables(bprm, current->mm, &exec_params,
					 &interp_params);
	if (retval < 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 */
	unsigned long flags = 0;

#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 elf_fdpic_loadmap);
	len += sizeof(struct elf_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 elf_fdpic_loadmap);
		len += sizeof(struct elf_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->have_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, v;	\
									\
		ent = (void __user *) csp;				\
		v._id = (id);						\
		v._val = (val);						\
		if (copy_to_user(ent + nr, &v, sizeof(v)))		\
			return -EFAULT;					\
		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->have_execfd) {
		nr = 0;
		csp -= 2 * sizeof(unsigned long);
		NEW_AUX_ENT(AT_EXECFD, bprm->execfd);
	}

	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);
	if (bprm->interp_flags & BINPRM_FLAGS_PRESERVE_ARGV0)
		flags |= AT_FLAGS_PRESERVE_ARGV0;
	NEW_AUX_ENT(AT_FLAGS,	flags);
	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);
	if (put_user(bprm->argc, (unsigned long __user *) csp))
		return -EFAULT;

	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--) {
		if (put_user((elf_caddr_t) p, argv++))
			return -EFAULT;
		len = strnlen_user(p, MAX_ARG_STRLEN);
		if (!len || len > MAX_ARG_STRLEN)
			return -EINVAL;
		p += len;
	}
	if (put_user(NULL, argv))
		return -EFAULT;
	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--) {
		if (put_user((elf_caddr_t)(unsigned long) p, envp++))
			return -EFAULT;
		len = strnlen_user(p, MAX_ARG_STRLEN);
		if (!len || len > MAX_ARG_STRLEN)
			return -EINVAL;
		p += len;
	}
	if (put_user(NULL, envp))
		return -EFAULT;
	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 elf_fdpic_loadmap *loadmap;
#ifdef CONFIG_MMU
	struct elf_fdpic_loadseg *mseg;
	unsigned long load_addr;
#endif
	struct elf_fdpic_loadseg *seg;
	struct elf_phdr *phdr;
	unsigned nloads, tmp;
	unsigned long stop;
	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;

	loadmap = kzalloc(struct_size(loadmap, segs, nloads), GFP_KERNEL);
	if (!loadmap)
		return -ENOMEM;

	params->loadmap = loadmap;

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

	/* 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) {
				Elf_Dyn __user *dyn;
				Elf_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(Elf_Dyn) != 0)
					goto dynamic_error;

				tmp = phdr->p_memsz / sizeof(Elf_Dyn);
				dyn = (Elf_Dyn __user *)params->dynamic_addr;
				if (get_user(d_tag, &dyn[tmp - 1].d_tag) ||
				    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 elf_fdpic_loadseg *seg;
	struct elf_phdr *phdr;
	unsigned long load_addr, base = ULONG_MAX, top = 0, maddr = 0;
	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 */
	maddr = vm_mmap(NULL, load_addr, top - base,
			PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, 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 elf_fdpic_loadseg *seg;
	struct elf_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;
		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

struct elf_prstatus_fdpic
{
	struct elf_prstatus_common	common;
	elf_gregset_t pr_reg;	/* GP registers */
	/* When using FDPIC, the loadmap addresses need to be communicated
	 * to GDB in order for GDB to do the necessary relocations.  The
	 * fields (below) used to communicate this information are placed
	 * immediately after ``pr_reg'', so that the loadmap addresses may
	 * be viewed as part of the register set if so desired.
	 */
	unsigned long pr_exec_fdpic_loadmap;
	unsigned long pr_interp_fdpic_loadmap;
	int pr_fpvalid;		/* True if math co-processor being used.  */
};

/* 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 = 4;
	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_common *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_kernel_old_timeval(cputime.utime);
		prstatus->pr_stime = ns_to_kernel_old_timeval(cputime.stime);
	} else {
		u64 utime, stime;

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

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

	/* 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);

	state = READ_ONCE(p->__state);
	i = state ? ffz(~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 elf_thread_status *next;
	struct elf_prstatus_fdpic prstatus;	/* NT_PRSTATUS */
	elf_fpregset_t fpu;		/* NT_PRFPREG */
	struct memelfnote notes[2];
	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 struct elf_thread_status *elf_dump_thread_status(long signr, struct task_struct *p, int *sz)
{
	const struct user_regset_view *view = task_user_regset_view(p);
	struct elf_thread_status *t;
	int i, ret;

	t = kzalloc(sizeof(struct elf_thread_status), GFP_KERNEL);
	if (!t)
		return t;

	fill_prstatus(&t->prstatus.common, p, signr);
	t->prstatus.pr_exec_fdpic_loadmap = p->mm->context.exec_fdpic_loadmap;
	t->prstatus.pr_interp_fdpic_loadmap = p->mm->context.interp_fdpic_loadmap;
	regset_get(p, &view->regsets[0],
		   sizeof(t->prstatus.pr_reg), &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]);

	for (i = 1; i < view->n; ++i) {
		const struct user_regset *regset = &view->regsets[i];
		if (regset->core_note_type != NT_PRFPREG)
			continue;
		if (regset->active && regset->active(p, regset) <= 0)
			continue;
		ret = regset_get(p, regset, sizeof(t->fpu), &t->fpu);
		if (ret >= 0)
			t->prstatus.pr_fpvalid = 1;
		break;
	}

	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]);
	}
	return t;
}

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 core_vma_metadata *vma_meta,
				    int vma_count)
{
	int i;

	for (i = 0; i < vma_count; i++) {
		struct core_vma_metadata *meta = vma_meta + i;

		if (!dump_user_range(cprm, meta->start, meta->dump_size))
			return false;
	}
	return true;
}

/*
 * 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)
{
	int has_dumped = 0;
	int segs;
	int i;
	struct elfhdr *elf = NULL;
	loff_t offset = 0, dataoff;
	struct memelfnote psinfo_note, auxv_note;
	struct elf_prpsinfo *psinfo = NULL;	/* NT_PRPSINFO */
	struct elf_thread_status *thread_list = NULL;
	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;

	/* alloc memory for large data structures: too large to be on stack */
	elf = kmalloc(sizeof(*elf), GFP_KERNEL);
	if (!elf)
		goto end_coredump;
	psinfo = kmalloc(sizeof(*psinfo), GFP_KERNEL);
	if (!psinfo)
		goto end_coredump;

	for (ct = current->signal->core_state->dumper.next;
					ct; ct = ct->next) {
		tmp = elf_dump_thread_status(cprm->siginfo->si_signo,
					     ct->task, &thread_status_size);
		if (!tmp)
			goto end_coredump;

		tmp->next = thread_list;
		thread_list = tmp;
	}

	/* now collect the dump for the current */
	tmp = elf_dump_thread_status(cprm->siginfo->si_signo,
				     current, &thread_status_size);
	if (!tmp)
		goto end_coredump;
	tmp->next = thread_list;
	thread_list = tmp;

	segs = cprm->vma_count + elf_core_extra_phdrs(cprm);

	/* 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_psinfo(psinfo, current->group_leader, current->mm);
	fill_note(&psinfo_note, "CORE", NT_PRPSINFO, sizeof(*psinfo), psinfo);
	thread_status_size += notesize(&psinfo_note);

	auxv = (elf_addr_t *) current->mm->saved_auxv;
	i = 0;
	do
		i += 2;
	while (auxv[i - 2] != AT_NULL);
	fill_note(&auxv_note, "CORE", NT_AUXV, i * sizeof(elf_addr_t), auxv);
	thread_status_size += notesize(&auxv_note);

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

	/* Write notes phdr entry */
	phdr4note = kmalloc(sizeof(*phdr4note), GFP_KERNEL);
	if (!phdr4note)
		goto end_coredump;

	fill_elf_note_phdr(phdr4note, thread_status_size, offset);
	offset += thread_status_size;

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

	offset += cprm->vma_data_size;
	offset += elf_core_extra_data_size(cprm);
	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 (i = 0; i < cprm->vma_count; i++) {
		struct core_vma_metadata *meta = cprm->vma_meta + i;
		struct elf_phdr phdr;
		size_t sz;

		sz = meta->end - meta->start;

		phdr.p_type = PT_LOAD;
		phdr.p_offset = offset;
		phdr.p_vaddr = meta->start;
		phdr.p_paddr = 0;
		phdr.p_filesz = meta->dump_size;
		phdr.p_memsz = sz;
		offset += phdr.p_filesz;
		phdr.p_flags = 0;
		if (meta->flags & VM_READ)
			phdr.p_flags |= PF_R;
		if (meta->flags & VM_WRITE)
			phdr.p_flags |= PF_W;
		if (meta->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 */
	if (!writenote(thread_list->notes, cprm))
		goto end_coredump;
	if (!writenote(&psinfo_note, cprm))
		goto end_coredump;
	if (!writenote(&auxv_note, cprm))
		goto end_coredump;
	for (i = 1; i < thread_list->num_notes; i++)
		if (!writenote(thread_list->notes + i, cprm))
			goto end_coredump;

	/* write out the thread status notes section */
	for (tmp = thread_list->next; tmp; tmp = tmp->next) {
		for (i = 0; i < tmp->num_notes; i++)
			if (!writenote(&tmp->notes[i], cprm))
				goto end_coredump;
	}

	dump_skip_to(cprm, dataoff);

	if (!elf_fdpic_dump_segments(cprm, cprm->vma_meta, cprm->vma_count))
		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:
	while (thread_list) {
		tmp = thread_list;
		thread_list = thread_list->next;
		kfree(tmp);
	}
	kfree(phdr4note);
	kfree(elf);
	kfree(psinfo);
	kfree(shdr4extnum);
	return has_dumped;
}

#endif		/* CONFIG_ELF_CORE */