mips/kernel/vpe.c

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2004, 2005 MIPS Technologies, Inc.  All rights reserved.
 * Copyright (C) 2013 Imagination Technologies Ltd.
 *
 * VPE spport module for loading a MIPS SP program into VPE1. The SP
 * environment is rather simple since there are no TLBs. It needs
 * to be relocatable (or partiall linked). Initialize your stack in
 * the startup-code. The loader looks for the symbol __start and sets
 * up the execution to resume from there. To load and run, simply do
 * a cat SP 'binary' to the /dev/vpe1 device.
 */
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/vmalloc.h>
#include <linux/elf.h>
#include <linux/seq_file.h>
#include <linux/syscalls.h>
#include <linux/moduleloader.h>
#include <linux/interrupt.h>
#include <linux/poll.h>
#include <linux/memblock.h>
#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/cacheflush.h>
#include <linux/atomic.h>
#include <asm/mips_mt.h>
#include <asm/processor.h>
#include <asm/vpe.h>

#ifndef ARCH_SHF_SMALL
#define ARCH_SHF_SMALL 0
#endif

/* If this is set, the section belongs in the init part of the module */
#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))

struct vpe_control vpecontrol = {
	.vpe_list_lock	= __SPIN_LOCK_UNLOCKED(vpe_list_lock),
	.vpe_list	= LIST_HEAD_INIT(vpecontrol.vpe_list),
	.tc_list_lock	= __SPIN_LOCK_UNLOCKED(tc_list_lock),
	.tc_list	= LIST_HEAD_INIT(vpecontrol.tc_list)
};

/* get the vpe associated with this minor */
struct vpe *get_vpe(int minor)
{
	struct vpe *res, *v;

	if (!cpu_has_mipsmt)
		return NULL;

	res = NULL;
	spin_lock(&vpecontrol.vpe_list_lock);
	list_for_each_entry(v, &vpecontrol.vpe_list, list) {
		if (v->minor == VPE_MODULE_MINOR) {
			res = v;
			break;
		}
	}
	spin_unlock(&vpecontrol.vpe_list_lock);

	return res;
}

/* get the vpe associated with this minor */
struct tc *get_tc(int index)
{
	struct tc *res, *t;

	res = NULL;
	spin_lock(&vpecontrol.tc_list_lock);
	list_for_each_entry(t, &vpecontrol.tc_list, list) {
		if (t->index == index) {
			res = t;
			break;
		}
	}
	spin_unlock(&vpecontrol.tc_list_lock);

	return res;
}

/* allocate a vpe and associate it with this minor (or index) */
struct vpe *alloc_vpe(int minor)
{
	struct vpe *v;

	v = kzalloc(sizeof(struct vpe), GFP_KERNEL);
	if (v == NULL)
		goto out;

	INIT_LIST_HEAD(&v->tc);
	spin_lock(&vpecontrol.vpe_list_lock);
	list_add_tail(&v->list, &vpecontrol.vpe_list);
	spin_unlock(&vpecontrol.vpe_list_lock);

	INIT_LIST_HEAD(&v->notify);
	v->minor = VPE_MODULE_MINOR;

out:
	return v;
}

/* allocate a tc. At startup only tc0 is running, all other can be halted. */
struct tc *alloc_tc(int index)
{
	struct tc *tc;

	tc = kzalloc(sizeof(struct tc), GFP_KERNEL);
	if (tc == NULL)
		goto out;

	INIT_LIST_HEAD(&tc->tc);
	tc->index = index;

	spin_lock(&vpecontrol.tc_list_lock);
	list_add_tail(&tc->list, &vpecontrol.tc_list);
	spin_unlock(&vpecontrol.tc_list_lock);

out:
	return tc;
}

/* clean up and free everything */
void release_vpe(struct vpe *v)
{
	list_del(&v->list);
	if (v->load_addr)
		release_progmem(v->load_addr);
	kfree(v);
}

/* Find some VPE program space */
void *alloc_progmem(unsigned long len)
{
	void *addr;

#ifdef CONFIG_MIPS_VPE_LOADER_TOM
	/*
	 * This means you must tell Linux to use less memory than you
	 * physically have, for example by passing a mem= boot argument.
	 */
	addr = pfn_to_kaddr(max_low_pfn);
	memset(addr, 0, len);
#else
	/* simple grab some mem for now */
	addr = kzalloc(len, GFP_KERNEL);
#endif

	return addr;
}

void release_progmem(void *ptr)
{
#ifndef CONFIG_MIPS_VPE_LOADER_TOM
	kfree(ptr);
#endif
}

/* Update size with this section: return offset. */
static long get_offset(unsigned long *size, Elf_Shdr *sechdr)
{
	long ret;

	ret = ALIGN(*size, sechdr->sh_addralign ? : 1);
	*size = ret + sechdr->sh_size;
	return ret;
}

/* Lay out the SHF_ALLOC sections in a way not dissimilar to how ld
   might -- code, read-only data, read-write data, small data.	Tally
   sizes, and place the offsets into sh_entsize fields: high bit means it
   belongs in init. */
static void layout_sections(struct module *mod, const Elf_Ehdr *hdr,
			    Elf_Shdr *sechdrs, const char *secstrings)
{
	static unsigned long const masks[][2] = {
		/* NOTE: all executable code must be the first section
		 * in this array; otherwise modify the text_size
		 * finder in the two loops below */
		{SHF_EXECINSTR | SHF_ALLOC, ARCH_SHF_SMALL},
		{SHF_ALLOC, SHF_WRITE | ARCH_SHF_SMALL},
		{SHF_WRITE | SHF_ALLOC, ARCH_SHF_SMALL},
		{ARCH_SHF_SMALL | SHF_ALLOC, 0}
	};
	unsigned int m, i;

	for (i = 0; i < hdr->e_shnum; i++)
		sechdrs[i].sh_entsize = ~0UL;

	for (m = 0; m < ARRAY_SIZE(masks); ++m) {
		for (i = 0; i < hdr->e_shnum; ++i) {
			Elf_Shdr *s = &sechdrs[i];

			if ((s->sh_flags & masks[m][0]) != masks[m][0]
			    || (s->sh_flags & masks[m][1])
			    || s->sh_entsize != ~0UL)
				continue;
			s->sh_entsize =
				get_offset((unsigned long *)&mod->core_layout.size, s);
		}

		if (m == 0)
			mod->core_layout.text_size = mod->core_layout.size;

	}
}

/* from module-elf32.c, but subverted a little */

struct mips_hi16 {
	struct mips_hi16 *next;
	Elf32_Addr *addr;
	Elf32_Addr value;
};

static struct mips_hi16 *mips_hi16_list;
static unsigned int gp_offs, gp_addr;

static int apply_r_mips_none(struct module *me, uint32_t *location,
			     Elf32_Addr v)
{
	return 0;
}

static int apply_r_mips_gprel16(struct module *me, uint32_t *location,
				Elf32_Addr v)
{
	int rel;

	if (!(*location & 0xffff)) {
		rel = (int)v - gp_addr;
	} else {
		/* .sbss + gp(relative) + offset */
		/* kludge! */
		rel =  (int)(short)((int)v + gp_offs +
				    (int)(short)(*location & 0xffff) - gp_addr);
	}

	if ((rel > 32768) || (rel < -32768)) {
		pr_debug("VPE loader: apply_r_mips_gprel16: relative address 0x%x out of range of gp register\n",
			 rel);
		return -ENOEXEC;
	}

	*location = (*location & 0xffff0000) | (rel & 0xffff);

	return 0;
}

static int apply_r_mips_pc16(struct module *me, uint32_t *location,
			     Elf32_Addr v)
{
	int rel;
	rel = (((unsigned int)v - (unsigned int)location));
	rel >>= 2; /* because the offset is in _instructions_ not bytes. */
	rel -= 1;  /* and one instruction less due to the branch delay slot. */

	if ((rel > 32768) || (rel < -32768)) {
		pr_debug("VPE loader: apply_r_mips_pc16: relative address out of range 0x%x\n",
			 rel);
		return -ENOEXEC;
	}

	*location = (*location & 0xffff0000) | (rel & 0xffff);

	return 0;
}

static int apply_r_mips_32(struct module *me, uint32_t *location,
			   Elf32_Addr v)
{
	*location += v;

	return 0;
}

static int apply_r_mips_26(struct module *me, uint32_t *location,
			   Elf32_Addr v)
{
	if (v % 4) {
		pr_debug("VPE loader: apply_r_mips_26: unaligned relocation\n");
		return -ENOEXEC;
	}

/*
 * Not desperately convinced this is a good check of an overflow condition
 * anyway. But it gets in the way of handling undefined weak symbols which
 * we want to set to zero.
 * if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
 * printk(KERN_ERR
 * "module %s: relocation overflow\n",
 * me->name);
 * return -ENOEXEC;
 * }
 */

	*location = (*location & ~0x03ffffff) |
		((*location + (v >> 2)) & 0x03ffffff);
	return 0;
}

static int apply_r_mips_hi16(struct module *me, uint32_t *location,
			     Elf32_Addr v)
{
	struct mips_hi16 *n;

	/*
	 * We cannot relocate this one now because we don't know the value of
	 * the carry we need to add.  Save the information, and let LO16 do the
	 * actual relocation.
	 */
	n = kmalloc(sizeof(*n), GFP_KERNEL);
	if (!n)
		return -ENOMEM;

	n->addr = location;
	n->value = v;
	n->next = mips_hi16_list;
	mips_hi16_list = n;

	return 0;
}

static int apply_r_mips_lo16(struct module *me, uint32_t *location,
			     Elf32_Addr v)
{
	unsigned long insnlo = *location;
	Elf32_Addr val, vallo;
	struct mips_hi16 *l, *next;

	/* Sign extend the addend we extract from the lo insn.	*/
	vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;

	if (mips_hi16_list != NULL) {

		l = mips_hi16_list;
		while (l != NULL) {
			unsigned long insn;

			/*
			 * The value for the HI16 had best be the same.
			 */
			if (v != l->value) {
				pr_debug("VPE loader: apply_r_mips_lo16/hi16: inconsistent value information\n");
				goto out_free;
			}

			/*
			 * Do the HI16 relocation.  Note that we actually don't
			 * need to know anything about the LO16 itself, except
			 * where to find the low 16 bits of the addend needed
			 * by the LO16.
			 */
			insn = *l->addr;
			val = ((insn & 0xffff) << 16) + vallo;
			val += v;

			/*
			 * Account for the sign extension that will happen in
			 * the low bits.
			 */
			val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;

			insn = (insn & ~0xffff) | val;
			*l->addr = insn;

			next = l->next;
			kfree(l);
			l = next;
		}

		mips_hi16_list = NULL;
	}

	/*
	 * Ok, we're done with the HI16 relocs.	 Now deal with the LO16.
	 */
	val = v + vallo;
	insnlo = (insnlo & ~0xffff) | (val & 0xffff);
	*location = insnlo;

	return 0;

out_free:
	while (l != NULL) {
		next = l->next;
		kfree(l);
		l = next;
	}
	mips_hi16_list = NULL;

	return -ENOEXEC;
}

static int (*reloc_handlers[]) (struct module *me, uint32_t *location,
				Elf32_Addr v) = {
	[R_MIPS_NONE]	= apply_r_mips_none,
	[R_MIPS_32]	= apply_r_mips_32,
	[R_MIPS_26]	= apply_r_mips_26,
	[R_MIPS_HI16]	= apply_r_mips_hi16,
	[R_MIPS_LO16]	= apply_r_mips_lo16,
	[R_MIPS_GPREL16] = apply_r_mips_gprel16,
	[R_MIPS_PC16] = apply_r_mips_pc16
};

static char *rstrs[] = {
	[R_MIPS_NONE]	= "MIPS_NONE",
	[R_MIPS_32]	= "MIPS_32",
	[R_MIPS_26]	= "MIPS_26",
	[R_MIPS_HI16]	= "MIPS_HI16",
	[R_MIPS_LO16]	= "MIPS_LO16",
	[R_MIPS_GPREL16] = "MIPS_GPREL16",
	[R_MIPS_PC16] = "MIPS_PC16"
};

static int apply_relocations(Elf32_Shdr *sechdrs,
		      const char *strtab,
		      unsigned int symindex,
		      unsigned int relsec,
		      struct module *me)
{
	Elf32_Rel *rel = (void *) sechdrs[relsec].sh_addr;
	Elf32_Sym *sym;
	uint32_t *location;
	unsigned int i;
	Elf32_Addr v;
	int res;

	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
		Elf32_Word r_info = rel[i].r_info;

		/* This is where to make the change */
		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
			+ rel[i].r_offset;
		/* This is the symbol it is referring to */
		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
			+ ELF32_R_SYM(r_info);

		if (!sym->st_value) {
			pr_debug("%s: undefined weak symbol %s\n",
				 me->name, strtab + sym->st_name);
			/* just print the warning, dont barf */
		}

		v = sym->st_value;

		res = reloc_handlers[ELF32_R_TYPE(r_info)](me, location, v);
		if (res) {
			char *r = rstrs[ELF32_R_TYPE(r_info)];
			pr_warn("VPE loader: .text+0x%x relocation type %s for symbol \"%s\" failed\n",
				rel[i].r_offset, r ? r : "UNKNOWN",
				strtab + sym->st_name);
			return res;
		}
	}

	return 0;
}

static inline void save_gp_address(unsigned int secbase, unsigned int rel)
{
	gp_addr = secbase + rel;
	gp_offs = gp_addr - (secbase & 0xffff0000);
}
/* end module-elf32.c */

/* Change all symbols so that sh_value encodes the pointer directly. */
static void simplify_symbols(Elf_Shdr *sechdrs,
			    unsigned int symindex,
			    const char *strtab,
			    const char *secstrings,
			    unsigned int nsecs, struct module *mod)
{
	Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
	unsigned long secbase, bssbase = 0;
	unsigned int i, n = sechdrs[symindex].sh_size / sizeof(Elf_Sym);
	int size;

	/* find the .bss section for COMMON symbols */
	for (i = 0; i < nsecs; i++) {
		if (strncmp(secstrings + sechdrs[i].sh_name, ".bss", 4) == 0) {
			bssbase = sechdrs[i].sh_addr;
			break;
		}
	}

	for (i = 1; i < n; i++) {
		switch (sym[i].st_shndx) {
		case SHN_COMMON:
			/* Allocate space for the symbol in the .bss section.
			   st_value is currently size.
			   We want it to have the address of the symbol. */

			size = sym[i].st_value;
			sym[i].st_value = bssbase;

			bssbase += size;
			break;

		case SHN_ABS:
			/* Don't need to do anything */
			break;

		case SHN_UNDEF:
			/* ret = -ENOENT; */
			break;

		case SHN_MIPS_SCOMMON:
			pr_debug("simplify_symbols: ignoring SHN_MIPS_SCOMMON symbol <%s> st_shndx %d\n",
				 strtab + sym[i].st_name, sym[i].st_shndx);
			/* .sbss section */
			break;

		default:
			secbase = sechdrs[sym[i].st_shndx].sh_addr;

			if (strncmp(strtab + sym[i].st_name, "_gp", 3) == 0)
				save_gp_address(secbase, sym[i].st_value);

			sym[i].st_value += secbase;
			break;
		}
	}
}

#ifdef DEBUG_ELFLOADER
static void dump_elfsymbols(Elf_Shdr *sechdrs, unsigned int symindex,
			    const char *strtab, struct module *mod)
{
	Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
	unsigned int i, n = sechdrs[symindex].sh_size / sizeof(Elf_Sym);

	pr_debug("dump_elfsymbols: n %d\n", n);
	for (i = 1; i < n; i++) {
		pr_debug(" i %d name <%s> 0x%x\n", i, strtab + sym[i].st_name,
			 sym[i].st_value);
	}
}
#endif

static int find_vpe_symbols(struct vpe *v, Elf_Shdr *sechdrs,
				      unsigned int symindex, const char *strtab,
				      struct module *mod)
{
	Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
	unsigned int i, n = sechdrs[symindex].sh_size / sizeof(Elf_Sym);

	for (i = 1; i < n; i++) {
		if (strcmp(strtab + sym[i].st_name, "__start") == 0)
			v->__start = sym[i].st_value;

		if (strcmp(strtab + sym[i].st_name, "vpe_shared") == 0)
			v->shared_ptr = (void *)sym[i].st_value;
	}

	if ((v->__start == 0) || (v->shared_ptr == NULL))
		return -1;

	return 0;
}

/*
 * Allocates a VPE with some program code space(the load address), copies the
 * contents of the program (p)buffer performing relocatations/etc, free's it
 * when finished.
 */
static int vpe_elfload(struct vpe *v)
{
	Elf_Ehdr *hdr;
	Elf_Shdr *sechdrs;
	long err = 0;
	char *secstrings, *strtab = NULL;
	unsigned int len, i, symindex = 0, strindex = 0, relocate = 0;
	struct module mod; /* so we can re-use the relocations code */

	memset(&mod, 0, sizeof(struct module));
	strcpy(mod.name, "VPE loader");

	hdr = (Elf_Ehdr *) v->pbuffer;
	len = v->plen;

	/* Sanity checks against insmoding binaries or wrong arch,
	   weird elf version */
	if (memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0
	    || (hdr->e_type != ET_REL && hdr->e_type != ET_EXEC)
	    || !elf_check_arch(hdr)
	    || hdr->e_shentsize != sizeof(*sechdrs)) {
		pr_warn("VPE loader: program wrong arch or weird elf version\n");

		return -ENOEXEC;
	}

	if (hdr->e_type == ET_REL)
		relocate = 1;

	if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr)) {
		pr_err("VPE loader: program length %u truncated\n", len);

		return -ENOEXEC;
	}

	/* Convenience variables */
	sechdrs = (void *)hdr + hdr->e_shoff;
	secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
	sechdrs[0].sh_addr = 0;

	/* And these should exist, but gcc whinges if we don't init them */
	symindex = strindex = 0;

	if (relocate) {
		for (i = 1; i < hdr->e_shnum; i++) {
			if ((sechdrs[i].sh_type != SHT_NOBITS) &&
			    (len < sechdrs[i].sh_offset + sechdrs[i].sh_size)) {
				pr_err("VPE program length %u truncated\n",
				       len);
				return -ENOEXEC;
			}

			/* Mark all sections sh_addr with their address in the
			   temporary image. */
			sechdrs[i].sh_addr = (size_t) hdr +
				sechdrs[i].sh_offset;

			/* Internal symbols and strings. */
			if (sechdrs[i].sh_type == SHT_SYMTAB) {
				symindex = i;
				strindex = sechdrs[i].sh_link;
				strtab = (char *)hdr +
					sechdrs[strindex].sh_offset;
			}
		}
		layout_sections(&mod, hdr, sechdrs, secstrings);
	}

	v->load_addr = alloc_progmem(mod.core_layout.size);
	if (!v->load_addr)
		return -ENOMEM;

	pr_info("VPE loader: loading to %p\n", v->load_addr);

	if (relocate) {
		for (i = 0; i < hdr->e_shnum; i++) {
			void *dest;

			if (!(sechdrs[i].sh_flags & SHF_ALLOC))
				continue;

			dest = v->load_addr + sechdrs[i].sh_entsize;

			if (sechdrs[i].sh_type != SHT_NOBITS)
				memcpy(dest, (void *)sechdrs[i].sh_addr,
				       sechdrs[i].sh_size);
			/* Update sh_addr to point to copy in image. */
			sechdrs[i].sh_addr = (unsigned long)dest;

			pr_debug(" section sh_name %s sh_addr 0x%x\n",
				 secstrings + sechdrs[i].sh_name,
				 sechdrs[i].sh_addr);
		}

		/* Fix up syms, so that st_value is a pointer to location. */
		simplify_symbols(sechdrs, symindex, strtab, secstrings,
				 hdr->e_shnum, &mod);

		/* Now do relocations. */
		for (i = 1; i < hdr->e_shnum; i++) {
			const char *strtab = (char *)sechdrs[strindex].sh_addr;
			unsigned int info = sechdrs[i].sh_info;

			/* Not a valid relocation section? */
			if (info >= hdr->e_shnum)
				continue;

			/* Don't bother with non-allocated sections */
			if (!(sechdrs[info].sh_flags & SHF_ALLOC))
				continue;

			if (sechdrs[i].sh_type == SHT_REL)
				err = apply_relocations(sechdrs, strtab,
							symindex, i, &mod);
			else if (sechdrs[i].sh_type == SHT_RELA)
				err = apply_relocate_add(sechdrs, strtab,
							 symindex, i, &mod);
			if (err < 0)
				return err;

		}
	} else {
		struct elf_phdr *phdr = (struct elf_phdr *)
						((char *)hdr + hdr->e_phoff);

		for (i = 0; i < hdr->e_phnum; i++) {
			if (phdr->p_type == PT_LOAD) {
				memcpy((void *)phdr->p_paddr,
				       (char *)hdr + phdr->p_offset,
				       phdr->p_filesz);
				memset((void *)phdr->p_paddr + phdr->p_filesz,
				       0, phdr->p_memsz - phdr->p_filesz);
		    }
		    phdr++;
		}

		for (i = 0; i < hdr->e_shnum; i++) {
			/* Internal symbols and strings. */
			if (sechdrs[i].sh_type == SHT_SYMTAB) {
				symindex = i;
				strindex = sechdrs[i].sh_link;
				strtab = (char *)hdr +
					sechdrs[strindex].sh_offset;

				/*
				 * mark symtab's address for when we try
				 * to find the magic symbols
				 */
				sechdrs[i].sh_addr = (size_t) hdr +
					sechdrs[i].sh_offset;
			}
		}
	}

	/* make sure it's physically written out */
	flush_icache_range((unsigned long)v->load_addr,
			   (unsigned long)v->load_addr + v->len);

	if ((find_vpe_symbols(v, sechdrs, symindex, strtab, &mod)) < 0) {
		if (v->__start == 0) {
			pr_warn("VPE loader: program does not contain a __start symbol\n");
			return -ENOEXEC;
		}

		if (v->shared_ptr == NULL)
			pr_warn("VPE loader: program does not contain vpe_shared symbol.\n"
				" Unable to use AMVP (AP/SP) facilities.\n");
	}

	pr_info(" elf loaded\n");
	return 0;
}

static int getcwd(char *buff, int size)
{
	mm_segment_t old_fs;
	int ret;

	old_fs = get_fs();
	set_fs(KERNEL_DS);

	ret = sys_getcwd(buff, size);

	set_fs(old_fs);

	return ret;
}

/* checks VPE is unused and gets ready to load program	*/
static int vpe_open(struct inode *inode, struct file *filp)
{
	enum vpe_state state;
	struct vpe_notifications *notifier;
	struct vpe *v;
	int ret;

	if (VPE_MODULE_MINOR != iminor(inode)) {
		/* assume only 1 device at the moment. */
		pr_warn("VPE loader: only vpe1 is supported\n");

		return -ENODEV;
	}

	v = get_vpe(aprp_cpu_index());
	if (v == NULL) {
		pr_warn("VPE loader: unable to get vpe\n");

		return -ENODEV;
	}

	state = xchg(&v->state, VPE_STATE_INUSE);
	if (state != VPE_STATE_UNUSED) {
		pr_debug("VPE loader: tc in use dumping regs\n");

		list_for_each_entry(notifier, &v->notify, list)
			notifier->stop(aprp_cpu_index());

		release_progmem(v->load_addr);
		cleanup_tc(get_tc(aprp_cpu_index()));
	}

	/* this of-course trashes what was there before... */
	v->pbuffer = vmalloc(P_SIZE);
	if (!v->pbuffer) {
		pr_warn("VPE loader: unable to allocate memory\n");
		return -ENOMEM;
	}
	v->plen = P_SIZE;
	v->load_addr = NULL;
	v->len = 0;

	v->cwd[0] = 0;
	ret = getcwd(v->cwd, VPE_PATH_MAX);
	if (ret < 0)
		pr_warn("VPE loader: open, getcwd returned %d\n", ret);

	v->shared_ptr = NULL;
	v->__start = 0;

	return 0;
}

static int vpe_release(struct inode *inode, struct file *filp)
{
#if defined(CONFIG_MIPS_VPE_LOADER_MT) || defined(CONFIG_MIPS_VPE_LOADER_CMP)
	struct vpe *v;
	Elf_Ehdr *hdr;
	int ret = 0;

	v = get_vpe(aprp_cpu_index());
	if (v == NULL)
		return -ENODEV;

	hdr = (Elf_Ehdr *) v->pbuffer;
	if (memcmp(hdr->e_ident, ELFMAG, SELFMAG) == 0) {
		if (vpe_elfload(v) >= 0) {
			vpe_run(v);
		} else {
			pr_warn("VPE loader: ELF load failed.\n");
			ret = -ENOEXEC;
		}
	} else {
		pr_warn("VPE loader: only elf files are supported\n");
		ret = -ENOEXEC;
	}

	/* It's good to be able to run the SP and if it chokes have a look at
	   the /dev/rt?. But if we reset the pointer to the shared struct we
	   lose what has happened. So perhaps if garbage is sent to the vpe
	   device, use it as a trigger for the reset. Hopefully a nice
	   executable will be along shortly. */
	if (ret < 0)
		v->shared_ptr = NULL;

	vfree(v->pbuffer);
	v->plen = 0;

	return ret;
#else
	pr_warn("VPE loader: ELF load failed.\n");
	return -ENOEXEC;
#endif
}

static ssize_t vpe_write(struct file *file, const char __user *buffer,
			 size_t count, loff_t *ppos)
{
	size_t ret = count;
	struct vpe *v;

	if (iminor(file_inode(file)) != VPE_MODULE_MINOR)
		return -ENODEV;

	v = get_vpe(aprp_cpu_index());

	if (v == NULL)
		return -ENODEV;

	if ((count + v->len) > v->plen) {
		pr_warn("VPE loader: elf size too big. Perhaps strip unneeded symbols\n");
		return -ENOMEM;
	}

	count -= copy_from_user(v->pbuffer + v->len, buffer, count);
	if (!count)
		return -EFAULT;

	v->len += count;
	return ret;
}

const struct file_operations vpe_fops = {
	.owner = THIS_MODULE,
	.open = vpe_open,
	.release = vpe_release,
	.write = vpe_write,
	.llseek = noop_llseek,
};

void *vpe_get_shared(int index)
{
	struct vpe *v = get_vpe(index);

	if (v == NULL)
		return NULL;

	return v->shared_ptr;
}
EXPORT_SYMBOL(vpe_get_shared);

int vpe_notify(int index, struct vpe_notifications *notify)
{
	struct vpe *v = get_vpe(index);

	if (v == NULL)
		return -1;

	list_add(&notify->list, &v->notify);
	return 0;
}
EXPORT_SYMBOL(vpe_notify);

char *vpe_getcwd(int index)
{
	struct vpe *v = get_vpe(index);

	if (v == NULL)
		return NULL;

	return v->cwd;
}
EXPORT_SYMBOL(vpe_getcwd);

module_init(vpe_module_init);
module_exit(vpe_module_exit);
MODULE_DESCRIPTION("MIPS VPE Loader");
MODULE_AUTHOR("Elizabeth Oldham, MIPS Technologies, Inc.");
MODULE_LICENSE("GPL");