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32 results

common.c

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  • vpe.c 21.76 KiB
    /*
     * 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/bootmem.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);
    	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 uneeded 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");