arch/mips/kernel/module.c - arm/linux-arm-legacy - Git at Google

 /*
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  *
  *  Copyright (C) 2001 Rusty Russell.
  *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
  *  Copyright (C) 2005 Thiemo Seufer
  */

 #undef DEBUG

 #include <linux/moduleloader.h>
 #include <linux/elf.h>
 #include <linux/mm.h>
 #include <linux/numa.h>
 #include <linux/vmalloc.h>
 #include <linux/slab.h>
 #include <linux/fs.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
 #include <linux/spinlock.h>
 #include <linux/jump_label.h>

 #include <asm/pgtable.h>	/* MODULE_START */

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

 static LIST_HEAD(dbe_list);
 static DEFINE_SPINLOCK(dbe_lock);

 #ifdef MODULE_START
 void *module_alloc(unsigned long size)
 {
 	return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END,
 				GFP_KERNEL, PAGE_KERNEL, NUMA_NO_NODE,
 				__builtin_return_address(0));
 }
 #endif

 int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v)
 {
 	return 0;
 }

 static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v)
 {
 	*location += v;

 	return 0;
 }

 static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v)
 {
 	if (v % 4) {
 		pr_err("module %s: dangerous R_MIPS_26 REL relocation\n",
 		       me->name);
 		return -ENOEXEC;
 	}

 	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_rel(struct module *me, u32 *location, Elf_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 = (Elf_Addr *)location;
 	n->value = v;
 	n->next = me->arch.r_mips_hi16_list;
 	me->arch.r_mips_hi16_list = n;

 	return 0;
 }

 static void free_relocation_chain(struct mips_hi16 *l)
 {
 	struct mips_hi16 *next;

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

 static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)
 {
 	unsigned long insnlo = *location;
 	struct mips_hi16 *l;
 	Elf_Addr val, vallo;

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

 	if (me->arch.r_mips_hi16_list != NULL) {
 		l = me->arch.r_mips_hi16_list;
 		while (l != NULL) {
 			struct mips_hi16 *next;
 			unsigned long insn;

 			/*
 			 * The value for the HI16 had best be the same.
 			 */
 			if (v != l->value)
 				goto out_danger;

 			/*
 			 * 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;
 		}

 		me->arch.r_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_danger:
 	free_relocation_chain(l);
 	me->arch.r_mips_hi16_list = NULL;

 	pr_err("module %s: dangerous R_MIPS_LO16 REL relocation\n", me->name);

 	return -ENOEXEC;
 }

 static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
 				Elf_Addr v) = {
 	[R_MIPS_NONE]		= apply_r_mips_none,
 	[R_MIPS_32]		= apply_r_mips_32_rel,
 	[R_MIPS_26]		= apply_r_mips_26_rel,
 	[R_MIPS_HI16]		= apply_r_mips_hi16_rel,
 	[R_MIPS_LO16]		= apply_r_mips_lo16_rel
 };

 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
 		   unsigned int symindex, unsigned int relsec,
 		   struct module *me)
 {
 	Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr;
 	Elf_Sym *sym;
 	u32 *location;
 	unsigned int i;
 	Elf_Addr v;
 	int res;

 	pr_debug("Applying relocate section %u to %u\n", relsec,
 	       sechdrs[relsec].sh_info);

 	me->arch.r_mips_hi16_list = NULL;
 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 		/* 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 = (Elf_Sym *)sechdrs[symindex].sh_addr
 			+ ELF_MIPS_R_SYM(rel[i]);
 		if (IS_ERR_VALUE(sym->st_value)) {
 			/* Ignore unresolved weak symbol */
 			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 				continue;
 			printk(KERN_WARNING "%s: Unknown symbol %s\n",
 			       me->name, strtab + sym->st_name);
 			return -ENOENT;
 		}

 		v = sym->st_value;

 		res = reloc_handlers_rel[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
 		if (res)
 			return res;
 	}

 	/*
 	 * Normally the hi16 list should be deallocated at this point.	A
 	 * malformed binary however could contain a series of R_MIPS_HI16
 	 * relocations not followed by a R_MIPS_LO16 relocation.  In that
 	 * case, free up the list and return an error.
 	 */
 	if (me->arch.r_mips_hi16_list) {
 		free_relocation_chain(me->arch.r_mips_hi16_list);
 		me->arch.r_mips_hi16_list = NULL;

 		return -ENOEXEC;
 	}

 	return 0;
 }

 /* Given an address, look for it in the module exception tables. */
 const struct exception_table_entry *search_module_dbetables(unsigned long addr)
 {
 	unsigned long flags;
 	const struct exception_table_entry *e = NULL;
 	struct mod_arch_specific *dbe;

 	spin_lock_irqsave(&dbe_lock, flags);
 	list_for_each_entry(dbe, &dbe_list, dbe_list) {
 		e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr);
 		if (e)
 			break;
 	}
 	spin_unlock_irqrestore(&dbe_lock, flags);

 	/* Now, if we found one, we are running inside it now, hence
 	   we cannot unload the module, hence no refcnt needed. */
 	return e;
 }

 /* Put in dbe list if necessary. */
 int module_finalize(const Elf_Ehdr *hdr,
 		    const Elf_Shdr *sechdrs,
 		    struct module *me)
 {
 	const Elf_Shdr *s;
 	char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

 	/* Make jump label nops. */
 	jump_label_apply_nops(me);

 	INIT_LIST_HEAD(&me->arch.dbe_list);
 	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 		if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
 			continue;
 		me->arch.dbe_start = (void *)s->sh_addr;
 		me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
 		spin_lock_irq(&dbe_lock);
 		list_add(&me->arch.dbe_list, &dbe_list);
 		spin_unlock_irq(&dbe_lock);
 	}
 	return 0;
 }

 void module_arch_cleanup(struct module *mod)
 {
 	spin_lock_irq(&dbe_lock);
 	list_del(&mod->arch.dbe_list);
 	spin_unlock_irq(&dbe_lock);
 }
	/*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*
	* Copyright (C) 2001 Rusty Russell.
	* Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
	* Copyright (C) 2005 Thiemo Seufer
	*/

	#undef DEBUG

	#include <linux/moduleloader.h>
	#include <linux/elf.h>
	#include <linux/mm.h>
	#include <linux/numa.h>
	#include <linux/vmalloc.h>
	#include <linux/slab.h>
	#include <linux/fs.h>
	#include <linux/string.h>
	#include <linux/kernel.h>
	#include <linux/spinlock.h>
	#include <linux/jump_label.h>

	#include <asm/pgtable.h> /* MODULE_START */

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

	static LIST_HEAD(dbe_list);
	static DEFINE_SPINLOCK(dbe_lock);

	#ifdef MODULE_START
	void *module_alloc(unsigned long size)
	{
	return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END,
	GFP_KERNEL, PAGE_KERNEL, NUMA_NO_NODE,
	__builtin_return_address(0));
	}
	#endif

	int apply_r_mips_none(struct module me, u32 location, Elf_Addr v)
	{
	return 0;
	}

	static int apply_r_mips_32_rel(struct module me, u32 location, Elf_Addr v)
	{
	*location += v;

	return 0;
	}

	static int apply_r_mips_26_rel(struct module me, u32 location, Elf_Addr v)
	{
	if (v % 4) {
	pr_err("module %s: dangerous R_MIPS_26 REL relocation\n",
	me->name);
	return -ENOEXEC;
	}

	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_rel(struct module me, u32 location, Elf_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 = (Elf_Addr *)location;
	n->value = v;
	n->next = me->arch.r_mips_hi16_list;
	me->arch.r_mips_hi16_list = n;

	return 0;
	}

	static void free_relocation_chain(struct mips_hi16 *l)
	{
	struct mips_hi16 *next;

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

	static int apply_r_mips_lo16_rel(struct module me, u32 location, Elf_Addr v)
	{
	unsigned long insnlo = *location;
	struct mips_hi16 *l;
	Elf_Addr val, vallo;

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

	if (me->arch.r_mips_hi16_list != NULL) {
	l = me->arch.r_mips_hi16_list;
	while (l != NULL) {
	struct mips_hi16 *next;
	unsigned long insn;

	/*
	* The value for the HI16 had best be the same.
	*/
	if (v != l->value)
	goto out_danger;

	/*
	* 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;
	}

	me->arch.r_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_danger:
	free_relocation_chain(l);
	me->arch.r_mips_hi16_list = NULL;

	pr_err("module %s: dangerous R_MIPS_LO16 REL relocation\n", me->name);

	return -ENOEXEC;
	}

	static int (reloc_handlers_rel[]) (struct module me, u32 *location,
	Elf_Addr v) = {
	[R_MIPS_NONE] = apply_r_mips_none,
	[R_MIPS_32] = apply_r_mips_32_rel,
	[R_MIPS_26] = apply_r_mips_26_rel,
	[R_MIPS_HI16] = apply_r_mips_hi16_rel,
	[R_MIPS_LO16] = apply_r_mips_lo16_rel
	};

	int apply_relocate(Elf_Shdr sechdrs, const char strtab,
	unsigned int symindex, unsigned int relsec,
	struct module *me)
	{
	Elf_Mips_Rel rel = (void ) sechdrs[relsec].sh_addr;
	Elf_Sym *sym;
	u32 *location;
	unsigned int i;
	Elf_Addr v;
	int res;

	pr_debug("Applying relocate section %u to %u\n", relsec,
	sechdrs[relsec].sh_info);

	me->arch.r_mips_hi16_list = NULL;
	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
	/* 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 = (Elf_Sym *)sechdrs[symindex].sh_addr
	+ ELF_MIPS_R_SYM(rel[i]);
	if (IS_ERR_VALUE(sym->st_value)) {
	/* Ignore unresolved weak symbol */
	if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
	continue;
	printk(KERN_WARNING "%s: Unknown symbol %s\n",
	me->name, strtab + sym->st_name);
	return -ENOENT;
	}

	v = sym->st_value;

	res = reloc_handlers_rel[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
	if (res)
	return res;
	}

	/*
	* Normally the hi16 list should be deallocated at this point. A
	* malformed binary however could contain a series of R_MIPS_HI16
	* relocations not followed by a R_MIPS_LO16 relocation. In that
	* case, free up the list and return an error.
	*/
	if (me->arch.r_mips_hi16_list) {
	free_relocation_chain(me->arch.r_mips_hi16_list);
	me->arch.r_mips_hi16_list = NULL;

	return -ENOEXEC;
	}

	return 0;
	}

	/* Given an address, look for it in the module exception tables. */
	const struct exception_table_entry *search_module_dbetables(unsigned long addr)
	{
	unsigned long flags;
	const struct exception_table_entry *e = NULL;
	struct mod_arch_specific *dbe;

	spin_lock_irqsave(&dbe_lock, flags);
	list_for_each_entry(dbe, &dbe_list, dbe_list) {
	e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr);
	if (e)
	break;
	}
	spin_unlock_irqrestore(&dbe_lock, flags);

	/* Now, if we found one, we are running inside it now, hence
	we cannot unload the module, hence no refcnt needed. */
	return e;
	}

	/* Put in dbe list if necessary. */
	int module_finalize(const Elf_Ehdr *hdr,
	const Elf_Shdr *sechdrs,
	struct module *me)
	{
	const Elf_Shdr *s;
	char secstrings = (void )hdr + sechdrs[hdr->e_shstrndx].sh_offset;

	/* Make jump label nops. */
	jump_label_apply_nops(me);

	INIT_LIST_HEAD(&me->arch.dbe_list);
	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
	if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
	continue;
	me->arch.dbe_start = (void *)s->sh_addr;
	me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
	spin_lock_irq(&dbe_lock);
	list_add(&me->arch.dbe_list, &dbe_list);
	spin_unlock_irq(&dbe_lock);
	}
	return 0;
	}

	void module_arch_cleanup(struct module *mod)
	{
	spin_lock_irq(&dbe_lock);
	list_del(&mod->arch.dbe_list);
	spin_unlock_irq(&dbe_lock);
	}