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

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *
  *  Copyright (C) 2001 Rusty Russell.
  *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
  *  Copyright (C) 2005 Thiemo Seufer
  */

 #undef DEBUG

 #include <linux/extable.h>
 #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>

 extern void jump_label_apply_nops(struct module *mod);

 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, 0, NUMA_NO_NODE,
 				__builtin_return_address(0));
 }
 #endif

 static void apply_r_mips_32(u32 *location, u32 base, Elf_Addr v)
 {
 	*location = base + v;
 }

 static int apply_r_mips_26(struct module *me, u32 *location, u32 base,
 			   Elf_Addr v)
 {
 	if (v % 4) {
 		pr_err("module %s: dangerous R_MIPS_26 relocation\n",
 		       me->name);
 		return -ENOEXEC;
 	}

 	if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
 		pr_err("module %s: relocation overflow\n",
 		       me->name);
 		return -ENOEXEC;
 	}

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

 	return 0;
 }

 static int apply_r_mips_hi16(struct module *me, u32 *location, Elf_Addr v,
 			     bool rela)
 {
 	struct mips_hi16 *n;

 	if (rela) {
 		*location = (*location & 0xffff0000) |
 			    ((((long long) v + 0x8000LL) >> 16) & 0xffff);
 		return 0;
 	}

 	/*
 	 * 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(struct module *me, u32 *location,
 			     u32 base, Elf_Addr v, bool rela)
 {
 	unsigned long insnlo = base;
 	struct mips_hi16 *l;
 	Elf_Addr val, vallo;

 	if (rela) {
 		*location = (*location & 0xffff0000) | (v & 0xffff);
 		return 0;
 	}

 	/* 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 relocation\n", me->name);

 	return -ENOEXEC;
 }

 static int apply_r_mips_pc(struct module *me, u32 *location, u32 base,
 			   Elf_Addr v, unsigned int bits)
 {
 	unsigned long mask = GENMASK(bits - 1, 0);
 	unsigned long se_bits;
 	long offset;

 	if (v % 4) {
 		pr_err("module %s: dangerous R_MIPS_PC%u relocation\n",
 		       me->name, bits);
 		return -ENOEXEC;
 	}

 	/* retrieve & sign extend implicit addend if any */
 	offset = base & mask;
 	offset |= (offset & BIT(bits - 1)) ? ~mask : 0;

 	offset += ((long)v - (long)location) >> 2;

 	/* check the sign bit onwards are identical - ie. we didn't overflow */
 	se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0;
 	if ((offset & ~mask) != (se_bits & ~mask)) {
 		pr_err("module %s: relocation overflow\n", me->name);
 		return -ENOEXEC;
 	}

 	*location = (*location & ~mask) | (offset & mask);

 	return 0;
 }

 static int apply_r_mips_pc16(struct module *me, u32 *location, u32 base,
 			     Elf_Addr v)
 {
 	return apply_r_mips_pc(me, location, base, v, 16);
 }

 static int apply_r_mips_pc21(struct module *me, u32 *location, u32 base,
 			     Elf_Addr v)
 {
 	return apply_r_mips_pc(me, location, base, v, 21);
 }

 static int apply_r_mips_pc26(struct module *me, u32 *location, u32 base,
 			     Elf_Addr v)
 {
 	return apply_r_mips_pc(me, location, base, v, 26);
 }

 static int apply_r_mips_64(u32 *location, Elf_Addr v, bool rela)
 {
 	if (WARN_ON(!rela))
 		return -EINVAL;

 	*(Elf_Addr *)location = v;

 	return 0;
 }

 static int apply_r_mips_higher(u32 *location, Elf_Addr v, bool rela)
 {
 	if (WARN_ON(!rela))
 		return -EINVAL;

 	*location = (*location & 0xffff0000) |
 		    ((((long long)v + 0x80008000LL) >> 32) & 0xffff);

 	return 0;
 }

 static int apply_r_mips_highest(u32 *location, Elf_Addr v, bool rela)
 {
 	if (WARN_ON(!rela))
 		return -EINVAL;

 	*location = (*location & 0xffff0000) |
 		    ((((long long)v + 0x800080008000LL) >> 48) & 0xffff);

 	return 0;
 }

 /**
  * reloc_handler() - Apply a particular relocation to a module
  * @type: type of the relocation to apply
  * @me: the module to apply the reloc to
  * @location: the address at which the reloc is to be applied
  * @base: the existing value at location for REL-style; 0 for RELA-style
  * @v: the value of the reloc, with addend for RELA-style
  * @rela: indication of is this a RELA (true) or REL (false) relocation
  *
  * Each implemented relocation function applies a particular type of
  * relocation to the module @me. Relocs that may be found in either REL or RELA
  * variants can be handled by making use of the @base & @v parameters which are
  * set to values which abstract the difference away from the particular reloc
  * implementations.
  *
  * Return: 0 upon success, else -ERRNO
  */
 static int reloc_handler(u32 type, struct module *me, u32 *location, u32 base,
 			 Elf_Addr v, bool rela)
 {
 	switch (type) {
 	case R_MIPS_NONE:
 		break;
 	case R_MIPS_32:
 		apply_r_mips_32(location, base, v);
 		break;
 	case R_MIPS_26:
 		return apply_r_mips_26(me, location, base, v);
 	case R_MIPS_HI16:
 		return apply_r_mips_hi16(me, location, v, rela);
 	case R_MIPS_LO16:
 		return apply_r_mips_lo16(me, location, base, v, rela);
 	case R_MIPS_PC16:
 		return apply_r_mips_pc16(me, location, base, v);
 	case R_MIPS_PC21_S2:
 		return apply_r_mips_pc21(me, location, base, v);
 	case R_MIPS_PC26_S2:
 		return apply_r_mips_pc26(me, location, base, v);
 	case R_MIPS_64:
 		return apply_r_mips_64(location, v, rela);
 	case R_MIPS_HIGHER:
 		return apply_r_mips_higher(location, v, rela);
 	case R_MIPS_HIGHEST:
 		return apply_r_mips_highest(location, v, rela);
 	default:
 		pr_err("%s: Unknown relocation type %u\n", me->name, type);
 		return -EINVAL;
 	}

 	return 0;
 }

 static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
 			    unsigned int symindex, unsigned int relsec,
 			    struct module *me, bool rela)
 {
 	union {
 		Elf_Mips_Rel *rel;
 		Elf_Mips_Rela *rela;
 	} r;
 	Elf_Sym *sym;
 	u32 *location, base;
 	unsigned int i, type;
 	Elf_Addr v;
 	int err = 0;
 	size_t reloc_sz;

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

 	r.rel = (void *)sechdrs[relsec].sh_addr;
 	reloc_sz = rela ? sizeof(*r.rela) : sizeof(*r.rel);
 	me->arch.r_mips_hi16_list = NULL;
 	for (i = 0; i < sechdrs[relsec].sh_size / reloc_sz; i++) {
 		/* This is where to make the change */
 		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 			+ r.rel->r_offset;
 		/* This is the symbol it is referring to */
 		sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 			+ ELF_MIPS_R_SYM(*r.rel);
 		if (sym->st_value >= -MAX_ERRNO) {
 			/* Ignore unresolved weak symbol */
 			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 				continue;
 			pr_warn("%s: Unknown symbol %s\n",
 				me->name, strtab + sym->st_name);
 			err = -ENOENT;
 			goto out;
 		}

 		type = ELF_MIPS_R_TYPE(*r.rel);

 		if (rela) {
 			v = sym->st_value + r.rela->r_addend;
 			base = 0;
 			r.rela = &r.rela[1];
 		} else {
 			v = sym->st_value;
 			base = *location;
 			r.rel = &r.rel[1];
 		}

 		err = reloc_handler(type, me, location, base, v, rela);
 		if (err)
 			goto out;
 	}

 out:
 	/*
 	 * 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, or if we hit
 	 * an error processing a reloc we might have gotten here before
 	 * reaching the R_MIPS_LO16. In either 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;
 		err = err ?: -ENOEXEC;
 	}

 	return err;
 }

 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
 		   unsigned int symindex, unsigned int relsec,
 		   struct module *me)
 {
 	return __apply_relocate(sechdrs, strtab, symindex, relsec, me, false);
 }

 #ifdef CONFIG_MODULES_USE_ELF_RELA
 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 		       unsigned int symindex, unsigned int relsec,
 		       struct module *me)
 {
 	return __apply_relocate(sechdrs, strtab, symindex, relsec, me, true);
 }
 #endif /* CONFIG_MODULES_USE_ELF_RELA */

 /* 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 - dbe->dbe_start, 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;

 	if (IS_ENABLED(CONFIG_JUMP_LABEL))
 		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);
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	*
	* Copyright (C) 2001 Rusty Russell.
	* Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
	* Copyright (C) 2005 Thiemo Seufer
	*/

	#undef DEBUG

	#include <linux/extable.h>
	#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>

	extern void jump_label_apply_nops(struct module *mod);

	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, 0, NUMA_NO_NODE,
	__builtin_return_address(0));
	}
	#endif

	static void apply_r_mips_32(u32 *location, u32 base, Elf_Addr v)
	{
	*location = base + v;
	}

	static int apply_r_mips_26(struct module me, u32 location, u32 base,
	Elf_Addr v)
	{
	if (v % 4) {
	pr_err("module %s: dangerous R_MIPS_26 relocation\n",
	me->name);
	return -ENOEXEC;
	}

	if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
	pr_err("module %s: relocation overflow\n",
	me->name);
	return -ENOEXEC;
	}

	location = (location & ~0x03ffffff) \|
	((base + (v >> 2)) & 0x03ffffff);

	return 0;
	}

	static int apply_r_mips_hi16(struct module me, u32 location, Elf_Addr v,
	bool rela)
	{
	struct mips_hi16 *n;

	if (rela) {
	location = (location & 0xffff0000) \|
	((((long long) v + 0x8000LL) >> 16) & 0xffff);
	return 0;
	}

	/*
	* 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(struct module me, u32 location,
	u32 base, Elf_Addr v, bool rela)
	{
	unsigned long insnlo = base;
	struct mips_hi16 *l;
	Elf_Addr val, vallo;

	if (rela) {
	location = (location & 0xffff0000) \| (v & 0xffff);
	return 0;
	}

	/* 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 relocation\n", me->name);

	return -ENOEXEC;
	}

	static int apply_r_mips_pc(struct module me, u32 location, u32 base,
	Elf_Addr v, unsigned int bits)
	{
	unsigned long mask = GENMASK(bits - 1, 0);
	unsigned long se_bits;
	long offset;

	if (v % 4) {
	pr_err("module %s: dangerous R_MIPS_PC%u relocation\n",
	me->name, bits);
	return -ENOEXEC;
	}

	/* retrieve & sign extend implicit addend if any */
	offset = base & mask;
	offset \|= (offset & BIT(bits - 1)) ? ~mask : 0;

	offset += ((long)v - (long)location) >> 2;

	/* check the sign bit onwards are identical - ie. we didn't overflow */
	se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0;
	if ((offset & ~mask) != (se_bits & ~mask)) {
	pr_err("module %s: relocation overflow\n", me->name);
	return -ENOEXEC;
	}

	location = (location & ~mask) \| (offset & mask);

	return 0;
	}

	static int apply_r_mips_pc16(struct module me, u32 location, u32 base,
	Elf_Addr v)
	{
	return apply_r_mips_pc(me, location, base, v, 16);
	}

	static int apply_r_mips_pc21(struct module me, u32 location, u32 base,
	Elf_Addr v)
	{
	return apply_r_mips_pc(me, location, base, v, 21);
	}

	static int apply_r_mips_pc26(struct module me, u32 location, u32 base,
	Elf_Addr v)
	{
	return apply_r_mips_pc(me, location, base, v, 26);
	}

	static int apply_r_mips_64(u32 *location, Elf_Addr v, bool rela)
	{
	if (WARN_ON(!rela))
	return -EINVAL;

	(Elf_Addr )location = v;

	return 0;
	}

	static int apply_r_mips_higher(u32 *location, Elf_Addr v, bool rela)
	{
	if (WARN_ON(!rela))
	return -EINVAL;

	location = (location & 0xffff0000) \|
	((((long long)v + 0x80008000LL) >> 32) & 0xffff);

	return 0;
	}

	static int apply_r_mips_highest(u32 *location, Elf_Addr v, bool rela)
	{
	if (WARN_ON(!rela))
	return -EINVAL;

	location = (location & 0xffff0000) \|
	((((long long)v + 0x800080008000LL) >> 48) & 0xffff);

	return 0;
	}

	/**
	* reloc_handler() - Apply a particular relocation to a module
	* @type: type of the relocation to apply
	* @me: the module to apply the reloc to
	* @location: the address at which the reloc is to be applied
	* @base: the existing value at location for REL-style; 0 for RELA-style
	* @v: the value of the reloc, with addend for RELA-style
	* @rela: indication of is this a RELA (true) or REL (false) relocation
	*
	* Each implemented relocation function applies a particular type of
	* relocation to the module @me. Relocs that may be found in either REL or RELA
	* variants can be handled by making use of the @base & @v parameters which are
	* set to values which abstract the difference away from the particular reloc
	* implementations.
	*
	* Return: 0 upon success, else -ERRNO
	*/
	static int reloc_handler(u32 type, struct module me, u32 location, u32 base,
	Elf_Addr v, bool rela)
	{
	switch (type) {
	case R_MIPS_NONE:
	break;
	case R_MIPS_32:
	apply_r_mips_32(location, base, v);
	break;
	case R_MIPS_26:
	return apply_r_mips_26(me, location, base, v);
	case R_MIPS_HI16:
	return apply_r_mips_hi16(me, location, v, rela);
	case R_MIPS_LO16:
	return apply_r_mips_lo16(me, location, base, v, rela);
	case R_MIPS_PC16:
	return apply_r_mips_pc16(me, location, base, v);
	case R_MIPS_PC21_S2:
	return apply_r_mips_pc21(me, location, base, v);
	case R_MIPS_PC26_S2:
	return apply_r_mips_pc26(me, location, base, v);
	case R_MIPS_64:
	return apply_r_mips_64(location, v, rela);
	case R_MIPS_HIGHER:
	return apply_r_mips_higher(location, v, rela);
	case R_MIPS_HIGHEST:
	return apply_r_mips_highest(location, v, rela);
	default:
	pr_err("%s: Unknown relocation type %u\n", me->name, type);
	return -EINVAL;
	}

	return 0;
	}

	static int __apply_relocate(Elf_Shdr sechdrs, const char strtab,
	unsigned int symindex, unsigned int relsec,
	struct module *me, bool rela)
	{
	union {
	Elf_Mips_Rel *rel;
	Elf_Mips_Rela *rela;
	} r;
	Elf_Sym *sym;
	u32 *location, base;
	unsigned int i, type;
	Elf_Addr v;
	int err = 0;
	size_t reloc_sz;

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

	r.rel = (void *)sechdrs[relsec].sh_addr;
	reloc_sz = rela ? sizeof(r.rela) : sizeof(r.rel);
	me->arch.r_mips_hi16_list = NULL;
	for (i = 0; i < sechdrs[relsec].sh_size / reloc_sz; i++) {
	/* This is where to make the change */
	location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
	+ r.rel->r_offset;
	/* This is the symbol it is referring to */
	sym = (Elf_Sym *)sechdrs[symindex].sh_addr
	+ ELF_MIPS_R_SYM(*r.rel);
	if (sym->st_value >= -MAX_ERRNO) {
	/* Ignore unresolved weak symbol */
	if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
	continue;
	pr_warn("%s: Unknown symbol %s\n",
	me->name, strtab + sym->st_name);
	err = -ENOENT;
	goto out;
	}

	type = ELF_MIPS_R_TYPE(*r.rel);

	if (rela) {
	v = sym->st_value + r.rela->r_addend;
	base = 0;
	r.rela = &r.rela[1];
	} else {
	v = sym->st_value;
	base = *location;
	r.rel = &r.rel[1];
	}

	err = reloc_handler(type, me, location, base, v, rela);
	if (err)
	goto out;
	}

	out:
	/*
	* 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, or if we hit
	* an error processing a reloc we might have gotten here before
	* reaching the R_MIPS_LO16. In either 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;
	err = err ?: -ENOEXEC;
	}

	return err;
	}

	int apply_relocate(Elf_Shdr sechdrs, const char strtab,
	unsigned int symindex, unsigned int relsec,
	struct module *me)
	{
	return __apply_relocate(sechdrs, strtab, symindex, relsec, me, false);
	}

	#ifdef CONFIG_MODULES_USE_ELF_RELA
	int apply_relocate_add(Elf_Shdr sechdrs, const char strtab,
	unsigned int symindex, unsigned int relsec,
	struct module *me)
	{
	return __apply_relocate(sechdrs, strtab, symindex, relsec, me, true);
	}
	#endif /* CONFIG_MODULES_USE_ELF_RELA */

	/* 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 - dbe->dbe_start, 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;

	if (IS_ENABLED(CONFIG_JUMP_LABEL))
	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);
	}