// 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);
}