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- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- *
- * Copyright (C) 2001 Rusty Russell.
- * Copyright (C) 2003, 2004 Ralf Baechle ([email protected])
- * 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);
- }
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