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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#undef DEBUG
#include <linux/extable.h>#include <linux/moduleloader.h>#include <linux/elf.h>#include <linux/mm.h>#include <linux/numa.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/jump_label.h>
struct mips_hi16 { struct mips_hi16 *next; Elf_Addr *addr; Elf_Addr value;};
static LIST_HEAD(dbe_list);static DEFINE_SPINLOCK(dbe_lock);
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_obj(*n); 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_RELAint 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);}