in kernel/module_64.c [526:747]
int apply_relocate_add(Elf64_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *me)
{
unsigned int i;
Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
Elf64_Sym *sym;
unsigned long *location;
unsigned long value;
pr_debug("Applying ADD relocate section %u to %u\n", relsec,
sechdrs[relsec].sh_info);
/* First time we're called, we can fix up .TOC. */
if (!me->arch.toc_fixed) {
sym = find_dot_toc(sechdrs, strtab, symindex);
/* It's theoretically possible that a module doesn't want a
* .TOC. so don't fail it just for that. */
if (sym)
sym->st_value = my_r2(sechdrs, me);
me->arch.toc_fixed = true;
}
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
/* This is where to make the change */
location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+ rela[i].r_offset;
/* This is the symbol it is referring to */
sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
+ ELF64_R_SYM(rela[i].r_info);
pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
location, (long)ELF64_R_TYPE(rela[i].r_info),
strtab + sym->st_name, (unsigned long)sym->st_value,
(long)rela[i].r_addend);
/* `Everything is relative'. */
value = sym->st_value + rela[i].r_addend;
switch (ELF64_R_TYPE(rela[i].r_info)) {
case R_PPC64_ADDR32:
/* Simply set it */
*(u32 *)location = value;
break;
case R_PPC64_ADDR64:
/* Simply set it */
*(unsigned long *)location = value;
break;
case R_PPC64_TOC:
*(unsigned long *)location = my_r2(sechdrs, me);
break;
case R_PPC64_TOC16:
/* Subtract TOC pointer */
value -= my_r2(sechdrs, me);
if (value + 0x8000 > 0xffff) {
pr_err("%s: bad TOC16 relocation (0x%lx)\n",
me->name, value);
return -ENOEXEC;
}
*((uint16_t *) location)
= (*((uint16_t *) location) & ~0xffff)
| (value & 0xffff);
break;
case R_PPC64_TOC16_LO:
/* Subtract TOC pointer */
value -= my_r2(sechdrs, me);
*((uint16_t *) location)
= (*((uint16_t *) location) & ~0xffff)
| (value & 0xffff);
break;
case R_PPC64_TOC16_DS:
/* Subtract TOC pointer */
value -= my_r2(sechdrs, me);
if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
me->name, value);
return -ENOEXEC;
}
*((uint16_t *) location)
= (*((uint16_t *) location) & ~0xfffc)
| (value & 0xfffc);
break;
case R_PPC64_TOC16_LO_DS:
/* Subtract TOC pointer */
value -= my_r2(sechdrs, me);
if ((value & 3) != 0) {
pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
me->name, value);
return -ENOEXEC;
}
*((uint16_t *) location)
= (*((uint16_t *) location) & ~0xfffc)
| (value & 0xfffc);
break;
case R_PPC64_TOC16_HA:
/* Subtract TOC pointer */
value -= my_r2(sechdrs, me);
value = ((value + 0x8000) >> 16);
*((uint16_t *) location)
= (*((uint16_t *) location) & ~0xffff)
| (value & 0xffff);
break;
case R_PPC_REL24:
/* FIXME: Handle weak symbols here --RR */
if (sym->st_shndx == SHN_UNDEF ||
sym->st_shndx == SHN_LIVEPATCH) {
/* External: go via stub */
value = stub_for_addr(sechdrs, value, me,
strtab + sym->st_name);
if (!value)
return -ENOENT;
if (!restore_r2(strtab + sym->st_name,
(u32 *)location + 1, me))
return -ENOEXEC;
} else
value += local_entry_offset(sym);
/* Convert value to relative */
value -= (unsigned long)location;
if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
pr_err("%s: REL24 %li out of range!\n",
me->name, (long int)value);
return -ENOEXEC;
}
/* Only replace bits 2 through 26 */
value = (*(uint32_t *)location & ~0x03fffffc)
| (value & 0x03fffffc);
if (patch_instruction((u32 *)location, ppc_inst(value)))
return -EFAULT;
break;
case R_PPC64_REL64:
/* 64 bits relative (used by features fixups) */
*location = value - (unsigned long)location;
break;
case R_PPC64_REL32:
/* 32 bits relative (used by relative exception tables) */
/* Convert value to relative */
value -= (unsigned long)location;
if (value + 0x80000000 > 0xffffffff) {
pr_err("%s: REL32 %li out of range!\n",
me->name, (long int)value);
return -ENOEXEC;
}
*(u32 *)location = value;
break;
case R_PPC64_TOCSAVE:
/*
* Marker reloc indicates we don't have to save r2.
* That would only save us one instruction, so ignore
* it.
*/
break;
case R_PPC64_ENTRY:
/*
* Optimize ELFv2 large code model entry point if
* the TOC is within 2GB range of current location.
*/
value = my_r2(sechdrs, me) - (unsigned long)location;
if (value + 0x80008000 > 0xffffffff)
break;
/*
* Check for the large code model prolog sequence:
* ld r2, ...(r12)
* add r2, r2, r12
*/
if ((((uint32_t *)location)[0] & ~0xfffc) != PPC_RAW_LD(_R2, _R12, 0))
break;
if (((uint32_t *)location)[1] != PPC_RAW_ADD(_R2, _R2, _R12))
break;
/*
* If found, replace it with:
* addis r2, r12, (.TOC.-func)@ha
* addi r2, r2, (.TOC.-func)@l
*/
((uint32_t *)location)[0] = PPC_RAW_ADDIS(_R2, _R12, PPC_HA(value));
((uint32_t *)location)[1] = PPC_RAW_ADDI(_R2, _R2, PPC_LO(value));
break;
case R_PPC64_REL16_HA:
/* Subtract location pointer */
value -= (unsigned long)location;
value = ((value + 0x8000) >> 16);
*((uint16_t *) location)
= (*((uint16_t *) location) & ~0xffff)
| (value & 0xffff);
break;
case R_PPC64_REL16_LO:
/* Subtract location pointer */
value -= (unsigned long)location;
*((uint16_t *) location)
= (*((uint16_t *) location) & ~0xffff)
| (value & 0xffff);
break;
default:
pr_err("%s: Unknown ADD relocation: %lu\n",
me->name,
(unsigned long)ELF64_R_TYPE(rela[i].r_info));
return -ENOEXEC;
}
}
return 0;
}