321 lines
8.9 KiB
C
321 lines
8.9 KiB
C
/* Kernel module help for PPC.
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Copyright (C) 2001 Rusty Russell.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/module.h>
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#include <linux/moduleloader.h>
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#include <linux/elf.h>
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#include <linux/vmalloc.h>
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#include <linux/fs.h>
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#include <linux/string.h>
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#include <linux/kernel.h>
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#include <linux/cache.h>
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(fmt , ...)
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#endif
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LIST_HEAD(module_bug_list);
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void *module_alloc(unsigned long size)
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{
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if (size == 0)
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return NULL;
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return vmalloc(size);
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}
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/* Free memory returned from module_alloc */
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void module_free(struct module *mod, void *module_region)
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{
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vfree(module_region);
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/* FIXME: If module_region == mod->init_region, trim exception
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table entries. */
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}
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/* Count how many different relocations (different symbol, different
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addend) */
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static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
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{
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unsigned int i, j, ret = 0;
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/* Sure, this is order(n^2), but it's usually short, and not
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time critical */
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for (i = 0; i < num; i++) {
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for (j = 0; j < i; j++) {
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/* If this addend appeared before, it's
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already been counted */
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if (ELF32_R_SYM(rela[i].r_info)
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== ELF32_R_SYM(rela[j].r_info)
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&& rela[i].r_addend == rela[j].r_addend)
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break;
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}
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if (j == i) ret++;
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}
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return ret;
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}
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/* Get the potential trampolines size required of the init and
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non-init sections */
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static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
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const Elf32_Shdr *sechdrs,
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const char *secstrings,
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int is_init)
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{
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unsigned long ret = 0;
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unsigned i;
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/* Everything marked ALLOC (this includes the exported
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symbols) */
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for (i = 1; i < hdr->e_shnum; i++) {
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/* If it's called *.init*, and we're not init, we're
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not interested */
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if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0)
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!= is_init)
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continue;
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/* We don't want to look at debug sections. */
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if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0)
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continue;
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if (sechdrs[i].sh_type == SHT_RELA) {
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DEBUGP("Found relocations in section %u\n", i);
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DEBUGP("Ptr: %p. Number: %u\n",
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(void *)hdr + sechdrs[i].sh_offset,
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sechdrs[i].sh_size / sizeof(Elf32_Rela));
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ret += count_relocs((void *)hdr
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+ sechdrs[i].sh_offset,
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sechdrs[i].sh_size
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/ sizeof(Elf32_Rela))
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* sizeof(struct ppc_plt_entry);
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}
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}
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return ret;
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}
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int module_frob_arch_sections(Elf32_Ehdr *hdr,
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Elf32_Shdr *sechdrs,
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char *secstrings,
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struct module *me)
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{
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unsigned int i;
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/* Find .plt and .init.plt sections */
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for (i = 0; i < hdr->e_shnum; i++) {
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if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)
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me->arch.init_plt_section = i;
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else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
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me->arch.core_plt_section = i;
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}
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if (!me->arch.core_plt_section || !me->arch.init_plt_section) {
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printk("Module doesn't contain .plt or .init.plt sections.\n");
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return -ENOEXEC;
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}
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/* Override their sizes */
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sechdrs[me->arch.core_plt_section].sh_size
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= get_plt_size(hdr, sechdrs, secstrings, 0);
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sechdrs[me->arch.init_plt_section].sh_size
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= get_plt_size(hdr, sechdrs, secstrings, 1);
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return 0;
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}
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int apply_relocate(Elf32_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *module)
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{
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printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n",
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module->name);
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return -ENOEXEC;
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}
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static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val)
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{
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if (entry->jump[0] == 0x3d600000 + ((val + 0x8000) >> 16)
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&& entry->jump[1] == 0x396b0000 + (val & 0xffff))
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return 1;
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return 0;
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}
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/* Set up a trampoline in the PLT to bounce us to the distant function */
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static uint32_t do_plt_call(void *location,
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Elf32_Addr val,
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Elf32_Shdr *sechdrs,
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struct module *mod)
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{
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struct ppc_plt_entry *entry;
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DEBUGP("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location);
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/* Init, or core PLT? */
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if (location >= mod->module_core
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&& location < mod->module_core + mod->core_size)
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entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
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else
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entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;
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/* Find this entry, or if that fails, the next avail. entry */
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while (entry->jump[0]) {
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if (entry_matches(entry, val)) return (uint32_t)entry;
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entry++;
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}
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/* Stolen from Paul Mackerras as well... */
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entry->jump[0] = 0x3d600000+((val+0x8000)>>16); /* lis r11,sym@ha */
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entry->jump[1] = 0x396b0000 + (val&0xffff); /* addi r11,r11,sym@l*/
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entry->jump[2] = 0x7d6903a6; /* mtctr r11 */
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entry->jump[3] = 0x4e800420; /* bctr */
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DEBUGP("Initialized plt for 0x%x at %p\n", val, entry);
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return (uint32_t)entry;
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}
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int apply_relocate_add(Elf32_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *module)
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{
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unsigned int i;
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Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
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Elf32_Sym *sym;
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uint32_t *location;
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uint32_t value;
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DEBUGP("Applying ADD relocate section %u to %u\n", relsec,
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sechdrs[relsec].sh_info);
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for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
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/* This is where to make the change */
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location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
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+ rela[i].r_offset;
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/* This is the symbol it is referring to. Note that all
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undefined symbols have been resolved. */
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sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
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+ ELF32_R_SYM(rela[i].r_info);
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/* `Everything is relative'. */
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value = sym->st_value + rela[i].r_addend;
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switch (ELF32_R_TYPE(rela[i].r_info)) {
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case R_PPC_ADDR32:
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/* Simply set it */
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*(uint32_t *)location = value;
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break;
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case R_PPC_ADDR16_LO:
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/* Low half of the symbol */
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*(uint16_t *)location = value;
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break;
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case R_PPC_ADDR16_HA:
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/* Sign-adjusted lower 16 bits: PPC ELF ABI says:
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(((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF.
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This is the same, only sane.
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*/
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*(uint16_t *)location = (value + 0x8000) >> 16;
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break;
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case R_PPC_REL24:
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if ((int)(value - (uint32_t)location) < -0x02000000
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|| (int)(value - (uint32_t)location) >= 0x02000000)
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value = do_plt_call(location, value,
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sechdrs, module);
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/* Only replace bits 2 through 26 */
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DEBUGP("REL24 value = %08X. location = %08X\n",
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value, (uint32_t)location);
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DEBUGP("Location before: %08X.\n",
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*(uint32_t *)location);
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*(uint32_t *)location
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= (*(uint32_t *)location & ~0x03fffffc)
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| ((value - (uint32_t)location)
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& 0x03fffffc);
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DEBUGP("Location after: %08X.\n",
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*(uint32_t *)location);
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DEBUGP("ie. jump to %08X+%08X = %08X\n",
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*(uint32_t *)location & 0x03fffffc,
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(uint32_t)location,
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(*(uint32_t *)location & 0x03fffffc)
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+ (uint32_t)location);
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break;
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case R_PPC_REL32:
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/* 32-bit relative jump. */
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*(uint32_t *)location = value - (uint32_t)location;
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break;
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default:
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printk("%s: unknown ADD relocation: %u\n",
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module->name,
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ELF32_R_TYPE(rela[i].r_info));
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return -ENOEXEC;
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}
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}
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return 0;
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}
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int module_finalize(const Elf_Ehdr *hdr,
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const Elf_Shdr *sechdrs,
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struct module *me)
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{
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char *secstrings;
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unsigned int i;
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me->arch.bug_table = NULL;
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me->arch.num_bugs = 0;
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/* Find the __bug_table section, if present */
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secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
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for (i = 1; i < hdr->e_shnum; i++) {
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if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table"))
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continue;
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me->arch.bug_table = (void *) sechdrs[i].sh_addr;
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me->arch.num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);
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break;
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}
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/*
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* Strictly speaking this should have a spinlock to protect against
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* traversals, but since we only traverse on BUG()s, a spinlock
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* could potentially lead to deadlock and thus be counter-productive.
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*/
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list_add(&me->arch.bug_list, &module_bug_list);
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return 0;
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}
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void module_arch_cleanup(struct module *mod)
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{
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list_del(&mod->arch.bug_list);
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}
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struct bug_entry *module_find_bug(unsigned long bugaddr)
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{
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struct mod_arch_specific *mod;
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unsigned int i;
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struct bug_entry *bug;
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list_for_each_entry(mod, &module_bug_list, bug_list) {
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bug = mod->bug_table;
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for (i = 0; i < mod->num_bugs; ++i, ++bug)
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if (bugaddr == bug->bug_addr)
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return bug;
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}
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return NULL;
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}
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