464 lines
13 KiB
C
464 lines
13 KiB
C
/* Kernel module help for PPC64.
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Copyright (C) 2001, 2003 Rusty Russell IBM Corporation.
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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/elf.h>
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#include <linux/moduleloader.h>
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#include <linux/err.h>
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#include <linux/vmalloc.h>
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#include <asm/module.h>
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#include <asm/uaccess.h>
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/* FIXME: We don't do .init separately. To do this, we'd need to have
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a separate r2 value in the init and core section, and stub between
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them, too.
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Using a magic allocator which places modules within 32MB solves
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this, and makes other things simpler. Anton?
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--RR. */
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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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/* There's actually a third entry here, but it's unused */
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struct ppc64_opd_entry
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{
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unsigned long funcaddr;
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unsigned long r2;
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};
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/* Like PPC32, we need little trampolines to do > 24-bit jumps (into
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the kernel itself). But on PPC64, these need to be used for every
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jump, actually, to reset r2 (TOC+0x8000). */
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struct ppc64_stub_entry
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{
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/* 28 byte jump instruction sequence (7 instructions) */
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unsigned char jump[28];
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unsigned char unused[4];
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/* Data for the above code */
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struct ppc64_opd_entry opd;
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};
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/* We use a stub to fix up r2 (TOC ptr) and to jump to the (external)
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function which may be more than 24-bits away. We could simply
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patch the new r2 value and function pointer into the stub, but it's
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significantly shorter to put these values at the end of the stub
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code, and patch the stub address (32-bits relative to the TOC ptr,
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r2) into the stub. */
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static struct ppc64_stub_entry ppc64_stub =
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{ .jump = {
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0x3d, 0x82, 0x00, 0x00, /* addis r12,r2, <high> */
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0x39, 0x8c, 0x00, 0x00, /* addi r12,r12, <low> */
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/* Save current r2 value in magic place on the stack. */
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0xf8, 0x41, 0x00, 0x28, /* std r2,40(r1) */
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0xe9, 0x6c, 0x00, 0x20, /* ld r11,32(r12) */
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0xe8, 0x4c, 0x00, 0x28, /* ld r2,40(r12) */
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0x7d, 0x69, 0x03, 0xa6, /* mtctr r11 */
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0x4e, 0x80, 0x04, 0x20 /* bctr */
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} };
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/* Count how many different 24-bit relocations (different symbol,
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different addend) */
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static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
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{
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unsigned int i, j, ret = 0;
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/* FIXME: Only count external ones --RR */
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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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/* Only count 24-bit relocs, others don't need stubs */
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if (ELF64_R_TYPE(rela[i].r_info) != R_PPC_REL24)
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continue;
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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 (rela[i].r_info == 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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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_exec(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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/* Get size of potential trampolines required. */
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static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
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const Elf64_Shdr *sechdrs)
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{
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/* One extra reloc so it's always 0-funcaddr terminated */
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unsigned long relocs = 1;
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unsigned i;
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/* Every relocated section... */
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for (i = 1; i < hdr->e_shnum; i++) {
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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: %lu\n",
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(void *)sechdrs[i].sh_addr,
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sechdrs[i].sh_size / sizeof(Elf64_Rela));
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relocs += count_relocs((void *)sechdrs[i].sh_addr,
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sechdrs[i].sh_size
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/ sizeof(Elf64_Rela));
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}
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}
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DEBUGP("Looks like a total of %lu stubs, max\n", relocs);
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return relocs * sizeof(struct ppc64_stub_entry);
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}
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static void dedotify_versions(struct modversion_info *vers,
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unsigned long size)
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{
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struct modversion_info *end;
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for (end = (void *)vers + size; vers < end; vers++)
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if (vers->name[0] == '.')
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memmove(vers->name, vers->name+1, strlen(vers->name));
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}
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/* Undefined symbols which refer to .funcname, hack to funcname */
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static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
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{
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unsigned int i;
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for (i = 1; i < numsyms; i++) {
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if (syms[i].st_shndx == SHN_UNDEF) {
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char *name = strtab + syms[i].st_name;
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if (name[0] == '.')
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memmove(name, name+1, strlen(name));
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}
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}
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}
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int module_frob_arch_sections(Elf64_Ehdr *hdr,
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Elf64_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 .toc and .stubs sections, symtab and strtab */
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for (i = 1; i < hdr->e_shnum; i++) {
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char *p;
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if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
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me->arch.stubs_section = i;
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else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0)
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me->arch.toc_section = i;
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else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
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dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
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sechdrs[i].sh_size);
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/* We don't handle .init for the moment: rename to _init */
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while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
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p[0] = '_';
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if (sechdrs[i].sh_type == SHT_SYMTAB)
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dedotify((void *)hdr + sechdrs[i].sh_offset,
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sechdrs[i].sh_size / sizeof(Elf64_Sym),
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(void *)hdr
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+ sechdrs[sechdrs[i].sh_link].sh_offset);
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}
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if (!me->arch.stubs_section) {
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printk("%s: doesn't contain .stubs.\n", me->name);
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return -ENOEXEC;
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}
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/* If we don't have a .toc, just use .stubs. We need to set r2
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to some reasonable value in case the module calls out to
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other functions via a stub, or if a function pointer escapes
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the module by some means. */
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if (!me->arch.toc_section)
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me->arch.toc_section = me->arch.stubs_section;
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/* Override the stubs size */
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sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
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return 0;
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}
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int apply_relocate(Elf64_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 *me)
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{
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printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n", me->name);
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return -ENOEXEC;
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}
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/* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this
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gives the value maximum span in an instruction which uses a signed
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offset) */
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static inline unsigned long my_r2(Elf64_Shdr *sechdrs, struct module *me)
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{
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return sechdrs[me->arch.toc_section].sh_addr + 0x8000;
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}
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/* Both low and high 16 bits are added as SIGNED additions, so if low
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16 bits has high bit set, high 16 bits must be adjusted. These
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macros do that (stolen from binutils). */
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#define PPC_LO(v) ((v) & 0xffff)
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#define PPC_HI(v) (((v) >> 16) & 0xffff)
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#define PPC_HA(v) PPC_HI ((v) + 0x8000)
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/* Patch stub to reference function and correct r2 value. */
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static inline int create_stub(Elf64_Shdr *sechdrs,
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struct ppc64_stub_entry *entry,
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struct ppc64_opd_entry *opd,
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struct module *me)
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{
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Elf64_Half *loc1, *loc2;
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long reladdr;
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*entry = ppc64_stub;
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loc1 = (Elf64_Half *)&entry->jump[2];
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loc2 = (Elf64_Half *)&entry->jump[6];
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/* Stub uses address relative to r2. */
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reladdr = (unsigned long)entry - my_r2(sechdrs, me);
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if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
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printk("%s: Address %p of stub out of range of %p.\n",
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me->name, (void *)reladdr, (void *)my_r2);
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return 0;
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}
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DEBUGP("Stub %p get data from reladdr %li\n", entry, reladdr);
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*loc1 = PPC_HA(reladdr);
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*loc2 = PPC_LO(reladdr);
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entry->opd.funcaddr = opd->funcaddr;
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entry->opd.r2 = opd->r2;
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return 1;
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}
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/* Create stub to jump to function described in this OPD: we need the
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stub to set up the TOC ptr (r2) for the function. */
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static unsigned long stub_for_addr(Elf64_Shdr *sechdrs,
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unsigned long opdaddr,
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struct module *me)
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{
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struct ppc64_stub_entry *stubs;
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struct ppc64_opd_entry *opd = (void *)opdaddr;
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unsigned int i, num_stubs;
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num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
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/* Find this stub, or if that fails, the next avail. entry */
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stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
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for (i = 0; stubs[i].opd.funcaddr; i++) {
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BUG_ON(i >= num_stubs);
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if (stubs[i].opd.funcaddr == opd->funcaddr)
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return (unsigned long)&stubs[i];
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}
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if (!create_stub(sechdrs, &stubs[i], opd, me))
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return 0;
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return (unsigned long)&stubs[i];
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}
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/* We expect a noop next: if it is, replace it with instruction to
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restore r2. */
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static int restore_r2(u32 *instruction, struct module *me)
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{
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if (*instruction != 0x60000000) {
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printk("%s: Expect noop after relocate, got %08x\n",
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me->name, *instruction);
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return 0;
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}
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*instruction = 0xe8410028; /* ld r2,40(r1) */
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return 1;
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}
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int apply_relocate_add(Elf64_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 *me)
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{
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unsigned int i;
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Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
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Elf64_Sym *sym;
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unsigned long *location;
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unsigned long 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 */
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sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
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+ ELF64_R_SYM(rela[i].r_info);
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DEBUGP("RELOC at %p: %li-type as %s (%lu) + %li\n",
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location, (long)ELF64_R_TYPE(rela[i].r_info),
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strtab + sym->st_name, (unsigned long)sym->st_value,
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(long)rela[i].r_addend);
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/* `Everything is relative'. */
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value = sym->st_value + rela[i].r_addend;
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switch (ELF64_R_TYPE(rela[i].r_info)) {
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case R_PPC64_ADDR32:
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/* Simply set it */
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*(u32 *)location = value;
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break;
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case R_PPC64_ADDR64:
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/* Simply set it */
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*(unsigned long *)location = value;
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break;
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case R_PPC64_TOC:
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*(unsigned long *)location = my_r2(sechdrs, me);
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break;
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case R_PPC64_TOC16:
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/* Subtract TOC pointer */
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value -= my_r2(sechdrs, me);
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if (value + 0x8000 > 0xffff) {
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printk("%s: bad TOC16 relocation (%lu)\n",
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me->name, value);
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return -ENOEXEC;
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}
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*((uint16_t *) location)
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= (*((uint16_t *) location) & ~0xffff)
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| (value & 0xffff);
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break;
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case R_PPC64_TOC16_DS:
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/* Subtract TOC pointer */
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value -= my_r2(sechdrs, me);
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if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
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printk("%s: bad TOC16_DS relocation (%lu)\n",
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me->name, value);
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return -ENOEXEC;
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}
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*((uint16_t *) location)
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= (*((uint16_t *) location) & ~0xfffc)
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| (value & 0xfffc);
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break;
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case R_PPC_REL24:
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/* FIXME: Handle weak symbols here --RR */
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if (sym->st_shndx == SHN_UNDEF) {
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/* External: go via stub */
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value = stub_for_addr(sechdrs, value, me);
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if (!value)
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return -ENOENT;
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if (!restore_r2((u32 *)location + 1, me))
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return -ENOEXEC;
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}
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/* Convert value to relative */
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value -= (unsigned long)location;
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if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
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printk("%s: REL24 %li out of range!\n",
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me->name, (long int)value);
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return -ENOEXEC;
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}
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/* Only replace bits 2 through 26 */
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*(uint32_t *)location
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= (*(uint32_t *)location & ~0x03fffffc)
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| (value & 0x03fffffc);
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break;
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default:
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printk("%s: Unknown ADD relocation: %lu\n",
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me->name,
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(unsigned long)ELF64_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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LIST_HEAD(module_bug_list);
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int module_finalize(const Elf_Ehdr *hdr,
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const Elf_Shdr *sechdrs, 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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