1 /* Kernel module help for PPC64.
2 Copyright (C) 2001, 2003 Rusty Russell IBM Corporation.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 #include <linux/module.h>
19 #include <linux/elf.h>
20 #include <linux/moduleloader.h>
21 #include <linux/err.h>
22 #include <linux/vmalloc.h>
23 #include <asm/module.h>
24 #include <asm/uaccess.h>
26 /* FIXME: We don't do .init separately. To do this, we'd need to have
27 a separate r2 value in the init and core section, and stub between
30 Using a magic allocator which places modules within 32MB solves
31 this, and makes other things simpler. Anton?
36 #define DEBUGP(fmt , ...)
39 /* There's actually a third entry here, but it's unused */
40 struct ppc64_opd_entry
42 unsigned long funcaddr;
46 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
47 the kernel itself). But on PPC64, these need to be used for every
48 jump, actually, to reset r2 (TOC+0x8000). */
49 struct ppc64_stub_entry
51 /* 28 byte jump instruction sequence (7 instructions) */
52 unsigned char jump[28];
53 unsigned char unused[4];
54 /* Data for the above code */
55 struct ppc64_opd_entry opd;
58 /* We use a stub to fix up r2 (TOC ptr) and to jump to the (external)
59 function which may be more than 24-bits away. We could simply
60 patch the new r2 value and function pointer into the stub, but it's
61 significantly shorter to put these values at the end of the stub
62 code, and patch the stub address (32-bits relative to the TOC ptr,
64 static struct ppc64_stub_entry ppc64_stub =
66 0x3d, 0x82, 0x00, 0x00, /* addis r12,r2, <high> */
67 0x39, 0x8c, 0x00, 0x00, /* addi r12,r12, <low> */
68 /* Save current r2 value in magic place on the stack. */
69 0xf8, 0x41, 0x00, 0x28, /* std r2,40(r1) */
70 0xe9, 0x6c, 0x00, 0x20, /* ld r11,32(r12) */
71 0xe8, 0x4c, 0x00, 0x28, /* ld r2,40(r12) */
72 0x7d, 0x69, 0x03, 0xa6, /* mtctr r11 */
73 0x4e, 0x80, 0x04, 0x20 /* bctr */
76 /* Count how many different 24-bit relocations (different symbol,
78 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
80 unsigned int i, j, ret = 0;
82 /* FIXME: Only count external ones --RR */
83 /* Sure, this is order(n^2), but it's usually short, and not
85 for (i = 0; i < num; i++) {
86 /* Only count 24-bit relocs, others don't need stubs */
87 if (ELF64_R_TYPE(rela[i].r_info) != R_PPC_REL24)
89 for (j = 0; j < i; j++) {
90 /* If this addend appeared before, it's
91 already been counted */
92 if (rela[i].r_info == rela[j].r_info
93 && rela[i].r_addend == rela[j].r_addend)
101 void *module_alloc(unsigned long size)
105 return vmalloc(size);
108 /* Free memory returned from module_alloc */
109 void module_free(struct module *mod, void *module_region)
111 vfree(module_region);
112 /* FIXME: If module_region == mod->init_region, trim exception
116 /* Get size of potential trampolines required. */
117 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
118 const Elf64_Shdr *sechdrs)
120 /* One extra reloc so it's always 0-funcaddr terminated */
121 unsigned long relocs = 1;
124 /* Every relocated section... */
125 for (i = 1; i < hdr->e_shnum; i++) {
126 if (sechdrs[i].sh_type == SHT_RELA) {
127 DEBUGP("Found relocations in section %u\n", i);
128 DEBUGP("Ptr: %p. Number: %lu\n",
129 (void *)sechdrs[i].sh_addr,
130 sechdrs[i].sh_size / sizeof(Elf64_Rela));
131 relocs += count_relocs((void *)sechdrs[i].sh_addr,
133 / sizeof(Elf64_Rela));
137 DEBUGP("Looks like a total of %lu stubs, max\n", relocs);
138 return relocs * sizeof(struct ppc64_stub_entry);
141 /* Undefined symbols which refer to .funcname, hack to funcname */
142 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
146 for (i = 1; i < numsyms; i++) {
147 if (syms[i].st_shndx == SHN_UNDEF) {
148 char *name = strtab + syms[i].st_name;
150 memmove(name, name+1, strlen(name));
155 int module_frob_arch_sections(Elf64_Ehdr *hdr,
162 /* Find .toc and .stubs sections, symtab and strtab */
163 for (i = 1; i < hdr->e_shnum; i++) {
165 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
166 me->arch.stubs_section = i;
167 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0)
168 me->arch.toc_section = i;
170 /* We don't handle .init for the moment: rename to _init */
171 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
174 if (sechdrs[i].sh_type == SHT_SYMTAB)
175 dedotify((void *)hdr + sechdrs[i].sh_offset,
176 sechdrs[i].sh_size / sizeof(Elf64_Sym),
178 + sechdrs[sechdrs[i].sh_link].sh_offset);
180 if (!me->arch.stubs_section || !me->arch.toc_section) {
181 printk("%s: doesn't contain .toc or .stubs.\n", me->name);
185 /* Override the stubs size */
186 sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
190 int apply_relocate(Elf64_Shdr *sechdrs,
192 unsigned int symindex,
196 printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n", me->name);
200 /* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this
201 gives the value maximum span in an instruction which uses a signed
203 static inline unsigned long my_r2(Elf64_Shdr *sechdrs, struct module *me)
205 return sechdrs[me->arch.toc_section].sh_addr + 0x8000;
208 /* Both low and high 16 bits are added as SIGNED additions, so if low
209 16 bits has high bit set, high 16 bits must be adjusted. These
210 macros do that (stolen from binutils). */
211 #define PPC_LO(v) ((v) & 0xffff)
212 #define PPC_HI(v) (((v) >> 16) & 0xffff)
213 #define PPC_HA(v) PPC_HI ((v) + 0x8000)
215 /* Patch stub to reference function and correct r2 value. */
216 static inline int create_stub(Elf64_Shdr *sechdrs,
217 struct ppc64_stub_entry *entry,
218 struct ppc64_opd_entry *opd,
221 Elf64_Half *loc1, *loc2;
226 loc1 = (Elf64_Half *)&entry->jump[2];
227 loc2 = (Elf64_Half *)&entry->jump[6];
229 /* Stub uses address relative to r2. */
230 reladdr = (unsigned long)entry - my_r2(sechdrs, me);
231 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
232 printk("%s: Address %p of stub out of range of %p.\n",
233 me->name, (void *)reladdr, (void *)my_r2);
236 DEBUGP("Stub %p get data from reladdr %li\n", entry, reladdr);
238 *loc1 = PPC_HA(reladdr);
239 *loc2 = PPC_LO(reladdr);
240 entry->opd.funcaddr = opd->funcaddr;
241 entry->opd.r2 = opd->r2;
245 /* Create stub to jump to function described in this OPD: we need the
246 stub to set up the TOC ptr (r2) for the function. */
247 static unsigned long stub_for_addr(Elf64_Shdr *sechdrs,
248 unsigned long opdaddr,
251 struct ppc64_stub_entry *stubs;
252 struct ppc64_opd_entry *opd = (void *)opdaddr;
253 unsigned int i, num_stubs;
255 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
257 /* Find this stub, or if that fails, the next avail. entry */
258 stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
259 for (i = 0; stubs[i].opd.funcaddr; i++) {
260 BUG_ON(i >= num_stubs);
262 if (stubs[i].opd.funcaddr == opd->funcaddr)
263 return (unsigned long)&stubs[i];
266 if (!create_stub(sechdrs, &stubs[i], opd, me))
269 return (unsigned long)&stubs[i];
272 /* We expect a noop next: if it is, replace it with instruction to
274 static int restore_r2(u32 *instruction, struct module *me)
276 if (*instruction != 0x60000000) {
277 printk("%s: Expect noop after relocate, got %08x\n",
278 me->name, *instruction);
281 *instruction = 0xe8410028; /* ld r2,40(r1) */
285 int apply_relocate_add(Elf64_Shdr *sechdrs,
287 unsigned int symindex,
292 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
294 unsigned long *location;
297 DEBUGP("Applying ADD relocate section %u to %u\n", relsec,
298 sechdrs[relsec].sh_info);
299 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
300 /* This is where to make the change */
301 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
303 /* This is the symbol it is referring to */
304 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
305 + ELF64_R_SYM(rela[i].r_info);
307 DEBUGP("RELOC at %p: %li-type as %s (%lu) + %li\n",
308 location, (long)ELF64_R_TYPE(rela[i].r_info),
309 strtab + sym->st_name, (unsigned long)sym->st_value,
310 (long)rela[i].r_addend);
312 /* `Everything is relative'. */
313 value = sym->st_value + rela[i].r_addend;
315 switch (ELF64_R_TYPE(rela[i].r_info)) {
318 *(u32 *)location = value;
323 *(unsigned long *)location = value;
327 *(unsigned long *)location = my_r2(sechdrs, me);
330 case R_PPC64_TOC16_DS:
331 /* Subtact TOC pointer */
332 value -= my_r2(sechdrs, me);
333 if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
334 printk("%s: bad TOC16_DS relocation (%lu)\n",
338 *((uint16_t *) location)
339 = (*((uint16_t *) location) & ~0xfffc)
344 /* FIXME: Handle weak symbols here --RR */
345 if (sym->st_shndx == SHN_UNDEF) {
346 /* External: go via stub */
347 value = stub_for_addr(sechdrs, value, me);
350 if (!restore_r2((u32 *)location + 1, me))
354 /* Convert value to relative */
355 value -= (unsigned long)location;
356 if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
357 printk("%s: REL24 %li out of range!\n",
358 me->name, (long int)value);
362 /* Only replace bits 2 through 26 */
363 *(uint32_t *)location
364 = (*(uint32_t *)location & ~0x03fffffc)
365 | (value & 0x03fffffc);
369 printk("%s: Unknown ADD relocation: %lu\n",
371 (unsigned long)ELF64_R_TYPE(rela[i].r_info));
379 LIST_HEAD(module_bug_list);
381 int module_finalize(const Elf_Ehdr *hdr,
382 const Elf_Shdr *sechdrs, struct module *me)
387 me->arch.bug_table = NULL;
388 me->arch.num_bugs = 0;
390 /* Find the __bug_table section, if present */
391 secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
392 for (i = 1; i < hdr->e_shnum; i++) {
393 if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table"))
395 me->arch.bug_table = (void *) sechdrs[i].sh_addr;
396 me->arch.num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);
401 * Strictly speaking this should have a spinlock to protect against
402 * traversals, but since we only traverse on BUG()s, a spinlock
403 * could potentially lead to deadlock and thus be counter-productive.
405 list_add(&me->arch.bug_list, &module_bug_list);
410 void module_arch_cleanup(struct module *mod)
412 list_del(&mod->arch.bug_list);
415 struct bug_entry *module_find_bug(unsigned long bugaddr)
417 struct mod_arch_specific *mod;
419 struct bug_entry *bug;
421 list_for_each_entry(mod, &module_bug_list, bug_list) {
422 bug = mod->bug_table;
423 for (i = 0; i < mod->num_bugs; ++i, ++bug)
424 if (bugaddr == bug->bug_addr)