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 <linux/ftrace.h>
24 #include <linux/bug.h>
25 #include <asm/module.h>
26 #include <asm/firmware.h>
27 #include <asm/code-patching.h>
28 #include <linux/sort.h>
29 #include <asm/setup.h>
31 /* FIXME: We don't do .init separately. To do this, we'd need to have
32 a separate r2 value in the init and core section, and stub between
35 Using a magic allocator which places modules within 32MB solves
36 this, and makes other things simpler. Anton?
41 #define DEBUGP(fmt , ...)
44 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
45 the kernel itself). But on PPC64, these need to be used for every
46 jump, actually, to reset r2 (TOC+0x8000). */
47 struct ppc64_stub_entry
49 /* 28 byte jump instruction sequence (7 instructions) */
52 /* Data for the above code */
53 struct ppc64_opd_entry opd;
56 /* We use a stub to fix up r2 (TOC ptr) and to jump to the (external)
57 function which may be more than 24-bits away. We could simply
58 patch the new r2 value and function pointer into the stub, but it's
59 significantly shorter to put these values at the end of the stub
60 code, and patch the stub address (32-bits relative to the TOC ptr,
62 static struct ppc64_stub_entry ppc64_stub =
64 0x3d820000, /* addis r12,r2, <high> */
65 0x398c0000, /* addi r12,r12, <low> */
66 /* Save current r2 value in magic place on the stack. */
67 0xf8410028, /* std r2,40(r1) */
68 0xe96c0020, /* ld r11,32(r12) */
69 0xe84c0028, /* ld r2,40(r12) */
70 0x7d6903a6, /* mtctr r11 */
74 /* Count how many different 24-bit relocations (different symbol,
76 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
78 unsigned int i, r_info, r_addend, _count_relocs;
80 /* FIXME: Only count external ones --RR */
84 for (i = 0; i < num; i++)
85 /* Only count 24-bit relocs, others don't need stubs */
86 if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
87 (r_info != ELF64_R_SYM(rela[i].r_info) ||
88 r_addend != rela[i].r_addend)) {
90 r_info = ELF64_R_SYM(rela[i].r_info);
91 r_addend = rela[i].r_addend;
97 static int relacmp(const void *_x, const void *_y)
99 const Elf64_Rela *x, *y;
101 y = (Elf64_Rela *)_x;
102 x = (Elf64_Rela *)_y;
104 /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
105 * make the comparison cheaper/faster. It won't affect the sorting or
106 * the counting algorithms' performance
108 if (x->r_info < y->r_info)
110 else if (x->r_info > y->r_info)
112 else if (x->r_addend < y->r_addend)
114 else if (x->r_addend > y->r_addend)
120 static void relaswap(void *_x, void *_y, int size)
122 uint64_t *x, *y, tmp;
128 for (i = 0; i < sizeof(Elf64_Rela) / sizeof(uint64_t); i++) {
135 /* Get size of potential trampolines required. */
136 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
137 const Elf64_Shdr *sechdrs)
139 /* One extra reloc so it's always 0-funcaddr terminated */
140 unsigned long relocs = 1;
143 /* Every relocated section... */
144 for (i = 1; i < hdr->e_shnum; i++) {
145 if (sechdrs[i].sh_type == SHT_RELA) {
146 DEBUGP("Found relocations in section %u\n", i);
147 DEBUGP("Ptr: %p. Number: %lu\n",
148 (void *)sechdrs[i].sh_addr,
149 sechdrs[i].sh_size / sizeof(Elf64_Rela));
151 /* Sort the relocation information based on a symbol and
152 * addend key. This is a stable O(n*log n) complexity
153 * alogrithm but it will reduce the complexity of
154 * count_relocs() to linear complexity O(n)
156 sort((void *)sechdrs[i].sh_addr,
157 sechdrs[i].sh_size / sizeof(Elf64_Rela),
158 sizeof(Elf64_Rela), relacmp, relaswap);
160 relocs += count_relocs((void *)sechdrs[i].sh_addr,
162 / sizeof(Elf64_Rela));
166 #ifdef CONFIG_DYNAMIC_FTRACE
167 /* make the trampoline to the ftrace_caller */
171 DEBUGP("Looks like a total of %lu stubs, max\n", relocs);
172 return relocs * sizeof(struct ppc64_stub_entry);
175 static void dedotify_versions(struct modversion_info *vers,
178 struct modversion_info *end;
180 for (end = (void *)vers + size; vers < end; vers++)
181 if (vers->name[0] == '.')
182 memmove(vers->name, vers->name+1, strlen(vers->name));
185 /* Undefined symbols which refer to .funcname, hack to funcname */
186 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
190 for (i = 1; i < numsyms; i++) {
191 if (syms[i].st_shndx == SHN_UNDEF) {
192 char *name = strtab + syms[i].st_name;
194 memmove(name, name+1, strlen(name));
199 int module_frob_arch_sections(Elf64_Ehdr *hdr,
206 /* Find .toc and .stubs sections, symtab and strtab */
207 for (i = 1; i < hdr->e_shnum; i++) {
209 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
210 me->arch.stubs_section = i;
211 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0)
212 me->arch.toc_section = i;
213 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
214 dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
217 /* We don't handle .init for the moment: rename to _init */
218 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
221 if (sechdrs[i].sh_type == SHT_SYMTAB)
222 dedotify((void *)hdr + sechdrs[i].sh_offset,
223 sechdrs[i].sh_size / sizeof(Elf64_Sym),
225 + sechdrs[sechdrs[i].sh_link].sh_offset);
228 if (!me->arch.stubs_section) {
229 printk("%s: doesn't contain .stubs.\n", me->name);
233 /* If we don't have a .toc, just use .stubs. We need to set r2
234 to some reasonable value in case the module calls out to
235 other functions via a stub, or if a function pointer escapes
236 the module by some means. */
237 if (!me->arch.toc_section)
238 me->arch.toc_section = me->arch.stubs_section;
240 /* Override the stubs size */
241 sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
245 /* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this
246 gives the value maximum span in an instruction which uses a signed
248 static inline unsigned long my_r2(Elf64_Shdr *sechdrs, struct module *me)
250 return sechdrs[me->arch.toc_section].sh_addr + 0x8000;
253 /* Both low and high 16 bits are added as SIGNED additions, so if low
254 16 bits has high bit set, high 16 bits must be adjusted. These
255 macros do that (stolen from binutils). */
256 #define PPC_LO(v) ((v) & 0xffff)
257 #define PPC_HI(v) (((v) >> 16) & 0xffff)
258 #define PPC_HA(v) PPC_HI ((v) + 0x8000)
260 /* Patch stub to reference function and correct r2 value. */
261 static inline int create_stub(Elf64_Shdr *sechdrs,
262 struct ppc64_stub_entry *entry,
263 struct ppc64_opd_entry *opd,
270 /* Stub uses address relative to r2. */
271 reladdr = (unsigned long)entry - my_r2(sechdrs, me);
272 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
273 printk("%s: Address %p of stub out of range of %p.\n",
274 me->name, (void *)reladdr, (void *)my_r2);
277 DEBUGP("Stub %p get data from reladdr %li\n", entry, reladdr);
279 entry->jump[0] |= PPC_HA(reladdr);
280 entry->jump[1] |= PPC_LO(reladdr);
281 entry->opd.funcaddr = opd->funcaddr;
282 entry->opd.r2 = opd->r2;
286 /* Create stub to jump to function described in this OPD: we need the
287 stub to set up the TOC ptr (r2) for the function. */
288 static unsigned long stub_for_addr(Elf64_Shdr *sechdrs,
289 unsigned long opdaddr,
292 struct ppc64_stub_entry *stubs;
293 struct ppc64_opd_entry *opd = (void *)opdaddr;
294 unsigned int i, num_stubs;
296 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
298 /* Find this stub, or if that fails, the next avail. entry */
299 stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
300 for (i = 0; stubs[i].opd.funcaddr; i++) {
301 BUG_ON(i >= num_stubs);
303 if (stubs[i].opd.funcaddr == opd->funcaddr)
304 return (unsigned long)&stubs[i];
307 if (!create_stub(sechdrs, &stubs[i], opd, me))
310 return (unsigned long)&stubs[i];
313 /* We expect a noop next: if it is, replace it with instruction to
315 static int restore_r2(u32 *instruction, struct module *me)
317 if (*instruction != PPC_INST_NOP) {
318 printk("%s: Expect noop after relocate, got %08x\n",
319 me->name, *instruction);
322 *instruction = 0xe8410028; /* ld r2,40(r1) */
326 int apply_relocate_add(Elf64_Shdr *sechdrs,
328 unsigned int symindex,
333 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
335 unsigned long *location;
338 DEBUGP("Applying ADD relocate section %u to %u\n", relsec,
339 sechdrs[relsec].sh_info);
340 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
341 /* This is where to make the change */
342 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
344 /* This is the symbol it is referring to */
345 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
346 + ELF64_R_SYM(rela[i].r_info);
348 DEBUGP("RELOC at %p: %li-type as %s (%lu) + %li\n",
349 location, (long)ELF64_R_TYPE(rela[i].r_info),
350 strtab + sym->st_name, (unsigned long)sym->st_value,
351 (long)rela[i].r_addend);
353 /* `Everything is relative'. */
354 value = sym->st_value + rela[i].r_addend;
356 switch (ELF64_R_TYPE(rela[i].r_info)) {
359 *(u32 *)location = value;
364 *(unsigned long *)location = value;
368 *(unsigned long *)location = my_r2(sechdrs, me);
372 /* Subtract TOC pointer */
373 value -= my_r2(sechdrs, me);
374 if (value + 0x8000 > 0xffff) {
375 printk("%s: bad TOC16 relocation (%lu)\n",
379 *((uint16_t *) location)
380 = (*((uint16_t *) location) & ~0xffff)
384 case R_PPC64_TOC16_LO:
385 /* Subtract TOC pointer */
386 value -= my_r2(sechdrs, me);
387 *((uint16_t *) location)
388 = (*((uint16_t *) location) & ~0xffff)
392 case R_PPC64_TOC16_DS:
393 /* Subtract TOC pointer */
394 value -= my_r2(sechdrs, me);
395 if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
396 printk("%s: bad TOC16_DS relocation (%lu)\n",
400 *((uint16_t *) location)
401 = (*((uint16_t *) location) & ~0xfffc)
405 case R_PPC64_TOC16_LO_DS:
406 /* Subtract TOC pointer */
407 value -= my_r2(sechdrs, me);
408 if ((value & 3) != 0) {
409 printk("%s: bad TOC16_LO_DS relocation (%lu)\n",
413 *((uint16_t *) location)
414 = (*((uint16_t *) location) & ~0xfffc)
418 case R_PPC64_TOC16_HA:
419 /* Subtract TOC pointer */
420 value -= my_r2(sechdrs, me);
421 value = ((value + 0x8000) >> 16);
422 *((uint16_t *) location)
423 = (*((uint16_t *) location) & ~0xffff)
428 /* FIXME: Handle weak symbols here --RR */
429 if (sym->st_shndx == SHN_UNDEF) {
430 /* External: go via stub */
431 value = stub_for_addr(sechdrs, value, me);
434 if (!restore_r2((u32 *)location + 1, me))
438 /* Convert value to relative */
439 value -= (unsigned long)location;
440 if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
441 printk("%s: REL24 %li out of range!\n",
442 me->name, (long int)value);
446 /* Only replace bits 2 through 26 */
447 *(uint32_t *)location
448 = (*(uint32_t *)location & ~0x03fffffc)
449 | (value & 0x03fffffc);
453 /* 64 bits relative (used by features fixups) */
454 *location = value - (unsigned long)location;
457 case R_PPC64_TOCSAVE:
459 * Marker reloc indicates we don't have to save r2.
460 * That would only save us one instruction, so ignore
466 printk("%s: Unknown ADD relocation: %lu\n",
468 (unsigned long)ELF64_R_TYPE(rela[i].r_info));
473 #ifdef CONFIG_DYNAMIC_FTRACE
474 me->arch.toc = my_r2(sechdrs, me);
475 me->arch.tramp = stub_for_addr(sechdrs,
476 (unsigned long)ftrace_caller,