1 /* Kernel module help for PPC64.
2 Copyright (C) 2001, 2003 Rusty Russell IBM Corporation.
3
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.
8
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.
13
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
17 */
18
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21 #include <linux/module.h>
22 #include <linux/elf.h>
23 #include <linux/moduleloader.h>
24 #include <linux/err.h>
25 #include <linux/vmalloc.h>
26 #include <linux/ftrace.h>
27 #include <linux/bug.h>
28 #include <linux/uaccess.h>
29 #include <asm/module.h>
30 #include <asm/firmware.h>
31 #include <asm/code-patching.h>
32 #include <linux/sort.h>
33 #include <asm/setup.h>
34 #include <asm/sections.h>
35
36 /* FIXME: We don't do .init separately. To do this, we'd need to have
37 a separate r2 value in the init and core section, and stub between
38 them, too.
39
40 Using a magic allocator which places modules within 32MB solves
41 this, and makes other things simpler. Anton?
42 --RR. */
43
44 #ifdef PPC64_ELF_ABI_v2
45
46 /* An address is simply the address of the function. */
47 typedef unsigned long func_desc_t;
48
func_desc(unsigned long addr)49 static func_desc_t func_desc(unsigned long addr)
50 {
51 return addr;
52 }
func_addr(unsigned long addr)53 static unsigned long func_addr(unsigned long addr)
54 {
55 return addr;
56 }
stub_func_addr(func_desc_t func)57 static unsigned long stub_func_addr(func_desc_t func)
58 {
59 return func;
60 }
61
62 /* PowerPC64 specific values for the Elf64_Sym st_other field. */
63 #define STO_PPC64_LOCAL_BIT 5
64 #define STO_PPC64_LOCAL_MASK (7 << STO_PPC64_LOCAL_BIT)
65 #define PPC64_LOCAL_ENTRY_OFFSET(other) \
66 (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
67
local_entry_offset(const Elf64_Sym * sym)68 static unsigned int local_entry_offset(const Elf64_Sym *sym)
69 {
70 /* sym->st_other indicates offset to local entry point
71 * (otherwise it will assume r12 is the address of the start
72 * of function and try to derive r2 from it). */
73 return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
74 }
75 #else
76
77 /* An address is address of the OPD entry, which contains address of fn. */
78 typedef struct ppc64_opd_entry func_desc_t;
79
func_desc(unsigned long addr)80 static func_desc_t func_desc(unsigned long addr)
81 {
82 return *(struct ppc64_opd_entry *)addr;
83 }
func_addr(unsigned long addr)84 static unsigned long func_addr(unsigned long addr)
85 {
86 return func_desc(addr).funcaddr;
87 }
stub_func_addr(func_desc_t func)88 static unsigned long stub_func_addr(func_desc_t func)
89 {
90 return func.funcaddr;
91 }
local_entry_offset(const Elf64_Sym * sym)92 static unsigned int local_entry_offset(const Elf64_Sym *sym)
93 {
94 return 0;
95 }
96 #endif
97
98 #define STUB_MAGIC 0x73747562 /* stub */
99
100 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
101 the kernel itself). But on PPC64, these need to be used for every
102 jump, actually, to reset r2 (TOC+0x8000). */
103 struct ppc64_stub_entry
104 {
105 /* 28 byte jump instruction sequence (7 instructions). We only
106 * need 6 instructions on ABIv2 but we always allocate 7 so
107 * so we don't have to modify the trampoline load instruction. */
108 u32 jump[7];
109 /* Used by ftrace to identify stubs */
110 u32 magic;
111 /* Data for the above code */
112 func_desc_t funcdata;
113 };
114
115 /*
116 * PPC64 uses 24 bit jumps, but we need to jump into other modules or
117 * the kernel which may be further. So we jump to a stub.
118 *
119 * For ELFv1 we need to use this to set up the new r2 value (aka TOC
120 * pointer). For ELFv2 it's the callee's responsibility to set up the
121 * new r2, but for both we need to save the old r2.
122 *
123 * We could simply patch the new r2 value and function pointer into
124 * the stub, but it's significantly shorter to put these values at the
125 * end of the stub code, and patch the stub address (32-bits relative
126 * to the TOC ptr, r2) into the stub.
127 */
128
129 static u32 ppc64_stub_insns[] = {
130 0x3d620000, /* addis r11,r2, <high> */
131 0x396b0000, /* addi r11,r11, <low> */
132 /* Save current r2 value in magic place on the stack. */
133 0xf8410000|R2_STACK_OFFSET, /* std r2,R2_STACK_OFFSET(r1) */
134 0xe98b0020, /* ld r12,32(r11) */
135 #ifdef PPC64_ELF_ABI_v1
136 /* Set up new r2 from function descriptor */
137 0xe84b0028, /* ld r2,40(r11) */
138 #endif
139 0x7d8903a6, /* mtctr r12 */
140 0x4e800420 /* bctr */
141 };
142
143 #ifdef CONFIG_DYNAMIC_FTRACE
module_trampoline_target(struct module * mod,unsigned long addr,unsigned long * target)144 int module_trampoline_target(struct module *mod, unsigned long addr,
145 unsigned long *target)
146 {
147 struct ppc64_stub_entry *stub;
148 func_desc_t funcdata;
149 u32 magic;
150
151 if (!within_module_core(addr, mod)) {
152 pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name);
153 return -EFAULT;
154 }
155
156 stub = (struct ppc64_stub_entry *)addr;
157
158 if (probe_kernel_read(&magic, &stub->magic, sizeof(magic))) {
159 pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
160 return -EFAULT;
161 }
162
163 if (magic != STUB_MAGIC) {
164 pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name);
165 return -EFAULT;
166 }
167
168 if (probe_kernel_read(&funcdata, &stub->funcdata, sizeof(funcdata))) {
169 pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
170 return -EFAULT;
171 }
172
173 *target = stub_func_addr(funcdata);
174
175 return 0;
176 }
177 #endif
178
179 /* Count how many different 24-bit relocations (different symbol,
180 different addend) */
count_relocs(const Elf64_Rela * rela,unsigned int num)181 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
182 {
183 unsigned int i, r_info, r_addend, _count_relocs;
184
185 /* FIXME: Only count external ones --RR */
186 _count_relocs = 0;
187 r_info = 0;
188 r_addend = 0;
189 for (i = 0; i < num; i++)
190 /* Only count 24-bit relocs, others don't need stubs */
191 if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
192 (r_info != ELF64_R_SYM(rela[i].r_info) ||
193 r_addend != rela[i].r_addend)) {
194 _count_relocs++;
195 r_info = ELF64_R_SYM(rela[i].r_info);
196 r_addend = rela[i].r_addend;
197 }
198
199 return _count_relocs;
200 }
201
relacmp(const void * _x,const void * _y)202 static int relacmp(const void *_x, const void *_y)
203 {
204 const Elf64_Rela *x, *y;
205
206 y = (Elf64_Rela *)_x;
207 x = (Elf64_Rela *)_y;
208
209 /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
210 * make the comparison cheaper/faster. It won't affect the sorting or
211 * the counting algorithms' performance
212 */
213 if (x->r_info < y->r_info)
214 return -1;
215 else if (x->r_info > y->r_info)
216 return 1;
217 else if (x->r_addend < y->r_addend)
218 return -1;
219 else if (x->r_addend > y->r_addend)
220 return 1;
221 else
222 return 0;
223 }
224
relaswap(void * _x,void * _y,int size)225 static void relaswap(void *_x, void *_y, int size)
226 {
227 uint64_t *x, *y, tmp;
228 int i;
229
230 y = (uint64_t *)_x;
231 x = (uint64_t *)_y;
232
233 for (i = 0; i < sizeof(Elf64_Rela) / sizeof(uint64_t); i++) {
234 tmp = x[i];
235 x[i] = y[i];
236 y[i] = tmp;
237 }
238 }
239
240 /* Get size of potential trampolines required. */
get_stubs_size(const Elf64_Ehdr * hdr,const Elf64_Shdr * sechdrs)241 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
242 const Elf64_Shdr *sechdrs)
243 {
244 /* One extra reloc so it's always 0-funcaddr terminated */
245 unsigned long relocs = 1;
246 unsigned i;
247
248 /* Every relocated section... */
249 for (i = 1; i < hdr->e_shnum; i++) {
250 if (sechdrs[i].sh_type == SHT_RELA) {
251 pr_debug("Found relocations in section %u\n", i);
252 pr_debug("Ptr: %p. Number: %Lu\n",
253 (void *)sechdrs[i].sh_addr,
254 sechdrs[i].sh_size / sizeof(Elf64_Rela));
255
256 /* Sort the relocation information based on a symbol and
257 * addend key. This is a stable O(n*log n) complexity
258 * alogrithm but it will reduce the complexity of
259 * count_relocs() to linear complexity O(n)
260 */
261 sort((void *)sechdrs[i].sh_addr,
262 sechdrs[i].sh_size / sizeof(Elf64_Rela),
263 sizeof(Elf64_Rela), relacmp, relaswap);
264
265 relocs += count_relocs((void *)sechdrs[i].sh_addr,
266 sechdrs[i].sh_size
267 / sizeof(Elf64_Rela));
268 }
269 }
270
271 #ifdef CONFIG_DYNAMIC_FTRACE
272 /* make the trampoline to the ftrace_caller */
273 relocs++;
274 #endif
275
276 pr_debug("Looks like a total of %lu stubs, max\n", relocs);
277 return relocs * sizeof(struct ppc64_stub_entry);
278 }
279
280 /* Still needed for ELFv2, for .TOC. */
dedotify_versions(struct modversion_info * vers,unsigned long size)281 static void dedotify_versions(struct modversion_info *vers,
282 unsigned long size)
283 {
284 struct modversion_info *end;
285
286 for (end = (void *)vers + size; vers < end; vers++)
287 if (vers->name[0] == '.') {
288 memmove(vers->name, vers->name+1, strlen(vers->name));
289 }
290 }
291
292 /*
293 * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
294 * seem to be defined (value set later).
295 */
dedotify(Elf64_Sym * syms,unsigned int numsyms,char * strtab)296 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
297 {
298 unsigned int i;
299
300 for (i = 1; i < numsyms; i++) {
301 if (syms[i].st_shndx == SHN_UNDEF) {
302 char *name = strtab + syms[i].st_name;
303 if (name[0] == '.') {
304 if (strcmp(name+1, "TOC.") == 0)
305 syms[i].st_shndx = SHN_ABS;
306 syms[i].st_name++;
307 }
308 }
309 }
310 }
311
find_dot_toc(Elf64_Shdr * sechdrs,const char * strtab,unsigned int symindex)312 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
313 const char *strtab,
314 unsigned int symindex)
315 {
316 unsigned int i, numsyms;
317 Elf64_Sym *syms;
318
319 syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
320 numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
321
322 for (i = 1; i < numsyms; i++) {
323 if (syms[i].st_shndx == SHN_ABS
324 && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
325 return &syms[i];
326 }
327 return NULL;
328 }
329
module_frob_arch_sections(Elf64_Ehdr * hdr,Elf64_Shdr * sechdrs,char * secstrings,struct module * me)330 int module_frob_arch_sections(Elf64_Ehdr *hdr,
331 Elf64_Shdr *sechdrs,
332 char *secstrings,
333 struct module *me)
334 {
335 unsigned int i;
336
337 /* Find .toc and .stubs sections, symtab and strtab */
338 for (i = 1; i < hdr->e_shnum; i++) {
339 char *p;
340 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
341 me->arch.stubs_section = i;
342 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0)
343 me->arch.toc_section = i;
344 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
345 dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
346 sechdrs[i].sh_size);
347
348 /* We don't handle .init for the moment: rename to _init */
349 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
350 p[0] = '_';
351
352 if (sechdrs[i].sh_type == SHT_SYMTAB)
353 dedotify((void *)hdr + sechdrs[i].sh_offset,
354 sechdrs[i].sh_size / sizeof(Elf64_Sym),
355 (void *)hdr
356 + sechdrs[sechdrs[i].sh_link].sh_offset);
357 }
358
359 if (!me->arch.stubs_section) {
360 pr_err("%s: doesn't contain .stubs.\n", me->name);
361 return -ENOEXEC;
362 }
363
364 /* If we don't have a .toc, just use .stubs. We need to set r2
365 to some reasonable value in case the module calls out to
366 other functions via a stub, or if a function pointer escapes
367 the module by some means. */
368 if (!me->arch.toc_section)
369 me->arch.toc_section = me->arch.stubs_section;
370
371 /* Override the stubs size */
372 sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
373 return 0;
374 }
375
376 /* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this
377 gives the value maximum span in an instruction which uses a signed
378 offset) */
my_r2(const Elf64_Shdr * sechdrs,struct module * me)379 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
380 {
381 return sechdrs[me->arch.toc_section].sh_addr + 0x8000;
382 }
383
384 /* Both low and high 16 bits are added as SIGNED additions, so if low
385 16 bits has high bit set, high 16 bits must be adjusted. These
386 macros do that (stolen from binutils). */
387 #define PPC_LO(v) ((v) & 0xffff)
388 #define PPC_HI(v) (((v) >> 16) & 0xffff)
389 #define PPC_HA(v) PPC_HI ((v) + 0x8000)
390
391 /* Patch stub to reference function and correct r2 value. */
create_stub(const Elf64_Shdr * sechdrs,struct ppc64_stub_entry * entry,unsigned long addr,struct module * me)392 static inline int create_stub(const Elf64_Shdr *sechdrs,
393 struct ppc64_stub_entry *entry,
394 unsigned long addr,
395 struct module *me)
396 {
397 long reladdr;
398
399 memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns));
400
401 /* Stub uses address relative to r2. */
402 reladdr = (unsigned long)entry - my_r2(sechdrs, me);
403 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
404 pr_err("%s: Address %p of stub out of range of %p.\n",
405 me->name, (void *)reladdr, (void *)my_r2);
406 return 0;
407 }
408 pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
409
410 entry->jump[0] |= PPC_HA(reladdr);
411 entry->jump[1] |= PPC_LO(reladdr);
412 entry->funcdata = func_desc(addr);
413 entry->magic = STUB_MAGIC;
414
415 return 1;
416 }
417
418 /* Create stub to jump to function described in this OPD/ptr: we need the
419 stub to set up the TOC ptr (r2) for the function. */
stub_for_addr(const Elf64_Shdr * sechdrs,unsigned long addr,struct module * me)420 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
421 unsigned long addr,
422 struct module *me)
423 {
424 struct ppc64_stub_entry *stubs;
425 unsigned int i, num_stubs;
426
427 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
428
429 /* Find this stub, or if that fails, the next avail. entry */
430 stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
431 for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
432 BUG_ON(i >= num_stubs);
433
434 if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
435 return (unsigned long)&stubs[i];
436 }
437
438 if (!create_stub(sechdrs, &stubs[i], addr, me))
439 return 0;
440
441 return (unsigned long)&stubs[i];
442 }
443
444 #ifdef CC_USING_MPROFILE_KERNEL
is_early_mcount_callsite(u32 * instruction)445 static bool is_early_mcount_callsite(u32 *instruction)
446 {
447 /*
448 * Check if this is one of the -mprofile-kernel sequences.
449 */
450 if (instruction[-1] == PPC_INST_STD_LR &&
451 instruction[-2] == PPC_INST_MFLR)
452 return true;
453
454 if (instruction[-1] == PPC_INST_MFLR)
455 return true;
456
457 return false;
458 }
459
460 /*
461 * In case of _mcount calls, do not save the current callee's TOC (in r2) into
462 * the original caller's stack frame. If we did we would clobber the saved TOC
463 * value of the original caller.
464 */
squash_toc_save_inst(const char * name,unsigned long addr)465 static void squash_toc_save_inst(const char *name, unsigned long addr)
466 {
467 struct ppc64_stub_entry *stub = (struct ppc64_stub_entry *)addr;
468
469 /* Only for calls to _mcount */
470 if (strcmp("_mcount", name) != 0)
471 return;
472
473 stub->jump[2] = PPC_INST_NOP;
474 }
475 #else
squash_toc_save_inst(const char * name,unsigned long addr)476 static void squash_toc_save_inst(const char *name, unsigned long addr) { }
477
478 /* without -mprofile-kernel, mcount calls are never early */
is_early_mcount_callsite(u32 * instruction)479 static bool is_early_mcount_callsite(u32 *instruction)
480 {
481 return false;
482 }
483 #endif
484
485 /* We expect a noop next: if it is, replace it with instruction to
486 restore r2. */
restore_r2(u32 * instruction,struct module * me)487 static int restore_r2(u32 *instruction, struct module *me)
488 {
489 u32 *prev_insn = instruction - 1;
490
491 if (is_early_mcount_callsite(prev_insn))
492 return 1;
493
494 /*
495 * Make sure the branch isn't a sibling call. Sibling calls aren't
496 * "link" branches and they don't return, so they don't need the r2
497 * restore afterwards.
498 */
499 if (!instr_is_relative_link_branch(*prev_insn))
500 return 1;
501
502 if (*instruction != PPC_INST_NOP) {
503 pr_err("%s: Expect noop after relocate, got %08x\n",
504 me->name, *instruction);
505 return 0;
506 }
507 /* ld r2,R2_STACK_OFFSET(r1) */
508 *instruction = PPC_INST_LD_TOC;
509 return 1;
510 }
511
apply_relocate_add(Elf64_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * me)512 int apply_relocate_add(Elf64_Shdr *sechdrs,
513 const char *strtab,
514 unsigned int symindex,
515 unsigned int relsec,
516 struct module *me)
517 {
518 unsigned int i;
519 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
520 Elf64_Sym *sym;
521 unsigned long *location;
522 unsigned long value;
523
524 pr_debug("Applying ADD relocate section %u to %u\n", relsec,
525 sechdrs[relsec].sh_info);
526
527 /* First time we're called, we can fix up .TOC. */
528 if (!me->arch.toc_fixed) {
529 sym = find_dot_toc(sechdrs, strtab, symindex);
530 /* It's theoretically possible that a module doesn't want a
531 * .TOC. so don't fail it just for that. */
532 if (sym)
533 sym->st_value = my_r2(sechdrs, me);
534 me->arch.toc_fixed = true;
535 }
536
537 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
538 /* This is where to make the change */
539 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
540 + rela[i].r_offset;
541 /* This is the symbol it is referring to */
542 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
543 + ELF64_R_SYM(rela[i].r_info);
544
545 pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
546 location, (long)ELF64_R_TYPE(rela[i].r_info),
547 strtab + sym->st_name, (unsigned long)sym->st_value,
548 (long)rela[i].r_addend);
549
550 /* `Everything is relative'. */
551 value = sym->st_value + rela[i].r_addend;
552
553 switch (ELF64_R_TYPE(rela[i].r_info)) {
554 case R_PPC64_ADDR32:
555 /* Simply set it */
556 *(u32 *)location = value;
557 break;
558
559 case R_PPC64_ADDR64:
560 /* Simply set it */
561 *(unsigned long *)location = value;
562 break;
563
564 case R_PPC64_TOC:
565 *(unsigned long *)location = my_r2(sechdrs, me);
566 break;
567
568 case R_PPC64_TOC16:
569 /* Subtract TOC pointer */
570 value -= my_r2(sechdrs, me);
571 if (value + 0x8000 > 0xffff) {
572 pr_err("%s: bad TOC16 relocation (0x%lx)\n",
573 me->name, value);
574 return -ENOEXEC;
575 }
576 *((uint16_t *) location)
577 = (*((uint16_t *) location) & ~0xffff)
578 | (value & 0xffff);
579 break;
580
581 case R_PPC64_TOC16_LO:
582 /* Subtract TOC pointer */
583 value -= my_r2(sechdrs, me);
584 *((uint16_t *) location)
585 = (*((uint16_t *) location) & ~0xffff)
586 | (value & 0xffff);
587 break;
588
589 case R_PPC64_TOC16_DS:
590 /* Subtract TOC pointer */
591 value -= my_r2(sechdrs, me);
592 if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
593 pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
594 me->name, value);
595 return -ENOEXEC;
596 }
597 *((uint16_t *) location)
598 = (*((uint16_t *) location) & ~0xfffc)
599 | (value & 0xfffc);
600 break;
601
602 case R_PPC64_TOC16_LO_DS:
603 /* Subtract TOC pointer */
604 value -= my_r2(sechdrs, me);
605 if ((value & 3) != 0) {
606 pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
607 me->name, value);
608 return -ENOEXEC;
609 }
610 *((uint16_t *) location)
611 = (*((uint16_t *) location) & ~0xfffc)
612 | (value & 0xfffc);
613 break;
614
615 case R_PPC64_TOC16_HA:
616 /* Subtract TOC pointer */
617 value -= my_r2(sechdrs, me);
618 value = ((value + 0x8000) >> 16);
619 *((uint16_t *) location)
620 = (*((uint16_t *) location) & ~0xffff)
621 | (value & 0xffff);
622 break;
623
624 case R_PPC_REL24:
625 /* FIXME: Handle weak symbols here --RR */
626 if (sym->st_shndx == SHN_UNDEF) {
627 /* External: go via stub */
628 value = stub_for_addr(sechdrs, value, me);
629 if (!value)
630 return -ENOENT;
631 if (!restore_r2((u32 *)location + 1, me))
632 return -ENOEXEC;
633
634 squash_toc_save_inst(strtab + sym->st_name, value);
635 } else
636 value += local_entry_offset(sym);
637
638 /* Convert value to relative */
639 value -= (unsigned long)location;
640 if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
641 pr_err("%s: REL24 %li out of range!\n",
642 me->name, (long int)value);
643 return -ENOEXEC;
644 }
645
646 /* Only replace bits 2 through 26 */
647 *(uint32_t *)location
648 = (*(uint32_t *)location & ~0x03fffffc)
649 | (value & 0x03fffffc);
650 break;
651
652 case R_PPC64_REL64:
653 /* 64 bits relative (used by features fixups) */
654 *location = value - (unsigned long)location;
655 break;
656
657 case R_PPC64_REL32:
658 /* 32 bits relative (used by relative exception tables) */
659 /* Convert value to relative */
660 value -= (unsigned long)location;
661 if (value + 0x80000000 > 0xffffffff) {
662 pr_err("%s: REL32 %li out of range!\n",
663 me->name, (long int)value);
664 return -ENOEXEC;
665 }
666 *(u32 *)location = value;
667 break;
668
669 case R_PPC64_TOCSAVE:
670 /*
671 * Marker reloc indicates we don't have to save r2.
672 * That would only save us one instruction, so ignore
673 * it.
674 */
675 break;
676
677 case R_PPC64_ENTRY:
678 /*
679 * Optimize ELFv2 large code model entry point if
680 * the TOC is within 2GB range of current location.
681 */
682 value = my_r2(sechdrs, me) - (unsigned long)location;
683 if (value + 0x80008000 > 0xffffffff)
684 break;
685 /*
686 * Check for the large code model prolog sequence:
687 * ld r2, ...(r12)
688 * add r2, r2, r12
689 */
690 if ((((uint32_t *)location)[0] & ~0xfffc)
691 != 0xe84c0000)
692 break;
693 if (((uint32_t *)location)[1] != 0x7c426214)
694 break;
695 /*
696 * If found, replace it with:
697 * addis r2, r12, (.TOC.-func)@ha
698 * addi r2, r12, (.TOC.-func)@l
699 */
700 ((uint32_t *)location)[0] = 0x3c4c0000 + PPC_HA(value);
701 ((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value);
702 break;
703
704 case R_PPC64_REL16_HA:
705 /* Subtract location pointer */
706 value -= (unsigned long)location;
707 value = ((value + 0x8000) >> 16);
708 *((uint16_t *) location)
709 = (*((uint16_t *) location) & ~0xffff)
710 | (value & 0xffff);
711 break;
712
713 case R_PPC64_REL16_LO:
714 /* Subtract location pointer */
715 value -= (unsigned long)location;
716 *((uint16_t *) location)
717 = (*((uint16_t *) location) & ~0xffff)
718 | (value & 0xffff);
719 break;
720
721 default:
722 pr_err("%s: Unknown ADD relocation: %lu\n",
723 me->name,
724 (unsigned long)ELF64_R_TYPE(rela[i].r_info));
725 return -ENOEXEC;
726 }
727 }
728
729 return 0;
730 }
731
732 #ifdef CONFIG_DYNAMIC_FTRACE
733
734 #ifdef CC_USING_MPROFILE_KERNEL
735
736 #define PACATOC offsetof(struct paca_struct, kernel_toc)
737
738 /*
739 * For mprofile-kernel we use a special stub for ftrace_caller() because we
740 * can't rely on r2 containing this module's TOC when we enter the stub.
741 *
742 * That can happen if the function calling us didn't need to use the toc. In
743 * that case it won't have setup r2, and the r2 value will be either the
744 * kernel's toc, or possibly another modules toc.
745 *
746 * To deal with that this stub uses the kernel toc, which is always accessible
747 * via the paca (in r13). The target (ftrace_caller()) is responsible for
748 * saving and restoring the toc before returning.
749 */
create_ftrace_stub(const Elf64_Shdr * sechdrs,struct module * me)750 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me)
751 {
752 struct ppc64_stub_entry *entry;
753 unsigned int i, num_stubs;
754 static u32 stub_insns[] = {
755 0xe98d0000 | PACATOC, /* ld r12,PACATOC(r13) */
756 0x3d8c0000, /* addis r12,r12,<high> */
757 0x398c0000, /* addi r12,r12,<low> */
758 0x7d8903a6, /* mtctr r12 */
759 0x4e800420, /* bctr */
760 };
761 long reladdr;
762
763 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*entry);
764
765 /* Find the next available stub entry */
766 entry = (void *)sechdrs[me->arch.stubs_section].sh_addr;
767 for (i = 0; i < num_stubs && stub_func_addr(entry->funcdata); i++, entry++);
768
769 if (i >= num_stubs) {
770 pr_err("%s: Unable to find a free slot for ftrace stub.\n", me->name);
771 return 0;
772 }
773
774 memcpy(entry->jump, stub_insns, sizeof(stub_insns));
775
776 /* Stub uses address relative to kernel toc (from the paca) */
777 reladdr = (unsigned long)ftrace_caller - kernel_toc_addr();
778 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
779 pr_err("%s: Address of ftrace_caller out of range of kernel_toc.\n", me->name);
780 return 0;
781 }
782
783 entry->jump[1] |= PPC_HA(reladdr);
784 entry->jump[2] |= PPC_LO(reladdr);
785
786 /* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */
787 entry->funcdata = func_desc((unsigned long)ftrace_caller);
788 entry->magic = STUB_MAGIC;
789
790 return (unsigned long)entry;
791 }
792 #else
create_ftrace_stub(const Elf64_Shdr * sechdrs,struct module * me)793 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me)
794 {
795 return stub_for_addr(sechdrs, (unsigned long)ftrace_caller, me);
796 }
797 #endif
798
module_finalize_ftrace(struct module * mod,const Elf_Shdr * sechdrs)799 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
800 {
801 mod->arch.toc = my_r2(sechdrs, mod);
802 mod->arch.tramp = create_ftrace_stub(sechdrs, mod);
803
804 if (!mod->arch.tramp)
805 return -ENOENT;
806
807 return 0;
808 }
809 #endif
810