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 #ifdef ARCH_RELOCATES_KCRCTAB
290 /* The TOC symbol has no CRC computed. To avoid CRC
291 * check failing, we must force it to the expected
292 * value (see CRC check in module.c).
293 */
294 if (!strcmp(vers->name, "TOC."))
295 vers->crc = -(unsigned long)reloc_start;
296 #endif
297 }
298 }
299
300 /*
301 * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
302 * seem to be defined (value set later).
303 */
dedotify(Elf64_Sym * syms,unsigned int numsyms,char * strtab)304 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
305 {
306 unsigned int i;
307
308 for (i = 1; i < numsyms; i++) {
309 if (syms[i].st_shndx == SHN_UNDEF) {
310 char *name = strtab + syms[i].st_name;
311 if (name[0] == '.') {
312 if (strcmp(name+1, "TOC.") == 0)
313 syms[i].st_shndx = SHN_ABS;
314 syms[i].st_name++;
315 }
316 }
317 }
318 }
319
find_dot_toc(Elf64_Shdr * sechdrs,const char * strtab,unsigned int symindex)320 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
321 const char *strtab,
322 unsigned int symindex)
323 {
324 unsigned int i, numsyms;
325 Elf64_Sym *syms;
326
327 syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
328 numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
329
330 for (i = 1; i < numsyms; i++) {
331 if (syms[i].st_shndx == SHN_ABS
332 && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
333 return &syms[i];
334 }
335 return NULL;
336 }
337
module_frob_arch_sections(Elf64_Ehdr * hdr,Elf64_Shdr * sechdrs,char * secstrings,struct module * me)338 int module_frob_arch_sections(Elf64_Ehdr *hdr,
339 Elf64_Shdr *sechdrs,
340 char *secstrings,
341 struct module *me)
342 {
343 unsigned int i;
344
345 /* Find .toc and .stubs sections, symtab and strtab */
346 for (i = 1; i < hdr->e_shnum; i++) {
347 char *p;
348 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
349 me->arch.stubs_section = i;
350 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0)
351 me->arch.toc_section = i;
352 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
353 dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
354 sechdrs[i].sh_size);
355
356 /* We don't handle .init for the moment: rename to _init */
357 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
358 p[0] = '_';
359
360 if (sechdrs[i].sh_type == SHT_SYMTAB)
361 dedotify((void *)hdr + sechdrs[i].sh_offset,
362 sechdrs[i].sh_size / sizeof(Elf64_Sym),
363 (void *)hdr
364 + sechdrs[sechdrs[i].sh_link].sh_offset);
365 }
366
367 if (!me->arch.stubs_section) {
368 pr_err("%s: doesn't contain .stubs.\n", me->name);
369 return -ENOEXEC;
370 }
371
372 /* If we don't have a .toc, just use .stubs. We need to set r2
373 to some reasonable value in case the module calls out to
374 other functions via a stub, or if a function pointer escapes
375 the module by some means. */
376 if (!me->arch.toc_section)
377 me->arch.toc_section = me->arch.stubs_section;
378
379 /* Override the stubs size */
380 sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
381 return 0;
382 }
383
384 /* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this
385 gives the value maximum span in an instruction which uses a signed
386 offset) */
my_r2(const Elf64_Shdr * sechdrs,struct module * me)387 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
388 {
389 return sechdrs[me->arch.toc_section].sh_addr + 0x8000;
390 }
391
392 /* Both low and high 16 bits are added as SIGNED additions, so if low
393 16 bits has high bit set, high 16 bits must be adjusted. These
394 macros do that (stolen from binutils). */
395 #define PPC_LO(v) ((v) & 0xffff)
396 #define PPC_HI(v) (((v) >> 16) & 0xffff)
397 #define PPC_HA(v) PPC_HI ((v) + 0x8000)
398
399 /* 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)400 static inline int create_stub(const Elf64_Shdr *sechdrs,
401 struct ppc64_stub_entry *entry,
402 unsigned long addr,
403 struct module *me)
404 {
405 long reladdr;
406
407 memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns));
408
409 /* Stub uses address relative to r2. */
410 reladdr = (unsigned long)entry - my_r2(sechdrs, me);
411 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
412 pr_err("%s: Address %p of stub out of range of %p.\n",
413 me->name, (void *)reladdr, (void *)my_r2);
414 return 0;
415 }
416 pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
417
418 entry->jump[0] |= PPC_HA(reladdr);
419 entry->jump[1] |= PPC_LO(reladdr);
420 entry->funcdata = func_desc(addr);
421 entry->magic = STUB_MAGIC;
422
423 return 1;
424 }
425
426 /* Create stub to jump to function described in this OPD/ptr: we need the
427 stub to set up the TOC ptr (r2) for the function. */
stub_for_addr(const Elf64_Shdr * sechdrs,unsigned long addr,struct module * me)428 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
429 unsigned long addr,
430 struct module *me)
431 {
432 struct ppc64_stub_entry *stubs;
433 unsigned int i, num_stubs;
434
435 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
436
437 /* Find this stub, or if that fails, the next avail. entry */
438 stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
439 for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
440 BUG_ON(i >= num_stubs);
441
442 if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
443 return (unsigned long)&stubs[i];
444 }
445
446 if (!create_stub(sechdrs, &stubs[i], addr, me))
447 return 0;
448
449 return (unsigned long)&stubs[i];
450 }
451
452 #ifdef CC_USING_MPROFILE_KERNEL
is_early_mcount_callsite(u32 * instruction)453 static bool is_early_mcount_callsite(u32 *instruction)
454 {
455 /*
456 * Check if this is one of the -mprofile-kernel sequences.
457 */
458 if (instruction[-1] == PPC_INST_STD_LR &&
459 instruction[-2] == PPC_INST_MFLR)
460 return true;
461
462 if (instruction[-1] == PPC_INST_MFLR)
463 return true;
464
465 return false;
466 }
467
468 /*
469 * In case of _mcount calls, do not save the current callee's TOC (in r2) into
470 * the original caller's stack frame. If we did we would clobber the saved TOC
471 * value of the original caller.
472 */
squash_toc_save_inst(const char * name,unsigned long addr)473 static void squash_toc_save_inst(const char *name, unsigned long addr)
474 {
475 struct ppc64_stub_entry *stub = (struct ppc64_stub_entry *)addr;
476
477 /* Only for calls to _mcount */
478 if (strcmp("_mcount", name) != 0)
479 return;
480
481 stub->jump[2] = PPC_INST_NOP;
482 }
483 #else
squash_toc_save_inst(const char * name,unsigned long addr)484 static void squash_toc_save_inst(const char *name, unsigned long addr) { }
485
486 /* without -mprofile-kernel, mcount calls are never early */
is_early_mcount_callsite(u32 * instruction)487 static bool is_early_mcount_callsite(u32 *instruction)
488 {
489 return false;
490 }
491 #endif
492
493 /* We expect a noop next: if it is, replace it with instruction to
494 restore r2. */
restore_r2(u32 * instruction,struct module * me)495 static int restore_r2(u32 *instruction, struct module *me)
496 {
497 u32 *prev_insn = instruction - 1;
498
499 if (is_early_mcount_callsite(prev_insn))
500 return 1;
501
502 /*
503 * Make sure the branch isn't a sibling call. Sibling calls aren't
504 * "link" branches and they don't return, so they don't need the r2
505 * restore afterwards.
506 */
507 if (!instr_is_relative_link_branch(*prev_insn))
508 return 1;
509
510 if (*instruction != PPC_INST_NOP) {
511 pr_err("%s: Expect noop after relocate, got %08x\n",
512 me->name, *instruction);
513 return 0;
514 }
515 /* ld r2,R2_STACK_OFFSET(r1) */
516 *instruction = PPC_INST_LD_TOC;
517 return 1;
518 }
519
apply_relocate_add(Elf64_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * me)520 int apply_relocate_add(Elf64_Shdr *sechdrs,
521 const char *strtab,
522 unsigned int symindex,
523 unsigned int relsec,
524 struct module *me)
525 {
526 unsigned int i;
527 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
528 Elf64_Sym *sym;
529 unsigned long *location;
530 unsigned long value;
531
532 pr_debug("Applying ADD relocate section %u to %u\n", relsec,
533 sechdrs[relsec].sh_info);
534
535 /* First time we're called, we can fix up .TOC. */
536 if (!me->arch.toc_fixed) {
537 sym = find_dot_toc(sechdrs, strtab, symindex);
538 /* It's theoretically possible that a module doesn't want a
539 * .TOC. so don't fail it just for that. */
540 if (sym)
541 sym->st_value = my_r2(sechdrs, me);
542 me->arch.toc_fixed = true;
543 }
544
545 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
546 /* This is where to make the change */
547 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
548 + rela[i].r_offset;
549 /* This is the symbol it is referring to */
550 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
551 + ELF64_R_SYM(rela[i].r_info);
552
553 pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
554 location, (long)ELF64_R_TYPE(rela[i].r_info),
555 strtab + sym->st_name, (unsigned long)sym->st_value,
556 (long)rela[i].r_addend);
557
558 /* `Everything is relative'. */
559 value = sym->st_value + rela[i].r_addend;
560
561 switch (ELF64_R_TYPE(rela[i].r_info)) {
562 case R_PPC64_ADDR32:
563 /* Simply set it */
564 *(u32 *)location = value;
565 break;
566
567 case R_PPC64_ADDR64:
568 /* Simply set it */
569 *(unsigned long *)location = value;
570 break;
571
572 case R_PPC64_TOC:
573 *(unsigned long *)location = my_r2(sechdrs, me);
574 break;
575
576 case R_PPC64_TOC16:
577 /* Subtract TOC pointer */
578 value -= my_r2(sechdrs, me);
579 if (value + 0x8000 > 0xffff) {
580 pr_err("%s: bad TOC16 relocation (0x%lx)\n",
581 me->name, value);
582 return -ENOEXEC;
583 }
584 *((uint16_t *) location)
585 = (*((uint16_t *) location) & ~0xffff)
586 | (value & 0xffff);
587 break;
588
589 case R_PPC64_TOC16_LO:
590 /* Subtract TOC pointer */
591 value -= my_r2(sechdrs, me);
592 *((uint16_t *) location)
593 = (*((uint16_t *) location) & ~0xffff)
594 | (value & 0xffff);
595 break;
596
597 case R_PPC64_TOC16_DS:
598 /* Subtract TOC pointer */
599 value -= my_r2(sechdrs, me);
600 if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
601 pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
602 me->name, value);
603 return -ENOEXEC;
604 }
605 *((uint16_t *) location)
606 = (*((uint16_t *) location) & ~0xfffc)
607 | (value & 0xfffc);
608 break;
609
610 case R_PPC64_TOC16_LO_DS:
611 /* Subtract TOC pointer */
612 value -= my_r2(sechdrs, me);
613 if ((value & 3) != 0) {
614 pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
615 me->name, value);
616 return -ENOEXEC;
617 }
618 *((uint16_t *) location)
619 = (*((uint16_t *) location) & ~0xfffc)
620 | (value & 0xfffc);
621 break;
622
623 case R_PPC64_TOC16_HA:
624 /* Subtract TOC pointer */
625 value -= my_r2(sechdrs, me);
626 value = ((value + 0x8000) >> 16);
627 *((uint16_t *) location)
628 = (*((uint16_t *) location) & ~0xffff)
629 | (value & 0xffff);
630 break;
631
632 case R_PPC_REL24:
633 /* FIXME: Handle weak symbols here --RR */
634 if (sym->st_shndx == SHN_UNDEF) {
635 /* External: go via stub */
636 value = stub_for_addr(sechdrs, value, me);
637 if (!value)
638 return -ENOENT;
639 if (!restore_r2((u32 *)location + 1, me))
640 return -ENOEXEC;
641
642 squash_toc_save_inst(strtab + sym->st_name, value);
643 } else
644 value += local_entry_offset(sym);
645
646 /* Convert value to relative */
647 value -= (unsigned long)location;
648 if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
649 pr_err("%s: REL24 %li out of range!\n",
650 me->name, (long int)value);
651 return -ENOEXEC;
652 }
653
654 /* Only replace bits 2 through 26 */
655 *(uint32_t *)location
656 = (*(uint32_t *)location & ~0x03fffffc)
657 | (value & 0x03fffffc);
658 break;
659
660 case R_PPC64_REL64:
661 /* 64 bits relative (used by features fixups) */
662 *location = value - (unsigned long)location;
663 break;
664
665 case R_PPC64_TOCSAVE:
666 /*
667 * Marker reloc indicates we don't have to save r2.
668 * That would only save us one instruction, so ignore
669 * it.
670 */
671 break;
672
673 case R_PPC64_ENTRY:
674 /*
675 * Optimize ELFv2 large code model entry point if
676 * the TOC is within 2GB range of current location.
677 */
678 value = my_r2(sechdrs, me) - (unsigned long)location;
679 if (value + 0x80008000 > 0xffffffff)
680 break;
681 /*
682 * Check for the large code model prolog sequence:
683 * ld r2, ...(r12)
684 * add r2, r2, r12
685 */
686 if ((((uint32_t *)location)[0] & ~0xfffc)
687 != 0xe84c0000)
688 break;
689 if (((uint32_t *)location)[1] != 0x7c426214)
690 break;
691 /*
692 * If found, replace it with:
693 * addis r2, r12, (.TOC.-func)@ha
694 * addi r2, r12, (.TOC.-func)@l
695 */
696 ((uint32_t *)location)[0] = 0x3c4c0000 + PPC_HA(value);
697 ((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value);
698 break;
699
700 case R_PPC64_REL16_HA:
701 /* Subtract location pointer */
702 value -= (unsigned long)location;
703 value = ((value + 0x8000) >> 16);
704 *((uint16_t *) location)
705 = (*((uint16_t *) location) & ~0xffff)
706 | (value & 0xffff);
707 break;
708
709 case R_PPC64_REL16_LO:
710 /* Subtract location pointer */
711 value -= (unsigned long)location;
712 *((uint16_t *) location)
713 = (*((uint16_t *) location) & ~0xffff)
714 | (value & 0xffff);
715 break;
716
717 default:
718 pr_err("%s: Unknown ADD relocation: %lu\n",
719 me->name,
720 (unsigned long)ELF64_R_TYPE(rela[i].r_info));
721 return -ENOEXEC;
722 }
723 }
724
725 return 0;
726 }
727
728 #ifdef CONFIG_DYNAMIC_FTRACE
729
730 #ifdef CC_USING_MPROFILE_KERNEL
731
732 #define PACATOC offsetof(struct paca_struct, kernel_toc)
733
734 /*
735 * For mprofile-kernel we use a special stub for ftrace_caller() because we
736 * can't rely on r2 containing this module's TOC when we enter the stub.
737 *
738 * That can happen if the function calling us didn't need to use the toc. In
739 * that case it won't have setup r2, and the r2 value will be either the
740 * kernel's toc, or possibly another modules toc.
741 *
742 * To deal with that this stub uses the kernel toc, which is always accessible
743 * via the paca (in r13). The target (ftrace_caller()) is responsible for
744 * saving and restoring the toc before returning.
745 */
create_ftrace_stub(const Elf64_Shdr * sechdrs,struct module * me)746 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me)
747 {
748 struct ppc64_stub_entry *entry;
749 unsigned int i, num_stubs;
750 static u32 stub_insns[] = {
751 0xe98d0000 | PACATOC, /* ld r12,PACATOC(r13) */
752 0x3d8c0000, /* addis r12,r12,<high> */
753 0x398c0000, /* addi r12,r12,<low> */
754 0x7d8903a6, /* mtctr r12 */
755 0x4e800420, /* bctr */
756 };
757 long reladdr;
758
759 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*entry);
760
761 /* Find the next available stub entry */
762 entry = (void *)sechdrs[me->arch.stubs_section].sh_addr;
763 for (i = 0; i < num_stubs && stub_func_addr(entry->funcdata); i++, entry++);
764
765 if (i >= num_stubs) {
766 pr_err("%s: Unable to find a free slot for ftrace stub.\n", me->name);
767 return 0;
768 }
769
770 memcpy(entry->jump, stub_insns, sizeof(stub_insns));
771
772 /* Stub uses address relative to kernel toc (from the paca) */
773 reladdr = (unsigned long)ftrace_caller - kernel_toc_addr();
774 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
775 pr_err("%s: Address of ftrace_caller out of range of kernel_toc.\n", me->name);
776 return 0;
777 }
778
779 entry->jump[1] |= PPC_HA(reladdr);
780 entry->jump[2] |= PPC_LO(reladdr);
781
782 /* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */
783 entry->funcdata = func_desc((unsigned long)ftrace_caller);
784 entry->magic = STUB_MAGIC;
785
786 return (unsigned long)entry;
787 }
788 #else
create_ftrace_stub(const Elf64_Shdr * sechdrs,struct module * me)789 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me)
790 {
791 return stub_for_addr(sechdrs, (unsigned long)ftrace_caller, me);
792 }
793 #endif
794
module_finalize_ftrace(struct module * mod,const Elf_Shdr * sechdrs)795 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
796 {
797 mod->arch.toc = my_r2(sechdrs, mod);
798 mod->arch.tramp = create_ftrace_stub(sechdrs, mod);
799
800 if (!mod->arch.tramp)
801 return -ENOENT;
802
803 return 0;
804 }
805 #endif
806