xref: /linux/arch/powerpc/kernel/module_64.c (revision 0883c2c06fb5bcf5b9e008270827e63c09a88c1e)
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 
49 static func_desc_t func_desc(unsigned long addr)
50 {
51 	return addr;
52 }
53 static unsigned long func_addr(unsigned long addr)
54 {
55 	return addr;
56 }
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 
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 
80 static func_desc_t func_desc(unsigned long addr)
81 {
82 	return *(struct ppc64_opd_entry *)addr;
83 }
84 static unsigned long func_addr(unsigned long addr)
85 {
86 	return func_desc(addr).funcaddr;
87 }
88 static unsigned long stub_func_addr(func_desc_t func)
89 {
90 	return func.funcaddr;
91 }
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
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) */
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 
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 
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. */
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. */
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  */
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 
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 
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) */
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. */
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. */
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
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  */
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
484 static void squash_toc_save_inst(const char *name, unsigned long addr) { }
485 
486 /* without -mprofile-kernel, mcount calls are never early */
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. */
495 static int restore_r2(u32 *instruction, struct module *me)
496 {
497 	if (*instruction != PPC_INST_NOP) {
498 		if (is_early_mcount_callsite(instruction - 1))
499 			return 1;
500 		pr_err("%s: Expect noop after relocate, got %08x\n",
501 		       me->name, *instruction);
502 		return 0;
503 	}
504 	/* ld r2,R2_STACK_OFFSET(r1) */
505 	*instruction = PPC_INST_LD_TOC;
506 	return 1;
507 }
508 
509 int apply_relocate_add(Elf64_Shdr *sechdrs,
510 		       const char *strtab,
511 		       unsigned int symindex,
512 		       unsigned int relsec,
513 		       struct module *me)
514 {
515 	unsigned int i;
516 	Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
517 	Elf64_Sym *sym;
518 	unsigned long *location;
519 	unsigned long value;
520 
521 	pr_debug("Applying ADD relocate section %u to %u\n", relsec,
522 	       sechdrs[relsec].sh_info);
523 
524 	/* First time we're called, we can fix up .TOC. */
525 	if (!me->arch.toc_fixed) {
526 		sym = find_dot_toc(sechdrs, strtab, symindex);
527 		/* It's theoretically possible that a module doesn't want a
528 		 * .TOC. so don't fail it just for that. */
529 		if (sym)
530 			sym->st_value = my_r2(sechdrs, me);
531 		me->arch.toc_fixed = true;
532 	}
533 
534 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
535 		/* This is where to make the change */
536 		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
537 			+ rela[i].r_offset;
538 		/* This is the symbol it is referring to */
539 		sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
540 			+ ELF64_R_SYM(rela[i].r_info);
541 
542 		pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
543 		       location, (long)ELF64_R_TYPE(rela[i].r_info),
544 		       strtab + sym->st_name, (unsigned long)sym->st_value,
545 		       (long)rela[i].r_addend);
546 
547 		/* `Everything is relative'. */
548 		value = sym->st_value + rela[i].r_addend;
549 
550 		switch (ELF64_R_TYPE(rela[i].r_info)) {
551 		case R_PPC64_ADDR32:
552 			/* Simply set it */
553 			*(u32 *)location = value;
554 			break;
555 
556 		case R_PPC64_ADDR64:
557 			/* Simply set it */
558 			*(unsigned long *)location = value;
559 			break;
560 
561 		case R_PPC64_TOC:
562 			*(unsigned long *)location = my_r2(sechdrs, me);
563 			break;
564 
565 		case R_PPC64_TOC16:
566 			/* Subtract TOC pointer */
567 			value -= my_r2(sechdrs, me);
568 			if (value + 0x8000 > 0xffff) {
569 				pr_err("%s: bad TOC16 relocation (0x%lx)\n",
570 				       me->name, value);
571 				return -ENOEXEC;
572 			}
573 			*((uint16_t *) location)
574 				= (*((uint16_t *) location) & ~0xffff)
575 				| (value & 0xffff);
576 			break;
577 
578 		case R_PPC64_TOC16_LO:
579 			/* Subtract TOC pointer */
580 			value -= my_r2(sechdrs, me);
581 			*((uint16_t *) location)
582 				= (*((uint16_t *) location) & ~0xffff)
583 				| (value & 0xffff);
584 			break;
585 
586 		case R_PPC64_TOC16_DS:
587 			/* Subtract TOC pointer */
588 			value -= my_r2(sechdrs, me);
589 			if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
590 				pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
591 				       me->name, value);
592 				return -ENOEXEC;
593 			}
594 			*((uint16_t *) location)
595 				= (*((uint16_t *) location) & ~0xfffc)
596 				| (value & 0xfffc);
597 			break;
598 
599 		case R_PPC64_TOC16_LO_DS:
600 			/* Subtract TOC pointer */
601 			value -= my_r2(sechdrs, me);
602 			if ((value & 3) != 0) {
603 				pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
604 				       me->name, value);
605 				return -ENOEXEC;
606 			}
607 			*((uint16_t *) location)
608 				= (*((uint16_t *) location) & ~0xfffc)
609 				| (value & 0xfffc);
610 			break;
611 
612 		case R_PPC64_TOC16_HA:
613 			/* Subtract TOC pointer */
614 			value -= my_r2(sechdrs, me);
615 			value = ((value + 0x8000) >> 16);
616 			*((uint16_t *) location)
617 				= (*((uint16_t *) location) & ~0xffff)
618 				| (value & 0xffff);
619 			break;
620 
621 		case R_PPC_REL24:
622 			/* FIXME: Handle weak symbols here --RR */
623 			if (sym->st_shndx == SHN_UNDEF) {
624 				/* External: go via stub */
625 				value = stub_for_addr(sechdrs, value, me);
626 				if (!value)
627 					return -ENOENT;
628 				if (!restore_r2((u32 *)location + 1, me))
629 					return -ENOEXEC;
630 
631 				squash_toc_save_inst(strtab + sym->st_name, value);
632 			} else
633 				value += local_entry_offset(sym);
634 
635 			/* Convert value to relative */
636 			value -= (unsigned long)location;
637 			if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
638 				pr_err("%s: REL24 %li out of range!\n",
639 				       me->name, (long int)value);
640 				return -ENOEXEC;
641 			}
642 
643 			/* Only replace bits 2 through 26 */
644 			*(uint32_t *)location
645 				= (*(uint32_t *)location & ~0x03fffffc)
646 				| (value & 0x03fffffc);
647 			break;
648 
649 		case R_PPC64_REL64:
650 			/* 64 bits relative (used by features fixups) */
651 			*location = value - (unsigned long)location;
652 			break;
653 
654 		case R_PPC64_TOCSAVE:
655 			/*
656 			 * Marker reloc indicates we don't have to save r2.
657 			 * That would only save us one instruction, so ignore
658 			 * it.
659 			 */
660 			break;
661 
662 		case R_PPC64_ENTRY:
663 			/*
664 			 * Optimize ELFv2 large code model entry point if
665 			 * the TOC is within 2GB range of current location.
666 			 */
667 			value = my_r2(sechdrs, me) - (unsigned long)location;
668 			if (value + 0x80008000 > 0xffffffff)
669 				break;
670 			/*
671 			 * Check for the large code model prolog sequence:
672 		         *	ld r2, ...(r12)
673 			 *	add r2, r2, r12
674 			 */
675 			if ((((uint32_t *)location)[0] & ~0xfffc)
676 			    != 0xe84c0000)
677 				break;
678 			if (((uint32_t *)location)[1] != 0x7c426214)
679 				break;
680 			/*
681 			 * If found, replace it with:
682 			 *	addis r2, r12, (.TOC.-func)@ha
683 			 *	addi r2, r12, (.TOC.-func)@l
684 			 */
685 			((uint32_t *)location)[0] = 0x3c4c0000 + PPC_HA(value);
686 			((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value);
687 			break;
688 
689 		case R_PPC64_REL16_HA:
690 			/* Subtract location pointer */
691 			value -= (unsigned long)location;
692 			value = ((value + 0x8000) >> 16);
693 			*((uint16_t *) location)
694 				= (*((uint16_t *) location) & ~0xffff)
695 				| (value & 0xffff);
696 			break;
697 
698 		case R_PPC64_REL16_LO:
699 			/* Subtract location pointer */
700 			value -= (unsigned long)location;
701 			*((uint16_t *) location)
702 				= (*((uint16_t *) location) & ~0xffff)
703 				| (value & 0xffff);
704 			break;
705 
706 		default:
707 			pr_err("%s: Unknown ADD relocation: %lu\n",
708 			       me->name,
709 			       (unsigned long)ELF64_R_TYPE(rela[i].r_info));
710 			return -ENOEXEC;
711 		}
712 	}
713 
714 	return 0;
715 }
716 
717 #ifdef CONFIG_DYNAMIC_FTRACE
718 
719 #ifdef CC_USING_MPROFILE_KERNEL
720 
721 #define PACATOC offsetof(struct paca_struct, kernel_toc)
722 
723 /*
724  * For mprofile-kernel we use a special stub for ftrace_caller() because we
725  * can't rely on r2 containing this module's TOC when we enter the stub.
726  *
727  * That can happen if the function calling us didn't need to use the toc. In
728  * that case it won't have setup r2, and the r2 value will be either the
729  * kernel's toc, or possibly another modules toc.
730  *
731  * To deal with that this stub uses the kernel toc, which is always accessible
732  * via the paca (in r13). The target (ftrace_caller()) is responsible for
733  * saving and restoring the toc before returning.
734  */
735 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me)
736 {
737 	struct ppc64_stub_entry *entry;
738 	unsigned int i, num_stubs;
739 	static u32 stub_insns[] = {
740 		0xe98d0000 | PACATOC, 	/* ld      r12,PACATOC(r13)	*/
741 		0x3d8c0000,		/* addis   r12,r12,<high>	*/
742 		0x398c0000, 		/* addi    r12,r12,<low>	*/
743 		0x7d8903a6, 		/* mtctr   r12			*/
744 		0x4e800420, 		/* bctr				*/
745 	};
746 	long reladdr;
747 
748 	num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*entry);
749 
750 	/* Find the next available stub entry */
751 	entry = (void *)sechdrs[me->arch.stubs_section].sh_addr;
752 	for (i = 0; i < num_stubs && stub_func_addr(entry->funcdata); i++, entry++);
753 
754 	if (i >= num_stubs) {
755 		pr_err("%s: Unable to find a free slot for ftrace stub.\n", me->name);
756 		return 0;
757 	}
758 
759 	memcpy(entry->jump, stub_insns, sizeof(stub_insns));
760 
761 	/* Stub uses address relative to kernel toc (from the paca) */
762 	reladdr = (unsigned long)ftrace_caller - kernel_toc_addr();
763 	if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
764 		pr_err("%s: Address of ftrace_caller out of range of kernel_toc.\n", me->name);
765 		return 0;
766 	}
767 
768 	entry->jump[1] |= PPC_HA(reladdr);
769 	entry->jump[2] |= PPC_LO(reladdr);
770 
771 	/* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */
772 	entry->funcdata = func_desc((unsigned long)ftrace_caller);
773 	entry->magic = STUB_MAGIC;
774 
775 	return (unsigned long)entry;
776 }
777 #else
778 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me)
779 {
780 	return stub_for_addr(sechdrs, (unsigned long)ftrace_caller, me);
781 }
782 #endif
783 
784 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
785 {
786 	mod->arch.toc = my_r2(sechdrs, mod);
787 	mod->arch.tramp = create_ftrace_stub(sechdrs, mod);
788 
789 	if (!mod->arch.tramp)
790 		return -ENOENT;
791 
792 	return 0;
793 }
794 #endif
795