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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Kernel module help for PPC64.
3 Copyright (C) 2001, 2003 Rusty Russell IBM Corporation.
4
5*/
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/module.h>
10#include <linux/elf.h>
11#include <linux/moduleloader.h>
12#include <linux/err.h>
13#include <linux/vmalloc.h>
14#include <linux/ftrace.h>
15#include <linux/bug.h>
16#include <linux/uaccess.h>
17#include <asm/module.h>
18#include <asm/firmware.h>
19#include <asm/code-patching.h>
20#include <linux/sort.h>
21#include <asm/setup.h>
22#include <asm/sections.h>
23#include <asm/inst.h>
24
25/* FIXME: We don't do .init separately. To do this, we'd need to have
26 a separate r2 value in the init and core section, and stub between
27 them, too.
28
29 Using a magic allocator which places modules within 32MB solves
30 this, and makes other things simpler. Anton?
31 --RR. */
32
33#ifdef PPC64_ELF_ABI_v2
34
35/* An address is simply the address of the function. */
36typedef unsigned long func_desc_t;
37
38static func_desc_t func_desc(unsigned long addr)
39{
40 return addr;
41}
42static unsigned long func_addr(unsigned long addr)
43{
44 return addr;
45}
46static unsigned long stub_func_addr(func_desc_t func)
47{
48 return func;
49}
50
51/* PowerPC64 specific values for the Elf64_Sym st_other field. */
52#define STO_PPC64_LOCAL_BIT 5
53#define STO_PPC64_LOCAL_MASK (7 << STO_PPC64_LOCAL_BIT)
54#define PPC64_LOCAL_ENTRY_OFFSET(other) \
55 (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
56
57static unsigned int local_entry_offset(const Elf64_Sym *sym)
58{
59 /* sym->st_other indicates offset to local entry point
60 * (otherwise it will assume r12 is the address of the start
61 * of function and try to derive r2 from it). */
62 return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
63}
64#else
65
66/* An address is address of the OPD entry, which contains address of fn. */
67typedef struct ppc64_opd_entry func_desc_t;
68
69static func_desc_t func_desc(unsigned long addr)
70{
71 return *(struct ppc64_opd_entry *)addr;
72}
73static unsigned long func_addr(unsigned long addr)
74{
75 return func_desc(addr).funcaddr;
76}
77static unsigned long stub_func_addr(func_desc_t func)
78{
79 return func.funcaddr;
80}
81static unsigned int local_entry_offset(const Elf64_Sym *sym)
82{
83 return 0;
84}
85
86void *dereference_module_function_descriptor(struct module *mod, void *ptr)
87{
88 if (ptr < (void *)mod->arch.start_opd ||
89 ptr >= (void *)mod->arch.end_opd)
90 return ptr;
91
92 return dereference_function_descriptor(ptr);
93}
94#endif
95
96#define STUB_MAGIC 0x73747562 /* stub */
97
98/* Like PPC32, we need little trampolines to do > 24-bit jumps (into
99 the kernel itself). But on PPC64, these need to be used for every
100 jump, actually, to reset r2 (TOC+0x8000). */
101struct ppc64_stub_entry
102{
103 /* 28 byte jump instruction sequence (7 instructions). We only
104 * need 6 instructions on ABIv2 but we always allocate 7 so
105 * so we don't have to modify the trampoline load instruction. */
106 u32 jump[7];
107 /* Used by ftrace to identify stubs */
108 u32 magic;
109 /* Data for the above code */
110 func_desc_t funcdata;
111};
112
113/*
114 * PPC64 uses 24 bit jumps, but we need to jump into other modules or
115 * the kernel which may be further. So we jump to a stub.
116 *
117 * For ELFv1 we need to use this to set up the new r2 value (aka TOC
118 * pointer). For ELFv2 it's the callee's responsibility to set up the
119 * new r2, but for both we need to save the old r2.
120 *
121 * We could simply patch the new r2 value and function pointer into
122 * the stub, but it's significantly shorter to put these values at the
123 * end of the stub code, and patch the stub address (32-bits relative
124 * to the TOC ptr, r2) into the stub.
125 *
126 * addis r11,r2, <high>
127 * addi r11,r11, <low>
128 * std r2,R2_STACK_OFFSET(r1)
129 * ld r12,32(r11)
130 * ld r2,40(r11)
131 * mtctr r12
132 * bctr
133 */
134static u32 ppc64_stub_insns[] = {
135 PPC_INST_ADDIS | __PPC_RT(R11) | __PPC_RA(R2),
136 PPC_INST_ADDI | __PPC_RT(R11) | __PPC_RA(R11),
137 /* Save current r2 value in magic place on the stack. */
138 PPC_INST_STD | __PPC_RS(R2) | __PPC_RA(R1) | R2_STACK_OFFSET,
139 PPC_INST_LD | __PPC_RT(R12) | __PPC_RA(R11) | 32,
140#ifdef PPC64_ELF_ABI_v1
141 /* Set up new r2 from function descriptor */
142 PPC_INST_LD | __PPC_RT(R2) | __PPC_RA(R11) | 40,
143#endif
144 PPC_INST_MTCTR | __PPC_RS(R12),
145 PPC_INST_BCTR,
146};
147
148/* Count how many different 24-bit relocations (different symbol,
149 different addend) */
150static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
151{
152 unsigned int i, r_info, r_addend, _count_relocs;
153
154 /* FIXME: Only count external ones --RR */
155 _count_relocs = 0;
156 r_info = 0;
157 r_addend = 0;
158 for (i = 0; i < num; i++)
159 /* Only count 24-bit relocs, others don't need stubs */
160 if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
161 (r_info != ELF64_R_SYM(rela[i].r_info) ||
162 r_addend != rela[i].r_addend)) {
163 _count_relocs++;
164 r_info = ELF64_R_SYM(rela[i].r_info);
165 r_addend = rela[i].r_addend;
166 }
167
168 return _count_relocs;
169}
170
171static int relacmp(const void *_x, const void *_y)
172{
173 const Elf64_Rela *x, *y;
174
175 y = (Elf64_Rela *)_x;
176 x = (Elf64_Rela *)_y;
177
178 /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
179 * make the comparison cheaper/faster. It won't affect the sorting or
180 * the counting algorithms' performance
181 */
182 if (x->r_info < y->r_info)
183 return -1;
184 else if (x->r_info > y->r_info)
185 return 1;
186 else if (x->r_addend < y->r_addend)
187 return -1;
188 else if (x->r_addend > y->r_addend)
189 return 1;
190 else
191 return 0;
192}
193
194/* Get size of potential trampolines required. */
195static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
196 const Elf64_Shdr *sechdrs)
197{
198 /* One extra reloc so it's always 0-funcaddr terminated */
199 unsigned long relocs = 1;
200 unsigned i;
201
202 /* Every relocated section... */
203 for (i = 1; i < hdr->e_shnum; i++) {
204 if (sechdrs[i].sh_type == SHT_RELA) {
205 pr_debug("Found relocations in section %u\n", i);
206 pr_debug("Ptr: %p. Number: %Lu\n",
207 (void *)sechdrs[i].sh_addr,
208 sechdrs[i].sh_size / sizeof(Elf64_Rela));
209
210 /* Sort the relocation information based on a symbol and
211 * addend key. This is a stable O(n*log n) complexity
212 * alogrithm but it will reduce the complexity of
213 * count_relocs() to linear complexity O(n)
214 */
215 sort((void *)sechdrs[i].sh_addr,
216 sechdrs[i].sh_size / sizeof(Elf64_Rela),
217 sizeof(Elf64_Rela), relacmp, NULL);
218
219 relocs += count_relocs((void *)sechdrs[i].sh_addr,
220 sechdrs[i].sh_size
221 / sizeof(Elf64_Rela));
222 }
223 }
224
225#ifdef CONFIG_DYNAMIC_FTRACE
226 /* make the trampoline to the ftrace_caller */
227 relocs++;
228#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
229 /* an additional one for ftrace_regs_caller */
230 relocs++;
231#endif
232#endif
233
234 pr_debug("Looks like a total of %lu stubs, max\n", relocs);
235 return relocs * sizeof(struct ppc64_stub_entry);
236}
237
238/* Still needed for ELFv2, for .TOC. */
239static void dedotify_versions(struct modversion_info *vers,
240 unsigned long size)
241{
242 struct modversion_info *end;
243
244 for (end = (void *)vers + size; vers < end; vers++)
245 if (vers->name[0] == '.') {
246 memmove(vers->name, vers->name+1, strlen(vers->name));
247 }
248}
249
250/*
251 * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
252 * seem to be defined (value set later).
253 */
254static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
255{
256 unsigned int i;
257
258 for (i = 1; i < numsyms; i++) {
259 if (syms[i].st_shndx == SHN_UNDEF) {
260 char *name = strtab + syms[i].st_name;
261 if (name[0] == '.') {
262 if (strcmp(name+1, "TOC.") == 0)
263 syms[i].st_shndx = SHN_ABS;
264 syms[i].st_name++;
265 }
266 }
267 }
268}
269
270static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
271 const char *strtab,
272 unsigned int symindex)
273{
274 unsigned int i, numsyms;
275 Elf64_Sym *syms;
276
277 syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
278 numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
279
280 for (i = 1; i < numsyms; i++) {
281 if (syms[i].st_shndx == SHN_ABS
282 && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
283 return &syms[i];
284 }
285 return NULL;
286}
287
288int module_frob_arch_sections(Elf64_Ehdr *hdr,
289 Elf64_Shdr *sechdrs,
290 char *secstrings,
291 struct module *me)
292{
293 unsigned int i;
294
295 /* Find .toc and .stubs sections, symtab and strtab */
296 for (i = 1; i < hdr->e_shnum; i++) {
297 char *p;
298 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
299 me->arch.stubs_section = i;
300 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) {
301 me->arch.toc_section = i;
302 if (sechdrs[i].sh_addralign < 8)
303 sechdrs[i].sh_addralign = 8;
304 }
305 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
306 dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
307 sechdrs[i].sh_size);
308
309 /* We don't handle .init for the moment: rename to _init */
310 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
311 p[0] = '_';
312
313 if (sechdrs[i].sh_type == SHT_SYMTAB)
314 dedotify((void *)hdr + sechdrs[i].sh_offset,
315 sechdrs[i].sh_size / sizeof(Elf64_Sym),
316 (void *)hdr
317 + sechdrs[sechdrs[i].sh_link].sh_offset);
318 }
319
320 if (!me->arch.stubs_section) {
321 pr_err("%s: doesn't contain .stubs.\n", me->name);
322 return -ENOEXEC;
323 }
324
325 /* If we don't have a .toc, just use .stubs. We need to set r2
326 to some reasonable value in case the module calls out to
327 other functions via a stub, or if a function pointer escapes
328 the module by some means. */
329 if (!me->arch.toc_section)
330 me->arch.toc_section = me->arch.stubs_section;
331
332 /* Override the stubs size */
333 sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
334 return 0;
335}
336
337#ifdef CONFIG_MPROFILE_KERNEL
338
339#define PACATOC offsetof(struct paca_struct, kernel_toc)
340
341/*
342 * ld r12,PACATOC(r13)
343 * addis r12,r12,<high>
344 * addi r12,r12,<low>
345 * mtctr r12
346 * bctr
347 */
348static u32 stub_insns[] = {
349 PPC_INST_LD | __PPC_RT(R12) | __PPC_RA(R13) | PACATOC,
350 PPC_INST_ADDIS | __PPC_RT(R12) | __PPC_RA(R12),
351 PPC_INST_ADDI | __PPC_RT(R12) | __PPC_RA(R12),
352 PPC_INST_MTCTR | __PPC_RS(R12),
353 PPC_INST_BCTR,
354};
355
356/*
357 * For mprofile-kernel we use a special stub for ftrace_caller() because we
358 * can't rely on r2 containing this module's TOC when we enter the stub.
359 *
360 * That can happen if the function calling us didn't need to use the toc. In
361 * that case it won't have setup r2, and the r2 value will be either the
362 * kernel's toc, or possibly another modules toc.
363 *
364 * To deal with that this stub uses the kernel toc, which is always accessible
365 * via the paca (in r13). The target (ftrace_caller()) is responsible for
366 * saving and restoring the toc before returning.
367 */
368static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
369 unsigned long addr,
370 struct module *me)
371{
372 long reladdr;
373
374 memcpy(entry->jump, stub_insns, sizeof(stub_insns));
375
376 /* Stub uses address relative to kernel toc (from the paca) */
377 reladdr = addr - kernel_toc_addr();
378 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
379 pr_err("%s: Address of %ps out of range of kernel_toc.\n",
380 me->name, (void *)addr);
381 return 0;
382 }
383
384 entry->jump[1] |= PPC_HA(reladdr);
385 entry->jump[2] |= PPC_LO(reladdr);
386
387 /* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */
388 entry->funcdata = func_desc(addr);
389 entry->magic = STUB_MAGIC;
390
391 return 1;
392}
393
394static bool is_mprofile_ftrace_call(const char *name)
395{
396 if (!strcmp("_mcount", name))
397 return true;
398#ifdef CONFIG_DYNAMIC_FTRACE
399 if (!strcmp("ftrace_caller", name))
400 return true;
401#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
402 if (!strcmp("ftrace_regs_caller", name))
403 return true;
404#endif
405#endif
406
407 return false;
408}
409#else
410static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
411 unsigned long addr,
412 struct module *me)
413{
414 return 0;
415}
416
417static bool is_mprofile_ftrace_call(const char *name)
418{
419 return false;
420}
421#endif
422
423/*
424 * r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the
425 * value maximum span in an instruction which uses a signed offset). Round down
426 * to a 256 byte boundary for the odd case where we are setting up r2 without a
427 * .toc section.
428 */
429static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
430{
431 return (sechdrs[me->arch.toc_section].sh_addr & ~0xfful) + 0x8000;
432}
433
434/* Patch stub to reference function and correct r2 value. */
435static inline int create_stub(const Elf64_Shdr *sechdrs,
436 struct ppc64_stub_entry *entry,
437 unsigned long addr,
438 struct module *me,
439 const char *name)
440{
441 long reladdr;
442
443 if (is_mprofile_ftrace_call(name))
444 return create_ftrace_stub(entry, addr, me);
445
446 memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns));
447
448 /* Stub uses address relative to r2. */
449 reladdr = (unsigned long)entry - my_r2(sechdrs, me);
450 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
451 pr_err("%s: Address %p of stub out of range of %p.\n",
452 me->name, (void *)reladdr, (void *)my_r2);
453 return 0;
454 }
455 pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
456
457 entry->jump[0] |= PPC_HA(reladdr);
458 entry->jump[1] |= PPC_LO(reladdr);
459 entry->funcdata = func_desc(addr);
460 entry->magic = STUB_MAGIC;
461
462 return 1;
463}
464
465/* Create stub to jump to function described in this OPD/ptr: we need the
466 stub to set up the TOC ptr (r2) for the function. */
467static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
468 unsigned long addr,
469 struct module *me,
470 const char *name)
471{
472 struct ppc64_stub_entry *stubs;
473 unsigned int i, num_stubs;
474
475 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
476
477 /* Find this stub, or if that fails, the next avail. entry */
478 stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
479 for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
480 if (WARN_ON(i >= num_stubs))
481 return 0;
482
483 if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
484 return (unsigned long)&stubs[i];
485 }
486
487 if (!create_stub(sechdrs, &stubs[i], addr, me, name))
488 return 0;
489
490 return (unsigned long)&stubs[i];
491}
492
493/* We expect a noop next: if it is, replace it with instruction to
494 restore r2. */
495static int restore_r2(const char *name, u32 *instruction, struct module *me)
496{
497 u32 *prev_insn = instruction - 1;
498
499 if (is_mprofile_ftrace_call(name))
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(ppc_inst(*prev_insn)))
508 return 1;
509
510 if (*instruction != PPC_INST_NOP) {
511 pr_err("%s: Expected nop after call, got %08x at %pS\n",
512 me->name, *instruction, instruction);
513 return 0;
514 }
515 /* ld r2,R2_STACK_OFFSET(r1) */
516 *instruction = PPC_INST_LD_TOC;
517 return 1;
518}
519
520int 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 sym->st_shndx == SHN_LIVEPATCH) {
636 /* External: go via stub */
637 value = stub_for_addr(sechdrs, value, me,
638 strtab + sym->st_name);
639 if (!value)
640 return -ENOENT;
641 if (!restore_r2(strtab + sym->st_name,
642 (u32 *)location + 1, me))
643 return -ENOEXEC;
644 } else
645 value += local_entry_offset(sym);
646
647 /* Convert value to relative */
648 value -= (unsigned long)location;
649 if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
650 pr_err("%s: REL24 %li out of range!\n",
651 me->name, (long int)value);
652 return -ENOEXEC;
653 }
654
655 /* Only replace bits 2 through 26 */
656 *(uint32_t *)location
657 = (*(uint32_t *)location & ~0x03fffffc)
658 | (value & 0x03fffffc);
659 break;
660
661 case R_PPC64_REL64:
662 /* 64 bits relative (used by features fixups) */
663 *location = value - (unsigned long)location;
664 break;
665
666 case R_PPC64_REL32:
667 /* 32 bits relative (used by relative exception tables) */
668 /* Convert value to relative */
669 value -= (unsigned long)location;
670 if (value + 0x80000000 > 0xffffffff) {
671 pr_err("%s: REL32 %li out of range!\n",
672 me->name, (long int)value);
673 return -ENOEXEC;
674 }
675 *(u32 *)location = value;
676 break;
677
678 case R_PPC64_TOCSAVE:
679 /*
680 * Marker reloc indicates we don't have to save r2.
681 * That would only save us one instruction, so ignore
682 * it.
683 */
684 break;
685
686 case R_PPC64_ENTRY:
687 /*
688 * Optimize ELFv2 large code model entry point if
689 * the TOC is within 2GB range of current location.
690 */
691 value = my_r2(sechdrs, me) - (unsigned long)location;
692 if (value + 0x80008000 > 0xffffffff)
693 break;
694 /*
695 * Check for the large code model prolog sequence:
696 * ld r2, ...(r12)
697 * add r2, r2, r12
698 */
699 if ((((uint32_t *)location)[0] & ~0xfffc) !=
700 (PPC_INST_LD | __PPC_RT(R2) | __PPC_RA(R12)))
701 break;
702 if (((uint32_t *)location)[1] !=
703 (PPC_INST_ADD | __PPC_RT(R2) | __PPC_RA(R2) | __PPC_RB(R12)))
704 break;
705 /*
706 * If found, replace it with:
707 * addis r2, r12, (.TOC.-func)@ha
708 * addi r2, r2, (.TOC.-func)@l
709 */
710 ((uint32_t *)location)[0] = PPC_INST_ADDIS | __PPC_RT(R2) |
711 __PPC_RA(R12) | PPC_HA(value);
712 ((uint32_t *)location)[1] = PPC_INST_ADDI | __PPC_RT(R2) |
713 __PPC_RA(R2) | PPC_LO(value);
714 break;
715
716 case R_PPC64_REL16_HA:
717 /* Subtract location pointer */
718 value -= (unsigned long)location;
719 value = ((value + 0x8000) >> 16);
720 *((uint16_t *) location)
721 = (*((uint16_t *) location) & ~0xffff)
722 | (value & 0xffff);
723 break;
724
725 case R_PPC64_REL16_LO:
726 /* Subtract location pointer */
727 value -= (unsigned long)location;
728 *((uint16_t *) location)
729 = (*((uint16_t *) location) & ~0xffff)
730 | (value & 0xffff);
731 break;
732
733 default:
734 pr_err("%s: Unknown ADD relocation: %lu\n",
735 me->name,
736 (unsigned long)ELF64_R_TYPE(rela[i].r_info));
737 return -ENOEXEC;
738 }
739 }
740
741 return 0;
742}
743
744#ifdef CONFIG_DYNAMIC_FTRACE
745int module_trampoline_target(struct module *mod, unsigned long addr,
746 unsigned long *target)
747{
748 struct ppc64_stub_entry *stub;
749 func_desc_t funcdata;
750 u32 magic;
751
752 if (!within_module_core(addr, mod)) {
753 pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name);
754 return -EFAULT;
755 }
756
757 stub = (struct ppc64_stub_entry *)addr;
758
759 if (copy_from_kernel_nofault(&magic, &stub->magic,
760 sizeof(magic))) {
761 pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
762 return -EFAULT;
763 }
764
765 if (magic != STUB_MAGIC) {
766 pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name);
767 return -EFAULT;
768 }
769
770 if (copy_from_kernel_nofault(&funcdata, &stub->funcdata,
771 sizeof(funcdata))) {
772 pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
773 return -EFAULT;
774 }
775
776 *target = stub_func_addr(funcdata);
777
778 return 0;
779}
780
781int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
782{
783 mod->arch.tramp = stub_for_addr(sechdrs,
784 (unsigned long)ftrace_caller,
785 mod,
786 "ftrace_caller");
787#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
788 mod->arch.tramp_regs = stub_for_addr(sechdrs,
789 (unsigned long)ftrace_regs_caller,
790 mod,
791 "ftrace_regs_caller");
792 if (!mod->arch.tramp_regs)
793 return -ENOENT;
794#endif
795
796 if (!mod->arch.tramp)
797 return -ENOENT;
798
799 return 0;
800}
801#endif
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#if defined(_CALL_ELF) && _CALL_ELF == 2
45
46/* An address is simply the address of the function. */
47typedef unsigned long func_desc_t;
48
49static func_desc_t func_desc(unsigned long addr)
50{
51 return addr;
52}
53static unsigned long func_addr(unsigned long addr)
54{
55 return addr;
56}
57static 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
68static 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. */
78typedef struct ppc64_opd_entry func_desc_t;
79
80static func_desc_t func_desc(unsigned long addr)
81{
82 return *(struct ppc64_opd_entry *)addr;
83}
84static unsigned long func_addr(unsigned long addr)
85{
86 return func_desc(addr).funcaddr;
87}
88static unsigned long stub_func_addr(func_desc_t func)
89{
90 return func.funcaddr;
91}
92static 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). */
103struct 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
129static 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#if !defined(_CALL_ELF) || _CALL_ELF != 2
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
144int 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) */
181static 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
202static 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
225static 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. */
241static 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. */
281static 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 */
304static 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
320static 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
338int 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) */
387static 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. */
400static 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. */
428static 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
453static 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 */
473static 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
484static void squash_toc_save_inst(const char *name, unsigned long addr) { }
485
486/* without -mprofile-kernel, mcount calls are never early */
487static 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. */
495static 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
509int 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 */
735static 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
778static 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
784int 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