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 <linux/kernel.h>
18 #include <asm/module.h>
19 #include <asm/firmware.h>
20 #include <asm/text-patching.h>
21 #include <linux/sort.h>
22 #include <asm/setup.h>
23 #include <asm/sections.h>
24 #include <asm/inst.h>
25
26 /* FIXME: We don't do .init separately. To do this, we'd need to have
27 a separate r2 value in the init and core section, and stub between
28 them, too.
29
30 Using a magic allocator which places modules within 32MB solves
31 this, and makes other things simpler. Anton?
32 --RR. */
33
module_elf_check_arch(Elf_Ehdr * hdr)34 bool module_elf_check_arch(Elf_Ehdr *hdr)
35 {
36 unsigned long abi_level = hdr->e_flags & 0x3;
37
38 if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2))
39 return abi_level == 2;
40 else
41 return abi_level < 2;
42 }
43
44 #ifdef CONFIG_PPC64_ELF_ABI_V2
45
func_desc(unsigned long addr)46 static func_desc_t func_desc(unsigned long addr)
47 {
48 func_desc_t desc = {
49 .addr = addr,
50 };
51
52 return desc;
53 }
54
55 /* PowerPC64 specific values for the Elf64_Sym st_other field. */
56 #define STO_PPC64_LOCAL_BIT 5
57 #define STO_PPC64_LOCAL_MASK (7 << STO_PPC64_LOCAL_BIT)
58 #define PPC64_LOCAL_ENTRY_OFFSET(other) \
59 (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
60
local_entry_offset(const Elf64_Sym * sym)61 static unsigned int local_entry_offset(const Elf64_Sym *sym)
62 {
63 /* sym->st_other indicates offset to local entry point
64 * (otherwise it will assume r12 is the address of the start
65 * of function and try to derive r2 from it). */
66 return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
67 }
68 #else
69
func_desc(unsigned long addr)70 static func_desc_t func_desc(unsigned long addr)
71 {
72 return *(struct func_desc *)addr;
73 }
local_entry_offset(const Elf64_Sym * sym)74 static unsigned int local_entry_offset(const Elf64_Sym *sym)
75 {
76 return 0;
77 }
78
dereference_module_function_descriptor(struct module * mod,void * ptr)79 void *dereference_module_function_descriptor(struct module *mod, void *ptr)
80 {
81 if (ptr < (void *)mod->arch.start_opd ||
82 ptr >= (void *)mod->arch.end_opd)
83 return ptr;
84
85 return dereference_function_descriptor(ptr);
86 }
87 #endif
88
func_addr(unsigned long addr)89 static unsigned long func_addr(unsigned long addr)
90 {
91 return func_desc(addr).addr;
92 }
93
stub_func_addr(func_desc_t func)94 static unsigned long stub_func_addr(func_desc_t func)
95 {
96 return func.addr;
97 }
98
99 #define STUB_MAGIC 0x73747562 /* stub */
100
101 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
102 the kernel itself). But on PPC64, these need to be used for every
103 jump, actually, to reset r2 (TOC+0x8000). */
104 struct ppc64_stub_entry {
105 /*
106 * 28 byte jump instruction sequence (7 instructions) that can
107 * hold ppc64_stub_insns or stub_insns. Must be 8-byte aligned
108 * with PCREL kernels that use prefix instructions in the stub.
109 */
110 u32 jump[7];
111 /* Used by ftrace to identify stubs */
112 u32 magic;
113 /* Data for the above code */
114 func_desc_t funcdata;
115 } __aligned(8);
116
117 struct ppc64_got_entry {
118 u64 addr;
119 };
120
121 /*
122 * PPC64 uses 24 bit jumps, but we need to jump into other modules or
123 * the kernel which may be further. So we jump to a stub.
124 *
125 * Target address and TOC are loaded from function descriptor in the
126 * ppc64_stub_entry.
127 *
128 * r12 is used to generate the target address, which is required for the
129 * ELFv2 global entry point calling convention.
130 *
131 * TOC handling:
132 * - PCREL does not have a TOC.
133 * - ELFv2 non-PCREL just has to save r2, the callee is responsible for
134 * setting its own TOC pointer at the global entry address.
135 * - ELFv1 must load the new TOC pointer from the function descriptor.
136 */
137 static u32 ppc64_stub_insns[] = {
138 #ifdef CONFIG_PPC_KERNEL_PCREL
139 /* pld r12,addr */
140 PPC_PREFIX_8LS | __PPC_PRFX_R(1),
141 PPC_INST_PLD | ___PPC_RT(_R12),
142 #else
143 PPC_RAW_ADDIS(_R11, _R2, 0),
144 PPC_RAW_ADDI(_R11, _R11, 0),
145 /* Save current r2 value in magic place on the stack. */
146 PPC_RAW_STD(_R2, _R1, R2_STACK_OFFSET),
147 PPC_RAW_LD(_R12, _R11, 32),
148 #ifdef CONFIG_PPC64_ELF_ABI_V1
149 /* Set up new r2 from function descriptor */
150 PPC_RAW_LD(_R2, _R11, 40),
151 #endif
152 #endif
153 PPC_RAW_MTCTR(_R12),
154 PPC_RAW_BCTR(),
155 };
156
157 /*
158 * Count how many different r_type relocations (different symbol,
159 * different addend).
160 */
count_relocs(const Elf64_Rela * rela,unsigned int num,unsigned long r_type)161 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num,
162 unsigned long r_type)
163 {
164 unsigned int i, r_info, r_addend, _count_relocs;
165
166 /* FIXME: Only count external ones --RR */
167 _count_relocs = 0;
168 r_info = 0;
169 r_addend = 0;
170 for (i = 0; i < num; i++)
171 /* Only count r_type relocs, others don't need stubs */
172 if (ELF64_R_TYPE(rela[i].r_info) == r_type &&
173 (r_info != ELF64_R_SYM(rela[i].r_info) ||
174 r_addend != rela[i].r_addend)) {
175 _count_relocs++;
176 r_info = ELF64_R_SYM(rela[i].r_info);
177 r_addend = rela[i].r_addend;
178 }
179
180 return _count_relocs;
181 }
182
relacmp(const void * _x,const void * _y)183 static int relacmp(const void *_x, const void *_y)
184 {
185 const Elf64_Rela *x, *y;
186
187 y = (Elf64_Rela *)_x;
188 x = (Elf64_Rela *)_y;
189
190 /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
191 * make the comparison cheaper/faster. It won't affect the sorting or
192 * the counting algorithms' performance
193 */
194 if (x->r_info < y->r_info)
195 return -1;
196 else if (x->r_info > y->r_info)
197 return 1;
198 else if (x->r_addend < y->r_addend)
199 return -1;
200 else if (x->r_addend > y->r_addend)
201 return 1;
202 else
203 return 0;
204 }
205
206 /* Get size of potential trampolines required. */
get_stubs_size(const Elf64_Ehdr * hdr,const Elf64_Shdr * sechdrs,char * secstrings,struct module * me)207 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
208 const Elf64_Shdr *sechdrs,
209 char *secstrings,
210 struct module *me)
211 {
212 /* One extra reloc so it's always 0-addr terminated */
213 unsigned long relocs = 1;
214 unsigned i;
215
216 /* Every relocated section... */
217 for (i = 1; i < hdr->e_shnum; i++) {
218 if (sechdrs[i].sh_type == SHT_RELA) {
219 pr_debug("Found relocations in section %u\n", i);
220 pr_debug("Ptr: %p. Number: %Lu\n",
221 (void *)sechdrs[i].sh_addr,
222 sechdrs[i].sh_size / sizeof(Elf64_Rela));
223
224 /* Sort the relocation information based on a symbol and
225 * addend key. This is a stable O(n*log n) complexity
226 * algorithm but it will reduce the complexity of
227 * count_relocs() to linear complexity O(n)
228 */
229 sort((void *)sechdrs[i].sh_addr,
230 sechdrs[i].sh_size / sizeof(Elf64_Rela),
231 sizeof(Elf64_Rela), relacmp, NULL);
232
233 relocs += count_relocs((void *)sechdrs[i].sh_addr,
234 sechdrs[i].sh_size
235 / sizeof(Elf64_Rela),
236 R_PPC_REL24);
237 #ifdef CONFIG_PPC_KERNEL_PCREL
238 relocs += count_relocs((void *)sechdrs[i].sh_addr,
239 sechdrs[i].sh_size
240 / sizeof(Elf64_Rela),
241 R_PPC64_REL24_NOTOC);
242 #endif
243 }
244 }
245
246 /* stubs for ftrace_caller and ftrace_regs_caller */
247 relocs += IS_ENABLED(CONFIG_DYNAMIC_FTRACE) + IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS);
248
249 #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
250 /* stubs for the function tracer */
251 for (i = 1; i < hdr->e_shnum; i++) {
252 if (!strcmp(secstrings + sechdrs[i].sh_name, "__patchable_function_entries")) {
253 me->arch.ool_stub_count = sechdrs[i].sh_size / sizeof(unsigned long);
254 me->arch.ool_stub_index = 0;
255 relocs += roundup(me->arch.ool_stub_count * sizeof(struct ftrace_ool_stub),
256 sizeof(struct ppc64_stub_entry)) /
257 sizeof(struct ppc64_stub_entry);
258 break;
259 }
260 }
261 #endif
262
263 pr_debug("Looks like a total of %lu stubs, max\n", relocs);
264 return relocs * sizeof(struct ppc64_stub_entry);
265 }
266
267 #ifdef CONFIG_PPC_KERNEL_PCREL
count_pcpu_relocs(const Elf64_Shdr * sechdrs,const Elf64_Rela * rela,unsigned int num,unsigned int symindex,unsigned int pcpu)268 static int count_pcpu_relocs(const Elf64_Shdr *sechdrs,
269 const Elf64_Rela *rela, unsigned int num,
270 unsigned int symindex, unsigned int pcpu)
271 {
272 unsigned int i, r_info, r_addend, _count_relocs;
273
274 _count_relocs = 0;
275 r_info = 0;
276 r_addend = 0;
277
278 for (i = 0; i < num; i++) {
279 Elf64_Sym *sym;
280
281 /* This is the symbol it is referring to */
282 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
283 + ELF64_R_SYM(rela[i].r_info);
284
285 if (sym->st_shndx == pcpu &&
286 (r_info != ELF64_R_SYM(rela[i].r_info) ||
287 r_addend != rela[i].r_addend)) {
288 _count_relocs++;
289 r_info = ELF64_R_SYM(rela[i].r_info);
290 r_addend = rela[i].r_addend;
291 }
292 }
293
294 return _count_relocs;
295 }
296
297 /* Get size of potential GOT required. */
get_got_size(const Elf64_Ehdr * hdr,const Elf64_Shdr * sechdrs,struct module * me)298 static unsigned long get_got_size(const Elf64_Ehdr *hdr,
299 const Elf64_Shdr *sechdrs,
300 struct module *me)
301 {
302 /* One extra reloc so it's always 0-addr terminated */
303 unsigned long relocs = 1;
304 unsigned int i, symindex = 0;
305
306 for (i = 1; i < hdr->e_shnum; i++) {
307 if (sechdrs[i].sh_type == SHT_SYMTAB) {
308 symindex = i;
309 break;
310 }
311 }
312 WARN_ON_ONCE(!symindex);
313
314 /* Every relocated section... */
315 for (i = 1; i < hdr->e_shnum; i++) {
316 if (sechdrs[i].sh_type == SHT_RELA) {
317 pr_debug("Found relocations in section %u\n", i);
318 pr_debug("Ptr: %p. Number: %llu\n", (void *)sechdrs[i].sh_addr,
319 sechdrs[i].sh_size / sizeof(Elf64_Rela));
320
321 /*
322 * Sort the relocation information based on a symbol and
323 * addend key. This is a stable O(n*log n) complexity
324 * algorithm but it will reduce the complexity of
325 * count_relocs() to linear complexity O(n)
326 */
327 sort((void *)sechdrs[i].sh_addr,
328 sechdrs[i].sh_size / sizeof(Elf64_Rela),
329 sizeof(Elf64_Rela), relacmp, NULL);
330
331 relocs += count_relocs((void *)sechdrs[i].sh_addr,
332 sechdrs[i].sh_size
333 / sizeof(Elf64_Rela),
334 R_PPC64_GOT_PCREL34);
335
336 /*
337 * Percpu data access typically gets linked with
338 * REL34 relocations, but the percpu section gets
339 * moved at load time and requires that to be
340 * converted to GOT linkage.
341 */
342 if (IS_ENABLED(CONFIG_SMP) && symindex)
343 relocs += count_pcpu_relocs(sechdrs,
344 (void *)sechdrs[i].sh_addr,
345 sechdrs[i].sh_size
346 / sizeof(Elf64_Rela),
347 symindex, me->arch.pcpu_section);
348 }
349 }
350
351 pr_debug("Looks like a total of %lu GOT entries, max\n", relocs);
352 return relocs * sizeof(struct ppc64_got_entry);
353 }
354 #else /* CONFIG_PPC_KERNEL_PCREL */
355
356 /* Still needed for ELFv2, for .TOC. */
dedotify_versions(struct modversion_info * vers,unsigned long size)357 static void dedotify_versions(struct modversion_info *vers,
358 unsigned long size)
359 {
360 struct modversion_info *end;
361
362 for (end = (void *)vers + size; vers < end; vers++)
363 if (vers->name[0] == '.') {
364 memmove(vers->name, vers->name+1, strlen(vers->name));
365 }
366 }
367
368 /* Same as normal versions, remove a leading dot if present. */
dedotify_ext_version_names(char * str_seq,unsigned long size)369 static void dedotify_ext_version_names(char *str_seq, unsigned long size)
370 {
371 unsigned long out = 0;
372 unsigned long in;
373 char last = '\0';
374
375 for (in = 0; in < size; in++) {
376 /* Skip one leading dot */
377 if (last == '\0' && str_seq[in] == '.')
378 in++;
379 last = str_seq[in];
380 str_seq[out++] = last;
381 }
382 /* Zero the trailing portion of the names table for robustness */
383 memset(&str_seq[out], 0, size - out);
384 }
385
386 /*
387 * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
388 * seem to be defined (value set later).
389 */
dedotify(Elf64_Sym * syms,unsigned int numsyms,char * strtab)390 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
391 {
392 unsigned int i;
393
394 for (i = 1; i < numsyms; i++) {
395 if (syms[i].st_shndx == SHN_UNDEF) {
396 char *name = strtab + syms[i].st_name;
397 if (name[0] == '.') {
398 if (strcmp(name+1, "TOC.") == 0)
399 syms[i].st_shndx = SHN_ABS;
400 syms[i].st_name++;
401 }
402 }
403 }
404 }
405
find_dot_toc(Elf64_Shdr * sechdrs,const char * strtab,unsigned int symindex)406 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
407 const char *strtab,
408 unsigned int symindex)
409 {
410 unsigned int i, numsyms;
411 Elf64_Sym *syms;
412
413 syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
414 numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
415
416 for (i = 1; i < numsyms; i++) {
417 if (syms[i].st_shndx == SHN_ABS
418 && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
419 return &syms[i];
420 }
421 return NULL;
422 }
423 #endif /* CONFIG_PPC_KERNEL_PCREL */
424
module_init_section(const char * name)425 bool module_init_section(const char *name)
426 {
427 /* We don't handle .init for the moment: always return false. */
428 return false;
429 }
430
module_frob_arch_sections(Elf64_Ehdr * hdr,Elf64_Shdr * sechdrs,char * secstrings,struct module * me)431 int module_frob_arch_sections(Elf64_Ehdr *hdr,
432 Elf64_Shdr *sechdrs,
433 char *secstrings,
434 struct module *me)
435 {
436 unsigned int i;
437
438 /* Find .toc and .stubs sections, symtab and strtab */
439 for (i = 1; i < hdr->e_shnum; i++) {
440 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
441 me->arch.stubs_section = i;
442 #ifdef CONFIG_PPC_KERNEL_PCREL
443 else if (strcmp(secstrings + sechdrs[i].sh_name, ".data..percpu") == 0)
444 me->arch.pcpu_section = i;
445 else if (strcmp(secstrings + sechdrs[i].sh_name, ".mygot") == 0) {
446 me->arch.got_section = i;
447 if (sechdrs[i].sh_addralign < 8)
448 sechdrs[i].sh_addralign = 8;
449 }
450 #else
451 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) {
452 me->arch.toc_section = i;
453 if (sechdrs[i].sh_addralign < 8)
454 sechdrs[i].sh_addralign = 8;
455 } else if (strcmp(secstrings + sechdrs[i].sh_name, "__versions") == 0)
456 dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
457 sechdrs[i].sh_size);
458 else if (strcmp(secstrings + sechdrs[i].sh_name, "__version_ext_names") == 0)
459 dedotify_ext_version_names((void *)hdr + sechdrs[i].sh_offset,
460 sechdrs[i].sh_size);
461
462 if (sechdrs[i].sh_type == SHT_SYMTAB)
463 dedotify((void *)hdr + sechdrs[i].sh_offset,
464 sechdrs[i].sh_size / sizeof(Elf64_Sym),
465 (void *)hdr
466 + sechdrs[sechdrs[i].sh_link].sh_offset);
467 #endif
468 }
469
470 if (!me->arch.stubs_section) {
471 pr_err("%s: doesn't contain .stubs.\n", me->name);
472 return -ENOEXEC;
473 }
474
475 #ifdef CONFIG_PPC_KERNEL_PCREL
476 if (!me->arch.got_section) {
477 pr_err("%s: doesn't contain .mygot.\n", me->name);
478 return -ENOEXEC;
479 }
480
481 /* Override the got size */
482 sechdrs[me->arch.got_section].sh_size = get_got_size(hdr, sechdrs, me);
483 #else
484 /* If we don't have a .toc, just use .stubs. We need to set r2
485 to some reasonable value in case the module calls out to
486 other functions via a stub, or if a function pointer escapes
487 the module by some means. */
488 if (!me->arch.toc_section)
489 me->arch.toc_section = me->arch.stubs_section;
490 #endif
491
492 /* Override the stubs size */
493 sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs, secstrings, me);
494
495 return 0;
496 }
497
498 #if defined(CONFIG_MPROFILE_KERNEL) || defined(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)
499
500 static u32 stub_insns[] = {
501 #ifdef CONFIG_PPC_KERNEL_PCREL
502 PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernelbase)),
503 PPC_RAW_NOP(), /* align the prefix insn */
504 /* paddi r12,r12,addr */
505 PPC_PREFIX_MLS | __PPC_PRFX_R(0),
506 PPC_INST_PADDI | ___PPC_RT(_R12) | ___PPC_RA(_R12),
507 PPC_RAW_MTCTR(_R12),
508 PPC_RAW_BCTR(),
509 #else
510 PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
511 PPC_RAW_ADDIS(_R12, _R12, 0),
512 PPC_RAW_ADDI(_R12, _R12, 0),
513 PPC_RAW_MTCTR(_R12),
514 PPC_RAW_BCTR(),
515 #endif
516 };
517
518 /*
519 * For mprofile-kernel we use a special stub for ftrace_caller() because we
520 * can't rely on r2 containing this module's TOC when we enter the stub.
521 *
522 * That can happen if the function calling us didn't need to use the toc. In
523 * that case it won't have setup r2, and the r2 value will be either the
524 * kernel's toc, or possibly another modules toc.
525 *
526 * To deal with that this stub uses the kernel toc, which is always accessible
527 * via the paca (in r13). The target (ftrace_caller()) is responsible for
528 * saving and restoring the toc before returning.
529 */
create_ftrace_stub(struct ppc64_stub_entry * entry,unsigned long addr,struct module * me)530 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
531 unsigned long addr,
532 struct module *me)
533 {
534 long reladdr;
535
536 if ((unsigned long)entry->jump % 8 != 0) {
537 pr_err("%s: Address of stub entry is not 8-byte aligned\n", me->name);
538 return 0;
539 }
540
541 BUILD_BUG_ON(sizeof(stub_insns) > sizeof(entry->jump));
542 memcpy(entry->jump, stub_insns, sizeof(stub_insns));
543
544 if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
545 /* Stub uses address relative to kernel base (from the paca) */
546 reladdr = addr - local_paca->kernelbase;
547 if (reladdr > 0x1FFFFFFFFL || reladdr < -0x200000000L) {
548 pr_err("%s: Address of %ps out of range of 34-bit relative address.\n",
549 me->name, (void *)addr);
550 return 0;
551 }
552
553 entry->jump[2] |= IMM_H18(reladdr);
554 entry->jump[3] |= IMM_L(reladdr);
555 } else {
556 /* Stub uses address relative to kernel toc (from the paca) */
557 reladdr = addr - kernel_toc_addr();
558 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
559 pr_err("%s: Address of %ps out of range of kernel_toc.\n",
560 me->name, (void *)addr);
561 return 0;
562 }
563
564 entry->jump[1] |= PPC_HA(reladdr);
565 entry->jump[2] |= PPC_LO(reladdr);
566 }
567
568 /* Even though we don't use funcdata in the stub, it's needed elsewhere. */
569 entry->funcdata = func_desc(addr);
570 entry->magic = STUB_MAGIC;
571
572 return 1;
573 }
574
is_mprofile_ftrace_call(const char * name)575 static bool is_mprofile_ftrace_call(const char *name)
576 {
577 if (!strcmp("_mcount", name))
578 return true;
579 #ifdef CONFIG_DYNAMIC_FTRACE
580 if (!strcmp("ftrace_caller", name))
581 return true;
582 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
583 if (!strcmp("ftrace_regs_caller", name))
584 return true;
585 #endif
586 #endif
587
588 return false;
589 }
590 #else
create_ftrace_stub(struct ppc64_stub_entry * entry,unsigned long addr,struct module * me)591 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
592 unsigned long addr,
593 struct module *me)
594 {
595 return 0;
596 }
597
is_mprofile_ftrace_call(const char * name)598 static bool is_mprofile_ftrace_call(const char *name)
599 {
600 return false;
601 }
602 #endif
603
604 /*
605 * r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the
606 * value maximum span in an instruction which uses a signed offset). Round down
607 * to a 256 byte boundary for the odd case where we are setting up r2 without a
608 * .toc section.
609 */
my_r2(const Elf64_Shdr * sechdrs,struct module * me)610 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
611 {
612 #ifndef CONFIG_PPC_KERNEL_PCREL
613 return (sechdrs[me->arch.toc_section].sh_addr & ~0xfful) + 0x8000;
614 #else
615 return -1;
616 #endif
617 }
618
619 /* 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,const char * name)620 static inline int create_stub(const Elf64_Shdr *sechdrs,
621 struct ppc64_stub_entry *entry,
622 unsigned long addr,
623 struct module *me,
624 const char *name)
625 {
626 long reladdr;
627 func_desc_t desc;
628 int i;
629
630 if (is_mprofile_ftrace_call(name))
631 return create_ftrace_stub(entry, addr, me);
632
633 if ((unsigned long)entry->jump % 8 != 0) {
634 pr_err("%s: Address of stub entry is not 8-byte aligned\n", me->name);
635 return 0;
636 }
637
638 BUILD_BUG_ON(sizeof(ppc64_stub_insns) > sizeof(entry->jump));
639 for (i = 0; i < ARRAY_SIZE(ppc64_stub_insns); i++) {
640 if (patch_instruction(&entry->jump[i],
641 ppc_inst(ppc64_stub_insns[i])))
642 return 0;
643 }
644
645 if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
646 /* Stub uses address relative to itself! */
647 reladdr = 0 + offsetof(struct ppc64_stub_entry, funcdata);
648 BUILD_BUG_ON(reladdr != 32);
649 if (reladdr > 0x1FFFFFFFFL || reladdr < -0x200000000L) {
650 pr_err("%s: Address of %p out of range of 34-bit relative address.\n",
651 me->name, (void *)reladdr);
652 return 0;
653 }
654 pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
655
656 /* May not even need this if we're relative to 0 */
657 if (patch_instruction(&entry->jump[0],
658 ppc_inst_prefix(entry->jump[0] | IMM_H18(reladdr),
659 entry->jump[1] | IMM_L(reladdr))))
660 return 0;
661
662 } else {
663 /* Stub uses address relative to r2. */
664 reladdr = (unsigned long)entry - my_r2(sechdrs, me);
665 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
666 pr_err("%s: Address %p of stub out of range of %p.\n",
667 me->name, (void *)reladdr, (void *)my_r2);
668 return 0;
669 }
670 pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
671
672 if (patch_instruction(&entry->jump[0],
673 ppc_inst(entry->jump[0] | PPC_HA(reladdr))))
674 return 0;
675
676 if (patch_instruction(&entry->jump[1],
677 ppc_inst(entry->jump[1] | PPC_LO(reladdr))))
678 return 0;
679 }
680
681 // func_desc_t is 8 bytes if ABIv2, else 16 bytes
682 desc = func_desc(addr);
683 for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) {
684 if (patch_u32(((u32 *)&entry->funcdata) + i, ((u32 *)&desc)[i]))
685 return 0;
686 }
687
688 if (patch_u32(&entry->magic, STUB_MAGIC))
689 return 0;
690
691 return 1;
692 }
693
694 /* Create stub to jump to function described in this OPD/ptr: we need the
695 stub to set up the TOC ptr (r2) for the function. */
stub_for_addr(const Elf64_Shdr * sechdrs,unsigned long addr,struct module * me,const char * name)696 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
697 unsigned long addr,
698 struct module *me,
699 const char *name)
700 {
701 struct ppc64_stub_entry *stubs;
702 unsigned int i, num_stubs;
703
704 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
705
706 /* Find this stub, or if that fails, the next avail. entry */
707 stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
708 for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
709 if (WARN_ON(i >= num_stubs))
710 return 0;
711
712 if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
713 return (unsigned long)&stubs[i];
714 }
715
716 if (!create_stub(sechdrs, &stubs[i], addr, me, name))
717 return 0;
718
719 return (unsigned long)&stubs[i];
720 }
721
722 #ifdef CONFIG_PPC_KERNEL_PCREL
723 /* Create GOT to load the location described in this ptr */
got_for_addr(const Elf64_Shdr * sechdrs,unsigned long addr,struct module * me,const char * name)724 static unsigned long got_for_addr(const Elf64_Shdr *sechdrs,
725 unsigned long addr,
726 struct module *me,
727 const char *name)
728 {
729 struct ppc64_got_entry *got;
730 unsigned int i, num_got;
731
732 if (!IS_ENABLED(CONFIG_PPC_KERNEL_PCREL))
733 return addr;
734
735 num_got = sechdrs[me->arch.got_section].sh_size / sizeof(*got);
736
737 /* Find this stub, or if that fails, the next avail. entry */
738 got = (void *)sechdrs[me->arch.got_section].sh_addr;
739 for (i = 0; got[i].addr; i++) {
740 if (WARN_ON(i >= num_got))
741 return 0;
742
743 if (got[i].addr == addr)
744 return (unsigned long)&got[i];
745 }
746
747 got[i].addr = addr;
748
749 return (unsigned long)&got[i];
750 }
751 #endif
752
753 /* We expect a noop next: if it is, replace it with instruction to
754 restore r2. */
restore_r2(const char * name,u32 * instruction,struct module * me)755 static int restore_r2(const char *name, u32 *instruction, struct module *me)
756 {
757 u32 *prev_insn = instruction - 1;
758 u32 insn_val = *instruction;
759
760 if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL))
761 return 0;
762
763 if (is_mprofile_ftrace_call(name))
764 return 0;
765
766 /*
767 * Make sure the branch isn't a sibling call. Sibling calls aren't
768 * "link" branches and they don't return, so they don't need the r2
769 * restore afterwards.
770 */
771 if (!instr_is_relative_link_branch(ppc_inst(*prev_insn)))
772 return 0;
773
774 /*
775 * For livepatch, the restore r2 instruction might have already been
776 * written previously, if the referenced symbol is in a previously
777 * unloaded module which is now being loaded again. In that case, skip
778 * the warning and the instruction write.
779 */
780 if (insn_val == PPC_INST_LD_TOC)
781 return 0;
782
783 if (insn_val != PPC_RAW_NOP()) {
784 pr_err("%s: Expected nop after call, got %08x at %pS\n",
785 me->name, insn_val, instruction);
786 return -ENOEXEC;
787 }
788
789 /* ld r2,R2_STACK_OFFSET(r1) */
790 return patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC));
791 }
792
apply_relocate_add(Elf64_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * me)793 int apply_relocate_add(Elf64_Shdr *sechdrs,
794 const char *strtab,
795 unsigned int symindex,
796 unsigned int relsec,
797 struct module *me)
798 {
799 unsigned int i;
800 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
801 Elf64_Sym *sym;
802 unsigned long *location;
803 unsigned long value;
804
805 pr_debug("Applying ADD relocate section %u to %u\n", relsec,
806 sechdrs[relsec].sh_info);
807
808 #ifndef CONFIG_PPC_KERNEL_PCREL
809 /* First time we're called, we can fix up .TOC. */
810 if (!me->arch.toc_fixed) {
811 sym = find_dot_toc(sechdrs, strtab, symindex);
812 /* It's theoretically possible that a module doesn't want a
813 * .TOC. so don't fail it just for that. */
814 if (sym)
815 sym->st_value = my_r2(sechdrs, me);
816 me->arch.toc_fixed = true;
817 }
818 #endif
819 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
820 /* This is where to make the change */
821 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
822 + rela[i].r_offset;
823 /* This is the symbol it is referring to */
824 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
825 + ELF64_R_SYM(rela[i].r_info);
826
827 pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
828 location, (long)ELF64_R_TYPE(rela[i].r_info),
829 strtab + sym->st_name, (unsigned long)sym->st_value,
830 (long)rela[i].r_addend);
831
832 /* `Everything is relative'. */
833 value = sym->st_value + rela[i].r_addend;
834
835 switch (ELF64_R_TYPE(rela[i].r_info)) {
836 case R_PPC64_ADDR32:
837 /* Simply set it */
838 *(u32 *)location = value;
839 break;
840
841 case R_PPC64_ADDR64:
842 /* Simply set it */
843 *(unsigned long *)location = value;
844 break;
845
846 #ifndef CONFIG_PPC_KERNEL_PCREL
847 case R_PPC64_TOC:
848 *(unsigned long *)location = my_r2(sechdrs, me);
849 break;
850
851 case R_PPC64_TOC16:
852 /* Subtract TOC pointer */
853 value -= my_r2(sechdrs, me);
854 if (value + 0x8000 > 0xffff) {
855 pr_err("%s: bad TOC16 relocation (0x%lx)\n",
856 me->name, value);
857 return -ENOEXEC;
858 }
859 *((uint16_t *) location)
860 = (*((uint16_t *) location) & ~0xffff)
861 | (value & 0xffff);
862 break;
863
864 case R_PPC64_TOC16_LO:
865 /* Subtract TOC pointer */
866 value -= my_r2(sechdrs, me);
867 *((uint16_t *) location)
868 = (*((uint16_t *) location) & ~0xffff)
869 | (value & 0xffff);
870 break;
871
872 case R_PPC64_TOC16_DS:
873 /* Subtract TOC pointer */
874 value -= my_r2(sechdrs, me);
875 if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
876 pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
877 me->name, value);
878 return -ENOEXEC;
879 }
880 *((uint16_t *) location)
881 = (*((uint16_t *) location) & ~0xfffc)
882 | (value & 0xfffc);
883 break;
884
885 case R_PPC64_TOC16_LO_DS:
886 /* Subtract TOC pointer */
887 value -= my_r2(sechdrs, me);
888 if ((value & 3) != 0) {
889 pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
890 me->name, value);
891 return -ENOEXEC;
892 }
893 *((uint16_t *) location)
894 = (*((uint16_t *) location) & ~0xfffc)
895 | (value & 0xfffc);
896 break;
897
898 case R_PPC64_TOC16_HA:
899 /* Subtract TOC pointer */
900 value -= my_r2(sechdrs, me);
901 value = ((value + 0x8000) >> 16);
902 *((uint16_t *) location)
903 = (*((uint16_t *) location) & ~0xffff)
904 | (value & 0xffff);
905 break;
906 #endif
907
908 case R_PPC_REL24:
909 #ifdef CONFIG_PPC_KERNEL_PCREL
910 /* PCREL still generates REL24 for mcount */
911 case R_PPC64_REL24_NOTOC:
912 #endif
913 /* FIXME: Handle weak symbols here --RR */
914 if (sym->st_shndx == SHN_UNDEF ||
915 sym->st_shndx == SHN_LIVEPATCH) {
916 /* External: go via stub */
917 value = stub_for_addr(sechdrs, value, me,
918 strtab + sym->st_name);
919 if (!value)
920 return -ENOENT;
921 if (restore_r2(strtab + sym->st_name,
922 (u32 *)location + 1, me))
923 return -ENOEXEC;
924 } else
925 value += local_entry_offset(sym);
926
927 /* Convert value to relative */
928 value -= (unsigned long)location;
929 if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
930 pr_err("%s: REL24 %li out of range!\n",
931 me->name, (long int)value);
932 return -ENOEXEC;
933 }
934
935 /* Only replace bits 2 through 26 */
936 value = (*(uint32_t *)location & ~PPC_LI_MASK) | PPC_LI(value);
937
938 if (patch_instruction((u32 *)location, ppc_inst(value)))
939 return -EFAULT;
940
941 break;
942
943 case R_PPC64_REL64:
944 /* 64 bits relative (used by features fixups) */
945 *location = value - (unsigned long)location;
946 break;
947
948 case R_PPC64_REL32:
949 /* 32 bits relative (used by relative exception tables) */
950 /* Convert value to relative */
951 value -= (unsigned long)location;
952 if (value + 0x80000000 > 0xffffffff) {
953 pr_err("%s: REL32 %li out of range!\n",
954 me->name, (long int)value);
955 return -ENOEXEC;
956 }
957 *(u32 *)location = value;
958 break;
959
960 #ifdef CONFIG_PPC_KERNEL_PCREL
961 case R_PPC64_PCREL34: {
962 unsigned long absvalue = value;
963
964 /* Convert value to relative */
965 value -= (unsigned long)location;
966
967 if (value + 0x200000000 > 0x3ffffffff) {
968 if (sym->st_shndx != me->arch.pcpu_section) {
969 pr_err("%s: REL34 %li out of range!\n",
970 me->name, (long)value);
971 return -ENOEXEC;
972 }
973
974 /*
975 * per-cpu section is special cased because
976 * it is moved during loading, so has to be
977 * converted to use GOT.
978 */
979 value = got_for_addr(sechdrs, absvalue, me,
980 strtab + sym->st_name);
981 if (!value)
982 return -ENOENT;
983 value -= (unsigned long)location;
984
985 /* Turn pla into pld */
986 if (patch_instruction((u32 *)location,
987 ppc_inst_prefix((*(u32 *)location & ~0x02000000),
988 (*((u32 *)location + 1) & ~0xf8000000) | 0xe4000000)))
989 return -EFAULT;
990 }
991
992 if (patch_instruction((u32 *)location,
993 ppc_inst_prefix((*(u32 *)location & ~0x3ffff) | IMM_H18(value),
994 (*((u32 *)location + 1) & ~0xffff) | IMM_L(value))))
995 return -EFAULT;
996
997 break;
998 }
999
1000 #else
1001 case R_PPC64_TOCSAVE:
1002 /*
1003 * Marker reloc indicates we don't have to save r2.
1004 * That would only save us one instruction, so ignore
1005 * it.
1006 */
1007 break;
1008 #endif
1009
1010 case R_PPC64_ENTRY:
1011 if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL))
1012 break;
1013
1014 /*
1015 * Optimize ELFv2 large code model entry point if
1016 * the TOC is within 2GB range of current location.
1017 */
1018 value = my_r2(sechdrs, me) - (unsigned long)location;
1019 if (value + 0x80008000 > 0xffffffff)
1020 break;
1021 /*
1022 * Check for the large code model prolog sequence:
1023 * ld r2, ...(r12)
1024 * add r2, r2, r12
1025 */
1026 if ((((uint32_t *)location)[0] & ~0xfffc) != PPC_RAW_LD(_R2, _R12, 0))
1027 break;
1028 if (((uint32_t *)location)[1] != PPC_RAW_ADD(_R2, _R2, _R12))
1029 break;
1030 /*
1031 * If found, replace it with:
1032 * addis r2, r12, (.TOC.-func)@ha
1033 * addi r2, r2, (.TOC.-func)@l
1034 */
1035 ((uint32_t *)location)[0] = PPC_RAW_ADDIS(_R2, _R12, PPC_HA(value));
1036 ((uint32_t *)location)[1] = PPC_RAW_ADDI(_R2, _R2, PPC_LO(value));
1037 break;
1038
1039 case R_PPC64_REL16_HA:
1040 /* Subtract location pointer */
1041 value -= (unsigned long)location;
1042 value = ((value + 0x8000) >> 16);
1043 *((uint16_t *) location)
1044 = (*((uint16_t *) location) & ~0xffff)
1045 | (value & 0xffff);
1046 break;
1047
1048 case R_PPC64_REL16_LO:
1049 /* Subtract location pointer */
1050 value -= (unsigned long)location;
1051 *((uint16_t *) location)
1052 = (*((uint16_t *) location) & ~0xffff)
1053 | (value & 0xffff);
1054 break;
1055
1056 #ifdef CONFIG_PPC_KERNEL_PCREL
1057 case R_PPC64_GOT_PCREL34:
1058 value = got_for_addr(sechdrs, value, me,
1059 strtab + sym->st_name);
1060 if (!value)
1061 return -ENOENT;
1062 value -= (unsigned long)location;
1063 ((uint32_t *)location)[0] = (((uint32_t *)location)[0] & ~0x3ffff) |
1064 ((value >> 16) & 0x3ffff);
1065 ((uint32_t *)location)[1] = (((uint32_t *)location)[1] & ~0xffff) |
1066 (value & 0xffff);
1067 break;
1068 #endif
1069
1070 default:
1071 pr_err("%s: Unknown ADD relocation: %lu\n",
1072 me->name,
1073 (unsigned long)ELF64_R_TYPE(rela[i].r_info));
1074 return -ENOEXEC;
1075 }
1076 }
1077
1078 return 0;
1079 }
1080
1081 #ifdef CONFIG_DYNAMIC_FTRACE
module_trampoline_target(struct module * mod,unsigned long addr,unsigned long * target)1082 int module_trampoline_target(struct module *mod, unsigned long addr,
1083 unsigned long *target)
1084 {
1085 struct ppc64_stub_entry *stub;
1086 func_desc_t funcdata;
1087 u32 magic;
1088
1089 if (!within_module_core(addr, mod)) {
1090 pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name);
1091 return -EFAULT;
1092 }
1093
1094 stub = (struct ppc64_stub_entry *)addr;
1095
1096 if (copy_from_kernel_nofault(&magic, &stub->magic,
1097 sizeof(magic))) {
1098 pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
1099 return -EFAULT;
1100 }
1101
1102 if (magic != STUB_MAGIC) {
1103 pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name);
1104 return -EFAULT;
1105 }
1106
1107 if (copy_from_kernel_nofault(&funcdata, &stub->funcdata,
1108 sizeof(funcdata))) {
1109 pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
1110 return -EFAULT;
1111 }
1112
1113 *target = stub_func_addr(funcdata);
1114
1115 return 0;
1116 }
1117
setup_ftrace_ool_stubs(const Elf64_Shdr * sechdrs,unsigned long addr,struct module * me)1118 static int setup_ftrace_ool_stubs(const Elf64_Shdr *sechdrs, unsigned long addr, struct module *me)
1119 {
1120 #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
1121 unsigned int i, total_stubs, num_stubs;
1122 struct ppc64_stub_entry *stub;
1123
1124 total_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stub);
1125 num_stubs = roundup(me->arch.ool_stub_count * sizeof(struct ftrace_ool_stub),
1126 sizeof(struct ppc64_stub_entry)) / sizeof(struct ppc64_stub_entry);
1127
1128 /* Find the next available entry */
1129 stub = (void *)sechdrs[me->arch.stubs_section].sh_addr;
1130 for (i = 0; stub_func_addr(stub[i].funcdata); i++)
1131 if (WARN_ON(i >= total_stubs))
1132 return -1;
1133
1134 if (WARN_ON(i + num_stubs > total_stubs))
1135 return -1;
1136
1137 stub += i;
1138 me->arch.ool_stubs = (struct ftrace_ool_stub *)stub;
1139
1140 /* reserve stubs */
1141 for (i = 0; i < num_stubs; i++)
1142 if (patch_u32((void *)&stub->funcdata, PPC_RAW_NOP()))
1143 return -1;
1144 #endif
1145
1146 return 0;
1147 }
1148
module_finalize_ftrace(struct module * mod,const Elf_Shdr * sechdrs)1149 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
1150 {
1151 mod->arch.tramp = stub_for_addr(sechdrs,
1152 (unsigned long)ftrace_caller,
1153 mod,
1154 "ftrace_caller");
1155 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
1156 mod->arch.tramp_regs = stub_for_addr(sechdrs,
1157 (unsigned long)ftrace_regs_caller,
1158 mod,
1159 "ftrace_regs_caller");
1160 if (!mod->arch.tramp_regs)
1161 return -ENOENT;
1162 #endif
1163
1164 if (!mod->arch.tramp)
1165 return -ENOENT;
1166
1167 if (setup_ftrace_ool_stubs(sechdrs, mod->arch.tramp, mod))
1168 return -ENOENT;
1169
1170 return 0;
1171 }
1172 #endif
1173