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/code-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 
34 #ifdef CONFIG_PPC64_ELF_ABI_V2
35 
func_desc(unsigned long addr)36 static func_desc_t func_desc(unsigned long addr)
37 {
38 	func_desc_t desc = {
39 		.addr = addr,
40 	};
41 
42 	return desc;
43 }
44 
45 /* PowerPC64 specific values for the Elf64_Sym st_other field.  */
46 #define STO_PPC64_LOCAL_BIT	5
47 #define STO_PPC64_LOCAL_MASK	(7 << STO_PPC64_LOCAL_BIT)
48 #define PPC64_LOCAL_ENTRY_OFFSET(other)					\
49  (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
50 
local_entry_offset(const Elf64_Sym * sym)51 static unsigned int local_entry_offset(const Elf64_Sym *sym)
52 {
53 	/* sym->st_other indicates offset to local entry point
54 	 * (otherwise it will assume r12 is the address of the start
55 	 * of function and try to derive r2 from it). */
56 	return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
57 }
58 #else
59 
func_desc(unsigned long addr)60 static func_desc_t func_desc(unsigned long addr)
61 {
62 	return *(struct func_desc *)addr;
63 }
local_entry_offset(const Elf64_Sym * sym)64 static unsigned int local_entry_offset(const Elf64_Sym *sym)
65 {
66 	return 0;
67 }
68 
dereference_module_function_descriptor(struct module * mod,void * ptr)69 void *dereference_module_function_descriptor(struct module *mod, void *ptr)
70 {
71 	if (ptr < (void *)mod->arch.start_opd ||
72 			ptr >= (void *)mod->arch.end_opd)
73 		return ptr;
74 
75 	return dereference_function_descriptor(ptr);
76 }
77 #endif
78 
func_addr(unsigned long addr)79 static unsigned long func_addr(unsigned long addr)
80 {
81 	return func_desc(addr).addr;
82 }
83 
stub_func_addr(func_desc_t func)84 static unsigned long stub_func_addr(func_desc_t func)
85 {
86 	return func.addr;
87 }
88 
89 #define STUB_MAGIC 0x73747562 /* stub */
90 
91 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
92    the kernel itself).  But on PPC64, these need to be used for every
93    jump, actually, to reset r2 (TOC+0x8000). */
94 struct ppc64_stub_entry
95 {
96 	/* 28 byte jump instruction sequence (7 instructions). We only
97 	 * need 6 instructions on ABIv2 but we always allocate 7 so
98 	 * so we don't have to modify the trampoline load instruction. */
99 	u32 jump[7];
100 	/* Used by ftrace to identify stubs */
101 	u32 magic;
102 	/* Data for the above code */
103 	func_desc_t funcdata;
104 };
105 
106 /*
107  * PPC64 uses 24 bit jumps, but we need to jump into other modules or
108  * the kernel which may be further.  So we jump to a stub.
109  *
110  * For ELFv1 we need to use this to set up the new r2 value (aka TOC
111  * pointer).  For ELFv2 it's the callee's responsibility to set up the
112  * new r2, but for both we need to save the old r2.
113  *
114  * We could simply patch the new r2 value and function pointer into
115  * the stub, but it's significantly shorter to put these values at the
116  * end of the stub code, and patch the stub address (32-bits relative
117  * to the TOC ptr, r2) into the stub.
118  */
119 static u32 ppc64_stub_insns[] = {
120 	PPC_RAW_ADDIS(_R11, _R2, 0),
121 	PPC_RAW_ADDI(_R11, _R11, 0),
122 	/* Save current r2 value in magic place on the stack. */
123 	PPC_RAW_STD(_R2, _R1, R2_STACK_OFFSET),
124 	PPC_RAW_LD(_R12, _R11, 32),
125 #ifdef CONFIG_PPC64_ELF_ABI_V1
126 	/* Set up new r2 from function descriptor */
127 	PPC_RAW_LD(_R2, _R11, 40),
128 #endif
129 	PPC_RAW_MTCTR(_R12),
130 	PPC_RAW_BCTR(),
131 };
132 
133 /* Count how many different 24-bit relocations (different symbol,
134    different addend) */
count_relocs(const Elf64_Rela * rela,unsigned int num)135 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
136 {
137 	unsigned int i, r_info, r_addend, _count_relocs;
138 
139 	/* FIXME: Only count external ones --RR */
140 	_count_relocs = 0;
141 	r_info = 0;
142 	r_addend = 0;
143 	for (i = 0; i < num; i++)
144 		/* Only count 24-bit relocs, others don't need stubs */
145 		if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
146 		    (r_info != ELF64_R_SYM(rela[i].r_info) ||
147 		     r_addend != rela[i].r_addend)) {
148 			_count_relocs++;
149 			r_info = ELF64_R_SYM(rela[i].r_info);
150 			r_addend = rela[i].r_addend;
151 		}
152 
153 	return _count_relocs;
154 }
155 
relacmp(const void * _x,const void * _y)156 static int relacmp(const void *_x, const void *_y)
157 {
158 	const Elf64_Rela *x, *y;
159 
160 	y = (Elf64_Rela *)_x;
161 	x = (Elf64_Rela *)_y;
162 
163 	/* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
164 	 * make the comparison cheaper/faster. It won't affect the sorting or
165 	 * the counting algorithms' performance
166 	 */
167 	if (x->r_info < y->r_info)
168 		return -1;
169 	else if (x->r_info > y->r_info)
170 		return 1;
171 	else if (x->r_addend < y->r_addend)
172 		return -1;
173 	else if (x->r_addend > y->r_addend)
174 		return 1;
175 	else
176 		return 0;
177 }
178 
179 /* Get size of potential trampolines required. */
get_stubs_size(const Elf64_Ehdr * hdr,const Elf64_Shdr * sechdrs)180 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
181 				    const Elf64_Shdr *sechdrs)
182 {
183 	/* One extra reloc so it's always 0-addr terminated */
184 	unsigned long relocs = 1;
185 	unsigned i;
186 
187 	/* Every relocated section... */
188 	for (i = 1; i < hdr->e_shnum; i++) {
189 		if (sechdrs[i].sh_type == SHT_RELA) {
190 			pr_debug("Found relocations in section %u\n", i);
191 			pr_debug("Ptr: %p.  Number: %Lu\n",
192 			       (void *)sechdrs[i].sh_addr,
193 			       sechdrs[i].sh_size / sizeof(Elf64_Rela));
194 
195 			/* Sort the relocation information based on a symbol and
196 			 * addend key. This is a stable O(n*log n) complexity
197 			 * algorithm but it will reduce the complexity of
198 			 * count_relocs() to linear complexity O(n)
199 			 */
200 			sort((void *)sechdrs[i].sh_addr,
201 			     sechdrs[i].sh_size / sizeof(Elf64_Rela),
202 			     sizeof(Elf64_Rela), relacmp, NULL);
203 
204 			relocs += count_relocs((void *)sechdrs[i].sh_addr,
205 					       sechdrs[i].sh_size
206 					       / sizeof(Elf64_Rela));
207 		}
208 	}
209 
210 #ifdef CONFIG_DYNAMIC_FTRACE
211 	/* make the trampoline to the ftrace_caller */
212 	relocs++;
213 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
214 	/* an additional one for ftrace_regs_caller */
215 	relocs++;
216 #endif
217 #endif
218 
219 	pr_debug("Looks like a total of %lu stubs, max\n", relocs);
220 	return relocs * sizeof(struct ppc64_stub_entry);
221 }
222 
223 /* Still needed for ELFv2, for .TOC. */
dedotify_versions(struct modversion_info * vers,unsigned long size)224 static void dedotify_versions(struct modversion_info *vers,
225 			      unsigned long size)
226 {
227 	struct modversion_info *end;
228 
229 	for (end = (void *)vers + size; vers < end; vers++)
230 		if (vers->name[0] == '.') {
231 			memmove(vers->name, vers->name+1, strlen(vers->name));
232 		}
233 }
234 
235 /*
236  * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
237  * seem to be defined (value set later).
238  */
dedotify(Elf64_Sym * syms,unsigned int numsyms,char * strtab)239 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
240 {
241 	unsigned int i;
242 
243 	for (i = 1; i < numsyms; i++) {
244 		if (syms[i].st_shndx == SHN_UNDEF) {
245 			char *name = strtab + syms[i].st_name;
246 			if (name[0] == '.') {
247 				if (strcmp(name+1, "TOC.") == 0)
248 					syms[i].st_shndx = SHN_ABS;
249 				syms[i].st_name++;
250 			}
251 		}
252 	}
253 }
254 
find_dot_toc(Elf64_Shdr * sechdrs,const char * strtab,unsigned int symindex)255 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
256 			       const char *strtab,
257 			       unsigned int symindex)
258 {
259 	unsigned int i, numsyms;
260 	Elf64_Sym *syms;
261 
262 	syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
263 	numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
264 
265 	for (i = 1; i < numsyms; i++) {
266 		if (syms[i].st_shndx == SHN_ABS
267 		    && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
268 			return &syms[i];
269 	}
270 	return NULL;
271 }
272 
module_init_section(const char * name)273 bool module_init_section(const char *name)
274 {
275 	/* We don't handle .init for the moment: always return false. */
276 	return false;
277 }
278 
module_frob_arch_sections(Elf64_Ehdr * hdr,Elf64_Shdr * sechdrs,char * secstrings,struct module * me)279 int module_frob_arch_sections(Elf64_Ehdr *hdr,
280 			      Elf64_Shdr *sechdrs,
281 			      char *secstrings,
282 			      struct module *me)
283 {
284 	unsigned int i;
285 
286 	/* Find .toc and .stubs sections, symtab and strtab */
287 	for (i = 1; i < hdr->e_shnum; i++) {
288 		if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
289 			me->arch.stubs_section = i;
290 		else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) {
291 			me->arch.toc_section = i;
292 			if (sechdrs[i].sh_addralign < 8)
293 				sechdrs[i].sh_addralign = 8;
294 		}
295 		else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
296 			dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
297 					  sechdrs[i].sh_size);
298 
299 		if (sechdrs[i].sh_type == SHT_SYMTAB)
300 			dedotify((void *)hdr + sechdrs[i].sh_offset,
301 				 sechdrs[i].sh_size / sizeof(Elf64_Sym),
302 				 (void *)hdr
303 				 + sechdrs[sechdrs[i].sh_link].sh_offset);
304 	}
305 
306 	if (!me->arch.stubs_section) {
307 		pr_err("%s: doesn't contain .stubs.\n", me->name);
308 		return -ENOEXEC;
309 	}
310 
311 	/* If we don't have a .toc, just use .stubs.  We need to set r2
312 	   to some reasonable value in case the module calls out to
313 	   other functions via a stub, or if a function pointer escapes
314 	   the module by some means.  */
315 	if (!me->arch.toc_section)
316 		me->arch.toc_section = me->arch.stubs_section;
317 
318 	/* Override the stubs size */
319 	sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
320 	return 0;
321 }
322 
323 #ifdef CONFIG_MPROFILE_KERNEL
324 
325 static u32 stub_insns[] = {
326 	PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
327 	PPC_RAW_ADDIS(_R12, _R12, 0),
328 	PPC_RAW_ADDI(_R12, _R12, 0),
329 	PPC_RAW_MTCTR(_R12),
330 	PPC_RAW_BCTR(),
331 };
332 
333 /*
334  * For mprofile-kernel we use a special stub for ftrace_caller() because we
335  * can't rely on r2 containing this module's TOC when we enter the stub.
336  *
337  * That can happen if the function calling us didn't need to use the toc. In
338  * that case it won't have setup r2, and the r2 value will be either the
339  * kernel's toc, or possibly another modules toc.
340  *
341  * To deal with that this stub uses the kernel toc, which is always accessible
342  * via the paca (in r13). The target (ftrace_caller()) is responsible for
343  * saving and restoring the toc before returning.
344  */
create_ftrace_stub(struct ppc64_stub_entry * entry,unsigned long addr,struct module * me)345 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
346 					unsigned long addr,
347 					struct module *me)
348 {
349 	long reladdr;
350 
351 	memcpy(entry->jump, stub_insns, sizeof(stub_insns));
352 
353 	/* Stub uses address relative to kernel toc (from the paca) */
354 	reladdr = addr - kernel_toc_addr();
355 	if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
356 		pr_err("%s: Address of %ps out of range of kernel_toc.\n",
357 							me->name, (void *)addr);
358 		return 0;
359 	}
360 
361 	entry->jump[1] |= PPC_HA(reladdr);
362 	entry->jump[2] |= PPC_LO(reladdr);
363 
364 	/* Even though we don't use funcdata in the stub, it's needed elsewhere. */
365 	entry->funcdata = func_desc(addr);
366 	entry->magic = STUB_MAGIC;
367 
368 	return 1;
369 }
370 
is_mprofile_ftrace_call(const char * name)371 static bool is_mprofile_ftrace_call(const char *name)
372 {
373 	if (!strcmp("_mcount", name))
374 		return true;
375 #ifdef CONFIG_DYNAMIC_FTRACE
376 	if (!strcmp("ftrace_caller", name))
377 		return true;
378 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
379 	if (!strcmp("ftrace_regs_caller", name))
380 		return true;
381 #endif
382 #endif
383 
384 	return false;
385 }
386 #else
create_ftrace_stub(struct ppc64_stub_entry * entry,unsigned long addr,struct module * me)387 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
388 					unsigned long addr,
389 					struct module *me)
390 {
391 	return 0;
392 }
393 
is_mprofile_ftrace_call(const char * name)394 static bool is_mprofile_ftrace_call(const char *name)
395 {
396 	return false;
397 }
398 #endif
399 
400 /*
401  * r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the
402  * value maximum span in an instruction which uses a signed offset). Round down
403  * to a 256 byte boundary for the odd case where we are setting up r2 without a
404  * .toc section.
405  */
my_r2(const Elf64_Shdr * sechdrs,struct module * me)406 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
407 {
408 	return (sechdrs[me->arch.toc_section].sh_addr & ~0xfful) + 0x8000;
409 }
410 
411 /* 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)412 static inline int create_stub(const Elf64_Shdr *sechdrs,
413 			      struct ppc64_stub_entry *entry,
414 			      unsigned long addr,
415 			      struct module *me,
416 			      const char *name)
417 {
418 	long reladdr;
419 	func_desc_t desc;
420 	int i;
421 
422 	if (is_mprofile_ftrace_call(name))
423 		return create_ftrace_stub(entry, addr, me);
424 
425 	for (i = 0; i < ARRAY_SIZE(ppc64_stub_insns); i++) {
426 		if (patch_instruction(&entry->jump[i],
427 				      ppc_inst(ppc64_stub_insns[i])))
428 			return 0;
429 	}
430 
431 	/* Stub uses address relative to r2. */
432 	reladdr = (unsigned long)entry - my_r2(sechdrs, me);
433 	if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
434 		pr_err("%s: Address %p of stub out of range of %p.\n",
435 		       me->name, (void *)reladdr, (void *)my_r2);
436 		return 0;
437 	}
438 	pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
439 
440 	if (patch_instruction(&entry->jump[0],
441 			      ppc_inst(entry->jump[0] | PPC_HA(reladdr))))
442 		return 0;
443 
444 	if (patch_instruction(&entry->jump[1],
445 			  ppc_inst(entry->jump[1] | PPC_LO(reladdr))))
446 		return 0;
447 
448 	// func_desc_t is 8 bytes if ABIv2, else 16 bytes
449 	desc = func_desc(addr);
450 	for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) {
451 		if (patch_instruction(((u32 *)&entry->funcdata) + i,
452 				      ppc_inst(((u32 *)(&desc))[i])))
453 			return 0;
454 	}
455 
456 	if (patch_instruction(&entry->magic, ppc_inst(STUB_MAGIC)))
457 		return 0;
458 
459 	return 1;
460 }
461 
462 /* Create stub to jump to function described in this OPD/ptr: we need the
463    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)464 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
465 				   unsigned long addr,
466 				   struct module *me,
467 				   const char *name)
468 {
469 	struct ppc64_stub_entry *stubs;
470 	unsigned int i, num_stubs;
471 
472 	num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
473 
474 	/* Find this stub, or if that fails, the next avail. entry */
475 	stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
476 	for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
477 		if (WARN_ON(i >= num_stubs))
478 			return 0;
479 
480 		if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
481 			return (unsigned long)&stubs[i];
482 	}
483 
484 	if (!create_stub(sechdrs, &stubs[i], addr, me, name))
485 		return 0;
486 
487 	return (unsigned long)&stubs[i];
488 }
489 
490 /* We expect a noop next: if it is, replace it with instruction to
491    restore r2. */
restore_r2(const char * name,u32 * instruction,struct module * me)492 static int restore_r2(const char *name, u32 *instruction, struct module *me)
493 {
494 	u32 *prev_insn = instruction - 1;
495 
496 	if (is_mprofile_ftrace_call(name))
497 		return 1;
498 
499 	/*
500 	 * Make sure the branch isn't a sibling call.  Sibling calls aren't
501 	 * "link" branches and they don't return, so they don't need the r2
502 	 * restore afterwards.
503 	 */
504 	if (!instr_is_relative_link_branch(ppc_inst(*prev_insn)))
505 		return 1;
506 
507 	if (*instruction != PPC_RAW_NOP()) {
508 		pr_err("%s: Expected nop after call, got %08x at %pS\n",
509 			me->name, *instruction, instruction);
510 		return 0;
511 	}
512 
513 	/* ld r2,R2_STACK_OFFSET(r1) */
514 	if (patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC)))
515 		return 0;
516 
517 	return 1;
518 }
519 
apply_relocate_add(Elf64_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * me)520 int apply_relocate_add(Elf64_Shdr *sechdrs,
521 		       const char *strtab,
522 		       unsigned int symindex,
523 		       unsigned int relsec,
524 		       struct module *me)
525 {
526 	unsigned int i;
527 	Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
528 	Elf64_Sym *sym;
529 	unsigned long *location;
530 	unsigned long value;
531 
532 	pr_debug("Applying ADD relocate section %u to %u\n", relsec,
533 	       sechdrs[relsec].sh_info);
534 
535 	/* First time we're called, we can fix up .TOC. */
536 	if (!me->arch.toc_fixed) {
537 		sym = find_dot_toc(sechdrs, strtab, symindex);
538 		/* It's theoretically possible that a module doesn't want a
539 		 * .TOC. so don't fail it just for that. */
540 		if (sym)
541 			sym->st_value = my_r2(sechdrs, me);
542 		me->arch.toc_fixed = true;
543 	}
544 
545 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
546 		/* This is where to make the change */
547 		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
548 			+ rela[i].r_offset;
549 		/* This is the symbol it is referring to */
550 		sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
551 			+ ELF64_R_SYM(rela[i].r_info);
552 
553 		pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
554 		       location, (long)ELF64_R_TYPE(rela[i].r_info),
555 		       strtab + sym->st_name, (unsigned long)sym->st_value,
556 		       (long)rela[i].r_addend);
557 
558 		/* `Everything is relative'. */
559 		value = sym->st_value + rela[i].r_addend;
560 
561 		switch (ELF64_R_TYPE(rela[i].r_info)) {
562 		case R_PPC64_ADDR32:
563 			/* Simply set it */
564 			*(u32 *)location = value;
565 			break;
566 
567 		case R_PPC64_ADDR64:
568 			/* Simply set it */
569 			*(unsigned long *)location = value;
570 			break;
571 
572 		case R_PPC64_TOC:
573 			*(unsigned long *)location = my_r2(sechdrs, me);
574 			break;
575 
576 		case R_PPC64_TOC16:
577 			/* Subtract TOC pointer */
578 			value -= my_r2(sechdrs, me);
579 			if (value + 0x8000 > 0xffff) {
580 				pr_err("%s: bad TOC16 relocation (0x%lx)\n",
581 				       me->name, value);
582 				return -ENOEXEC;
583 			}
584 			*((uint16_t *) location)
585 				= (*((uint16_t *) location) & ~0xffff)
586 				| (value & 0xffff);
587 			break;
588 
589 		case R_PPC64_TOC16_LO:
590 			/* Subtract TOC pointer */
591 			value -= my_r2(sechdrs, me);
592 			*((uint16_t *) location)
593 				= (*((uint16_t *) location) & ~0xffff)
594 				| (value & 0xffff);
595 			break;
596 
597 		case R_PPC64_TOC16_DS:
598 			/* Subtract TOC pointer */
599 			value -= my_r2(sechdrs, me);
600 			if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
601 				pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
602 				       me->name, value);
603 				return -ENOEXEC;
604 			}
605 			*((uint16_t *) location)
606 				= (*((uint16_t *) location) & ~0xfffc)
607 				| (value & 0xfffc);
608 			break;
609 
610 		case R_PPC64_TOC16_LO_DS:
611 			/* Subtract TOC pointer */
612 			value -= my_r2(sechdrs, me);
613 			if ((value & 3) != 0) {
614 				pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
615 				       me->name, value);
616 				return -ENOEXEC;
617 			}
618 			*((uint16_t *) location)
619 				= (*((uint16_t *) location) & ~0xfffc)
620 				| (value & 0xfffc);
621 			break;
622 
623 		case R_PPC64_TOC16_HA:
624 			/* Subtract TOC pointer */
625 			value -= my_r2(sechdrs, me);
626 			value = ((value + 0x8000) >> 16);
627 			*((uint16_t *) location)
628 				= (*((uint16_t *) location) & ~0xffff)
629 				| (value & 0xffff);
630 			break;
631 
632 		case R_PPC_REL24:
633 			/* FIXME: Handle weak symbols here --RR */
634 			if (sym->st_shndx == SHN_UNDEF ||
635 			    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 			value = (*(uint32_t *)location & ~PPC_LI_MASK) | PPC_LI(value);
657 
658 			if (patch_instruction((u32 *)location, ppc_inst(value)))
659 				return -EFAULT;
660 
661 			break;
662 
663 		case R_PPC64_REL64:
664 			/* 64 bits relative (used by features fixups) */
665 			*location = value - (unsigned long)location;
666 			break;
667 
668 		case R_PPC64_REL32:
669 			/* 32 bits relative (used by relative exception tables) */
670 			/* Convert value to relative */
671 			value -= (unsigned long)location;
672 			if (value + 0x80000000 > 0xffffffff) {
673 				pr_err("%s: REL32 %li out of range!\n",
674 				       me->name, (long int)value);
675 				return -ENOEXEC;
676 			}
677 			*(u32 *)location = value;
678 			break;
679 
680 		case R_PPC64_TOCSAVE:
681 			/*
682 			 * Marker reloc indicates we don't have to save r2.
683 			 * That would only save us one instruction, so ignore
684 			 * it.
685 			 */
686 			break;
687 
688 		case R_PPC64_ENTRY:
689 			/*
690 			 * Optimize ELFv2 large code model entry point if
691 			 * the TOC is within 2GB range of current location.
692 			 */
693 			value = my_r2(sechdrs, me) - (unsigned long)location;
694 			if (value + 0x80008000 > 0xffffffff)
695 				break;
696 			/*
697 			 * Check for the large code model prolog sequence:
698 		         *	ld r2, ...(r12)
699 			 *	add r2, r2, r12
700 			 */
701 			if ((((uint32_t *)location)[0] & ~0xfffc) != PPC_RAW_LD(_R2, _R12, 0))
702 				break;
703 			if (((uint32_t *)location)[1] != PPC_RAW_ADD(_R2, _R2, _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_RAW_ADDIS(_R2, _R12, PPC_HA(value));
711 			((uint32_t *)location)[1] = PPC_RAW_ADDI(_R2, _R2, PPC_LO(value));
712 			break;
713 
714 		case R_PPC64_REL16_HA:
715 			/* Subtract location pointer */
716 			value -= (unsigned long)location;
717 			value = ((value + 0x8000) >> 16);
718 			*((uint16_t *) location)
719 				= (*((uint16_t *) location) & ~0xffff)
720 				| (value & 0xffff);
721 			break;
722 
723 		case R_PPC64_REL16_LO:
724 			/* Subtract location pointer */
725 			value -= (unsigned long)location;
726 			*((uint16_t *) location)
727 				= (*((uint16_t *) location) & ~0xffff)
728 				| (value & 0xffff);
729 			break;
730 
731 		default:
732 			pr_err("%s: Unknown ADD relocation: %lu\n",
733 			       me->name,
734 			       (unsigned long)ELF64_R_TYPE(rela[i].r_info));
735 			return -ENOEXEC;
736 		}
737 	}
738 
739 	return 0;
740 }
741 
742 #ifdef CONFIG_DYNAMIC_FTRACE
module_trampoline_target(struct module * mod,unsigned long addr,unsigned long * target)743 int module_trampoline_target(struct module *mod, unsigned long addr,
744 			     unsigned long *target)
745 {
746 	struct ppc64_stub_entry *stub;
747 	func_desc_t funcdata;
748 	u32 magic;
749 
750 	if (!within_module_core(addr, mod)) {
751 		pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name);
752 		return -EFAULT;
753 	}
754 
755 	stub = (struct ppc64_stub_entry *)addr;
756 
757 	if (copy_from_kernel_nofault(&magic, &stub->magic,
758 			sizeof(magic))) {
759 		pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
760 		return -EFAULT;
761 	}
762 
763 	if (magic != STUB_MAGIC) {
764 		pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name);
765 		return -EFAULT;
766 	}
767 
768 	if (copy_from_kernel_nofault(&funcdata, &stub->funcdata,
769 			sizeof(funcdata))) {
770 		pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
771                 return -EFAULT;
772 	}
773 
774 	*target = stub_func_addr(funcdata);
775 
776 	return 0;
777 }
778 
module_finalize_ftrace(struct module * mod,const Elf_Shdr * sechdrs)779 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
780 {
781 	mod->arch.tramp = stub_for_addr(sechdrs,
782 					(unsigned long)ftrace_caller,
783 					mod,
784 					"ftrace_caller");
785 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
786 	mod->arch.tramp_regs = stub_for_addr(sechdrs,
787 					(unsigned long)ftrace_regs_caller,
788 					mod,
789 					"ftrace_regs_caller");
790 	if (!mod->arch.tramp_regs)
791 		return -ENOENT;
792 #endif
793 
794 	if (!mod->arch.tramp)
795 		return -ENOENT;
796 
797 	return 0;
798 }
799 #endif
800